Version bump to 1.2

* move ETag requirement from vcard4android to davdroid
* more debug info
* vcard4android: support for custom labels (X-ABLabel)

.gitignore

@@ -1,61 +1,92 @@
-### ANDROID
+# Created by https://www.gitignore.io
 
-# built application files
+### Android ###
+# Built application files
 *.apk
 *.ap_
 
-# files for the dex VM
+# Files for the Dalvik VM
 *.dex
 
 # Java class files
 *.class
 
-# generated files
+# Generated files
 bin/
-doc/javadoc/
 gen/
 
+# Gradle files
+.gradle/
+build/
+
 # Local configuration file (sdk path, etc)
 local.properties
 
-# Eclipse project files
-.classpath
-.project
-
 # Proguard folder generated by Eclipse
 proguard/
 
-# Intellij project files
+# Log Files
+*.log
+
+
+### Intellij ###
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm
+
 *.iml
+
+## Directory-based project format:
+.idea/
+# if you remove the above rule, at least ignore the following:
+
+# User-specific stuff:
+# .idea/workspace.xml
+# .idea/tasks.xml
+# .idea/dictionaries
+
+# Sensitive or high-churn files:
+# .idea/dataSources.ids
+# .idea/dataSources.xml
+# .idea/sqlDataSources.xml
+# .idea/dynamic.xml
+# .idea/uiDesigner.xml
+
+# Gradle:
+# .idea/gradle.xml
+# .idea/libraries
+
+# Mongo Explorer plugin:
+# .idea/mongoSettings.xml
+
+## File-based project format:
 *.ipr
 *.iws
-.idea/
+
+## Plugin-specific files:
+
+# IntelliJ
+out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
 
 
-### ECLIPSE
+### Gradle ###
+.gradle
+build/
 
-*.pydevproject
-.metadata
-bin/**
-tmp/**
-tmp/**/*
-*.tmp
-*.bak
-*.swp
-*~.nib
-local.properties
-.classpath
-.settings/
-.loadpath
+# Ignore Gradle GUI config
+gradle-app.setting
 
-# External tool builders
-.externalToolBuilders/
+### external libs ###
+.svn
 
-# Locally stored "Eclipse launch configurations"
-*.launch
-
-# CDT-specific
-.cproject
-
-# PDT-specific
-.buildpath
+# Javadoc
+javadoc/

.gitmodules

@@ -0,0 +1,13 @@
+[submodule "dav4android"]
+	path = dav4android
+	url = https://gitlab.com/bitfireAT/dav4android.git
+[submodule "ical4android"]
+	path = ical4android
+	url = https://gitlab.com/bitfireAT/ical4android.git
+[submodule "vcard4android"]
+	path = vcard4android
+	url = https://gitlab.com/bitfireAT/vcard4android.git
+[submodule "MemorizingTrustManager"]
+	path = MemorizingTrustManager
+	url = https://github.com/ge0rg/MemorizingTrustManager
+	ignore = dirty

AndroidManifest.xml

@@ -1,79 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    package="at.bitfire.davdroid"
-    android:versionCode="38"
-    android:versionName="0.6" android:installLocation="internalOnly">
-
-    <uses-sdk
-        android:minSdkVersion="14"
-        android:targetSdkVersion="19" />
-
-    <uses-permission android:name="android.permission.INTERNET" />
-    <uses-permission android:name="android.permission.AUTHENTICATE_ACCOUNTS" />
-    <uses-permission android:name="android.permission.READ_CONTACTS" />
-    <uses-permission android:name="android.permission.WRITE_CONTACTS" />
-    <uses-permission android:name="android.permission.READ_CALENDAR" />
-    <uses-permission android:name="android.permission.WRITE_CALENDAR" />
-    <uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS" />
-
-    <application
-        android:allowBackup="false"
-        android:icon="@drawable/ic_launcher"
-        android:label="@string/app_name"
-        android:theme="@style/AppTheme"
-        android:process=":sync" >
-        <service
-            android:name=".syncadapter.AccountAuthenticatorService"
-            android:exported="false" >
-            <intent-filter>
-                <action android:name="android.accounts.AccountAuthenticator" />
-            </intent-filter>
-
-            <meta-data
-                android:name="android.accounts.AccountAuthenticator"
-                android:resource="@xml/account_authenticator" />
-        </service>
-        <service
-            android:name=".syncadapter.ContactsSyncAdapterService"
-            android:exported="true" >
-            <intent-filter>
-                <action android:name="android.content.SyncAdapter" />
-            </intent-filter>
-
-            <meta-data
-                android:name="android.content.SyncAdapter"
-                android:resource="@xml/sync_contacts" />
-            <meta-data
-                android:name="android.provider.CONTACTS_STRUCTURE"
-                android:resource="@xml/contacts" />
-        </service>
-        <service
-            android:name=".syncadapter.CalendarsSyncAdapterService"
-            android:exported="true" >
-            <intent-filter>
-                <action android:name="android.content.SyncAdapter" />
-            </intent-filter>
-
-            <meta-data
-                android:name="android.content.SyncAdapter"
-                android:resource="@xml/sync_calendars" />
-        </service>
-
-        <activity
-            android:name=".MainActivity"
-            android:label="@string/app_name" >
-            <intent-filter>
-                <action android:name="android.intent.action.MAIN" />
-                <category android:name="android.intent.category.LAUNCHER" />
-            </intent-filter>
-        </activity>
-        <activity
-            android:name=".syncadapter.AddAccountActivity"
-            android:excludeFromRecents="true" >
-        </activity>
-        <activity
-            android:name=".syncadapter.GeneralSettingsActivity" >
-        </activity>
-        </application>
-
-</manifest>

CONTRIBUTING.md

@@ -1,58 +0,0 @@
-
-DAVdroid is free and open-source software, licensed under the [GPLv3 License](COPYING).
-If you like our project, please contribute to it.
-
-# How to contribute
-
-## Reporting issues
-
-An issue might be a bug, an enhancement request or something in between. If you think you
-have found a bug or if you want to request some enhancement, please:
-
-1. Read the [Configuration](http://davdroid.bitfire.at/configuration) and [FAQ](http://davdroid.bitfire.at/faq/)
-   pages carefully. The most common issues/usage challenges are explained there.
-2. Search the Web for the problem, maybe ask competent friends or in forums.
-3. Browse through the [open issues](https://github.com/rfc2822/davdroid/issues). You can
-   also search the issues in the search field on top of the page. Please have a look
-   into the closed issues, too, because many requests have already been handled (and can't/won't
-   be fixed, for instance).
-4. **[Fetch verbose logs](https://github.com/rfc2822/davdroid/wiki/How-to-view-the-logs) and prepare
-   them. Remove `Authorization: Basic xxxxxx` headers and other private data.** Extracting the
-   logs may be cumbersome work in the first time, but it's absolutely necessary in order to
-   handle your issue.
-5. [Create a new issue](https://github.com/rfc2822/davdroid/issues/new), containing
-   * a useful summary of the problem ("Crash when syncing contacts with large photos" instead of "CRASH PLEASE HELP"),
-   * your DAVdroid version and source ("DAVdroid 0.5.10 from F-Droid"),
-   * your Android version and device model ("Samsung Galaxy S2 running Android 4.4.2 (CyanogenMod 11-20140504-SNAPSHOT-M6-i9100)"),
-   * your CalDAV/CardDAV server software, version and hosting information ("OwnCloud 6, hosted on virtual server"),
-   * a problem description, including **instructions on how to reproduce the problem** (we need to
-     reproduce the problem before we can fix it!),
-   * **verbose logs including the network traffic** (see step before). Enquote the logs with three backticks ```
-     before and after, or post them onto http://gist.github.com and provide a link.
-
-
-## Pull requests
-
-We're very happy about pull requests for
-
-* source code,
-* documentation,
-* translation (strings).
-
-However, if you want to contribute source code, please talk with us in the
-corresponding issue before because will only merge pull requests that
-
-* match our product goals,
-* have the necessary code quality,
-* don't interfere with other near-term future development.
-
-However, feel free to fork the repository and do your changes anyway
-(that's why it's open-source). Just don't expect your strategic changes to be
-merged if there's no consensus in the issue before.
-
-
-## Donations
-
-If you want to support this project, please also consider [donating to DAVdroid](http://davdroid.bitfire.at/donate)
-or [purchasing it in one of the commercial stores](http://davdroid.bitfire.at/download).
-

README.md

@@ -1,21 +1,34 @@
 
-DAVDROID
+DAVdroid
 ========
 
-Please see the [DAVdroid Web site](http://davdroid.bitfire.at) for
-detailled information about DAVdroid.
+Please see the [DAVdroid Web site](https://davdroid.bitfire.at) for
+comprehensive information about DAVdroid.
 
-DAVdroid is licensed under the [GPLv3 License](COPYING).
+DAVdroid is licensed under the [GPLv3 License](LICENSE).
 
-Twitter: [@davdroidapp](https://twitter.com/davdroidapp)
+News and updates: [@davdroidapp](https://twitter.com/davdroidapp)
+
+Help and discussion: [DAVdroid forums](https://davdroid.bitfire.at/forums)
+
+Parts of DAVdroid have been outsourced into these libraries:
+
+* [dav4android](https://gitlab.com/bitfireAT/dav4android) – WebDAV/CalDav/CardDAV framework
+* [ical4android](https://gitlab.com/bitfireAT/ical4android) – iCalendar processing and Calendar Provider access
+* [vcard4android](https://gitlab.com/bitfireAT/vcard4android) – VCard processing and Contacts Provider access
+
+[![Flattr this!](https://api.flattr.com/button/flattr-badge-large.png)](https://flattr.com/submit/auto?user_id=bitfire&url=https://davdroid.bitfire.at&title=DAVdroid&category=software)
 
 
 USED THIRD-PARTY LIBRARIES
 ==========================
 
-* [Apache HttpClient](http://hc.apache.org) ([httpclientandroidlib](https://code.google.com/p/httpclientandroidlib/) flavour) – [Apache License](http://www.apache.org/licenses/)
-* [iCal4j](http://ical4j.sourceforge.net/) – [New BSD License](http://sourceforge.net/p/ical4j/ical4j/ci/default/tree/LICENSE)
-* [ez-vcard](https://code.google.com/p/ez-vcard/) – [New BSD License](http://opensource.org/licenses/BSD-3-Clause)
-* [Simple XML Serialization](http://simple.sourceforge.net/) – [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
-* [Project Lombok](http://projectlombok.org/) – [MIT License](http://opensource.org/licenses/mit-license.php)
+Those libraries are used by DAVdroid (alphabetically):
 
+* [dnsjava](http://www.xbill.org/dnsjava/) – [BSD License](http://www.xbill.org/dnsjava/dnsjava-current/LICENSE)
+* [ez-vcard](https://code.google.com/p/ez-vcard/) – [New BSD License](http://opensource.org/licenses/BSD-3-Clause)
+* [iCal4j](http://ical4j.sourceforge.net/) – [New BSD License](http://sourceforge.net/p/ical4j/ical4j/ci/default/tree/LICENSE)
+* [MemorizingTrustManager](https://github.com/ge0rg/MemorizingTrustManager) – [MIT License](https://raw.githubusercontent.com/ge0rg/MemorizingTrustManager/master/LICENSE.txt)
+* [okhttp](https://square.github.io/okhttp/) – [Apache License, Version 2.0](https://square.github.io/okhttp/#license)
+* [Project Lombok](http://projectlombok.org/) – [MIT License](http://opensource.org/licenses/mit-license.php)
+* [SLF4J](http://www.slf4j.org/) – [MIT License](http://www.slf4j.org/license.html)

app/.gitignore

@@ -0,0 +1,2 @@
+build
+target

app/build.gradle

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+apply plugin: 'com.android.application'
+
+android {
+    compileSdkVersion 23
+    buildToolsVersion "23.0.3"
+
+    defaultConfig {
+        applicationId "at.bitfire.davdroid"
+        minSdkVersion 14
+        targetSdkVersion 23
+
+        versionCode 109
+
+        buildConfigField "long", "buildTime", System.currentTimeMillis() + "L"
+    }
+
+    productFlavors {
+        standard {
+            versionName "1.2"
+        }
+        gplay {
+            versionName "1.2-gplay"
+        }
+    }
+
+    buildTypes {
+        debug {
+            minifyEnabled false
+        }
+        release {
+            minifyEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
+        }
+    }
+
+    lintOptions {
+        disable 'GoogleAppIndexingWarning'      // we don't need Google indexing, thanks
+        disable 'GradleDependency'
+        disable 'GradleDynamicVersion'
+        disable 'IconColors'
+        disable 'IconLauncherShape'
+        disable 'IconMissingDensityFolder'
+        disable 'ImpliedQuantity'
+        disable 'MissingTranslation'
+        disable 'MissingQuantity'
+        disable 'Recycle'           // doesn't understand Lombok's @Cleanup
+        disable 'RtlEnabled'
+        disable 'RtlHardcoded'
+        disable 'Typos'
+    }
+    packagingOptions {
+        exclude 'LICENSE'
+        exclude 'META-INF/LICENSE.txt'
+        exclude 'META-INF/NOTICE.txt'
+    }
+}
+
+dependencies {
+    compile project(':dav4android')
+    compile project(':ical4android')
+    compile project(':vcard4android')
+
+    compile 'com.android.support:appcompat-v7:23.+'
+    compile 'com.android.support:cardview-v7:23.+'
+    compile 'com.android.support:design:23.+'
+    compile 'com.android.support:preference-v14:23.+'
+
+    compile 'com.github.yukuku:ambilwarna:2.0.1'
+    compile project(':MemorizingTrustManager')
+
+    compile 'dnsjava:dnsjava:2.1.7'
+    compile 'org.apache.commons:commons-lang3:3.4'
+    compile 'org.apache.commons:commons-collections4:4.1'
+    provided 'org.projectlombok:lombok:1.16.8'
+
+    // for tests
+    testCompile 'junit:junit:4.12'
+    testCompile 'com.squareup.okhttp3:mockwebserver:3.3.1'
+    androidTestCompile 'com.squareup.okhttp3:mockwebserver:3.3.1'
+}

app/lint.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright (c) 2013 – 2015 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<lint>
+    <issue id="InvalidPackage" severity="ignore" />
+    <issue id="MissingTranslation" severity="warning" />
+</lint>

app/proguard-rules.txt

@@ -0,0 +1,41 @@
+
+# ProGuard usage for DAVdroid:
+# 	shrinking		yes (main reason for using ProGuard)
+# 	optimization		yes
+# 	obfuscation		no (DAVdroid is open-source)
+# 	preverification		no
+
+-dontobfuscate
+
+-optimizations !code/simplification/arithmetic,!code/simplification/cast,!field/*,!class/merging/*
+-optimizationpasses 5
+-allowaccessmodification
+-dontpreverify
+
+# ez-vcard
+-dontwarn ezvcard.io.json.**			# JSON serializer (for jCards) not used
+-dontwarn freemarker.**				# freemarker templating library (for creating hCards) not used
+-dontwarn org.jsoup.**				# jsoup library (for hCard parsing) not used
+-dontwarn sun.misc.Perf
+-keep class ezvcard.property.** { *; }		# keep all VCard properties (created at runtime)
+
+# ical4j: ignore unused dynamic libraries
+-dontwarn aQute.**
+-dontwarn groovy.**				# Groovy-based ContentBuilder not used
+-dontwarn org.codehaus.groovy.**
+-dontwarn org.apache.commons.logging.**		# Commons logging is not available
+-dontwarn net.fortuna.ical4j.model.**		# ignore warnings from Groovy dependency
+-keep class net.fortuna.ical4j.model.** { *; }	# keep all model classes (properties/factories, created at runtime)
+
+# okhttp
+-dontwarn java.nio.file.**		# not available on Android
+-dontwarn org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement
+
+# MemorizingTrustManager
+-dontwarn de.duenndns.ssl.MemorizingTrustManager
+
+# dnsjava
+-dontwarn sun.net.spi.nameservice.**		# not available on Android
+
+# DAVdroid + libs
+-keep class at.bitfire.** { *; }	# all DAVdroid code is required

app/src/androidTest/java/at/bitfire/davdroid/SSLSocketFactoryCompatTest.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid;
+
+import android.os.Build;
+import android.test.InstrumentationTestCase;
+
+import java.io.IOException;
+import java.net.Socket;
+
+import javax.net.ssl.SSLSocket;
+
+import de.duenndns.ssl.MemorizingTrustManager;
+import okhttp3.mockwebserver.MockWebServer;
+
+public class SSLSocketFactoryCompatTest extends InstrumentationTestCase {
+
+    SSLSocketFactoryCompat factory;
+    MockWebServer server = new MockWebServer();
+
+    @Override
+    protected void setUp() throws Exception {
+        factory = new SSLSocketFactoryCompat(new MemorizingTrustManager(getInstrumentation().getTargetContext().getApplicationContext()));
+        server.start();
+    }
+
+    @Override
+    protected void tearDown() throws Exception {
+        server.shutdown();
+    }
+
+
+    public void testUpgradeTLS() throws IOException {
+        Socket s = factory.createSocket(server.getHostName(), server.getPort());
+        assertTrue(s instanceof SSLSocket);
+
+        SSLSocket ssl = (SSLSocket)s;
+        assertFalse(org.apache.commons.lang3.ArrayUtils.contains(ssl.getEnabledProtocols(), "SSLv3"));
+        assertTrue(org.apache.commons.lang3.ArrayUtils.contains(ssl.getEnabledProtocols(), "TLSv1"));
+
+        if (Build.VERSION.SDK_INT >= 16) {
+            assertTrue(org.apache.commons.lang3.ArrayUtils.contains(ssl.getEnabledProtocols(), "TLSv1.1"));
+            assertTrue(org.apache.commons.lang3.ArrayUtils.contains(ssl.getEnabledProtocols(), "TLSv1.2"));
+        }
+    }
+
+}

app/src/androidTest/java/at/bitfire/davdroid/model/CollectionInfoTest.java

@@ -0,0 +1,110 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.model;
+
+import android.content.ContentValues;
+
+import junit.framework.TestCase;
+
+import java.io.IOException;
+
+import at.bitfire.dav4android.DavResource;
+import at.bitfire.dav4android.exception.DavException;
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.dav4android.property.ResourceType;
+import at.bitfire.davdroid.HttpClient;
+import at.bitfire.davdroid.model.ServiceDB.Collections;
+import okhttp3.mockwebserver.MockResponse;
+import okhttp3.mockwebserver.MockWebServer;
+
+public class CollectionInfoTest extends TestCase {
+
+    MockWebServer server = new MockWebServer();
+
+    public void testFromDavResource() throws IOException, HttpException, DavException {
+        // r/w address book
+        server.enqueue(new MockResponse()
+                .setResponseCode(207)
+                .setBody("<multistatus xmlns='DAV:' xmlns:CARD='urn:ietf:params:xml:ns:carddav'>" +
+                        "<response>" +
+                        "   <href>/</href>" +
+                        "   <propstat><prop>" +
+                        "       <resourcetype><collection/><CARD:addressbook/></resourcetype>" +
+                        "       <displayname>My Contacts</displayname>" +
+                        "       <CARD:addressbook-description>My Contacts Description</CARD:addressbook-description>" +
+                        "   </prop></propstat>" +
+                        "</response>" +
+                        "</multistatus>"));
+
+        DavResource dav = new DavResource(HttpClient.create(), server.url("/"));
+        dav.propfind(0, ResourceType.NAME);
+        CollectionInfo info = CollectionInfo.fromDavResource(dav);
+        assertEquals(CollectionInfo.Type.ADDRESS_BOOK, info.type);
+        assertFalse(info.readOnly);
+        assertEquals("My Contacts", info.displayName);
+        assertEquals("My Contacts Description", info.description);
+
+        // read-only calendar, no display name
+        server.enqueue(new MockResponse()
+                .setResponseCode(207)
+                .setBody("<multistatus xmlns='DAV:' xmlns:CAL='urn:ietf:params:xml:ns:caldav' xmlns:ICAL='http://apple.com/ns/ical/'>" +
+                        "<response>" +
+                        "   <href>/</href>" +
+                        "   <propstat><prop>" +
+                        "       <resourcetype><collection/><CAL:calendar/></resourcetype>" +
+                        "       <current-user-privilege-set><privilege><read/></privilege></current-user-privilege-set>" +
+                        "       <CAL:calendar-description>My Calendar</CAL:calendar-description>" +
+                        "       <CAL:calendar-timezone>tzdata</CAL:calendar-timezone>" +
+                        "       <ICAL:calendar-color>#ff0000</ICAL:calendar-color>" +
+                        "   </prop></propstat>" +
+                        "</response>" +
+                        "</multistatus>"));
+
+        dav = new DavResource(HttpClient.create(), server.url("/"));
+        dav.propfind(0, ResourceType.NAME);
+        info = CollectionInfo.fromDavResource(dav);
+        assertEquals(CollectionInfo.Type.CALENDAR, info.type);
+        assertTrue(info.readOnly);
+        assertNull(info.displayName);
+        assertEquals("My Calendar", info.description);
+        assertEquals(0xFFFF0000, (int)info.color);
+        assertEquals("tzdata", info.timeZone);
+        assertTrue(info.supportsVEVENT);
+        assertTrue(info.supportsVTODO);
+    }
+
+    public void testFromDB() {
+        ContentValues values = new ContentValues();
+        values.put(Collections.ID, 1);
+        values.put(Collections.SERVICE_ID, 1);
+        values.put(Collections.URL, "http://example.com");
+        values.put(Collections.READ_ONLY, 1);
+        values.put(Collections.DISPLAY_NAME, "display name");
+        values.put(Collections.DESCRIPTION, "description");
+        values.put(Collections.COLOR, 0xFFFF0000);
+        values.put(Collections.TIME_ZONE, "tzdata");
+        values.put(Collections.SUPPORTS_VEVENT, 1);
+        values.put(Collections.SUPPORTS_VTODO, 1);
+        values.put(Collections.SYNC, 1);
+
+        CollectionInfo info = CollectionInfo.fromDB(values);
+        assertEquals(1, info.id);
+        assertEquals(1, (long)info.serviceID);
+        assertEquals("http://example.com", info.url);
+        assertTrue(info.readOnly);
+        assertEquals("display name", info.displayName);
+        assertEquals("description", info.description);
+        assertEquals(0xFFFF0000, (int)info.color);
+        assertEquals("tzdata", info.timeZone);
+        assertTrue(info.supportsVEVENT);
+        assertTrue(info.supportsVTODO);
+        assertTrue(info.selected);
+    }
+
+}

app/src/androidTest/java/at/bitfire/davdroid/ui/setup/DavResourceFinderTest.java

@@ -0,0 +1,189 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui.setup;
+
+import android.test.InstrumentationTestCase;
+
+import java.io.IOException;
+import java.net.URI;
+
+import at.bitfire.dav4android.DavResource;
+import at.bitfire.dav4android.exception.DavException;
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.dav4android.property.AddressbookHomeSet;
+import at.bitfire.dav4android.property.ResourceType;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.HttpClient;
+import at.bitfire.davdroid.ui.setup.DavResourceFinder;
+import at.bitfire.davdroid.ui.setup.DavResourceFinder.Configuration.ServiceInfo;
+import at.bitfire.davdroid.ui.setup.LoginCredentials;
+import okhttp3.OkHttpClient;
+import okhttp3.mockwebserver.Dispatcher;
+import okhttp3.mockwebserver.MockResponse;
+import okhttp3.mockwebserver.MockWebServer;
+import okhttp3.mockwebserver.RecordedRequest;
+
+public class DavResourceFinderTest extends InstrumentationTestCase {
+
+    MockWebServer server = new MockWebServer();
+
+    DavResourceFinder finder;
+    OkHttpClient client;
+    LoginCredentials credentials;
+
+    private static final String
+            PATH_NO_DAV = "/nodav",
+
+            PATH_CALDAV = "/caldav",
+            PATH_CARDDAV = "/carddav",
+            PATH_CALDAV_AND_CARDDAV = "/both-caldav-carddav",
+
+            SUBPATH_PRINCIPAL = "/principal",
+            SUBPATH_ADDRESSBOOK_HOMESET = "/addressbooks",
+            SUBPATH_ADDRESSBOOK = "/addressbooks/private-contacts";
+
+    @Override
+    protected void setUp() throws Exception {
+        server.setDispatcher(new TestDispatcher());
+        server.start();
+
+        credentials = new LoginCredentials(URI.create("/"), "mock", "12345", true);
+        finder = new DavResourceFinder(getInstrumentation().getContext(), credentials);
+
+        client = HttpClient.create();
+        client = HttpClient.addAuthentication(client, credentials.userName, credentials.password, credentials.authPreemptive);
+    }
+
+    @Override
+    protected void tearDown() throws Exception {
+        server.shutdown();
+    }
+
+
+    public void testRememberIfAddressBookOrHomeset() throws IOException, HttpException, DavException {
+        ServiceInfo info;
+
+        // before dav.propfind(), no info is available
+        DavResource dav = new DavResource(client, server.url(PATH_CARDDAV + SUBPATH_PRINCIPAL));
+        finder.rememberIfAddressBookOrHomeset(dav, info = new ServiceInfo());
+        assertEquals(0, info.collections.size());
+        assertEquals(0, info.homeSets.size());
+
+        // recognize home set
+        dav.propfind(0, AddressbookHomeSet.NAME);
+        finder.rememberIfAddressBookOrHomeset(dav, info = new ServiceInfo());
+        assertEquals(0, info.collections.size());
+        assertEquals(1, info.homeSets.size());
+        assertEquals(server.url(PATH_CARDDAV + SUBPATH_ADDRESSBOOK_HOMESET + "/").uri(), info.homeSets.iterator().next());
+
+        // recognize address book
+        dav = new DavResource(client, server.url(PATH_CARDDAV + SUBPATH_ADDRESSBOOK));
+        dav.propfind(0, ResourceType.NAME);
+        finder.rememberIfAddressBookOrHomeset(dav, info = new ServiceInfo());
+        assertEquals(1, info.collections.size());
+        assertEquals(server.url(PATH_CARDDAV + SUBPATH_ADDRESSBOOK + "/").uri(), info.collections.keySet().iterator().next());
+        assertEquals(0, info.homeSets.size());
+    }
+
+    public void testProvidesService() throws IOException {
+        assertFalse(finder.providesService(server.url(PATH_NO_DAV), DavResourceFinder.Service.CALDAV));
+        assertFalse(finder.providesService(server.url(PATH_NO_DAV), DavResourceFinder.Service.CARDDAV));
+
+        assertTrue(finder.providesService(server.url(PATH_CALDAV), DavResourceFinder.Service.CALDAV));
+        assertFalse(finder.providesService(server.url(PATH_CALDAV), DavResourceFinder.Service.CARDDAV));
+
+        assertTrue(finder.providesService(server.url(PATH_CARDDAV), DavResourceFinder.Service.CARDDAV));
+        assertFalse(finder.providesService(server.url(PATH_CARDDAV), DavResourceFinder.Service.CALDAV));
+
+        assertTrue(finder.providesService(server.url(PATH_CALDAV_AND_CARDDAV), DavResourceFinder.Service.CALDAV));
+        assertTrue(finder.providesService(server.url(PATH_CALDAV_AND_CARDDAV), DavResourceFinder.Service.CARDDAV));
+    }
+
+    public void testGetCurrentUserPrincipal() throws IOException, HttpException, DavException {
+        assertNull(finder.getCurrentUserPrincipal(server.url(PATH_NO_DAV), DavResourceFinder.Service.CALDAV));
+        assertNull(finder.getCurrentUserPrincipal(server.url(PATH_NO_DAV), DavResourceFinder.Service.CARDDAV));
+
+        assertEquals(
+                server.url(PATH_CALDAV + SUBPATH_PRINCIPAL).uri(),
+                finder.getCurrentUserPrincipal(server.url(PATH_CALDAV), DavResourceFinder.Service.CALDAV)
+        );
+        assertNull(finder.getCurrentUserPrincipal(server.url(PATH_CALDAV), DavResourceFinder.Service.CARDDAV));
+
+        assertEquals(
+                server.url(PATH_CARDDAV + SUBPATH_PRINCIPAL).uri(),
+                finder.getCurrentUserPrincipal(server.url(PATH_CARDDAV), DavResourceFinder.Service.CARDDAV)
+        );
+        assertNull(finder.getCurrentUserPrincipal(server.url(PATH_CARDDAV), DavResourceFinder.Service.CALDAV));
+    }
+
+
+    // mock server
+
+    public class TestDispatcher extends Dispatcher {
+
+        @Override
+        public MockResponse dispatch(RecordedRequest rq) throws InterruptedException {
+            if (!checkAuth(rq))
+                return new MockResponse().setResponseCode(401);
+
+            String path = rq.getPath();
+
+            if ("OPTIONS".equalsIgnoreCase(rq.getMethod())) {
+                String dav = null;
+                if (path.startsWith(PATH_CALDAV))
+                    dav = "calendar-access";
+                else if (path.startsWith(PATH_CARDDAV))
+                    dav = "addressbook";
+                else if (path.startsWith(PATH_CALDAV_AND_CARDDAV))
+                    dav = "calendar-access, addressbook";
+                MockResponse response = new MockResponse().setResponseCode(200);
+                if (dav != null)
+                       response.addHeader("DAV", dav);
+                return response;
+
+            } else if ("PROPFIND".equalsIgnoreCase(rq.getMethod())) {
+                String props = null;
+                switch (path) {
+                    case PATH_CALDAV:
+                    case PATH_CARDDAV:
+                        props = "<current-user-principal><href>" + path + SUBPATH_PRINCIPAL + "</href></current-user-principal>";
+                        break;
+
+                    case PATH_CARDDAV + SUBPATH_PRINCIPAL:
+                        props = "<CARD:addressbook-home-set>" +
+                                "   <href>" + PATH_CARDDAV + SUBPATH_ADDRESSBOOK_HOMESET + "</href>" +
+                                "</CARD:addressbook-home-set>";
+                        break;
+                    case PATH_CARDDAV + SUBPATH_ADDRESSBOOK:
+                        props = "<resourcetype>" +
+                                "   <collection/>" +
+                                "   <CARD:addressbook/>" +
+                                "</resourcetype>";
+                        break;
+                }
+                App.log.info("Sending props: " + props);
+                return new MockResponse()
+                        .setResponseCode(207)
+                        .setBody("<multistatus xmlns='DAV:' xmlns:CARD='urn:ietf:params:xml:ns:carddav'>" +
+                                "<response>" +
+                                "   <href>" + rq.getPath() + "</href>" +
+                                "   <propstat><prop>" + props + "</prop></propstat>" +
+                                "</response>" +
+                                "</multistatus>");
+            }
+
+            return new MockResponse().setResponseCode(404);
+        }
+
+        private boolean checkAuth(RecordedRequest rq) {
+            return "Basic bW9jazoxMjM0NQ==".equals(rq.getHeader("Authorization"));
+        }
+    }
+
+}

app/src/androidTest/res/values/strings.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (c) 2013 – 2015 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<resources>
+
+    <string name="app_name">DavdroidTest</string>
+
+</resources>

app/src/gplay/res/menu/activity_accounts_drawer.xml

@@ -0,0 +1,55 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<menu xmlns:tools="http://schemas.android.com/tools"
+      xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <item
+        android:id="@+id/nav_about"
+        android:icon="@drawable/ic_info_dark"
+        android:title="@string/navigation_drawer_about"/>
+    <item
+        android:id="@+id/nav_app_settings"
+        android:icon="@drawable/ic_settings_dark"
+        android:title="@string/navigation_drawer_settings"/>
+
+    <item android:title="@string/navigation_drawer_news_updates">
+        <menu>
+            <item
+                android:id="@+id/nav_twitter"
+                android:icon="@drawable/twitter"
+                android:title="\@davdroidapp"
+                tools:ignore="HardcodedText"/>
+        </menu>
+    </item>
+
+    <item android:title="@string/navigation_drawer_external_links">
+        <menu>
+            <item
+                android:id="@+id/nav_website"
+                android:icon="@drawable/ic_home_dark"
+                android:title="@string/navigation_drawer_website"/>
+            <item
+                android:id="@+id/nav_faq"
+                android:icon="@drawable/ic_help_dark"
+                android:title="@string/navigation_drawer_faq"/>
+            <item
+                android:id="@+id/nav_forums"
+                android:icon="@drawable/ic_forum_dark"
+                android:title="@string/navigation_drawer_forums"/>
+            <item
+                android:id="@+id/nav_donate"
+                android:icon="@drawable/ic_attach_money_dark"
+                android:title="(entry disabled)"
+                android:visible="false"
+                tools:ignore="HardcodedText"/>
+        </menu>
+    </item>
+
+</menu>

app/src/main/AndroidManifest.xml

@@ -0,0 +1,201 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (c) 2013 – 2015 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+-->
+<manifest package="at.bitfire.davdroid"
+          xmlns:android="http://schemas.android.com/apk/res/android"
+          xmlns:tools="http://schemas.android.com/tools"
+          android:installLocation="internalOnly">
+
+    <!-- normal permissions -->
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
+    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
+    <uses-permission android:name="android.permission.INTERNET"/>
+    <uses-permission android:name="android.permission.GET_ACCOUNTS"/>
+    <uses-permission android:name="android.permission.MANAGE_ACCOUNTS"/>
+    <uses-permission android:name="android.permission.READ_SYNC_SETTINGS"/>
+    <uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS"/>
+
+    <!-- legacy permissions -->
+    <uses-permission
+        android:name="android.permission.AUTHENTICATE_ACCOUNTS"
+        android:maxSdkVersion="22"
+        tools:ignore="UnusedAttribute"/>
+    <!--
+         for writing external log files; permission only required for SDK <= 18 because since then,
+         writing to app-private directory doesn't require extra permissions
+    -->
+    <uses-permission
+        android:name="android.permission.READ_EXTERNAL_STORAGE"
+        android:maxSdkVersion="18"
+        tools:ignore="UnusedAttribute"/>
+    <uses-permission
+        android:name="android.permission.WRITE_EXTERNAL_STORAGE"
+        android:maxSdkVersion="18"
+        tools:ignore="UnusedAttribute"/>
+
+    <!-- other permissions -->
+    <!-- android.permission-group.CONTACTS -->
+    <uses-permission android:name="android.permission.READ_CONTACTS"/>
+    <uses-permission android:name="android.permission.WRITE_CONTACTS"/>
+    <!-- android.permission-group.CALENDAR -->
+    <uses-permission android:name="android.permission.READ_CALENDAR"/>
+    <uses-permission android:name="android.permission.WRITE_CALENDAR"/>
+
+    <!-- ical4android declares task access permissions -->
+
+    <application
+        android:name=".App"
+        android:allowBackup="true"
+        android:fullBackupContent="false"
+        android:icon="@drawable/ic_launcher"
+        android:label="@string/app_name"
+        android:theme="@style/AppTheme"
+        tools:ignore="UnusedAttribute">
+
+        <receiver
+            android:name=".App$ReinitLoggingReceiver"
+            android:exported="false"
+            android:process=":sync">
+            <intent-filter>
+                <action android:name="at.bitfire.davdroid.REINIT_LOGGER"/>
+            </intent-filter>
+        </receiver>
+        <receiver
+            android:name=".AccountSettings$AppUpdatedReceiver"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.PACKAGE_REPLACED" />
+                <data android:scheme="package" android:path="at.bitfire.davdroid" />
+            </intent-filter>
+        </receiver>
+
+        <service
+            android:name=".syncadapter.AccountAuthenticatorService"
+            android:exported="false">
+            <intent-filter>
+                <action android:name="android.accounts.AccountAuthenticator"/>
+            </intent-filter>
+
+            <meta-data
+                android:name="android.accounts.AccountAuthenticator"
+                android:resource="@xml/account_authenticator"/>
+        </service>
+        <service
+            android:name=".syncadapter.ContactsSyncAdapterService"
+            android:exported="true"
+            android:process=":sync"
+            tools:ignore="ExportedService">
+            <intent-filter>
+                <action android:name="android.content.SyncAdapter"/>
+            </intent-filter>
+
+            <meta-data
+                android:name="android.content.SyncAdapter"
+                android:resource="@xml/sync_contacts"/>
+            <meta-data
+                android:name="android.provider.CONTACTS_STRUCTURE"
+                android:resource="@xml/contacts"/>
+        </service>
+        <service
+            android:name=".syncadapter.CalendarsSyncAdapterService"
+            android:exported="true"
+            android:process=":sync"
+            tools:ignore="ExportedService">
+            <intent-filter>
+                <action android:name="android.content.SyncAdapter"/>
+            </intent-filter>
+
+            <meta-data
+                android:name="android.content.SyncAdapter"
+                android:resource="@xml/sync_calendars"/>
+        </service>
+        <service
+            android:name=".syncadapter.TasksSyncAdapterService"
+            android:exported="true"
+            android:process=":sync"
+            tools:ignore="ExportedService">
+            <intent-filter>
+                <action android:name="android.content.SyncAdapter"/>
+            </intent-filter>
+
+            <meta-data
+                android:name="android.content.SyncAdapter"
+                android:resource="@xml/sync_tasks"/>
+        </service>
+
+        <service
+            android:name=".DavService"
+            android:enabled="true">
+        </service>
+        <receiver
+            android:name=".AccountsChangedReceiver"
+            android:enabled="true"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.accounts.LOGIN_ACCOUNTS_CHANGED"/>
+            </intent-filter>
+        </receiver>
+        
+        <activity
+            android:name=".ui.AccountsActivity"
+            android:label="@string/app_name"
+            android:theme="@style/AppTheme.NoActionBar">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
+        </activity>
+
+        <activity
+            android:name=".ui.AboutActivity"
+            android:label="@string/app_name"
+            android:theme="@style/AppTheme.NoActionBar"
+            android:parentActivityName=".ui.AccountsActivity"/>
+
+        <activity
+            android:name=".ui.AppSettingsActivity"
+            android:label="@string/app_settings"
+            android:parentActivityName=".ui.AccountsActivity"/>
+
+        <activity android:name=".ui.PermissionsActivity"
+                  android:label="@string/permissions_title"
+                  android:parentActivityName=".ui.AccountsActivity"/>
+
+        <activity
+            android:name=".ui.setup.LoginActivity"
+            android:label="@string/login_title"
+            android:parentActivityName=".ui.AccountsActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+            </intent-filter>
+        </activity>
+
+        <activity
+            android:name=".ui.AccountActivity"
+            android:parentActivityName=".ui.AccountsActivity">
+        </activity>
+        <activity android:name=".ui.AccountSettingsActivity"/>
+        <activity android:name=".ui.CreateAddressBookActivity"
+            android:label="@string/create_addressbook"/>
+        <activity android:name=".ui.CreateCalendarActivity"
+                  android:label="@string/create_calendar"/>
+
+        <activity
+            android:name=".ui.DebugInfoActivity"
+            android:exported="true"
+            android:label="@string/debug_info_title">
+        </activity>
+
+        <!-- MemorizingTrustManager -->
+        <activity
+            android:name="de.duenndns.ssl.MemorizingActivity"
+            android:theme="@android:style/Theme.Holo.Light.Dialog.NoActionBar"/>
+
+    </application>
+
+</manifest>

app/src/main/assets/apache2.html

@@ -0,0 +1,153 @@
+<h3>Apache License, Version 2.0, January 2004</h3>
+<p><a href="http://www.apache.org/licenses/">http://www.apache.org/licenses/</a> </p>
+<p>TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION</p>
+<p><strong><a name="definitions">1. Definitions</a></strong>.</p>
+<p>"License" shall mean the terms and conditions for use, reproduction, and
+distribution as defined by Sections 1 through 9 of this document.</p>
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+<p>"Legal Entity" shall mean the union of the acting entity and all other
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+entity, whether by contract or otherwise, or (ii) ownership of fifty
+percent (50%) or more of the outstanding shares, or (iii) beneficial
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+<p>"You" (or "Your") shall mean an individual or Legal Entity exercising
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+including but not limited to software source code, documentation source,
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+conditions of this License, without any additional terms or conditions.
+Notwithstanding the above, nothing herein shall supersede or modify the
+terms of any separate license agreement you may have executed with Licensor
+regarding such Contributions.</p>
+<p><strong><a name="trademarks">6. Trademarks</a></strong>. This License does not grant
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+under no legal theory, whether in tort (including negligence), contract, or
+otherwise, unless required by applicable law (such as deliberate and
+grossly negligent acts) or agreed to in writing, shall any Contributor be
+liable to You for damages, including any direct, indirect, special,
+incidental, or consequential damages of any character arising as a result
+of this License or out of the use or inability to use the Work (including
+but not limited to damages for loss of goodwill, work stoppage, computer
+failure or malfunction, or any and all other commercial damages or losses),
+even if such Contributor has been advised of the possibility of such
+damages.</p>
+<p><strong><a name="additional">9. Accepting Warranty or Additional Liability</a></strong>.
+While redistributing the Work or Derivative Works thereof, You may choose
+to offer, and charge a fee for, acceptance of support, warranty, indemnity,
+or other liability obligations and/or rights consistent with this License.
+However, in accepting such obligations, You may act only on Your own behalf
+and on Your sole responsibility, not on behalf of any other Contributor,
+and only if You agree to indemnify, defend, and hold each Contributor
+harmless for any liability incurred by, or claims asserted against, such
+Contributor by reason of your accepting any such warranty or additional
+liability.</p>
+
+<p>END OF TERMS AND CONDITIONS</p>

app/src/main/assets/bsd-3clause.html

@@ -0,0 +1,28 @@
+<h3>BSD License (3-clause)</h3>
+
+<p>Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:</p>
+
+<p>o Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.</p>
+
+<p>o Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.</p>
+
+<p>o Neither the name of Ben Fortuna nor the names of any other contributors
+may be used to endorse or promote products derived from this software
+without specific prior written permission.</p>
+
+<p>THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.</p>

app/src/main/assets/bsd.html

@@ -0,0 +1,23 @@
+<h3>BSD License</h3>
+
+<p>Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:</p>
+
+<p>1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.</p>
+
+<p>2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.</p>
+
+<p>THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.</p>
+

app/src/main/assets/gpl-3.0-standalone.html

@@ -0,0 +1,628 @@
+<h3 style="text-align: center;">GNU GENERAL PUBLIC LICENSE</h3>
+<p style="text-align: center;">Version 3, 29 June 2007</p>
+
+<p>Copyright &copy; 2007 Free Software Foundation, Inc.
+ &lt;<a href="http://fsf.org/">http://fsf.org/</a>&gt;</p><p>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.</p>
+
+<h3><a name="preamble"></a>Preamble</h3>
+
+<p>The GNU General Public License is a free, copyleft license for
+software and other kinds of works.</p>
+
+<p>The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+the GNU General Public License is intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.  We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors.  You can apply it to
+your programs, too.</p>
+
+<p>When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.</p>
+
+<p>To protect your rights, we need to prevent others from denying you
+these rights or asking you to surrender the rights.  Therefore, you have
+certain responsibilities if you distribute copies of the software, or if
+you modify it: responsibilities to respect the freedom of others.</p>
+
+<p>For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must pass on to the recipients the same
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+or can get the source code.  And you must show them these terms so they
+know their rights.</p>
+
+<p>Developers that use the GNU GPL protect your rights with two steps:
+(1) assert copyright on the software, and (2) offer you this License
+giving you legal permission to copy, distribute and/or modify it.</p>
+
+<p>For the developers' and authors' protection, the GPL clearly explains
+that there is no warranty for this free software.  For both users' and
+authors' sake, the GPL requires that modified versions be marked as
+changed, so that their problems will not be attributed erroneously to
+authors of previous versions.</p>
+
+<p>Some devices are designed to deny users access to install or run
+modified versions of the software inside them, although the manufacturer
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+pattern of such abuse occurs in the area of products for individuals to
+use, which is precisely where it is most unacceptable.  Therefore, we
+have designed this version of the GPL to prohibit the practice for those
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+stand ready to extend this provision to those domains in future versions
+of the GPL, as needed to protect the freedom of users.</p>
+
+<p>Finally, every program is threatened constantly by software patents.
+States should not allow patents to restrict development and use of
+software on general-purpose computers, but in those that do, we wish to
+avoid the special danger that patents applied to a free program could
+make it effectively proprietary.  To prevent this, the GPL assures that
+patents cannot be used to render the program non-free.</p>
+
+<p>The precise terms and conditions for copying, distribution and
+modification follow.</p>
+
+<h3><a name="terms"></a>TERMS AND CONDITIONS</h3>
+
+<h4><a name="section0"></a>0. Definitions.</h4>
+
+<p>&ldquo;This License&rdquo; refers to version 3 of the GNU General Public License.</p>
+
+<p>&ldquo;Copyright&rdquo; also means copyright-like laws that apply to other kinds of
+works, such as semiconductor masks.</p>
+ 
+<p>&ldquo;The Program&rdquo; refers to any copyrightable work licensed under this
+License.  Each licensee is addressed as &ldquo;you&rdquo;.  &ldquo;Licensees&rdquo; and
+&ldquo;recipients&rdquo; may be individuals or organizations.</p>
+
+<p>To &ldquo;modify&rdquo; a work means to copy from or adapt all or part of the work
+in a fashion requiring copyright permission, other than the making of an
+exact copy.  The resulting work is called a &ldquo;modified version&rdquo; of the
+earlier work or a work &ldquo;based on&rdquo; the earlier work.</p>
+
+<p>A &ldquo;covered work&rdquo; means either the unmodified Program or a work based
+on the Program.</p>
+
+<p>To &ldquo;propagate&rdquo; a work means to do anything with it that, without
+permission, would make you directly or secondarily liable for
+infringement under applicable copyright law, except executing it on a
+computer or modifying a private copy.  Propagation includes copying,
+distribution (with or without modification), making available to the
+public, and in some countries other activities as well.</p>
+
+<p>To &ldquo;convey&rdquo; a work means any kind of propagation that enables other
+parties to make or receive copies.  Mere interaction with a user through
+a computer network, with no transfer of a copy, is not conveying.</p>
+
+<p>An interactive user interface displays &ldquo;Appropriate Legal Notices&rdquo;
+to the extent that it includes a convenient and prominently visible
+feature that (1) displays an appropriate copyright notice, and (2)
+tells the user that there is no warranty for the work (except to the
+extent that warranties are provided), that licensees may convey the
+work under this License, and how to view a copy of this License.  If
+the interface presents a list of user commands or options, such as a
+menu, a prominent item in the list meets this criterion.</p>
+
+<h4><a name="section1"></a>1. Source Code.</h4>
+
+<p>The &ldquo;source code&rdquo; for a work means the preferred form of the work
+for making modifications to it.  &ldquo;Object code&rdquo; means any non-source
+form of a work.</p>
+
+<p>A &ldquo;Standard Interface&rdquo; means an interface that either is an official
+standard defined by a recognized standards body, or, in the case of
+interfaces specified for a particular programming language, one that
+is widely used among developers working in that language.</p>
+
+<p>The &ldquo;System Libraries&rdquo; of an executable work include anything, other
+than the work as a whole, that (a) is included in the normal form of
+packaging a Major Component, but which is not part of that Major
+Component, and (b) serves only to enable use of the work with that
+Major Component, or to implement a Standard Interface for which an
+implementation is available to the public in source code form.  A
+&ldquo;Major Component&rdquo;, in this context, means a major essential component
+(kernel, window system, and so on) of the specific operating system
+(if any) on which the executable work runs, or a compiler used to
+produce the work, or an object code interpreter used to run it.</p>
+
+<p>The &ldquo;Corresponding Source&rdquo; for a work in object code form means all
+the source code needed to generate, install, and (for an executable
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+the work, and the source code for shared libraries and dynamically
+linked subprograms that the work is specifically designed to require,
+such as by intimate data communication or control flow between those
+subprograms and other parts of the work.</p>
+
+<p>The Corresponding Source need not include anything that users
+can regenerate automatically from other parts of the Corresponding
+Source.</p>
+
+<p>The Corresponding Source for a work in source code form is that
+same work.</p>
+
+<h4><a name="section2"></a>2. Basic Permissions.</h4>
+
+<p>All rights granted under this License are granted for the term of
+copyright on the Program, and are irrevocable provided the stated
+conditions are met.  This License explicitly affirms your unlimited
+permission to run the unmodified Program.  The output from running a
+covered work is covered by this License only if the output, given its
+content, constitutes a covered work.  This License acknowledges your
+rights of fair use or other equivalent, as provided by copyright law.</p>
+
+<p>You may make, run and propagate covered works that you do not
+convey, without conditions so long as your license otherwise remains
+in force.  You may convey covered works to others for the sole purpose
+of having them make modifications exclusively for you, or provide you
+with facilities for running those works, provided that you comply with
+the terms of this License in conveying all material for which you do
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+for you must do so exclusively on your behalf, under your direction
+and control, on terms that prohibit them from making any copies of
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+
+<p>Conveying under any other circumstances is permitted solely under
+the conditions stated below.  Sublicensing is not allowed; section 10
+makes it unnecessary.</p>
+
+<h4><a name="section3"></a>3. Protecting Users' Legal Rights From Anti-Circumvention Law.</h4>
+
+<p>No covered work shall be deemed part of an effective technological
+measure under any applicable law fulfilling obligations under article
+11 of the WIPO copyright treaty adopted on 20 December 1996, or
+similar laws prohibiting or restricting circumvention of such
+measures.</p>
+
+<p>When you convey a covered work, you waive any legal power to forbid
+circumvention of technological measures to the extent such circumvention
+is effected by exercising rights under this License with respect to
+the covered work, and you disclaim any intention to limit operation or
+modification of the work as a means of enforcing, against the work's
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+technological measures.</p>
+
+<h4><a name="section4"></a>4. Conveying Verbatim Copies.</h4>
+
+<p>You may convey verbatim copies of the Program's source code as you
+receive it, in any medium, provided that you conspicuously and
+appropriately publish on each copy an appropriate copyright notice;
+keep intact all notices stating that this License and any
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+keep intact all notices of the absence of any warranty; and give all
+recipients a copy of this License along with the Program.</p>
+
+<p>You may charge any price or no price for each copy that you convey,
+and you may offer support or warranty protection for a fee.</p>
+
+<h4><a name="section5"></a>5. Conveying Modified Source Versions.</h4>
+
+<p>You may convey a work based on the Program, or the modifications to
+produce it from the Program, in the form of source code under the
+terms of section 4, provided that you also meet all of these conditions:</p>
+
+<ul>
+<li>a) The work must carry prominent notices stating that you modified
+    it, and giving a relevant date.</li>
+
+<li>b) The work must carry prominent notices stating that it is
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+    7.  This requirement modifies the requirement in section 4 to
+    &ldquo;keep intact all notices&rdquo;.</li>
+
+<li>c) You must license the entire work, as a whole, under this
+    License to anyone who comes into possession of a copy.  This
+    License will therefore apply, along with any applicable section 7
+    additional terms, to the whole of the work, and all its parts,
+    regardless of how they are packaged.  This License gives no
+    permission to license the work in any other way, but it does not
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+
+<li>d) If the work has interactive user interfaces, each must display
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+    work need not make them do so.</li>
+</ul>
+
+<p>A compilation of a covered work with other separate and independent
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+and which are not combined with it such as to form a larger program,
+in or on a volume of a storage or distribution medium, is called an
+&ldquo;aggregate&rdquo; if the compilation and its resulting copyright are not
+used to limit the access or legal rights of the compilation's users
+beyond what the individual works permit.  Inclusion of a covered work
+in an aggregate does not cause this License to apply to the other
+parts of the aggregate.</p>
+
+<h4><a name="section6"></a>6. Conveying Non-Source Forms.</h4>
+
+<p>You may convey a covered work in object code form under the terms
+of sections 4 and 5, provided that you also convey the
+machine-readable Corresponding Source under the terms of this License,
+in one of these ways:</p>
+
+<ul>
+<li>a) Convey the object code in, or embodied in, a physical product
+    (including a physical distribution medium), accompanied by the
+    Corresponding Source fixed on a durable physical medium
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+
+<li>b) Convey the object code in, or embodied in, a physical product
+    (including a physical distribution medium), accompanied by a
+    written offer, valid for at least three years and valid for as
+    long as you offer spare parts or customer support for that product
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+    copy of the Corresponding Source for all the software in the
+    product that is covered by this License, on a durable physical
+    medium customarily used for software interchange, for a price no
+    more than your reasonable cost of physically performing this
+    conveying of source, or (2) access to copy the
+    Corresponding Source from a network server at no charge.</li>
+
+<li>c) Convey individual copies of the object code with a copy of the
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+    alternative is allowed only occasionally and noncommercially, and
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+
+<li>d) Convey the object code by offering access from a designated
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+    Corresponding Source along with the object code.  If the place to
+    copy the object code is a network server, the Corresponding Source
+    may be on a different server (operated by you or a third party)
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+    clear directions next to the object code saying where to find the
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+    Corresponding Source, you remain obligated to ensure that it is
+    available for as long as needed to satisfy these requirements.</li>
+
+<li>e) Convey the object code using peer-to-peer transmission, provided
+    you inform other peers where the object code and Corresponding
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+    charge under subsection 6d.</li>
+</ul>
+
+<p>A separable portion of the object code, whose source code is excluded
+from the Corresponding Source as a System Library, need not be
+included in conveying the object code work.</p>
+
+<p>A &ldquo;User Product&rdquo; is either (1) a &ldquo;consumer product&rdquo;, which means any
+tangible personal property which is normally used for personal, family,
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+
+<p>&ldquo;Installation Information&rdquo; for a User Product means any methods,
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+modification has been made.</p>
+
+<p>If you convey an object code work under this section in, or with, or
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+Corresponding Source conveyed under this section must be accompanied
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+if neither you nor any third party retains the ability to install
+modified object code on the User Product (for example, the work has
+been installed in ROM).</p>
+
+<p>The requirement to provide Installation Information does not include a
+requirement to continue to provide support service, warranty, or updates
+for a work that has been modified or installed by the recipient, or for
+the User Product in which it has been modified or installed.  Access to a
+network may be denied when the modification itself materially and
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+
+<p>Corresponding Source conveyed, and Installation Information provided,
+in accord with this section must be in a format that is publicly
+documented (and with an implementation available to the public in
+source code form), and must require no special password or key for
+unpacking, reading or copying.</p>
+
+<h4><a name="section7"></a>7. Additional Terms.</h4>
+
+<p>&ldquo;Additional permissions&rdquo; are terms that supplement the terms of this
+License by making exceptions from one or more of its conditions.
+Additional permissions that are applicable to the entire Program shall
+be treated as though they were included in this License, to the extent
+that they are valid under applicable law.  If additional permissions
+apply only to part of the Program, that part may be used separately
+under those permissions, but the entire Program remains governed by
+this License without regard to the additional permissions.</p>
+
+<p>When you convey a copy of a covered work, you may at your option
+remove any additional permissions from that copy, or from any part of
+it.  (Additional permissions may be written to require their own
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+for which you have or can give appropriate copyright permission.</p>
+
+<p>Notwithstanding any other provision of this License, for material you
+add to a covered work, you may (if authorized by the copyright holders of
+that material) supplement the terms of this License with terms:</p>
+
+<ul>
+<li>a) Disclaiming warranty or limiting liability differently from the
+    terms of sections 15 and 16 of this License; or</li>
+
+<li>b) Requiring preservation of specified reasonable legal notices or
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+</ul>
+
+<p>All other non-permissive additional terms are considered &ldquo;further
+restrictions&rdquo; within the meaning of section 10.  If the Program as you
+received it, or any part of it, contains a notice stating that it is
+governed by this License along with a term that is a further
+restriction, you may remove that term.  If a license document contains
+a further restriction but permits relicensing or conveying under this
+License, you may add to a covered work material governed by the terms
+of that license document, provided that the further restriction does
+not survive such relicensing or conveying.</p>
+
+<p>If you add terms to a covered work in accord with this section, you
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+
+<p>Additional terms, permissive or non-permissive, may be stated in the
+form of a separately written license, or stated as exceptions;
+the above requirements apply either way.</p>
+
+<h4><a name="section8"></a>8. Termination.</h4>
+
+<p>You may not propagate or modify a covered work except as expressly
+provided under this License.  Any attempt otherwise to propagate or
+modify it is void, and will automatically terminate your rights under
+this License (including any patent licenses granted under the third
+paragraph of section 11).</p>
+
+<p>However, if you cease all violation of this License, then your
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+holder fails to notify you of the violation by some reasonable means
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+
+<p>Moreover, your license from a particular copyright holder is
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+received notice of violation of this License (for any work) from that
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+
+<p>Termination of your rights under this section does not terminate the
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+
+<h4><a name="section9"></a>9. Acceptance Not Required for Having Copies.</h4>
+
+<p>You are not required to accept this License in order to receive or
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+occurring solely as a consequence of using peer-to-peer transmission
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+covered work, you indicate your acceptance of this License to do so.</p>
+
+<h4><a name="section10"></a>10. Automatic Licensing of Downstream Recipients.</h4>
+
+<p>Each time you convey a covered work, the recipient automatically
+receives a license from the original licensors, to run, modify and
+propagate that work, subject to this License.  You are not responsible
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+
+<p>An &ldquo;entity transaction&rdquo; is a transaction transferring control of an
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+<p>You may not impose any further restrictions on the exercise of the
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+sale, or importing the Program or any portion of it.</p>
+
+<h4><a name="section11"></a>11. Patents.</h4>
+
+<p>A &ldquo;contributor&rdquo; is a copyright holder who authorizes use under this
+License of the Program or a work on which the Program is based.  The
+work thus licensed is called the contributor's &ldquo;contributor version&rdquo;.</p>
+
+<p>A contributor's &ldquo;essential patent claims&rdquo; are all patent claims
+owned or controlled by the contributor, whether already acquired or
+hereafter acquired, that would be infringed by some manner, permitted
+by this License, of making, using, or selling its contributor version,
+but do not include claims that would be infringed only as a
+consequence of further modification of the contributor version.  For
+purposes of this definition, &ldquo;control&rdquo; includes the right to grant
+patent sublicenses in a manner consistent with the requirements of
+this License.</p>
+
+<p>Each contributor grants you a non-exclusive, worldwide, royalty-free
+patent license under the contributor's essential patent claims, to
+make, use, sell, offer for sale, import and otherwise run, modify and
+propagate the contents of its contributor version.</p>
+
+<p>In the following three paragraphs, a &ldquo;patent license&rdquo; is any express
+agreement or commitment, however denominated, not to enforce a patent
+(such as an express permission to practice a patent or covenant not to
+sue for patent infringement).  To &ldquo;grant&rdquo; such a patent license to a
+party means to make such an agreement or commitment not to enforce a
+patent against the party.</p>
+
+<p>If you convey a covered work, knowingly relying on a patent license,
+and the Corresponding Source of the work is not available for anyone
+to copy, free of charge and under the terms of this License, through a
+publicly available network server or other readily accessible means,
+then you must either (1) cause the Corresponding Source to be so
+available, or (2) arrange to deprive yourself of the benefit of the
+patent license for this particular work, or (3) arrange, in a manner
+consistent with the requirements of this License, to extend the patent
+license to downstream recipients.  &ldquo;Knowingly relying&rdquo; means you have
+actual knowledge that, but for the patent license, your conveying the
+covered work in a country, or your recipient's use of the covered work
+in a country, would infringe one or more identifiable patents in that
+country that you have reason to believe are valid.</p>
+  
+<p>If, pursuant to or in connection with a single transaction or
+arrangement, you convey, or propagate by procuring conveyance of, a
+covered work, and grant a patent license to some of the parties
+receiving the covered work authorizing them to use, propagate, modify
+or convey a specific copy of the covered work, then the patent license
+you grant is automatically extended to all recipients of the covered
+work and works based on it.</p>
+
+<p>A patent license is &ldquo;discriminatory&rdquo; if it does not include within
+the scope of its coverage, prohibits the exercise of, or is
+conditioned on the non-exercise of one or more of the rights that are
+specifically granted under this License.  You may not convey a covered
+work if you are a party to an arrangement with a third party that is
+in the business of distributing software, under which you make payment
+to the third party based on the extent of your activity of conveying
+the work, and under which the third party grants, to any of the
+parties who would receive the covered work from you, a discriminatory
+patent license (a) in connection with copies of the covered work
+conveyed by you (or copies made from those copies), or (b) primarily
+for and in connection with specific products or compilations that
+contain the covered work, unless you entered into that arrangement,
+or that patent license was granted, prior to 28 March 2007.</p>
+
+<p>Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.</p>
+
+<h4><a name="section12"></a>12. No Surrender of Others' Freedom.</h4>
+
+<p>If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot convey a
+covered work so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you may
+not convey it at all.  For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.</p>
+
+<h4><a name="section13"></a>13. Use with the GNU Affero General Public License.</h4>
+
+<p>Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU Affero General Public License into a single
+combined work, and to convey the resulting work.  The terms of this
+License will continue to apply to the part which is the covered work,
+but the special requirements of the GNU Affero General Public License,
+section 13, concerning interaction through a network will apply to the
+combination as such.</p>
+
+<h4><a name="section14"></a>14. Revised Versions of this License.</h4>
+
+<p>The Free Software Foundation may publish revised and/or new versions of
+the GNU General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.</p>
+
+<p>Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU General
+Public License &ldquo;or any later version&rdquo; applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.</p>
+
+<p>If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.</p>
+
+<p>Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.</p>
+
+<h4><a name="section15"></a>15. Disclaimer of Warranty.</h4>
+
+<p>THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM &ldquo;AS IS&rdquo; WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.</p>
+
+<h4><a name="section16"></a>16. Limitation of Liability.</h4>
+
+<p>IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.</p>
+
+<h4><a name="section17"></a>17. Interpretation of Sections 15 and 16.</h4>
+
+<p>If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.</p>
+
+<p>END OF TERMS AND CONDITIONS</p>

app/src/main/assets/mit.html

@@ -0,0 +1,7 @@
+<h3>The MIT License (MIT)</h3>
+
+<p>Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:</p>
+
+<p>The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.</p>
+
+<p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.</p>

app/src/main/java/at/bitfire/davdroid/AccountSettings.java

@@ -0,0 +1,448 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+package at.bitfire.davdroid;
+
+import android.accounts.Account;
+import android.accounts.AccountManager;
+import android.annotation.SuppressLint;
+import android.app.Notification;
+import android.app.NotificationManager;
+import android.content.BroadcastReceiver;
+import android.content.ContentProviderClient;
+import android.content.ContentResolver;
+import android.content.ContentValues;
+import android.content.Context;
+import android.content.Intent;
+import android.content.PeriodicSync;
+import android.database.sqlite.SQLiteDatabase;
+import android.graphics.drawable.BitmapDrawable;
+import android.os.Bundle;
+import android.provider.CalendarContract;
+import android.provider.ContactsContract;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.v7.app.NotificationCompat;
+import android.text.TextUtils;
+
+import java.lang.reflect.Method;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.logging.Level;
+
+import at.bitfire.davdroid.model.ServiceDB;
+import at.bitfire.davdroid.model.ServiceDB.Collections;
+import at.bitfire.davdroid.model.ServiceDB.HomeSets;
+import at.bitfire.davdroid.model.ServiceDB.Services;
+import at.bitfire.davdroid.resource.LocalAddressBook;
+import at.bitfire.davdroid.resource.LocalCalendar;
+import at.bitfire.davdroid.resource.LocalTaskList;
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.ical4android.TaskProvider;
+import at.bitfire.vcard4android.ContactsStorageException;
+import at.bitfire.vcard4android.GroupMethod;
+import lombok.Cleanup;
+import okhttp3.HttpUrl;
+
+public class AccountSettings {
+    private final static int CURRENT_VERSION = 4;
+    private final static String
+            KEY_SETTINGS_VERSION = "version",
+
+            KEY_USERNAME = "user_name",
+            KEY_AUTH_PREEMPTIVE = "auth_preemptive",
+
+            KEY_WIFI_ONLY = "wifi_only",            // sync on WiFi only (default: false)
+            KEY_WIFI_ONLY_SSID = "wifi_only_ssid";  // restrict sync to specific WiFi SSID
+
+    /** Whether to use RFC 6868 for VCards
+     *  value = null (not existing)      use RFC6868-style encoding (default value)
+     *          "0"                      don't use RFC 6868-style encoding
+     */
+    private final static String KEY_VCARD_RFC6868 = "vcard_rfc6868";
+
+    /** Time range limitation to the past [in days]
+        value = null            default value (DEFAULT_TIME_RANGE_PAST_DAYS)
+              < 0 (-1)          no limit
+              >= 0              entries more than n days in the past won't be synchronized
+     */
+    private final static String KEY_TIME_RANGE_PAST_DAYS = "time_range_past_days";
+    private final static int DEFAULT_TIME_RANGE_PAST_DAYS = 90;
+
+    /* Whether DAVdroid sets the local calendar color to the value from service DB at every sync
+       value = null (not existing)     true (default)
+               "0"                     false */
+    private final static String KEY_MANAGE_CALENDAR_COLORS = "manage_calendar_colors";
+
+    /** Contact group method:
+        value = null (not existing)     groups as separate VCards (default)
+                "CATEGORIES"            groups are per-contact CATEGORIES
+    */
+    private final static String KEY_CONTACT_GROUP_METHOD = "contact_group_method";
+
+    public final static long SYNC_INTERVAL_MANUALLY = -1;
+
+    final Context context;
+    final AccountManager accountManager;
+    final Account account;
+
+
+    public AccountSettings(@NonNull Context context, @NonNull Account account) throws InvalidAccountException {
+        this.context = context;
+        this.account = account;
+
+        accountManager = AccountManager.get(context);
+
+        synchronized(AccountSettings.class) {
+            String versionStr = accountManager.getUserData(account, KEY_SETTINGS_VERSION);
+            if (versionStr == null)
+                throw new InvalidAccountException(account);
+
+            int version = 0;
+            try {
+                version = Integer.parseInt(versionStr);
+            } catch (NumberFormatException ignored) {
+            }
+            App.log.info("Account " + account.name + " has version " + version + ", current version: " + CURRENT_VERSION);
+
+            if (version < CURRENT_VERSION) {
+                Notification notify = new NotificationCompat.Builder(context)
+                        .setSmallIcon(R.drawable.ic_new_releases_light)
+                        .setLargeIcon(((BitmapDrawable)context.getResources().getDrawable(R.drawable.ic_launcher)).getBitmap())
+                        .setContentTitle(context.getString(R.string.settings_version_update))
+                        .setContentText(context.getString(R.string.settings_version_update_settings_updated))
+                        .setSubText(context.getString(R.string.settings_version_update_install_hint))
+                        .setStyle(new NotificationCompat.BigTextStyle()
+                                .bigText(context.getString(R.string.settings_version_update_settings_updated)))
+                        .setCategory(NotificationCompat.CATEGORY_SYSTEM)
+                        .setPriority(NotificationCompat.PRIORITY_HIGH)
+                        .setLocalOnly(true)
+                        .build();
+                NotificationManager nm = (NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE);
+                nm.notify(Constants.NOTIFICATION_ACCOUNT_SETTINGS_UPDATED, notify);
+
+                update(version);
+            }
+        }
+    }
+
+    public static Bundle initialUserData(String userName, boolean preemptive) {
+        Bundle bundle = new Bundle();
+        bundle.putString(KEY_SETTINGS_VERSION, String.valueOf(CURRENT_VERSION));
+        bundle.putString(KEY_USERNAME, userName);
+        bundle.putString(KEY_AUTH_PREEMPTIVE, Boolean.toString(preemptive));
+        return bundle;
+    }
+
+
+    // authentication settings
+
+    public String username() { return accountManager.getUserData(account, KEY_USERNAME); }
+    public void username(@NonNull String userName) { accountManager.setUserData(account, KEY_USERNAME, userName); }
+
+    public String password() { return accountManager.getPassword(account); }
+    public void password(@NonNull String password) { accountManager.setPassword(account, password); }
+
+    public boolean preemptiveAuth() { return Boolean.parseBoolean(accountManager.getUserData(account, KEY_AUTH_PREEMPTIVE)); }
+    public void preemptiveAuth(boolean preemptive) { accountManager.setUserData(account, KEY_AUTH_PREEMPTIVE, Boolean.toString(preemptive)); }
+
+
+    // sync. settings
+
+    public Long getSyncInterval(@NonNull String authority) {
+        if (ContentResolver.getIsSyncable(account, authority) <= 0)
+            return null;
+
+        if (ContentResolver.getSyncAutomatically(account, authority)) {
+            List<PeriodicSync> syncs = ContentResolver.getPeriodicSyncs(account, authority);
+            if (syncs.isEmpty())
+                return SYNC_INTERVAL_MANUALLY;
+            else
+                return syncs.get(0).period;
+        } else
+            return SYNC_INTERVAL_MANUALLY;
+    }
+
+    public void setSyncInterval(@NonNull String authority, long seconds) {
+        if (seconds == SYNC_INTERVAL_MANUALLY) {
+            ContentResolver.setSyncAutomatically(account, authority, false);
+        } else {
+            ContentResolver.setSyncAutomatically(account, authority, true);
+            ContentResolver.addPeriodicSync(account, authority, new Bundle(), seconds);
+        }
+    }
+
+    public boolean getSyncWifiOnly() {
+        return accountManager.getUserData(account, KEY_WIFI_ONLY) != null;
+    }
+
+    public void setSyncWiFiOnly(boolean wiFiOnly) {
+        accountManager.setUserData(account, KEY_WIFI_ONLY, wiFiOnly ? "1" : null);
+    }
+
+    @Nullable
+    public String getSyncWifiOnlySSID() {
+        return accountManager.getUserData(account, KEY_WIFI_ONLY_SSID);
+    }
+
+    public void setSyncWifiOnlySSID(String ssid) {
+        accountManager.setUserData(account, KEY_WIFI_ONLY_SSID, ssid);
+    }
+
+
+    // CardDAV settings
+
+    public boolean getVCardRFC6868() {
+        return accountManager.getUserData(account, KEY_VCARD_RFC6868) == null;
+    }
+
+    public void setVCardRFC6868(boolean use) {
+        accountManager.setUserData(account, KEY_VCARD_RFC6868, use ? null : "0");
+    }
+
+
+    // CalDAV settings
+
+    @Nullable
+    public Integer getTimeRangePastDays() {
+        String strDays = accountManager.getUserData(account, KEY_TIME_RANGE_PAST_DAYS);
+        if (strDays != null) {
+            int days = Integer.valueOf(strDays);
+            return days < 0 ? null : days;
+        } else
+            return DEFAULT_TIME_RANGE_PAST_DAYS;
+    }
+
+    public void setTimeRangePastDays(@Nullable Integer days) {
+        accountManager.setUserData(account, KEY_TIME_RANGE_PAST_DAYS, String.valueOf(days == null ? -1 : days));
+    }
+
+    public boolean getManageCalendarColors() {
+        return accountManager.getUserData(account, KEY_MANAGE_CALENDAR_COLORS) == null;
+    }
+
+    public void setManageCalendarColors(boolean manage) {
+        accountManager.setUserData(account, KEY_MANAGE_CALENDAR_COLORS, manage ? null : "0");
+    }
+
+
+    // CardDAV settings
+
+    @NonNull
+    public GroupMethod getGroupMethod() {
+        final String name = accountManager.getUserData(account, KEY_CONTACT_GROUP_METHOD);
+        return name != null ?
+                GroupMethod.valueOf(name) :
+                GroupMethod.GROUP_VCARDS;
+    }
+
+    public void setGroupMethod(@NonNull GroupMethod method) {
+        final String name = method == GroupMethod.GROUP_VCARDS ? null : method.name();
+        accountManager.setUserData(account, KEY_CONTACT_GROUP_METHOD, name);
+    }
+
+
+    // update from previous account settings
+
+    private void update(int fromVersion) {
+        for (int toVersion = fromVersion + 1; toVersion <= CURRENT_VERSION; toVersion++) {
+            App.log.info("Updating account " + account.name + " from version " + fromVersion + " to " + toVersion);
+            try {
+                Method updateProc = getClass().getDeclaredMethod("update_" + fromVersion + "_" + toVersion);
+                updateProc.invoke(this);
+                accountManager.setUserData(account, KEY_SETTINGS_VERSION, String.valueOf(toVersion));
+            } catch (Exception e) {
+                App.log.log(Level.SEVERE, "Couldn't update account settings", e);
+            }
+            fromVersion = toVersion;
+        }
+    }
+
+    @SuppressWarnings({ "Recycle", "unused" })
+    private void update_1_2() throws ContactsStorageException {
+        /* - KEY_ADDRESSBOOK_URL ("addressbook_url"),
+           - KEY_ADDRESSBOOK_CTAG ("addressbook_ctag"),
+           - KEY_ADDRESSBOOK_VCARD_VERSION ("addressbook_vcard_version") are not used anymore (now stored in ContactsContract.SyncState)
+           - KEY_LAST_ANDROID_VERSION ("last_android_version") has been added
+        */
+
+        // move previous address book info to ContactsContract.SyncState
+        @Cleanup("release") ContentProviderClient provider = context.getContentResolver().acquireContentProviderClient(ContactsContract.AUTHORITY);
+        if (provider == null)
+            throw new ContactsStorageException("Couldn't access Contacts provider");
+
+        LocalAddressBook addr = new LocalAddressBook(account, provider);
+
+        // until now, ContactsContract.Settings.UNGROUPED_VISIBLE was not set explicitly
+        ContentValues values = new ContentValues();
+        values.put(ContactsContract.Settings.UNGROUPED_VISIBLE, 1);
+        addr.updateSettings(values);
+
+        String url = accountManager.getUserData(account, "addressbook_url");
+        if (!TextUtils.isEmpty(url))
+            addr.setURL(url);
+        accountManager.setUserData(account, "addressbook_url", null);
+
+        String cTag = accountManager.getUserData(account, "addressbook_ctag");
+        if (!TextUtils.isEmpty(cTag))
+            addr.setCTag(cTag);
+        accountManager.setUserData(account, "addressbook_ctag", null);
+    }
+
+    @SuppressWarnings({ "Recycle", "unused" })
+    private void update_2_3() {
+        // Don't show a warning for Android updates anymore
+        accountManager.setUserData(account, "last_android_version", null);
+
+        Long serviceCardDAV = null, serviceCalDAV = null;
+
+        ServiceDB.OpenHelper dbHelper = new ServiceDB.OpenHelper(context);
+        try {
+            SQLiteDatabase db = dbHelper.getWritableDatabase();
+            // we have to create the WebDAV Service database only from the old address book, calendar and task list URLs
+
+            // CardDAV: migrate address books
+            ContentProviderClient client = context.getContentResolver().acquireContentProviderClient(ContactsContract.AUTHORITY);
+            if (client != null)
+                try {
+                    LocalAddressBook addrBook = new LocalAddressBook(account, client);
+                    String url = addrBook.getURL();
+                    if (url != null) {
+                        App.log.fine("Migrating address book " + url);
+
+                        // insert CardDAV service
+                        ContentValues values = new ContentValues();
+                        values.put(Services.ACCOUNT_NAME, account.name);
+                        values.put(Services.SERVICE, Services.SERVICE_CARDDAV);
+                        serviceCardDAV = db.insert(Services._TABLE, null, values);
+
+                        // insert address book
+                        values.clear();
+                        values.put(Collections.SERVICE_ID, serviceCardDAV);
+                        values.put(Collections.URL, url);
+                        values.put(Collections.SYNC, 1);
+                        db.insert(Collections._TABLE, null, values);
+
+                        // insert home set
+                        HttpUrl homeSet = HttpUrl.parse(url).resolve("../");
+                        values.clear();
+                        values.put(HomeSets.SERVICE_ID, serviceCardDAV);
+                        values.put(HomeSets.URL, homeSet.toString());
+                        db.insert(HomeSets._TABLE, null, values);
+                    }
+
+                } catch (ContactsStorageException e) {
+                    App.log.log(Level.SEVERE, "Couldn't migrate address book", e);
+                } finally {
+                    client.release();
+                }
+
+            // CalDAV: migrate calendars + task lists
+            Set<String> collections = new HashSet<>();
+            Set<HttpUrl> homeSets = new HashSet<>();
+
+            client = context.getContentResolver().acquireContentProviderClient(CalendarContract.AUTHORITY);
+            if (client != null)
+                try {
+                    LocalCalendar calendars[] = (LocalCalendar[])LocalCalendar.find(account, client, LocalCalendar.Factory.INSTANCE, null, null);
+                    for (LocalCalendar calendar : calendars) {
+                        String url = calendar.getName();
+                        App.log.fine("Migrating calendar " + url);
+                        collections.add(url);
+                        homeSets.add(HttpUrl.parse(url).resolve("../"));
+                    }
+                } catch (CalendarStorageException e) {
+                    App.log.log(Level.SEVERE, "Couldn't migrate calendars", e);
+                } finally {
+                    client.release();
+                }
+
+            TaskProvider provider = LocalTaskList.acquireTaskProvider(context.getContentResolver());
+            if (provider != null)
+                try {
+                    LocalTaskList[] taskLists = (LocalTaskList[])LocalTaskList.find(account, provider, LocalTaskList.Factory.INSTANCE, null, null);
+                    for (LocalTaskList taskList : taskLists) {
+                        String url = taskList.getSyncId();
+                        App.log.fine("Migrating task list " + url);
+                        collections.add(url);
+                        homeSets.add(HttpUrl.parse(url).resolve("../"));
+                    }
+                } catch (CalendarStorageException e) {
+                    App.log.log(Level.SEVERE, "Couldn't migrate task lists", e);
+                } finally {
+                    provider.close();
+                }
+
+            if (!collections.isEmpty()) {
+                // insert CalDAV service
+                ContentValues values = new ContentValues();
+                values.put(Services.ACCOUNT_NAME, account.name);
+                values.put(Services.SERVICE, Services.SERVICE_CALDAV);
+                serviceCalDAV = db.insert(Services._TABLE, null, values);
+
+                // insert collections
+                for (String url : collections) {
+                    values.clear();
+                    values.put(Collections.SERVICE_ID, serviceCalDAV);
+                    values.put(Collections.URL, url);
+                    values.put(Collections.SYNC, 1);
+                    db.insert(Collections._TABLE, null, values);
+                }
+
+                // insert home sets
+                for (HttpUrl homeSet : homeSets) {
+                    values.clear();
+                    values.put(HomeSets.SERVICE_ID, serviceCalDAV);
+                    values.put(HomeSets.URL, homeSet.toString());
+                    db.insert(HomeSets._TABLE, null, values);
+                }
+            }
+        } finally {
+            dbHelper.close();
+        }
+
+        // initiate service detection (refresh) to get display names, colors etc.
+        Intent refresh = new Intent(context, DavService.class);
+        refresh.setAction(DavService.ACTION_REFRESH_COLLECTIONS);
+        if (serviceCardDAV != null) {
+            refresh.putExtra(DavService.EXTRA_DAV_SERVICE_ID, serviceCardDAV);
+            context.startService(refresh);
+        }
+        if (serviceCalDAV != null) {
+            refresh.putExtra(DavService.EXTRA_DAV_SERVICE_ID, serviceCalDAV);
+            context.startService(refresh);
+        }
+    }
+
+    @SuppressWarnings({ "Recycle", "unused" })
+    private void update_3_4() {
+        setGroupMethod(GroupMethod.CATEGORIES);
+    }
+
+
+    public static class AppUpdatedReceiver extends BroadcastReceiver {
+
+        @Override
+        @SuppressLint("UnsafeProtectedBroadcastReceiver")
+        public void onReceive(Context context, Intent intent) {
+            App.log.info("DAVdroid was updated, checking for AccountSettings version");
+
+            // peek into AccountSettings to initiate a possible migration
+            AccountManager accountManager = AccountManager.get(context);
+            for (Account account : accountManager.getAccountsByType(Constants.ACCOUNT_TYPE))
+                try {
+                    App.log.info("Checking account " + account.name);
+                    new AccountSettings(context, account);
+                } catch (InvalidAccountException e) {
+                    App.log.log(Level.SEVERE, "Couldn't check for updated account settings", e);
+                }
+        }
+
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/AccountsChangedReceiver.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid;
+
+import android.accounts.OnAccountsUpdateListener;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+
+import java.util.LinkedList;
+import java.util.List;
+
+public class AccountsChangedReceiver extends BroadcastReceiver {
+
+    protected static final List<OnAccountsUpdateListener> listeners = new LinkedList<>();
+
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        Intent serviceIntent = new Intent(context, DavService.class);
+        serviceIntent.setAction(DavService.ACTION_ACCOUNTS_UPDATED);
+        context.startService(serviceIntent);
+
+        for (OnAccountsUpdateListener listener : listeners)
+            listener.onAccountsUpdated(null);
+    }
+
+    public static void registerListener(OnAccountsUpdateListener listener, boolean callImmediately) {
+        listeners.add(listener);
+        if (callImmediately)
+            listener.onAccountsUpdated(null);
+    }
+
+    public static void unregisterListener(OnAccountsUpdateListener listener) {
+        listeners.remove(listener);
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/App.java

@@ -0,0 +1,145 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid;
+
+import android.app.Application;
+import android.app.NotificationManager;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.graphics.drawable.BitmapDrawable;
+import android.support.v7.app.NotificationCompat;
+import android.util.Log;
+
+import org.apache.commons.lang3.time.DateFormatUtils;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.logging.FileHandler;
+import java.util.logging.Handler;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import javax.net.ssl.HostnameVerifier;
+
+import at.bitfire.davdroid.log.LogcatHandler;
+import at.bitfire.davdroid.log.PlainTextFormatter;
+import at.bitfire.davdroid.model.ServiceDB;
+import at.bitfire.davdroid.model.Settings;
+import de.duenndns.ssl.MemorizingTrustManager;
+import lombok.Cleanup;
+import lombok.Getter;
+import okhttp3.internal.tls.OkHostnameVerifier;
+
+public class App extends Application {
+    public static final String FLAVOR_GOOGLE_PLAY = "gplay";
+
+    public static final String LOG_TO_EXTERNAL_STORAGE = "logToExternalStorage";
+
+    @Getter
+    private static MemorizingTrustManager memorizingTrustManager;
+
+    @Getter
+    private static SSLSocketFactoryCompat sslSocketFactoryCompat;
+
+    @Getter
+    private static HostnameVerifier hostnameVerifier;
+
+    public final static Logger log = Logger.getLogger("davdroid");
+    static {
+        at.bitfire.dav4android.Constants.log = Logger.getLogger("davdroid.dav4android");
+    }
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+
+        // initialize MemorizingTrustManager
+        memorizingTrustManager = new MemorizingTrustManager(this);
+        sslSocketFactoryCompat = new SSLSocketFactoryCompat(memorizingTrustManager);
+        hostnameVerifier = memorizingTrustManager.wrapHostnameVerifier(OkHostnameVerifier.INSTANCE);
+
+        // initializer logger
+        reinitLogger();
+    }
+
+    public void reinitLogger() {
+        // don't use Android default logging, we have our own handlers
+        log.setUseParentHandlers(false);
+
+        @Cleanup ServiceDB.OpenHelper dbHelper = new ServiceDB.OpenHelper(this);
+        Settings settings = new Settings(dbHelper.getReadableDatabase());
+
+        boolean logToFile = settings.getBoolean(LOG_TO_EXTERNAL_STORAGE, false),
+                logVerbose = logToFile || Log.isLoggable(log.getName(), Log.DEBUG);
+
+        // set logging level according to preferences
+        log.setLevel(logVerbose ? Level.ALL : Level.INFO);
+
+        // remove all handlers
+        for (Handler handler : log.getHandlers())
+            log.removeHandler(handler);
+
+        // add logcat handler
+        log.addHandler(LogcatHandler.INSTANCE);
+
+        NotificationManager nm = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
+        // log to external file according to preferences
+        if (logToFile) {
+            NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
+            builder .setSmallIcon(R.drawable.ic_sd_storage_light)
+                    .setLargeIcon(((BitmapDrawable)getResources().getDrawable(R.drawable.ic_launcher)).getBitmap())
+                    .setContentTitle(getString(R.string.logging_davdroid_file_logging))
+                    .setLocalOnly(true);
+
+            File dir = getExternalFilesDir(null);
+            if (dir != null)
+                try {
+                    String fileName = new File(dir, "davdroid-" + android.os.Process.myPid() + "-" +
+                            DateFormatUtils.format(System.currentTimeMillis(), "yyyyMMdd-HHmmss") + ".txt").toString();
+                    log.info("Logging to " + fileName);
+
+                    FileHandler fileHandler = new FileHandler(fileName);
+                    fileHandler.setFormatter(PlainTextFormatter.DEFAULT);
+                    log.addHandler(fileHandler);
+                    builder .setContentText(dir.getPath())
+                            .setSubText(getString(R.string.logging_to_external_storage_warning))
+                            .setCategory(NotificationCompat.CATEGORY_STATUS)
+                            .setPriority(NotificationCompat.PRIORITY_HIGH)
+                            .setStyle(new NotificationCompat.BigTextStyle()
+                                    .bigText(getString(R.string.logging_to_external_storage, dir.getPath())))
+                            .setOngoing(true);
+
+                } catch (IOException e) {
+                    log.log(Level.SEVERE, "Couldn't create external log file", e);
+
+                    builder .setContentText(getString(R.string.logging_couldnt_create_file, e.getLocalizedMessage()))
+                            .setCategory(NotificationCompat.CATEGORY_ERROR);
+                }
+            else
+                builder.setContentText(getString(R.string.logging_no_external_storage));
+
+            nm.notify(Constants.NOTIFICATION_EXTERNAL_FILE_LOGGING, builder.build());
+        } else
+            nm.cancel(Constants.NOTIFICATION_EXTERNAL_FILE_LOGGING);
+    }
+
+
+    public static class ReinitLoggingReceiver extends BroadcastReceiver {
+
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            log.info("Received broadcast: re-initializing logger");
+
+            App app = (App)context.getApplicationContext();
+            app.reinitLogger();
+        }
+
+    }
+}

app/src/main/java/at/bitfire/davdroid/ArrayUtils.java

@@ -1,10 +1,10 @@
-/*******************************************************************************
- * Copyright (c) 2014 Ricki Hirner (bitfire web engineering).
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the GNU Public License v3.0
  * which accompanies this distribution, and is available at
  * http://www.gnu.org/licenses/gpl.html
- ******************************************************************************/
+ */
 package at.bitfire.davdroid;
 
 import java.lang.reflect.Array;

app/src/main/java/at/bitfire/davdroid/Constants.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+package at.bitfire.davdroid;
+
+import android.net.Uri;
+
+public class Constants {
+
+	public static final String
+		ACCOUNT_TYPE = "bitfire.at.davdroid";
+
+    // notification IDs
+    public final static int
+            NOTIFICATION_ACCOUNT_SETTINGS_UPDATED = 0,
+            NOTIFICATION_EXTERNAL_FILE_LOGGING = 1,
+            NOTIFICATION_REFRESH_COLLECTIONS = 2,
+            NOTIFICATION_CONTACTS_SYNC = 10,
+            NOTIFICATION_CALENDAR_SYNC = 11,
+            NOTIFICATION_TASK_SYNC = 12,
+            NOTIFICATION_PERMISSIONS = 20;
+
+    public static final Uri webUri = Uri.parse("https://davdroid.bitfire.at/?pk_campaign=davdroid-app");
+
+}

app/src/main/java/at/bitfire/davdroid/DavService.java

@@ -0,0 +1,427 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid;
+
+import android.accounts.Account;
+import android.accounts.AccountManager;
+import android.app.Notification;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.app.Service;
+import android.content.ContentValues;
+import android.content.Intent;
+import android.database.Cursor;
+import android.database.DatabaseUtils;
+import android.database.sqlite.SQLiteDatabase;
+import android.graphics.drawable.BitmapDrawable;
+import android.os.Binder;
+import android.os.IBinder;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.v7.app.NotificationCompat;
+import android.text.TextUtils;
+
+import org.apache.commons.collections4.iterators.IteratorChain;
+import org.apache.commons.collections4.iterators.SingletonIterator;
+
+import java.io.IOException;
+import java.lang.ref.WeakReference;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.logging.Level;
+
+import at.bitfire.dav4android.DavResource;
+import at.bitfire.dav4android.UrlUtils;
+import at.bitfire.dav4android.exception.DavException;
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.dav4android.property.AddressbookHomeSet;
+import at.bitfire.dav4android.property.CalendarHomeSet;
+import at.bitfire.dav4android.property.CalendarProxyReadFor;
+import at.bitfire.dav4android.property.CalendarProxyWriteFor;
+import at.bitfire.dav4android.property.GroupMembership;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.davdroid.model.ServiceDB.Collections;
+import at.bitfire.davdroid.model.ServiceDB.HomeSets;
+import at.bitfire.davdroid.model.ServiceDB.OpenHelper;
+import at.bitfire.davdroid.model.ServiceDB.Services;
+import at.bitfire.davdroid.ui.DebugInfoActivity;
+import lombok.Cleanup;
+import okhttp3.HttpUrl;
+import okhttp3.OkHttpClient;
+
+public class DavService extends Service {
+
+    public static final String
+            ACTION_ACCOUNTS_UPDATED = "accountsUpdated",
+            ACTION_REFRESH_COLLECTIONS = "refreshCollections",
+            EXTRA_DAV_SERVICE_ID = "davServiceID";
+
+    private final IBinder binder = new InfoBinder();
+
+    private final Set<Long> runningRefresh = new HashSet<>();
+    private final List<WeakReference<RefreshingStatusListener>> refreshingStatusListeners = new LinkedList<>();
+
+
+    @Override
+    public int onStartCommand(Intent intent, int flags, int startId) {
+        if (intent != null) {
+            String action = intent.getAction();
+            long id = intent.getLongExtra(EXTRA_DAV_SERVICE_ID, -1);
+
+            switch (action) {
+                case ACTION_ACCOUNTS_UPDATED:
+                    cleanupAccounts();
+                    break;
+                case ACTION_REFRESH_COLLECTIONS:
+                    if (runningRefresh.add(id)) {
+                        new Thread(new RefreshCollections(id)).start();
+                        for (WeakReference<RefreshingStatusListener> ref : refreshingStatusListeners) {
+                            RefreshingStatusListener listener = ref.get();
+                            if (listener != null)
+                                listener.onDavRefreshStatusChanged(id, true);
+                        }
+                    }
+                    break;
+            }
+        }
+
+        return START_NOT_STICKY;
+    }
+
+
+    /* BOUND SERVICE PART
+       for communicating with the activities
+    */
+
+    @Override
+    public IBinder onBind(Intent intent) {
+        return binder;
+    }
+
+    public interface RefreshingStatusListener {
+        void onDavRefreshStatusChanged(long id, boolean refreshing);
+    }
+
+    public class InfoBinder extends Binder {
+        public boolean isRefreshing(long id) {
+            return runningRefresh.contains(id);
+        }
+
+        public void addRefreshingStatusListener(@NonNull RefreshingStatusListener listener, boolean callImmediate) {
+            refreshingStatusListeners.add(new WeakReference<>(listener));
+            if (callImmediate)
+                for (long id : runningRefresh)
+                    listener.onDavRefreshStatusChanged(id, true);
+        }
+
+        public void removeRefreshingStatusListener(@NonNull RefreshingStatusListener listener) {
+            for (Iterator<WeakReference<RefreshingStatusListener>> iterator = refreshingStatusListeners.iterator(); iterator.hasNext(); ) {
+                RefreshingStatusListener item = iterator.next().get();
+                if (listener.equals(item))
+                    iterator.remove();
+            }
+        }
+    }
+
+
+    /* ACTION RUNNABLES
+       which actually do the work
+     */
+
+    void cleanupAccounts() {
+        App.log.info("Cleaning up orphaned accounts");
+
+        final OpenHelper dbHelper = new OpenHelper(this);
+        try {
+            SQLiteDatabase db = dbHelper.getWritableDatabase();
+
+            List<String> sqlAccountNames = new LinkedList<>();
+            AccountManager am = AccountManager.get(this);
+            for (Account account : am.getAccountsByType(Constants.ACCOUNT_TYPE))
+                sqlAccountNames.add(DatabaseUtils.sqlEscapeString(account.name));
+
+            if (sqlAccountNames.isEmpty())
+                db.delete(Services._TABLE, null, null);
+            else
+                db.delete(Services._TABLE, Services.ACCOUNT_NAME + " NOT IN (" + TextUtils.join(",", sqlAccountNames) + ")", null);
+        } finally {
+            dbHelper.close();
+        }
+    }
+
+    private class RefreshCollections implements Runnable {
+        final long service;
+        final OpenHelper dbHelper;
+        SQLiteDatabase db;
+
+        RefreshCollections(long davServiceId) {
+            this.service = davServiceId;
+            dbHelper = new OpenHelper(DavService.this);
+        }
+
+        @Override
+        public void run() {
+            Account account = null;
+
+            try {
+                db = dbHelper.getWritableDatabase();
+
+                String serviceType = serviceType();
+                App.log.info("Refreshing " + serviceType + " collections of service #" + service);
+
+                // get account
+                account = account();
+
+                // create authenticating OkHttpClient (credentials taken from account settings)
+                OkHttpClient httpClient = HttpClient.create(DavService.this, account);
+
+                // refresh home sets: principal
+                Set<HttpUrl> homeSets = readHomeSets();
+                HttpUrl principal = readPrincipal();
+                if (principal != null) {
+                    App.log.fine("Querying principal for home sets");
+                    DavResource dav = new DavResource(httpClient, principal);
+                    queryHomeSets(serviceType, dav, homeSets);
+
+                    // refresh home sets: calendar-proxy-read/write-for
+                    CalendarProxyReadFor proxyRead = (CalendarProxyReadFor)dav.properties.get(CalendarProxyReadFor.NAME);
+                    if (proxyRead != null)
+                        for (String href : proxyRead.principals) {
+                            App.log.fine("Principal is a read-only proxy for " + href + ", checking for home sets");
+                            queryHomeSets(serviceType, new DavResource(httpClient, dav.location.resolve(href)), homeSets);
+                        }
+                    CalendarProxyWriteFor proxyWrite = (CalendarProxyWriteFor)dav.properties.get(CalendarProxyWriteFor.NAME);
+                    if (proxyWrite != null)
+                        for (String href : proxyWrite.principals) {
+                            App.log.fine("Principal is a read-write proxy for " + href + ", checking for home sets");
+                            queryHomeSets(serviceType, new DavResource(httpClient, dav.location.resolve(href)), homeSets);
+                        }
+
+                    // refresh home sets: direct group memberships
+                    GroupMembership groupMembership = (GroupMembership)dav.properties.get(GroupMembership.NAME);
+                    if (groupMembership != null)
+                        for (String href : groupMembership.hrefs) {
+                            App.log.fine("Principal is member of group " + href + ", checking for home sets");
+                            DavResource group = new DavResource(httpClient, dav.location.resolve(href));
+                            try {
+                                queryHomeSets(serviceType, group, homeSets);
+                            } catch(HttpException|DavException e) {
+                                App.log.log(Level.WARNING, "Couldn't query member group ", e);
+                            }
+                        }
+                }
+
+                // now refresh collections (taken from home sets)
+                Map<HttpUrl, CollectionInfo> collections = readCollections();
+
+                // (remember selections before)
+                Set<HttpUrl> selectedCollections = new HashSet<>();
+                for (CollectionInfo info : collections.values())
+                    if (info.selected)
+                        selectedCollections.add(HttpUrl.parse(info.url));
+
+                for (Iterator<HttpUrl> itHomeSets = homeSets.iterator(); itHomeSets.hasNext(); ) {
+                    HttpUrl homeSet = itHomeSets.next();
+                    App.log.fine("Listing home set " + homeSet);
+
+                    DavResource dav = new DavResource(httpClient, homeSet);
+                    try {
+                        dav.propfind(1, CollectionInfo.DAV_PROPERTIES);
+                        IteratorChain<DavResource> itCollections = new IteratorChain<>(dav.members.iterator(), new SingletonIterator(dav));
+                        while (itCollections.hasNext()) {
+                            DavResource member = itCollections.next();
+                            CollectionInfo info = CollectionInfo.fromDavResource(member);
+                            info.confirmed = true;
+                            App.log.log(Level.FINE, "Found collection", info);
+
+                            if ((serviceType.equals(Services.SERVICE_CARDDAV) && info.type == CollectionInfo.Type.ADDRESS_BOOK) ||
+                                (serviceType.equals(Services.SERVICE_CALDAV) && info.type == CollectionInfo.Type.CALENDAR))
+                                collections.put(member.location, info);
+                        }
+                    } catch(HttpException e) {
+                        if (e.status == 403 || e.status == 404 || e.status == 410)
+                            // delete home set only if it was not accessible (40x)
+                            itHomeSets.remove();
+                    }
+                }
+
+                // check/refresh unconfirmed collections
+                for (Iterator<Map.Entry<HttpUrl, CollectionInfo>> iterator = collections.entrySet().iterator(); iterator.hasNext(); ) {
+                    Map.Entry<HttpUrl, CollectionInfo> entry = iterator.next();
+                    HttpUrl url = entry.getKey();
+                    CollectionInfo info = entry.getValue();
+
+                    if (!info.confirmed)
+                        try {
+                            DavResource dav = new DavResource(httpClient, url);
+                            dav.propfind(0, CollectionInfo.DAV_PROPERTIES);
+                            info = CollectionInfo.fromDavResource(dav);
+                            info.confirmed = true;
+
+                            // remove unusable collections
+                            if ((serviceType.equals(Services.SERVICE_CARDDAV) && info.type != CollectionInfo.Type.ADDRESS_BOOK) ||
+                                (serviceType.equals(Services.SERVICE_CALDAV) && info.type != CollectionInfo.Type.CALENDAR))
+                                iterator.remove();
+                        } catch(HttpException e) {
+                            if (e.status == 403 || e.status == 404 || e.status == 410)
+                                // delete collection only if it was not accessible (40x)
+                                iterator.remove();
+                            else
+                                throw e;
+                        }
+                }
+
+                // restore selections
+                for (HttpUrl url : selectedCollections) {
+                    CollectionInfo info = collections.get(url);
+                    if (info != null)
+                        info.selected = true;
+                }
+
+                try {
+                    db.beginTransactionNonExclusive();
+                    saveHomeSets(homeSets);
+                    saveCollections(collections.values());
+                    db.setTransactionSuccessful();
+                } finally {
+                    db.endTransaction();
+                }
+
+            } catch(InvalidAccountException e) {
+                App.log.log(Level.SEVERE, "Invalid account", e);
+            } catch(IOException|HttpException|DavException e) {
+                App.log.log(Level.SEVERE, "Couldn't refresh collection list", e);
+
+                Intent debugIntent = new Intent(DavService.this, DebugInfoActivity.class);
+                debugIntent.putExtra(DebugInfoActivity.KEY_THROWABLE, e);
+                if (account != null)
+                    debugIntent.putExtra(DebugInfoActivity.KEY_ACCOUNT, account);
+
+                NotificationManager nm = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
+                Notification notify = new NotificationCompat.Builder(DavService.this)
+                        .setSmallIcon(R.drawable.ic_error_light)
+                        .setLargeIcon(((BitmapDrawable)getResources().getDrawable(R.drawable.ic_launcher)).getBitmap())
+                        .setContentTitle(getString(R.string.dav_service_refresh_failed))
+                        .setContentText(getString(R.string.dav_service_refresh_couldnt_refresh))
+                        .setContentIntent(PendingIntent.getActivity(DavService.this, 0, debugIntent, PendingIntent.FLAG_UPDATE_CURRENT))
+                        .build();
+                nm.notify(Constants.NOTIFICATION_REFRESH_COLLECTIONS, notify);
+            } finally {
+                dbHelper.close();
+
+                runningRefresh.remove(service);
+                for (WeakReference<RefreshingStatusListener> ref : refreshingStatusListeners) {
+                    RefreshingStatusListener listener = ref.get();
+                    if (listener != null)
+                        listener.onDavRefreshStatusChanged(service, false);
+                }
+            }
+        }
+
+        /**
+         * Checks if the given URL defines home sets and adds them to the home set list.
+         * @param serviceType       CalDAV/CardDAV (calendar home set / addressbook home set)
+         * @param dav               DavResource to check
+         * @param homeSets          set where found home set URLs will be put into
+         */
+        private void queryHomeSets(String serviceType, DavResource dav, Set<HttpUrl> homeSets) throws IOException, HttpException, DavException {
+            if (Services.SERVICE_CARDDAV.equals(serviceType)) {
+                dav.propfind(0, AddressbookHomeSet.NAME, GroupMembership.NAME);
+                AddressbookHomeSet addressbookHomeSet = (AddressbookHomeSet)dav.properties.get(AddressbookHomeSet.NAME);
+                if (addressbookHomeSet != null)
+                    for (String href : addressbookHomeSet.hrefs)
+                        homeSets.add(UrlUtils.withTrailingSlash(dav.location.resolve(href)));
+            } else if (Services.SERVICE_CALDAV.equals(serviceType)) {
+                dav.propfind(0, CalendarHomeSet.NAME, CalendarProxyReadFor.NAME, CalendarProxyWriteFor.NAME, GroupMembership.NAME);
+                CalendarHomeSet calendarHomeSet = (CalendarHomeSet)dav.properties.get(CalendarHomeSet.NAME);
+                if (calendarHomeSet != null)
+                    for (String href : calendarHomeSet.hrefs)
+                        homeSets.add(UrlUtils.withTrailingSlash(dav.location.resolve(href)));
+            }
+        }
+
+
+        @NonNull
+        private Account account() {
+            @Cleanup Cursor cursor = db.query(Services._TABLE, new String[] { Services.ACCOUNT_NAME }, Services.ID + "=?", new String[] { String.valueOf(service) }, null, null, null);
+            if (cursor.moveToNext()) {
+                return new Account(cursor.getString(0), Constants.ACCOUNT_TYPE);
+            } else
+                throw new IllegalArgumentException("Service not found");
+        }
+
+        @NonNull
+        private String serviceType() {
+            @Cleanup Cursor cursor = db.query(Services._TABLE, new String[] { Services.SERVICE }, Services.ID + "=?", new String[] { String.valueOf(service) }, null, null, null);
+            if (cursor.moveToNext())
+                return cursor.getString(0);
+            else
+                throw new IllegalArgumentException("Service not found");
+        }
+
+        @Nullable
+        private HttpUrl readPrincipal() {
+            @Cleanup Cursor cursor = db.query(Services._TABLE, new String[] { Services.PRINCIPAL }, Services.ID + "=?", new String[] { String.valueOf(service) }, null, null, null);
+            if (cursor.moveToNext()) {
+                String principal = cursor.getString(0);
+                if (principal != null)
+                    return HttpUrl.parse(cursor.getString(0));
+            }
+            return null;
+        }
+
+        @NonNull
+        private Set<HttpUrl> readHomeSets() {
+            Set<HttpUrl> homeSets = new LinkedHashSet<>();
+            @Cleanup Cursor cursor = db.query(HomeSets._TABLE, new String[] { HomeSets.URL }, HomeSets.SERVICE_ID + "=?", new String[] { String.valueOf(service) }, null, null, null);
+            while (cursor.moveToNext())
+                homeSets.add(HttpUrl.parse(cursor.getString(0)));
+            return homeSets;
+        }
+
+        private void saveHomeSets(Set<HttpUrl> homeSets) {
+            db.delete(HomeSets._TABLE, HomeSets.SERVICE_ID + "=?", new String[] { String.valueOf(service) });
+            for (HttpUrl homeSet : homeSets) {
+                ContentValues values = new ContentValues(1);
+                values.put(HomeSets.SERVICE_ID, service);
+                values.put(HomeSets.URL, homeSet.toString());
+                db.insertOrThrow(HomeSets._TABLE, null, values);
+            }
+        }
+
+        @NonNull
+        private Map<HttpUrl, CollectionInfo> readCollections() {
+            Map<HttpUrl, CollectionInfo> collections = new LinkedHashMap<>();
+            @Cleanup Cursor cursor = db.query(Collections._TABLE, null, Collections.SERVICE_ID + "=?", new String[]{String.valueOf(service)}, null, null, null);
+            while (cursor.moveToNext()) {
+                ContentValues values = new ContentValues();
+                DatabaseUtils.cursorRowToContentValues(cursor, values);
+                collections.put(HttpUrl.parse(values.getAsString(Collections.URL)), CollectionInfo.fromDB(values));
+            }
+            return collections;
+        }
+
+        private void saveCollections(Iterable<CollectionInfo> collections) {
+            db.delete(Collections._TABLE, HomeSets.SERVICE_ID + "=?", new String[] { String.valueOf(service) });
+            for (CollectionInfo collection : collections) {
+                ContentValues values = collection.toDB();
+                App.log.log(Level.FINE, "Saving collection", values);
+                values.put(Collections.SERVICE_ID, service);
+                db.insertWithOnConflict(Collections._TABLE, null, values, SQLiteDatabase.CONFLICT_REPLACE);
+            }
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/DavUtils.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid;
+
+import android.support.annotation.NonNull;
+
+import org.apache.commons.lang3.StringUtils;
+
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+
+import okhttp3.HttpUrl;
+
+public class DavUtils {
+
+    public static String ARGBtoCalDAVColor(int colorWithAlpha) {
+        byte alpha = (byte)(colorWithAlpha >> 24);
+        int color = colorWithAlpha & 0xFFFFFF;
+        return String.format("#%06X%02X", color, alpha);
+    }
+
+    public static String lastSegmentOfUrl(@NonNull String url) {
+        // the list returned by HttpUrl.pathSegments() is unmodifiable, so we have to create a copy
+        List<String> segments = new LinkedList<>(HttpUrl.parse(url).pathSegments());
+        Collections.reverse(segments);
+
+        for (String segment : segments)
+            if (!StringUtils.isEmpty(segment))
+                return segment;
+
+        return "/";
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/HttpClient.java

@@ -0,0 +1,157 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid;
+
+import android.accounts.Account;
+import android.content.Context;
+import android.os.Build;
+import android.support.annotation.NonNull;
+
+import java.io.IOException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.Locale;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import at.bitfire.dav4android.BasicDigestAuthenticator;
+import lombok.RequiredArgsConstructor;
+import okhttp3.Credentials;
+import okhttp3.Interceptor;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+import okhttp3.logging.HttpLoggingInterceptor;
+
+public class HttpClient {
+    private static final OkHttpClient client = new OkHttpClient();
+    private static final UserAgentInterceptor userAgentInterceptor = new UserAgentInterceptor();
+
+    private static final String userAgent;
+    static {
+        String date = new SimpleDateFormat("yyyy/MM/dd", Locale.US).format(new Date(BuildConfig.buildTime));
+        userAgent = "DAVdroid/" + BuildConfig.VERSION_NAME + " (" + date + "; dav4android; okhttp3) Android/" + Build.VERSION.RELEASE;
+    }
+
+    private HttpClient() {
+    }
+
+    public static OkHttpClient create(@NonNull Context context, @NonNull Account account, @NonNull final Logger logger) throws InvalidAccountException {
+        OkHttpClient.Builder builder = defaultBuilder(logger);
+
+        // use account settings for authentication and logging
+        AccountSettings settings = new AccountSettings(context, account);
+
+        if (settings.preemptiveAuth())
+            builder.addNetworkInterceptor(new PreemptiveAuthenticationInterceptor(settings.username(), settings.password()));
+        else
+            builder.authenticator(new BasicDigestAuthenticator(null, settings.username(), settings.password()));
+
+        return builder.build();
+    }
+
+    public static OkHttpClient create(@NonNull Logger logger) {
+        return defaultBuilder(logger).build();
+    }
+
+    public static OkHttpClient create(@NonNull Context context, @NonNull Account account) throws InvalidAccountException {
+        return create(context, account, App.log);
+    }
+
+    public static OkHttpClient create() {
+        return create(App.log);
+    }
+
+    private static OkHttpClient.Builder defaultBuilder(@NonNull final Logger logger) {
+        OkHttpClient.Builder builder = client.newBuilder();
+
+        // use MemorizingTrustManager to manage self-signed certificates
+        if (App.getSslSocketFactoryCompat() != null)
+            builder.sslSocketFactory(App.getSslSocketFactoryCompat(), App.getMemorizingTrustManager());
+        if (App.getHostnameVerifier() != null)
+            builder.hostnameVerifier(App.getHostnameVerifier());
+
+        // set timeouts
+        builder.connectTimeout(30, TimeUnit.SECONDS);
+        builder.writeTimeout(30, TimeUnit.SECONDS);
+        builder.readTimeout(120, TimeUnit.SECONDS);
+
+        // don't allow redirects, because it would break PROPFIND handling
+        builder.followRedirects(false);
+
+        // add User-Agent to every request
+        builder.addNetworkInterceptor(userAgentInterceptor);
+
+        // add cookie store for non-persistent cookies (some services like Horde use cookies for session tracking)
+        builder.cookieJar(new MemoryCookieStore());
+
+        // add network logging, if requested
+        if (logger.isLoggable(Level.FINEST)) {
+            HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor(new HttpLoggingInterceptor.Logger() {
+                @Override
+                public void log(String message) {
+                    logger.finest(message);
+                }
+            });
+            loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
+            builder.addInterceptor(loggingInterceptor);
+        }
+
+        return builder;
+    }
+
+    private static OkHttpClient.Builder addAuthentication(@NonNull OkHttpClient.Builder builder, @NonNull String username, @NonNull String password, boolean preemptive) {
+        if (preemptive)
+            builder.addNetworkInterceptor(new PreemptiveAuthenticationInterceptor(username, password));
+        else
+            builder.authenticator(new BasicDigestAuthenticator(null, username, password));
+        return builder;
+    }
+
+    public static OkHttpClient addAuthentication(@NonNull OkHttpClient client, @NonNull String username, @NonNull String password, boolean preemptive) {
+        OkHttpClient.Builder builder = client.newBuilder();
+        addAuthentication(builder, username, password, preemptive);
+        return builder.build();
+    }
+
+    public static OkHttpClient addAuthentication(@NonNull OkHttpClient client, @NonNull String host, @NonNull String username, @NonNull String password) {
+        return client.newBuilder()
+                .authenticator(new BasicDigestAuthenticator(host, username, password))
+                .build();
+    }
+
+
+    static class UserAgentInterceptor implements Interceptor {
+        @Override
+        public Response intercept(Chain chain) throws IOException {
+            Locale locale = Locale.getDefault();
+            Request request = chain.request().newBuilder()
+                    .header("User-Agent", userAgent)
+                    .header("Accept-Language", locale.getLanguage() + "-" + locale.getCountry() + ", " + locale.getLanguage() + ";q=0.7, *;q=0.5")
+                    .build();
+            return chain.proceed(request);
+        }
+    }
+
+    @RequiredArgsConstructor
+    static class PreemptiveAuthenticationInterceptor implements Interceptor {
+        final String username, password;
+
+        @Override
+        public Response intercept(Chain chain) throws IOException {
+            App.log.fine("Adding basic authorization header for user " + username);
+            Request request = chain.request().newBuilder()
+                    .header("Authorization", Credentials.basic(username, password))
+                    .build();
+            return chain.proceed(request);
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/InvalidAccountException.java

@@ -0,0 +1,19 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid;
+
+import android.accounts.Account;
+
+public class InvalidAccountException extends Exception {
+
+    public InvalidAccountException(Account account) {
+        super("Invalid account: " + account);
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/MemoryCookieStore.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid;
+
+import org.apache.commons.collections4.MapIterator;
+import org.apache.commons.collections4.keyvalue.MultiKey;
+import org.apache.commons.collections4.map.HashedMap;
+import org.apache.commons.collections4.map.MultiKeyMap;
+
+import java.util.LinkedList;
+import java.util.List;
+
+import okhttp3.Cookie;
+import okhttp3.CookieJar;
+import okhttp3.HttpUrl;
+
+/**
+ * Primitive cookie store that stores cookies in a (volatile) hash map.
+ * Will be sufficient for session cookies.
+ */
+public class MemoryCookieStore implements CookieJar {
+
+    /**
+     * Stored cookies. The multi-key consists of three parts: name, domain, and path.
+     * This ensures that cookies can be overwritten. [RFC 6265 5.3 Storage Model]
+     * Not thread-safe!
+     */
+    protected final MultiKeyMap<String, Cookie> storage = MultiKeyMap.multiKeyMap(new HashedMap<MultiKey<? extends String>, Cookie>());
+
+    @Override
+    public void saveFromResponse(HttpUrl url, List<Cookie> cookies) {
+        synchronized(storage) {
+            for (Cookie cookie : cookies)
+                storage.put(cookie.name(), cookie.domain(), cookie.path(), cookie);
+        }
+    }
+
+    @Override
+    public List<Cookie> loadForRequest(HttpUrl url) {
+        List<Cookie> cookies = new LinkedList<>();
+
+        synchronized(storage) {
+            MapIterator<MultiKey<? extends String>, Cookie> iter = storage.mapIterator();
+            while (iter.hasNext()) {
+                iter.next();
+                Cookie cookie = iter.getValue();
+
+                // remove expired cookies
+                if (cookie.expiresAt() <= System.currentTimeMillis()) {
+                    iter.remove();
+                    continue;
+                }
+
+                // add applicable cookies
+                if (cookie.matches(url))
+                    cookies.add(cookie);
+            }
+        }
+
+        return cookies;
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/SSLSocketFactoryCompat.java

@@ -0,0 +1,171 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid;
+
+import android.os.Build;
+import android.support.annotation.NonNull;
+import android.text.TextUtils;
+
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.Socket;
+import java.security.GeneralSecurityException;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Locale;
+
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLSocket;
+import javax.net.ssl.SSLSocketFactory;
+import javax.net.ssl.X509TrustManager;
+
+import de.duenndns.ssl.MemorizingTrustManager;
+import lombok.Cleanup;
+
+public class SSLSocketFactoryCompat extends SSLSocketFactory {
+
+    private SSLSocketFactory delegate;
+
+    // Android 5.0+ (API level21) provides reasonable default settings
+    // but it still allows SSLv3
+    // https://developer.android.com/reference/javax/net/ssl/SSLSocket.html
+    static String protocols[] = null, cipherSuites[] = null;
+    static {
+        try {
+            @Cleanup SSLSocket socket = (SSLSocket)SSLSocketFactory.getDefault().createSocket();
+            if (socket != null) {
+                /* set reasonable protocol versions */
+                // - enable all supported protocols (enables TLSv1.1 and TLSv1.2 on Android <5.0)
+                // - remove all SSL versions (especially SSLv3) because they're insecure now
+                List<String> protocols = new LinkedList<>();
+                for (String protocol : socket.getSupportedProtocols())
+                    if (!protocol.toUpperCase(Locale.US).contains("SSL"))
+                        protocols.add(protocol);
+                App.log.info("Setting allowed TLS protocols: " + TextUtils.join(", ", protocols));
+                SSLSocketFactoryCompat.protocols = protocols.toArray(new String[protocols.size()]);
+
+                /* set up reasonable cipher suites */
+                if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
+                    // choose known secure cipher suites
+                    List<String> allowedCiphers = Arrays.asList(
+                            // TLS 1.2
+                            "TLS_RSA_WITH_AES_256_GCM_SHA384",
+                            "TLS_RSA_WITH_AES_128_GCM_SHA256",
+                            "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256",
+                            "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256",
+                            "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384",
+                            "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256",
+                            "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256",
+                            // maximum interoperability
+                            "TLS_RSA_WITH_3DES_EDE_CBC_SHA",
+                            "TLS_RSA_WITH_AES_128_CBC_SHA",
+                            // additionally
+                            "TLS_RSA_WITH_AES_256_CBC_SHA",
+                            "TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA",
+                            "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA",
+                            "TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA",
+                            "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA");
+                    List<String> availableCiphers = Arrays.asList(socket.getSupportedCipherSuites());
+                    App.log.info("Available cipher suites: " + TextUtils.join(", ", availableCiphers));
+                    App.log.info("Cipher suites enabled by default: " + TextUtils.join(", ", socket.getEnabledCipherSuites()));
+
+                    // take all allowed ciphers that are available and put them into preferredCiphers
+                    HashSet<String> preferredCiphers = new HashSet<>(allowedCiphers);
+                    preferredCiphers.retainAll(availableCiphers);
+
+                    /* For maximum security, preferredCiphers should *replace* enabled ciphers (thus disabling
+                     * ciphers which are enabled by default, but have become unsecure), but I guess for
+                     * the security level of DAVdroid and maximum compatibility, disabling of insecure
+                     * ciphers should be a server-side task */
+
+                    // add preferred ciphers to enabled ciphers
+                    HashSet<String> enabledCiphers = preferredCiphers;
+                    enabledCiphers.addAll(new HashSet<>(Arrays.asList(socket.getEnabledCipherSuites())));
+
+                    App.log.info("Enabling (only) those TLS ciphers: " + TextUtils.join(", ", enabledCiphers));
+                    SSLSocketFactoryCompat.cipherSuites = enabledCiphers.toArray(new String[enabledCiphers.size()]);
+                }
+            }
+        } catch (IOException e) {
+            App.log.severe("Couldn't determine default TLS settings");
+        }
+    }
+
+    public SSLSocketFactoryCompat(@NonNull MemorizingTrustManager mtm) {
+        try {
+            SSLContext sslContext = SSLContext.getInstance("TLS");
+            sslContext.init(null, new X509TrustManager[] { mtm }, null);
+            delegate = sslContext.getSocketFactory();
+        } catch (GeneralSecurityException e) {
+            throw new AssertionError(); // The system has no TLS. Just give up.
+        }
+    }
+
+    private void upgradeTLS(SSLSocket ssl) {
+        if (protocols != null)
+            ssl.setEnabledProtocols(protocols);
+
+        if (cipherSuites != null)
+            ssl.setEnabledCipherSuites(cipherSuites);
+    }
+
+
+    @Override
+    public String[] getDefaultCipherSuites() {
+        return cipherSuites;
+    }
+
+    @Override
+    public String[] getSupportedCipherSuites() {
+        return cipherSuites;
+    }
+
+    @Override
+    public Socket createSocket(Socket s, String host, int port, boolean autoClose) throws IOException {
+        Socket ssl = delegate.createSocket(s, host, port, autoClose);
+        if (ssl instanceof SSLSocket)
+            upgradeTLS((SSLSocket)ssl);
+        return ssl;
+    }
+
+    @Override
+    public Socket createSocket(String host, int port) throws IOException {
+        Socket ssl = delegate.createSocket(host, port);
+        if (ssl instanceof SSLSocket)
+            upgradeTLS((SSLSocket)ssl);
+        return ssl;
+    }
+
+    @Override
+    public Socket createSocket(String host, int port, InetAddress localHost, int localPort) throws IOException {
+        Socket ssl = delegate.createSocket(host, port, localHost, localPort);
+        if (ssl instanceof SSLSocket)
+            upgradeTLS((SSLSocket)ssl);
+        return ssl;
+    }
+
+    @Override
+    public Socket createSocket(InetAddress host, int port) throws IOException {
+        Socket ssl = delegate.createSocket(host, port);
+        if (ssl instanceof SSLSocket)
+            upgradeTLS((SSLSocket)ssl);
+        return ssl;
+    }
+
+    @Override
+    public Socket createSocket(InetAddress address, int port, InetAddress localAddress, int localPort) throws IOException {
+        Socket ssl = delegate.createSocket(address, port, localAddress, localPort);
+        if (ssl instanceof SSLSocket)
+            upgradeTLS((SSLSocket)ssl);
+        return ssl;
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/log/LogcatHandler.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.log;
+
+import android.util.Log;
+
+import org.apache.commons.lang3.math.NumberUtils;
+
+import java.util.logging.Handler;
+import java.util.logging.Level;
+import java.util.logging.LogRecord;
+
+public class LogcatHandler extends Handler {
+    private static final int MAX_LINE_LENGTH = 3000;
+    public static final LogcatHandler INSTANCE = new LogcatHandler();
+
+    private LogcatHandler() {
+        super();
+        setFormatter(PlainTextFormatter.LOGCAT);
+        setLevel(Level.ALL);
+    }
+
+    @Override
+    public void publish(LogRecord r) {
+        String text = getFormatter().format(r);
+        int level = r.getLevel().intValue();
+
+        int end = text.length();
+        for (int pos = 0; pos < end; pos += MAX_LINE_LENGTH) {
+            String line = text.substring(pos, NumberUtils.min(pos + MAX_LINE_LENGTH, end));
+
+            if (level >= Level.SEVERE.intValue())
+                Log.e(r.getLoggerName(), line);
+            else if (level >= Level.WARNING.intValue())
+                Log.w(r.getLoggerName(), line);
+            else if (level >= Level.CONFIG.intValue())
+                Log.i(r.getLoggerName(), line);
+            else if (level >= Level.FINER.intValue())
+                Log.d(r.getLoggerName(), line);
+            else
+                Log.v(r.getLoggerName(), line);
+        }
+    }
+
+    @Override
+    public void flush() {
+    }
+
+    @Override
+    public void close() {
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/log/PlainTextFormatter.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.log;
+
+import org.apache.commons.lang3.StringUtils;
+import org.apache.commons.lang3.exception.ExceptionUtils;
+import org.apache.commons.lang3.time.DateFormatUtils;
+
+import java.util.logging.Formatter;
+import java.util.logging.LogRecord;
+
+public class PlainTextFormatter extends Formatter {
+    public final static PlainTextFormatter
+            LOGCAT = new PlainTextFormatter(true),
+            DEFAULT = new PlainTextFormatter(false);
+
+    private final boolean logcat;
+
+    private PlainTextFormatter(boolean onLogcat) {
+        this.logcat = onLogcat;
+    }
+
+    @Override
+    @SuppressWarnings("ThrowableResultOfMethodCallIgnored")
+    public String format(LogRecord r) {
+        StringBuilder builder = new StringBuilder();
+
+        if (!logcat)
+            builder .append(DateFormatUtils.format(r.getMillis(), "yyyy-MM-dd HH:mm:ss"))
+                    .append(" ").append(r.getThreadID()).append(" ");
+
+        builder.append(String.format("[%s] %s", shortClassName(r.getSourceClassName()), r.getMessage()));
+
+        if (r.getThrown() != null)
+            builder .append("\nEXCEPTION ")
+                    .append(ExceptionUtils.getStackTrace(r.getThrown()));
+
+        if (r.getParameters() != null) {
+            int idx = 1;
+            for (Object param : r.getParameters())
+                builder.append("\n\tPARAMETER #").append(idx++).append(" = ").append(param);
+        }
+
+        if (!logcat)
+            builder.append("\n");
+
+        return builder.toString();
+    }
+
+    private String shortClassName(String className) {
+        String s = StringUtils.replace(className, "at.bitfire.davdroid.", "");
+        return StringUtils.replace(s, "at.bitfire.", "");
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/log/StringHandler.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.log;
+
+import java.util.logging.Handler;
+import java.util.logging.LogRecord;
+
+public class StringHandler extends Handler {
+
+    StringBuilder builder = new StringBuilder();
+
+    public StringHandler() {
+        super();
+        setFormatter(PlainTextFormatter.DEFAULT);
+    }
+
+    @Override
+    public void publish(LogRecord record) {
+        builder.append(getFormatter().format(record));
+    }
+
+    @Override
+    public void flush() {
+    }
+
+    @Override
+    public void close() {
+    }
+
+    @Override
+    public String toString() {
+        return builder.toString();
+    }
+}

app/src/main/java/at/bitfire/davdroid/model/CollectionInfo.java

@@ -0,0 +1,163 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.model;
+
+import android.content.ContentValues;
+
+import org.apache.commons.lang3.StringUtils;
+
+import java.io.Serializable;
+
+import at.bitfire.dav4android.DavResource;
+import at.bitfire.dav4android.Property;
+import at.bitfire.dav4android.property.AddressbookDescription;
+import at.bitfire.dav4android.property.CalendarColor;
+import at.bitfire.dav4android.property.CalendarDescription;
+import at.bitfire.dav4android.property.CalendarTimezone;
+import at.bitfire.dav4android.property.CurrentUserPrivilegeSet;
+import at.bitfire.dav4android.property.DisplayName;
+import at.bitfire.dav4android.property.ResourceType;
+import at.bitfire.dav4android.property.SupportedAddressData;
+import at.bitfire.dav4android.property.SupportedCalendarComponentSet;
+import at.bitfire.davdroid.model.ServiceDB.Collections;
+import lombok.ToString;
+
+@ToString
+public class CollectionInfo implements Serializable {
+    public long id;
+    public Long serviceID;
+
+    public enum Type {
+        ADDRESS_BOOK,
+        CALENDAR
+    }
+    public Type type;
+
+    public String url;
+
+    public boolean readOnly;
+    public String displayName, description;
+    public Integer color;
+
+    public String timeZone;
+    public Boolean supportsVEVENT;
+    public Boolean supportsVTODO;
+
+    public boolean selected;
+
+    // non-persistent properties
+    public boolean confirmed;
+
+
+    public static final Property.Name[] DAV_PROPERTIES = {
+            ResourceType.NAME,
+            CurrentUserPrivilegeSet.NAME,
+            DisplayName.NAME,
+            AddressbookDescription.NAME, SupportedAddressData.NAME,
+            CalendarDescription.NAME, CalendarColor.NAME, SupportedCalendarComponentSet.NAME
+    };
+
+    public static CollectionInfo fromDavResource(DavResource dav) {
+        CollectionInfo info = new CollectionInfo();
+        info.url = dav.location.toString();
+
+        ResourceType type = (ResourceType)dav.properties.get(ResourceType.NAME);
+        if (type != null) {
+            if (type.types.contains(ResourceType.ADDRESSBOOK))
+                info.type = Type.ADDRESS_BOOK;
+            else if (type.types.contains(ResourceType.CALENDAR))
+                info.type = Type.CALENDAR;
+        }
+
+        info.readOnly = false;
+        CurrentUserPrivilegeSet privilegeSet = (CurrentUserPrivilegeSet)dav.properties.get(CurrentUserPrivilegeSet.NAME);
+        if (privilegeSet != null)
+            info.readOnly = !privilegeSet.mayWriteContent;
+
+        DisplayName displayName = (DisplayName)dav.properties.get(DisplayName.NAME);
+        if (displayName != null && !StringUtils.isEmpty(displayName.displayName))
+            info.displayName = displayName.displayName;
+
+        if (info.type == Type.ADDRESS_BOOK) {
+            AddressbookDescription addressbookDescription = (AddressbookDescription)dav.properties.get(AddressbookDescription.NAME);
+            if (addressbookDescription != null)
+                info.description = addressbookDescription.description;
+
+        } else if (info.type == Type.CALENDAR) {
+            CalendarDescription calendarDescription = (CalendarDescription)dav.properties.get(CalendarDescription.NAME);
+            if (calendarDescription != null)
+                info.description = calendarDescription.description;
+
+            CalendarColor calendarColor = (CalendarColor)dav.properties.get(CalendarColor.NAME);
+            if (calendarColor != null)
+                info.color = calendarColor.color;
+
+            CalendarTimezone timeZone = (CalendarTimezone)dav.properties.get(CalendarTimezone.NAME);
+            if (timeZone != null)
+                info.timeZone = timeZone.vTimeZone;
+
+            info.supportsVEVENT = info.supportsVTODO = true;
+            SupportedCalendarComponentSet supportedCalendarComponentSet = (SupportedCalendarComponentSet)dav.properties.get(SupportedCalendarComponentSet.NAME);
+            if (supportedCalendarComponentSet != null) {
+                info.supportsVEVENT = supportedCalendarComponentSet.supportsEvents;
+                info.supportsVTODO = supportedCalendarComponentSet.supportsTasks;
+            }
+        }
+
+        return info;
+    }
+
+
+    public static CollectionInfo fromDB(ContentValues values) {
+        CollectionInfo info = new CollectionInfo();
+        info.id = values.getAsLong(Collections.ID);
+        info.serviceID = values.getAsLong(Collections.SERVICE_ID);
+
+        info.url = values.getAsString(Collections.URL);
+        info.readOnly = values.getAsInteger(Collections.READ_ONLY) != 0;
+        info.displayName = values.getAsString(Collections.DISPLAY_NAME);
+        info.description = values.getAsString(Collections.DESCRIPTION);
+
+        info.color = values.getAsInteger(Collections.COLOR);
+
+        info.timeZone = values.getAsString(Collections.TIME_ZONE);
+        info.supportsVEVENT = getAsBooleanOrNull(values, Collections.SUPPORTS_VEVENT);
+        info.supportsVTODO = getAsBooleanOrNull(values, Collections.SUPPORTS_VTODO);
+
+        info.selected = values.getAsInteger(Collections.SYNC) != 0;
+        return info;
+    }
+
+    public ContentValues toDB() {
+        ContentValues values = new ContentValues();
+        // Collections.SERVICE_ID is never changed
+
+        values.put(Collections.URL, url);
+        values.put(Collections.READ_ONLY, readOnly ? 1 : 0);
+        values.put(Collections.DISPLAY_NAME, displayName);
+        values.put(Collections.DESCRIPTION, description);
+        values.put(Collections.COLOR, color);
+
+        values.put(Collections.TIME_ZONE, timeZone);
+        if (supportsVEVENT != null)
+            values.put(Collections.SUPPORTS_VEVENT, supportsVEVENT ? 1 : 0);
+        if (supportsVTODO != null)
+            values.put(Collections.SUPPORTS_VTODO, supportsVTODO ? 1 : 0);
+
+        values.put(Collections.SYNC, selected ? 1 : 0);
+        return values;
+    }
+
+
+    private static Boolean getAsBooleanOrNull(ContentValues values, String field) {
+        Integer i = values.getAsInteger(field);
+        return (i == null) ? null : (i != 0);
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/model/ServiceDB.java

@@ -0,0 +1,186 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.model;
+
+import android.content.Context;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteException;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.os.Build;
+
+import at.bitfire.davdroid.App;
+import lombok.Cleanup;
+
+public class ServiceDB {
+
+    public static class Settings {
+        public static final String
+                _TABLE = "settings",
+                NAME = "setting",
+                VALUE = "value";
+    }
+
+    public static class Services {
+        public static final String
+                _TABLE = "services",
+                ID = "_id",
+                ACCOUNT_NAME = "accountName",
+                SERVICE = "service",
+                PRINCIPAL = "principal";
+
+        // allowed values for SERVICE column
+        public static final String
+                SERVICE_CALDAV = "caldav",
+                SERVICE_CARDDAV = "carddav";
+    }
+
+    public static class HomeSets {
+        public static final String
+                _TABLE = "homesets",
+                ID = "_id",
+                SERVICE_ID = "serviceID",
+                URL = "url";
+    }
+
+    public static class Collections {
+        public static final String
+                _TABLE = "collections",
+                ID = "_id",
+                SERVICE_ID = "serviceID",
+                URL = "url",
+                READ_ONLY = "readOnly",
+                DISPLAY_NAME = "displayName",
+                DESCRIPTION = "description",
+                COLOR = "color",
+                TIME_ZONE = "timezone",
+                SUPPORTS_VEVENT = "supportsVEVENT",
+                SUPPORTS_VTODO = "supportsVTODO",
+                SYNC = "sync";
+    }
+
+
+    public static class OpenHelper extends SQLiteOpenHelper {
+        private static final String DATABASE_NAME = "services.db";
+        private static final int DATABASE_VERSION = 1;
+
+        public OpenHelper(Context context) {
+            super(context, DATABASE_NAME, null, DATABASE_VERSION);
+
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
+                setWriteAheadLoggingEnabled(true);
+        }
+
+        @Override
+        public void onOpen(SQLiteDatabase db) {
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
+                db.setForeignKeyConstraintsEnabled(true);
+            else {
+                if (!db.enableWriteAheadLogging())
+                    App.log.warning("Couldn't enable write-ahead logging");
+
+                db.execSQL("PRAGMA foreign_keys=ON;");
+            }
+        }
+
+        @Override
+        public void onCreate(SQLiteDatabase db) {
+            App.log.info("Creating database " + db.getPath());
+
+            db.execSQL("CREATE TABLE " + Settings._TABLE + "(" +
+                    Settings.NAME + " TEXT NOT NULL," +
+                    Settings.VALUE + " TEXT NOT NULL" +
+            ")");
+            db.execSQL("CREATE UNIQUE INDEX settings_name ON " + Settings._TABLE + " (" + Settings.NAME + ")");
+
+            db.execSQL("CREATE TABLE " + Services._TABLE + "(" +
+                    Services.ID + " INTEGER PRIMARY KEY AUTOINCREMENT," +
+                    Services.ACCOUNT_NAME + " TEXT NOT NULL," +
+                    Services.SERVICE + " TEXT NOT NULL," +
+                    Services.PRINCIPAL + " TEXT NULL" +
+            ")");
+            db.execSQL("CREATE UNIQUE INDEX services_account ON " + Services._TABLE + " (" + Services.ACCOUNT_NAME + "," + Services.SERVICE + ")");
+
+            db.execSQL("CREATE TABLE " + HomeSets._TABLE + "(" +
+                    HomeSets.ID + " INTEGER PRIMARY KEY AUTOINCREMENT," +
+                    HomeSets.SERVICE_ID + " INTEGER NOT NULL REFERENCES " + Services._TABLE +" ON DELETE CASCADE," +
+                    HomeSets.URL + " TEXT NOT NULL" +
+             ")");
+            db.execSQL("CREATE UNIQUE INDEX homesets_service_url ON " + HomeSets._TABLE + "(" + HomeSets.SERVICE_ID + "," + HomeSets.URL + ")");
+
+            db.execSQL("CREATE TABLE " + Collections._TABLE + "(" +
+                    Collections.ID + " INTEGER PRIMARY KEY AUTOINCREMENT," +
+                    Collections.SERVICE_ID + " INTEGER NOT NULL REFERENCES " + Services._TABLE +" ON DELETE CASCADE," +
+                    Collections.URL + " TEXT NOT NULL," +
+                    Collections.READ_ONLY + " INTEGER DEFAULT 0 NOT NULL," +
+                    Collections.DISPLAY_NAME + " TEXT NULL," +
+                    Collections.DESCRIPTION + " TEXT NULL," +
+                    Collections.COLOR + " INTEGER NULL," +
+                    Collections.TIME_ZONE + " TEXT NULL," +
+                    Collections.SUPPORTS_VEVENT + " INTEGER NULL," +
+                    Collections.SUPPORTS_VTODO + " INTEGER NULL," +
+                    Collections.SYNC + " INTEGER DEFAULT 0 NOT NULL" +
+            ")");
+            db.execSQL("CREATE UNIQUE INDEX collections_service_url ON " + Collections._TABLE + "(" + Collections.SERVICE_ID + "," + Collections.URL + ")");
+        }
+
+        @Override
+        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+        }
+
+
+        public void dump(StringBuilder sb) {
+            SQLiteDatabase db = getReadableDatabase();
+            db.beginTransactionNonExclusive();
+
+            // iterate through all tables
+            @Cleanup Cursor cursorTables = db.query("sqlite_master", new String[] { "name" }, "type='table'", null, null, null, null);
+            while (cursorTables.moveToNext()) {
+                String table = cursorTables.getString(0);
+                sb.append(table).append("\n");
+                @Cleanup Cursor cursor = db.query(table, null, null, null, null, null, null);
+
+                // print columns
+                int cols = cursor.getColumnCount();
+                sb.append("\t| ");
+                for (int i = 0; i < cols; i++) {
+                    sb.append(" ");
+                    sb.append(cursor.getColumnName(i));
+                    sb.append(" |");
+                }
+                sb.append("\n");
+
+                // print rows
+                while (cursor.moveToNext()) {
+                    sb.append("\t| ");
+                    for (int i = 0; i < cols; i++) {
+                        sb.append(" ");
+                        try {
+                            String value = cursor.getString(i);
+                            if (value != null)
+                                sb.append(value
+                                        .replace("\r", "<CR>")
+                                        .replace("\n", "<LF>"));
+                            else
+                                sb.append("<null>");
+
+                        } catch (SQLiteException e) {
+                            sb.append("<unprintable>");
+                        }
+                        sb.append(" |");
+                    }
+                    sb.append("\n");
+                }
+                sb.append("----------\n");
+            }
+            db.endTransaction();
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/model/Settings.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.model;
+
+import android.content.ContentValues;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+
+import lombok.Cleanup;
+
+public class Settings {
+
+    final SQLiteDatabase db;
+
+    public Settings(SQLiteDatabase db) {
+        this.db = db;
+    }
+
+    public boolean getBoolean(String name, boolean defaultValue) {
+        @Cleanup Cursor cursor = db.query(ServiceDB.Settings._TABLE, new String[] { ServiceDB.Settings.VALUE },
+                ServiceDB.Settings.NAME + "=?", new String[] { name }, null, null, null);
+        if (cursor.moveToNext())
+            return cursor.getInt(0) != 0;
+        else
+            return defaultValue;
+    }
+
+    public void putBoolean(String name, boolean value) {
+        ContentValues values = new ContentValues(2);
+        values.put(ServiceDB.Settings.NAME, name);
+        values.put(ServiceDB.Settings.VALUE, value ? 1 : 0);
+        db.insertWithOnConflict(ServiceDB.Settings._TABLE, null, values, SQLiteDatabase.CONFLICT_REPLACE);
+    }
+
+    public void remove(String name) {
+        db.delete(ServiceDB.Settings._TABLE, ServiceDB.Settings.NAME + "=?", new String[] { name });
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/model/UnknownProperties.java

@@ -0,0 +1,22 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.model;
+
+import android.provider.ContactsContract.RawContacts;
+
+public class UnknownProperties {
+
+    public static final String CONTENT_ITEM_TYPE = "x.davdroid/unknown-properties";
+
+    public static final String
+            MIMETYPE = RawContacts.Data.MIMETYPE,
+            RAW_CONTACT_ID = RawContacts.Data.RAW_CONTACT_ID,
+            UNKNOWN_PROPERTIES = RawContacts.Data.DATA1;
+
+}

app/src/main/java/at/bitfire/davdroid/resource/LocalAddressBook.java

@@ -0,0 +1,229 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+package at.bitfire.davdroid.resource;
+
+import android.accounts.Account;
+import android.content.ContentProviderClient;
+import android.content.ContentUris;
+import android.content.ContentValues;
+import android.database.Cursor;
+import android.net.Uri;
+import android.os.Bundle;
+import android.os.Parcel;
+import android.os.RemoteException;
+import android.provider.ContactsContract.Groups;
+import android.provider.ContactsContract.RawContacts;
+import android.support.annotation.NonNull;
+
+import java.io.FileNotFoundException;
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+
+import at.bitfire.vcard4android.AndroidAddressBook;
+import at.bitfire.vcard4android.AndroidContact;
+import at.bitfire.vcard4android.AndroidGroup;
+import at.bitfire.vcard4android.ContactsStorageException;
+import lombok.Cleanup;
+
+
+public class LocalAddressBook extends AndroidAddressBook implements LocalCollection {
+
+    protected static final String
+            SYNC_STATE_CTAG = "ctag",
+            SYNC_STATE_URL = "url";
+
+    private final Bundle syncState = new Bundle();
+
+    /**
+     * Whether contact groups (LocalGroup resources) are included in query results for
+     * {@link #getAll()}, {@link #getDeleted()}, {@link #getDirty()} and
+     * {@link #getWithoutFileName()}.
+     */
+    public boolean includeGroups = true;
+
+
+    public LocalAddressBook(Account account, ContentProviderClient provider) {
+        super(account, provider, LocalGroup.Factory.INSTANCE, LocalContact.Factory.INSTANCE);
+    }
+
+    public LocalContact findContactByUID(String uid) throws ContactsStorageException, FileNotFoundException {
+        LocalContact[] contacts = (LocalContact[])queryContacts(LocalContact.COLUMN_UID + "=?", new String[] { uid });
+        if (contacts.length == 0)
+            throw new FileNotFoundException();
+        return contacts[0];
+    }
+
+    @Override
+    public LocalResource[] getAll() throws ContactsStorageException {
+        List<LocalResource> all = new LinkedList<>();
+        Collections.addAll(all, (LocalResource[])queryContacts(null, null));
+        if (includeGroups)
+            Collections.addAll(all, (LocalResource[])queryGroups(null, null));
+        return all.toArray(new LocalResource[all.size()]);
+    }
+
+    /**
+     * Returns an array of local contacts/groups which have been deleted locally. (DELETED != 0).
+     */
+    @Override
+    public LocalResource[] getDeleted() throws ContactsStorageException {
+        List<LocalResource> deleted = new LinkedList<>();
+        Collections.addAll(deleted, getDeletedContacts());
+        if (includeGroups)
+            Collections.addAll(deleted, getDeletedGroups());
+        return deleted.toArray(new LocalResource[deleted.size()]);
+    }
+
+    /**
+     * Returns an array of local contacts/groups which have been changed locally (DIRTY != 0).
+     */
+    @Override
+    public LocalResource[] getDirty() throws ContactsStorageException {
+        List<LocalResource> dirty = new LinkedList<>();
+        Collections.addAll(dirty, getDirtyContacts());
+        if (includeGroups)
+            Collections.addAll(dirty, getDirtyGroups());
+        return dirty.toArray(new LocalResource[dirty.size()]);
+    }
+
+    /**
+     * Returns an array of local contacts which don't have a file name yet.
+     */
+    @Override
+    public LocalResource[] getWithoutFileName() throws ContactsStorageException {
+        List<LocalResource> nameless = new LinkedList<>();
+        Collections.addAll(nameless, (LocalContact[])queryContacts(AndroidContact.COLUMN_FILENAME + " IS NULL", null));
+        if (includeGroups)
+            Collections.addAll(nameless, (LocalGroup[])queryGroups(AndroidGroup.COLUMN_FILENAME + " IS NULL", null));
+        return nameless.toArray(new LocalResource[nameless.size()]);
+    }
+
+    public void deleteAll() throws ContactsStorageException {
+        try {
+            provider.delete(syncAdapterURI(RawContacts.CONTENT_URI), null, null);
+            provider.delete(syncAdapterURI(Groups.CONTENT_URI), null, null);
+        } catch(RemoteException e) {
+            throw new ContactsStorageException("Couldn't delete all local contacts and groups", e);
+        }
+    }
+
+
+    public LocalContact[] getDeletedContacts() throws ContactsStorageException {
+        return (LocalContact[])queryContacts(RawContacts.DELETED + "!= 0", null);
+    }
+
+    public LocalContact[] getDirtyContacts() throws ContactsStorageException {
+        return (LocalContact[])queryContacts(RawContacts.DIRTY + "!= 0", null);
+    }
+
+    public LocalGroup[] getDeletedGroups() throws ContactsStorageException {
+        return (LocalGroup[])queryGroups(Groups.DELETED + "!= 0", null);
+    }
+
+    public LocalGroup[] getDirtyGroups() throws ContactsStorageException {
+        return (LocalGroup[])queryGroups(Groups.DIRTY + "!= 0", null);
+    }
+
+
+    /**
+     * Finds the first group with the given title. If there is no group with this
+     * title, a new group is created.
+     * @param title     title of the group to look for
+     * @return          id of the group with given title
+     * @throws ContactsStorageException on contact provider errors
+     */
+    public long findOrCreateGroup(@NonNull String title) throws ContactsStorageException {
+        try {
+            @Cleanup Cursor cursor = provider.query(syncAdapterURI(Groups.CONTENT_URI),
+                    new String[] { Groups._ID  },
+                    Groups.TITLE + "=?", new String[] { title },
+                    null);
+            if (cursor != null && cursor.moveToNext())
+                return cursor.getLong(0);
+
+            ContentValues values = new ContentValues();
+            values.put(Groups.TITLE, title);
+            Uri uri = provider.insert(syncAdapterURI(Groups.CONTENT_URI), values);
+            return ContentUris.parseId(uri);
+        } catch(RemoteException e) {
+            throw new ContactsStorageException("Couldn't find local contact group", e);
+        }
+    }
+
+    public void removeEmptyGroups() throws ContactsStorageException {
+        // find groups without members
+        /** should be done using {@link Groups.SUMMARY_COUNT}, but it's not implemented in Android yet */
+        for (LocalGroup group : (LocalGroup[])queryGroups(null, null))
+            if (group.getMembers().length == 0)
+                group.delete();
+    }
+
+    public void removeGroups() throws ContactsStorageException {
+        try {
+            provider.delete(syncAdapterURI(Groups.CONTENT_URI), null, null);
+        } catch(RemoteException e) {
+            throw new ContactsStorageException("Couldn't remove all groups", e);
+        }
+    }
+
+
+    // SYNC STATE
+
+    @SuppressWarnings("Recycle")
+    protected void readSyncState() throws ContactsStorageException {
+        @Cleanup("recycle") Parcel parcel = Parcel.obtain();
+        byte[] raw = getSyncState();
+        syncState.clear();
+        if (raw != null) {
+            parcel.unmarshall(raw, 0, raw.length);
+            parcel.setDataPosition(0);
+            syncState.putAll(parcel.readBundle());
+        }
+    }
+
+    @SuppressWarnings("Recycle")
+    protected void writeSyncState() throws ContactsStorageException {
+        @Cleanup("recycle") Parcel parcel = Parcel.obtain();
+        parcel.writeBundle(syncState);
+        setSyncState(parcel.marshall());
+    }
+
+    public String getURL() throws ContactsStorageException {
+        synchronized (syncState) {
+            readSyncState();
+            return syncState.getString(SYNC_STATE_URL);
+        }
+    }
+
+    public void setURL(String url) throws ContactsStorageException {
+        synchronized (syncState) {
+            readSyncState();
+            syncState.putString(SYNC_STATE_URL, url);
+            writeSyncState();
+        }
+    }
+
+    @Override
+    public String getCTag() throws ContactsStorageException {
+        synchronized (syncState) {
+            readSyncState();
+            return syncState.getString(SYNC_STATE_CTAG);
+        }
+    }
+
+    @Override
+    public void setCTag(String cTag) throws ContactsStorageException {
+        synchronized (syncState) {
+            readSyncState();
+            syncState.putString(SYNC_STATE_CTAG, cTag);
+            writeSyncState();
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/resource/LocalCalendar.java

@@ -0,0 +1,266 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.resource;
+
+import android.accounts.Account;
+import android.annotation.TargetApi;
+import android.content.ContentProviderClient;
+import android.content.ContentProviderOperation;
+import android.content.ContentUris;
+import android.content.ContentValues;
+import android.database.Cursor;
+import android.net.Uri;
+import android.os.Build;
+import android.os.RemoteException;
+import android.provider.CalendarContract;
+import android.provider.CalendarContract.Calendars;
+import android.provider.CalendarContract.Events;
+import android.provider.CalendarContract.Reminders;
+import android.support.annotation.NonNull;
+import android.text.TextUtils;
+
+import net.fortuna.ical4j.model.component.VTimeZone;
+
+import org.apache.commons.lang3.StringUtils;
+
+import java.io.FileNotFoundException;
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.DavUtils;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.ical4android.AndroidCalendar;
+import at.bitfire.ical4android.AndroidCalendarFactory;
+import at.bitfire.ical4android.BatchOperation;
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.ical4android.DateUtils;
+import at.bitfire.vcard4android.ContactsStorageException;
+import lombok.Cleanup;
+
+public class LocalCalendar extends AndroidCalendar implements LocalCollection {
+
+    public static final int defaultColor = 0xFF8bc34a;     // light green 500
+
+    public static final String COLUMN_CTAG = Calendars.CAL_SYNC1;
+
+    protected static final int
+            DIRTY_INCREASE_SEQUENCE = 1,
+            DIRTY_DONT_INCREASE_SEQUENCE = 2;
+
+    static String[] BASE_INFO_COLUMNS = new String[] {
+            Events._ID,
+            Events._SYNC_ID,
+            LocalEvent.COLUMN_ETAG
+    };
+
+    @Override
+    protected String[] eventBaseInfoColumns() {
+        return BASE_INFO_COLUMNS;
+    }
+
+
+    protected LocalCalendar(Account account, ContentProviderClient provider, long id) {
+        super(account, provider, LocalEvent.Factory.INSTANCE, id);
+    }
+
+    public static Uri create(@NonNull Account account, @NonNull ContentProviderClient provider, @NonNull CollectionInfo info) throws CalendarStorageException {
+        ContentValues values = valuesFromCollectionInfo(info, true);
+
+        // ACCOUNT_NAME and ACCOUNT_TYPE are required (see docs)! If it's missing, other apps will crash.
+        values.put(Calendars.ACCOUNT_NAME, account.name);
+        values.put(Calendars.ACCOUNT_TYPE, account.type);
+        values.put(Calendars.OWNER_ACCOUNT, account.name);
+
+        // flag as visible & synchronizable at creation, might be changed by user at any time
+        values.put(Calendars.VISIBLE, 1);
+        values.put(Calendars.SYNC_EVENTS, 1);
+
+        return create(account, provider, values);
+    }
+
+    public void update(CollectionInfo info, boolean updateColor) throws CalendarStorageException {
+        update(valuesFromCollectionInfo(info, updateColor));
+    }
+
+    @TargetApi(15)
+    private static ContentValues valuesFromCollectionInfo(CollectionInfo info, boolean withColor) {
+        ContentValues values = new ContentValues();
+        values.put(Calendars.NAME, info.url);
+        values.put(Calendars.CALENDAR_DISPLAY_NAME, !TextUtils.isEmpty(info.displayName) ? info.displayName : DavUtils.lastSegmentOfUrl(info.url));
+
+        if (withColor)
+            values.put(Calendars.CALENDAR_COLOR, info.color != null ? info.color : defaultColor);
+
+        if (info.readOnly)
+            values.put(Calendars.CALENDAR_ACCESS_LEVEL, Calendars.CAL_ACCESS_READ);
+        else {
+            values.put(Calendars.CALENDAR_ACCESS_LEVEL, Calendars.CAL_ACCESS_OWNER);
+            values.put(Calendars.CAN_MODIFY_TIME_ZONE, 1);
+            values.put(Calendars.CAN_ORGANIZER_RESPOND, 1);
+        }
+
+        if (!TextUtils.isEmpty(info.timeZone)) {
+            VTimeZone timeZone = DateUtils.parseVTimeZone(info.timeZone);
+            if (timeZone != null && timeZone.getTimeZoneId() != null)
+                values.put(Calendars.CALENDAR_TIME_ZONE, DateUtils.findAndroidTimezoneID(timeZone.getTimeZoneId().getValue()));
+        }
+        values.put(Calendars.ALLOWED_REMINDERS, Reminders.METHOD_ALERT);
+        if (Build.VERSION.SDK_INT >= 15) {
+            values.put(Calendars.ALLOWED_AVAILABILITY, StringUtils.join(new int[] { Reminders.AVAILABILITY_TENTATIVE, Reminders.AVAILABILITY_FREE, Reminders.AVAILABILITY_BUSY }, ","));
+            values.put(Calendars.ALLOWED_ATTENDEE_TYPES, StringUtils.join(new int[] { CalendarContract.Attendees.TYPE_OPTIONAL, CalendarContract.Attendees.TYPE_REQUIRED, CalendarContract.Attendees.TYPE_RESOURCE }, ", "));
+        }
+        return values;
+    }
+
+
+    @Override
+    public LocalResource[] getAll() throws CalendarStorageException, ContactsStorageException {
+        return (LocalEvent[])queryEvents(Events.ORIGINAL_ID + " IS NULL", null);
+    }
+
+    @Override
+    public LocalEvent[] getDeleted() throws CalendarStorageException {
+        return (LocalEvent[])queryEvents(Events.DELETED + "!=0 AND " + Events.ORIGINAL_ID + " IS NULL", null);
+    }
+
+    @Override
+    public LocalEvent[] getWithoutFileName() throws CalendarStorageException {
+        return (LocalEvent[])queryEvents(Events._SYNC_ID + " IS NULL AND " + Events.ORIGINAL_ID + " IS NULL", null);
+    }
+
+    @Override
+    public LocalResource[] getDirty() throws CalendarStorageException, FileNotFoundException {
+        List<LocalResource> dirty = new LinkedList<>();
+
+        // get dirty events which are not required to have an increased SEQUENCE value
+        Collections.addAll(dirty, (LocalEvent[])queryEvents(Events.DIRTY + "=" + DIRTY_DONT_INCREASE_SEQUENCE + " AND " + Events.ORIGINAL_ID + " IS NULL", null));
+
+        // get dirty events which are required to have an increased SEQUENCE value
+        for (LocalEvent event : (LocalEvent[])queryEvents(Events.DIRTY + "=" + DIRTY_INCREASE_SEQUENCE + " AND " + Events.ORIGINAL_ID + " IS NULL", null)) {
+            if (event.getEvent().sequence == null)      // sequence has not been assigned yet (i.e. this event was just locally created)
+                event.getEvent().sequence = 0;
+            else
+                event.getEvent().sequence++;
+            dirty.add(event);
+        }
+
+        return dirty.toArray(new LocalResource[dirty.size()]);
+    }
+
+
+    @Override
+    @SuppressWarnings("Recycle")
+    public String getCTag() throws CalendarStorageException {
+        try {
+            @Cleanup Cursor cursor = provider.query(calendarSyncURI(), new String[] { COLUMN_CTAG }, null, null, null);
+            if (cursor != null && cursor.moveToNext())
+                return cursor.getString(0);
+        } catch (RemoteException e) {
+            throw new CalendarStorageException("Couldn't read local (last known) CTag", e);
+        }
+        return null;
+    }
+
+    @Override
+    public void setCTag(String cTag) throws CalendarStorageException, ContactsStorageException {
+        try {
+            ContentValues values = new ContentValues(1);
+            values.put(COLUMN_CTAG, cTag);
+            provider.update(calendarSyncURI(), values, null, null);
+        } catch (RemoteException e) {
+            throw new CalendarStorageException("Couldn't write local (last known) CTag", e);
+        }
+    }
+
+    @SuppressWarnings("Recycle")
+    public void processDirtyExceptions() throws CalendarStorageException {
+        // process deleted exceptions
+        App.log.info("Processing deleted exceptions");
+        try {
+            @Cleanup Cursor cursor = provider.query(
+                    syncAdapterURI(Events.CONTENT_URI),
+                    new String[] { Events._ID, Events.ORIGINAL_ID, LocalEvent.COLUMN_SEQUENCE },
+                    Events.DELETED + "!=0 AND " + Events.ORIGINAL_ID + " IS NOT NULL", null, null);
+            while (cursor != null && cursor.moveToNext()) {
+                App.log.fine("Found deleted exception, removing; then re-schuling original event");
+                long    id = cursor.getLong(0),             // can't be null (by definition)
+                        originalID = cursor.getLong(1);     // can't be null (by query)
+
+                // get original event's SEQUENCE
+                @Cleanup Cursor cursor2 = provider.query(
+                        syncAdapterURI(ContentUris.withAppendedId(Events.CONTENT_URI, originalID)),
+                        new String[] { LocalEvent.COLUMN_SEQUENCE },
+                        null, null, null);
+                int originalSequence = (cursor2 == null || cursor2.isNull(0)) ? 0 : cursor2.getInt(0);
+
+                BatchOperation batch = new BatchOperation(provider);
+                // re-schedule original event and set it to DIRTY
+                batch.enqueue(ContentProviderOperation.newUpdate(
+                        syncAdapterURI(ContentUris.withAppendedId(Events.CONTENT_URI, originalID)))
+                        .withValue(LocalEvent.COLUMN_SEQUENCE, originalSequence + 1)
+                        .withValue(Events.DIRTY, DIRTY_INCREASE_SEQUENCE)
+                        .build());
+                // remove exception
+                batch.enqueue(ContentProviderOperation.newDelete(
+                        syncAdapterURI(ContentUris.withAppendedId(Events.CONTENT_URI, id))).build());
+                batch.commit();
+            }
+        } catch (RemoteException e) {
+            throw new CalendarStorageException("Couldn't process locally modified exception", e);
+        }
+
+        // process dirty exceptions
+        App.log.info("Processing dirty exceptions");
+        try {
+            @Cleanup Cursor cursor = provider.query(
+                    syncAdapterURI(Events.CONTENT_URI),
+                    new String[] { Events._ID, Events.ORIGINAL_ID, LocalEvent.COLUMN_SEQUENCE },
+                    Events.DIRTY + "!=0 AND " + Events.ORIGINAL_ID + " IS NOT NULL", null, null);
+            while (cursor != null && cursor.moveToNext()) {
+                App.log.fine("Found dirty exception, increasing SEQUENCE to re-schedule");
+                long    id = cursor.getLong(0),             // can't be null (by definition)
+                        originalID = cursor.getLong(1);     // can't be null (by query)
+                int sequence = cursor.isNull(2) ? 0 : cursor.getInt(2);
+
+                BatchOperation batch = new BatchOperation(provider);
+                // original event to DIRTY
+                batch.enqueue(ContentProviderOperation.newUpdate(
+                        syncAdapterURI(ContentUris.withAppendedId(Events.CONTENT_URI, originalID)))
+                        .withValue(Events.DIRTY, DIRTY_DONT_INCREASE_SEQUENCE)
+                        .build());
+                // increase SEQUENCE and set DIRTY to 0
+                batch.enqueue(ContentProviderOperation.newUpdate(
+                                syncAdapterURI(ContentUris.withAppendedId(Events.CONTENT_URI, id)))
+                                .withValue(LocalEvent.COLUMN_SEQUENCE, sequence + 1)
+                                .withValue(Events.DIRTY, 0)
+                                .build());
+                batch.commit();
+            }
+        } catch (RemoteException e) {
+            throw new CalendarStorageException("Couldn't process locally modified exception", e);
+        }
+    }
+
+
+    public static class Factory implements AndroidCalendarFactory {
+        public static final Factory INSTANCE = new Factory();
+
+        @Override
+        public AndroidCalendar newInstance(Account account, ContentProviderClient provider, long id) {
+            return new LocalCalendar(account, provider, id);
+        }
+
+        @Override
+        public AndroidCalendar[] newArray(int size) {
+            return new LocalCalendar[size];
+        }
+    }
+}

app/src/main/java/at/bitfire/davdroid/resource/LocalCollection.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.resource;
+
+import java.io.FileNotFoundException;
+
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.vcard4android.ContactsStorageException;
+
+public interface LocalCollection {
+
+    LocalResource[] getDeleted() throws CalendarStorageException, ContactsStorageException;
+    LocalResource[] getWithoutFileName()  throws CalendarStorageException, ContactsStorageException;
+    LocalResource[] getDirty() throws CalendarStorageException, ContactsStorageException, FileNotFoundException;
+
+    LocalResource[] getAll() throws CalendarStorageException, ContactsStorageException;
+
+    String getCTag() throws CalendarStorageException, ContactsStorageException;
+    void setCTag(String cTag) throws CalendarStorageException, ContactsStorageException;
+}

app/src/main/java/at/bitfire/davdroid/resource/LocalContact.java

@@ -0,0 +1,196 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.resource;
+
+import android.content.ContentProviderOperation;
+import android.content.ContentValues;
+import android.os.RemoteException;
+import android.provider.ContactsContract;
+import android.provider.ContactsContract.CommonDataKinds.GroupMembership;
+import android.provider.ContactsContract.RawContacts.Data;
+import android.support.annotation.NonNull;
+
+import java.io.FileNotFoundException;
+import java.util.HashSet;
+import java.util.Set;
+
+import at.bitfire.davdroid.BuildConfig;
+import at.bitfire.davdroid.model.UnknownProperties;
+import at.bitfire.vcard4android.AndroidAddressBook;
+import at.bitfire.vcard4android.AndroidContact;
+import at.bitfire.vcard4android.AndroidContactFactory;
+import at.bitfire.vcard4android.BatchOperation;
+import at.bitfire.vcard4android.CachedGroupMembership;
+import at.bitfire.vcard4android.Contact;
+import at.bitfire.vcard4android.ContactsStorageException;
+import ezvcard.Ezvcard;
+
+public class LocalContact extends AndroidContact implements LocalResource {
+    static {
+        Contact.productID = "+//IDN bitfire.at//DAVdroid/" + BuildConfig.VERSION_NAME + " vcard4android ez-vcard/" + Ezvcard.VERSION;
+    }
+
+    protected final Set<Long>
+            cachedGroupMemberships = new HashSet<>(),
+            groupMemberships = new HashSet<>();
+
+
+    protected LocalContact(AndroidAddressBook addressBook, long id, String fileName, String eTag) {
+        super(addressBook, id, fileName, eTag);
+    }
+
+    public LocalContact(AndroidAddressBook addressBook, Contact contact, String fileName, String eTag) {
+        super(addressBook, contact, fileName, eTag);
+    }
+
+    public void clearDirty(String eTag) throws ContactsStorageException {
+        try {
+            ContentValues values = new ContentValues(1);
+            values.put(ContactsContract.RawContacts.DIRTY, 0);
+            values.put(COLUMN_ETAG, eTag);
+            addressBook.provider.update(rawContactSyncURI(), values, null, null);
+
+            this.eTag = eTag;
+        } catch (RemoteException e) {
+            throw new ContactsStorageException("Couldn't clear dirty flag", e);
+        }
+    }
+
+    public void updateFileNameAndUID(String uid) throws ContactsStorageException {
+        try {
+            String newFileName = uid + ".vcf";
+
+            ContentValues values = new ContentValues(2);
+            values.put(COLUMN_FILENAME, newFileName);
+            values.put(COLUMN_UID, uid);
+            addressBook.provider.update(rawContactSyncURI(), values, null, null);
+
+            fileName = newFileName;
+        } catch (RemoteException e) {
+            throw new ContactsStorageException("Couldn't update UID", e);
+        }
+    }
+
+
+    @Override
+    protected void populateData(String mimeType, ContentValues row) {
+        switch (mimeType) {
+            case CachedGroupMembership.CONTENT_ITEM_TYPE:
+                cachedGroupMemberships.add(row.getAsLong(CachedGroupMembership.GROUP_ID));
+                break;
+            case GroupMembership.CONTENT_ITEM_TYPE:
+                groupMemberships.add(row.getAsLong(GroupMembership.GROUP_ROW_ID));
+                break;
+            case UnknownProperties.CONTENT_ITEM_TYPE:
+                contact.unknownProperties = row.getAsString(UnknownProperties.UNKNOWN_PROPERTIES);
+                break;
+        }
+    }
+
+    @Override
+    protected void insertDataRows(BatchOperation batch) throws ContactsStorageException {
+        super.insertDataRows(batch);
+
+        if (contact.unknownProperties != null) {
+            ContentProviderOperation.Builder builder = ContentProviderOperation.newInsert(dataSyncURI());
+            if (id == null)
+                builder.withValueBackReference(UnknownProperties.RAW_CONTACT_ID, 0);
+            else
+                builder.withValue(UnknownProperties.RAW_CONTACT_ID, id);
+            builder .withValue(UnknownProperties.MIMETYPE, UnknownProperties.CONTENT_ITEM_TYPE)
+                    .withValue(UnknownProperties.UNKNOWN_PROPERTIES, contact.unknownProperties);
+            batch.enqueue(builder.build());
+        }
+
+    }
+
+
+    public void addToGroup(BatchOperation batch, long groupID) {
+        assertID();
+        batch.enqueue(ContentProviderOperation
+                .newInsert(dataSyncURI())
+                .withValue(GroupMembership.MIMETYPE, GroupMembership.CONTENT_ITEM_TYPE)
+                .withValue(GroupMembership.RAW_CONTACT_ID, id)
+                .withValue(GroupMembership.GROUP_ROW_ID, groupID)
+                .build()
+        );
+
+        batch.enqueue(ContentProviderOperation
+                .newInsert(dataSyncURI())
+                .withValue(CachedGroupMembership.MIMETYPE, CachedGroupMembership.CONTENT_ITEM_TYPE)
+                .withValue(CachedGroupMembership.RAW_CONTACT_ID, id)
+                .withValue(CachedGroupMembership.GROUP_ID, groupID)
+                .withYieldAllowed(true)
+                .build()
+        );
+    }
+
+    public void removeGroupMemberships(BatchOperation batch) {
+        assertID();
+        batch.enqueue(ContentProviderOperation
+                .newDelete(dataSyncURI())
+                .withSelection(
+                        Data.RAW_CONTACT_ID + "=? AND " + Data.MIMETYPE + " IN (?,?)",
+                        new String[] { String.valueOf(id), GroupMembership.CONTENT_ITEM_TYPE, CachedGroupMembership.CONTENT_ITEM_TYPE }
+                )
+                .withYieldAllowed(true)
+                .build()
+        );
+    }
+
+    /**
+     * Returns the IDs of all groups the contact was member of (cached memberships).
+     * Cached memberships are kept in sync with memberships by DAVdroid and are used to determine
+     * whether a membership has been deleted/added when a raw contact is dirty.
+     * @return set of {@link GroupMembership#GROUP_ROW_ID} (may be empty)
+     * @throws ContactsStorageException   on contact provider errors
+     * @throws FileNotFoundException      if the current contact can't be found
+     */
+    @NonNull
+    public Set<Long> getCachedGroupMemberships() throws ContactsStorageException, FileNotFoundException {
+        getContact();
+        return cachedGroupMemberships;
+    }
+
+    /**
+     * Returns the IDs of all groups the contact is member of.
+     * @return set of {@link GroupMembership#GROUP_ROW_ID}s (may be empty)
+     * @throws ContactsStorageException   on contact provider errors
+     * @throws FileNotFoundException      if the current contact can't be found
+     */
+    @NonNull
+    public Set<Long> getGroupMemberships() throws ContactsStorageException, FileNotFoundException {
+        getContact();
+        return groupMemberships;
+    }
+
+
+    // factory
+
+    static class Factory extends AndroidContactFactory {
+        static final Factory INSTANCE = new Factory();
+
+        @Override
+        public LocalContact newInstance(AndroidAddressBook addressBook, long id, String fileName, String eTag) {
+            return new LocalContact(addressBook, id, fileName, eTag);
+        }
+
+        @Override
+        public LocalContact newInstance(AndroidAddressBook addressBook, Contact contact, String fileName, String eTag) {
+            return new LocalContact(addressBook, contact, fileName, eTag);
+        }
+
+        @Override
+        public LocalContact[] newArray(int size) {
+            return new LocalContact[size];
+        }
+
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/resource/LocalEvent.java

@@ -0,0 +1,146 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.resource;
+
+import android.annotation.TargetApi;
+import android.content.ContentProviderOperation;
+import android.content.ContentValues;
+import android.os.Build;
+import android.os.RemoteException;
+import android.provider.CalendarContract;
+import android.provider.CalendarContract.Events;
+import android.support.annotation.NonNull;
+
+import net.fortuna.ical4j.model.property.ProdId;
+
+import at.bitfire.davdroid.BuildConfig;
+import at.bitfire.ical4android.AndroidCalendar;
+import at.bitfire.ical4android.AndroidEvent;
+import at.bitfire.ical4android.AndroidEventFactory;
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.ical4android.Event;
+import lombok.Getter;
+import lombok.Setter;
+
+@TargetApi(17)
+public class LocalEvent extends AndroidEvent implements LocalResource {
+    static {
+        Event.prodId = new ProdId("+//IDN bitfire.at//DAVdroid/" + BuildConfig.VERSION_NAME + " ical4android ical4j/2.x");
+    }
+
+    static final String COLUMN_ETAG = CalendarContract.Events.SYNC_DATA1,
+                        COLUMN_UID = Build.VERSION.SDK_INT >= 17 ? Events.UID_2445 : Events.SYNC_DATA2,
+                        COLUMN_SEQUENCE = CalendarContract.Events.SYNC_DATA3;
+
+    @Getter protected String fileName;
+    @Getter @Setter protected String eTag;
+
+    public LocalEvent(@NonNull AndroidCalendar calendar, Event event, String fileName, String eTag) {
+        super(calendar, event);
+        this.fileName = fileName;
+        this.eTag = eTag;
+    }
+
+    protected LocalEvent(@NonNull AndroidCalendar calendar, long id, ContentValues baseInfo) {
+        super(calendar, id, baseInfo);
+        if (baseInfo != null) {
+            fileName = baseInfo.getAsString(Events._SYNC_ID);
+            eTag = baseInfo.getAsString(COLUMN_ETAG);
+        }
+    }
+
+
+    /* process LocalEvent-specific fields */
+
+    @Override
+    protected void populateEvent(ContentValues values) {
+        super.populateEvent(values);
+        fileName = values.getAsString(Events._SYNC_ID);
+        eTag = values.getAsString(COLUMN_ETAG);
+        event.uid = values.getAsString(COLUMN_UID);
+
+        event.sequence = values.getAsInteger(COLUMN_SEQUENCE);
+    }
+
+    @Override
+    protected void buildEvent(Event recurrence, ContentProviderOperation.Builder builder) {
+        super.buildEvent(recurrence, builder);
+
+        boolean buildException = recurrence != null;
+        Event eventToBuild = buildException ? recurrence : event;
+
+        builder .withValue(COLUMN_UID, event.uid)
+                .withValue(COLUMN_SEQUENCE, eventToBuild.sequence)
+                .withValue(CalendarContract.Events.DIRTY, 0)
+                .withValue(CalendarContract.Events.DELETED, 0);
+
+        if (buildException)
+            builder.withValue(Events.ORIGINAL_SYNC_ID, fileName);
+        else
+            builder .withValue(Events._SYNC_ID, fileName)
+                    .withValue(COLUMN_ETAG, eTag);
+    }
+
+
+    /* custom queries */
+
+    public void updateFileNameAndUID(String uid) throws CalendarStorageException {
+        try {
+            String newFileName = uid + ".ics";
+
+            ContentValues values = new ContentValues(2);
+            values.put(Events._SYNC_ID, newFileName);
+            values.put(COLUMN_UID, uid);
+            calendar.provider.update(eventSyncURI(), values, null, null);
+
+            fileName = newFileName;
+            if (event != null)
+                event.uid = uid;
+
+        } catch (RemoteException e) {
+            throw new CalendarStorageException("Couldn't update UID", e);
+        }
+    }
+
+    @Override
+    public void clearDirty(String eTag) throws CalendarStorageException {
+        try {
+            ContentValues values = new ContentValues(2);
+            values.put(CalendarContract.Events.DIRTY, 0);
+            values.put(COLUMN_ETAG, eTag);
+            if (event != null)
+                values.put(COLUMN_SEQUENCE, event.sequence);
+            calendar.provider.update(eventSyncURI(), values, null, null);
+
+            this.eTag = eTag;
+        } catch (RemoteException e) {
+            throw new CalendarStorageException("Couldn't update UID", e);
+        }
+    }
+
+
+    static class Factory implements AndroidEventFactory {
+        static final Factory INSTANCE = new Factory();
+
+        @Override
+        public AndroidEvent newInstance(AndroidCalendar calendar, long id, ContentValues baseInfo) {
+            return new LocalEvent(calendar, id, baseInfo);
+        }
+
+        @Override
+        public AndroidEvent newInstance(AndroidCalendar calendar, Event event) {
+            return new LocalEvent(calendar, event, null, null);
+        }
+
+        @Override
+        public AndroidEvent[] newArray(int size) {
+            return new LocalEvent[size];
+        }
+    }
+}

app/src/main/java/at/bitfire/davdroid/resource/LocalGroup.java

@@ -0,0 +1,253 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.resource;
+
+import android.content.ContentProviderOperation;
+import android.content.ContentUris;
+import android.content.ContentValues;
+import android.database.Cursor;
+import android.os.Parcel;
+import android.os.RemoteException;
+import android.provider.ContactsContract;
+import android.provider.ContactsContract.CommonDataKinds.GroupMembership;
+import android.provider.ContactsContract.Groups;
+import android.provider.ContactsContract.RawContacts;
+import android.provider.ContactsContract.RawContacts.Data;
+import android.provider.ContactsContract.RawContactsEntity;
+
+import org.apache.commons.lang3.ArrayUtils;
+
+import java.io.FileNotFoundException;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.logging.Level;
+
+import at.bitfire.dav4android.Constants;
+import at.bitfire.vcard4android.AndroidAddressBook;
+import at.bitfire.vcard4android.AndroidGroup;
+import at.bitfire.vcard4android.AndroidGroupFactory;
+import at.bitfire.vcard4android.BatchOperation;
+import at.bitfire.vcard4android.CachedGroupMembership;
+import at.bitfire.vcard4android.Contact;
+import at.bitfire.vcard4android.ContactsStorageException;
+import lombok.Cleanup;
+import lombok.ToString;
+
+@ToString(callSuper=true)
+public class LocalGroup extends AndroidGroup implements LocalResource {
+    /** marshalled list of member UIDs, as sent by server */
+    public static final String COLUMN_PENDING_MEMBERS = Groups.SYNC3;
+
+    public LocalGroup(AndroidAddressBook addressBook, long id, String fileName, String eTag) {
+        super(addressBook, id, fileName, eTag);
+    }
+
+    public LocalGroup(AndroidAddressBook addressBook, Contact contact, String fileName, String eTag) {
+        super(addressBook, contact, fileName, eTag);
+    }
+
+
+    @Override
+    public void clearDirty(String eTag) throws ContactsStorageException {
+        assertID();
+
+        ContentValues values = new ContentValues(2);
+        values.put(Groups.DIRTY, 0);
+        values.put(COLUMN_ETAG, this.eTag = eTag);
+        update(values);
+
+        // update cached group memberships
+        BatchOperation batch = new BatchOperation(addressBook.provider);
+
+        // delete cached group memberships
+        batch.enqueue(ContentProviderOperation
+                .newDelete(addressBook.syncAdapterURI(ContactsContract.Data.CONTENT_URI))
+                .withSelection(
+                        CachedGroupMembership.MIMETYPE + "=? AND " + CachedGroupMembership.GROUP_ID + "=?",
+                        new String[] { CachedGroupMembership.CONTENT_ITEM_TYPE, String.valueOf(id) }
+                ).build()
+        );
+
+        // insert updated cached group memberships
+        for (long member : getMembers())
+            batch.enqueue(ContentProviderOperation
+                    .newInsert(addressBook.syncAdapterURI(ContactsContract.Data.CONTENT_URI))
+                    .withValue(CachedGroupMembership.MIMETYPE, CachedGroupMembership.CONTENT_ITEM_TYPE)
+                    .withValue(CachedGroupMembership.RAW_CONTACT_ID, member)
+                    .withValue(CachedGroupMembership.GROUP_ID, id)
+                    .withYieldAllowed(true)
+                    .build()
+            );
+
+        batch.commit();
+    }
+
+    @Override
+    public void updateFileNameAndUID(String uid) throws ContactsStorageException {
+        String newFileName = uid + ".vcf";
+
+        ContentValues values = new ContentValues(2);
+        values.put(COLUMN_FILENAME, newFileName);
+        values.put(COLUMN_UID, uid);
+        update(values);
+
+        fileName = newFileName;
+    }
+
+    @Override
+    protected ContentValues contentValues() {
+        ContentValues values = super.contentValues();
+
+        @Cleanup("recycle") Parcel members = Parcel.obtain();
+        members.writeStringList(contact.members);
+        values.put(COLUMN_PENDING_MEMBERS, members.marshall());
+
+        return values;
+    }
+
+
+    /**
+     * Marks all members of the current group as dirty.
+     */
+    public void markMembersDirty() throws ContactsStorageException {
+        assertID();
+        BatchOperation batch = new BatchOperation(addressBook.provider);
+
+        for (long member : getMembers())
+            batch.enqueue(ContentProviderOperation
+                    .newUpdate(addressBook.syncAdapterURI(ContentUris.withAppendedId(RawContacts.CONTENT_URI, member)))
+                    .withValue(RawContacts.DIRTY, 1)
+                    .withYieldAllowed(true)
+                    .build()
+            );
+
+        batch.commit();
+    }
+
+    /**
+     * Processes all groups with non-null {@link #COLUMN_PENDING_MEMBERS}: the pending memberships
+     * are (if possible) applied, keeping cached memberships in sync.
+     * @param addressBook    address book to take groups from
+     * @throws ContactsStorageException on contact provider errors
+     */
+    public static void applyPendingMemberships(LocalAddressBook addressBook) throws ContactsStorageException {
+        try {
+            @Cleanup Cursor cursor = addressBook.provider.query(
+                    addressBook.syncAdapterURI(Groups.CONTENT_URI),
+                    new String[] { Groups._ID, COLUMN_PENDING_MEMBERS },
+                    COLUMN_PENDING_MEMBERS + " IS NOT NULL", new String[] {},
+                    null
+            );
+
+            BatchOperation batch = new BatchOperation(addressBook.provider);
+            while (cursor != null && cursor.moveToNext()) {
+                long id = cursor.getLong(0);
+                Constants.log.fine("Assigning members to group " + id);
+
+                // delete all memberships and cached memberships for this group
+                batch.enqueue(ContentProviderOperation
+                        .newDelete(addressBook.syncAdapterURI(ContactsContract.Data.CONTENT_URI))
+                        .withSelection(
+                                "(" + GroupMembership.MIMETYPE + "=? AND " + GroupMembership.GROUP_ROW_ID + "=?) OR (" +
+                                      CachedGroupMembership.MIMETYPE + "=? AND " + CachedGroupMembership.GROUP_ID + "=?)",
+                                new String[] { GroupMembership.CONTENT_ITEM_TYPE, String.valueOf(id), CachedGroupMembership.CONTENT_ITEM_TYPE, String.valueOf(id) })
+                        .withYieldAllowed(true)
+                        .build()
+                );
+
+                // extract list of member UIDs
+                List<String> members = new LinkedList<>();
+                byte[] raw = cursor.getBlob(1);
+                @Cleanup("recycle") Parcel parcel = Parcel.obtain();
+                parcel.unmarshall(raw, 0, raw.length);
+                parcel.setDataPosition(0);
+                parcel.readStringList(members);
+
+                // insert memberships
+                for (String uid : members) {
+                    Constants.log.fine("Assigning member: " + uid);
+                    try {
+                        LocalContact member = addressBook.findContactByUID(uid);
+                        member.addToGroup(batch, id);
+                    } catch(FileNotFoundException e) {
+                        Constants.log.log(Level.WARNING, "Group member not found: " + uid, e);
+                    }
+                }
+
+                // remove pending memberships
+                batch.enqueue(ContentProviderOperation
+                        .newUpdate(addressBook.syncAdapterURI(ContentUris.withAppendedId(Groups.CONTENT_URI, id)))
+                        .withValue(COLUMN_PENDING_MEMBERS, null)
+                        .withYieldAllowed(true)
+                        .build()
+                );
+
+                batch.commit();
+            }
+        } catch(RemoteException e) {
+            throw new ContactsStorageException("Couldn't get pending memberships", e);
+        }
+    }
+
+
+    // helpers
+
+    private void assertID() {
+        if (id == null)
+            throw new IllegalStateException("Group has not been saved yet");
+    }
+
+    /**
+     * Lists all members of this group.
+     * @return list of all members' raw contact IDs
+     * @throws ContactsStorageException on contact provider errors
+     */
+    protected long[] getMembers() throws ContactsStorageException {
+        assertID();
+        List<Long> members = new LinkedList<>();
+        try {
+            @Cleanup Cursor cursor = addressBook.provider.query(
+                    addressBook.syncAdapterURI(ContactsContract.Data.CONTENT_URI),
+                    new String[] { Data.RAW_CONTACT_ID },
+                    GroupMembership.MIMETYPE + "=? AND " + GroupMembership.GROUP_ROW_ID + "=?",
+                    new String[] { GroupMembership.CONTENT_ITEM_TYPE, String.valueOf(id) },
+                    null
+            );
+            while (cursor != null && cursor.moveToNext())
+                members.add(cursor.getLong(0));
+        } catch(RemoteException e) {
+            throw new ContactsStorageException("Couldn't list group members", e);
+        }
+        return ArrayUtils.toPrimitive(members.toArray(new Long[members.size()]));
+    }
+
+
+    // factory
+
+    static class Factory extends AndroidGroupFactory {
+        static final Factory INSTANCE = new Factory();
+
+        @Override
+        public LocalGroup newInstance(AndroidAddressBook addressBook, long id, String fileName, String eTag) {
+            return new LocalGroup(addressBook, id, fileName, eTag);
+        }
+
+        @Override
+        public LocalGroup newInstance(AndroidAddressBook addressBook, Contact contact, String fileName, String eTag) {
+            return new LocalGroup(addressBook, contact, fileName, eTag);
+        }
+
+        @Override
+        public LocalGroup[] newArray(int size) {
+            return new LocalGroup[size];
+        }
+
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/resource/LocalResource.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.resource;
+
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.vcard4android.ContactsStorageException;
+
+public interface LocalResource {
+
+    Long getId();
+
+    String getFileName();
+    String getETag();
+
+    int delete() throws CalendarStorageException, ContactsStorageException;
+
+    void updateFileNameAndUID(String uuid) throws CalendarStorageException, ContactsStorageException;
+    void clearDirty(String eTag) throws CalendarStorageException, ContactsStorageException;
+
+}

app/src/main/java/at/bitfire/davdroid/resource/LocalTask.java

@@ -0,0 +1,138 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.resource;
+
+import android.content.ContentProviderOperation;
+import android.content.ContentValues;
+import android.os.RemoteException;
+import android.provider.CalendarContract.Events;
+import android.support.annotation.NonNull;
+
+import net.fortuna.ical4j.model.property.ProdId;
+
+import org.dmfs.provider.tasks.TaskContract.Tasks;
+
+import java.io.FileNotFoundException;
+import java.text.ParseException;
+
+import at.bitfire.davdroid.BuildConfig;
+import at.bitfire.ical4android.AndroidTask;
+import at.bitfire.ical4android.AndroidTaskFactory;
+import at.bitfire.ical4android.AndroidTaskList;
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.ical4android.Task;
+import lombok.Getter;
+import lombok.Setter;
+
+public class LocalTask extends AndroidTask implements LocalResource {
+    static {
+        Task.prodId = new ProdId("+//IDN bitfire.at//DAVdroid/" + BuildConfig.VERSION_NAME + " ical4android ical4j/2.x");
+    }
+
+    static final String COLUMN_ETAG = Tasks.SYNC1,
+                        COLUMN_UID = Tasks.SYNC2,
+                        COLUMN_SEQUENCE = Tasks.SYNC3;
+
+    @Getter protected String fileName;
+    @Getter @Setter protected String eTag;
+
+    public LocalTask(@NonNull AndroidTaskList taskList, Task task, String fileName, String eTag) {
+        super(taskList, task);
+        this.fileName = fileName;
+        this.eTag = eTag;
+    }
+
+    protected LocalTask(@NonNull AndroidTaskList taskList, long id, ContentValues baseInfo) {
+        super(taskList, id);
+        if (baseInfo != null) {
+            fileName = baseInfo.getAsString(Events._SYNC_ID);
+            eTag = baseInfo.getAsString(COLUMN_ETAG);
+        }
+    }
+
+
+    /* process LocalTask-specific fields */
+
+    @Override
+    protected void populateTask(ContentValues values) throws FileNotFoundException, RemoteException, ParseException {
+        super.populateTask(values);
+
+        fileName = values.getAsString(Events._SYNC_ID);
+        eTag = values.getAsString(COLUMN_ETAG);
+        task.uid = values.getAsString(COLUMN_UID);
+
+        task.sequence = values.getAsInteger(COLUMN_SEQUENCE);
+    }
+
+    @Override
+    protected void buildTask(ContentProviderOperation.Builder builder, boolean update) {
+        super.buildTask(builder, update);
+        builder .withValue(Tasks._SYNC_ID, fileName)
+                .withValue(COLUMN_UID, task.uid)
+                .withValue(COLUMN_SEQUENCE, task.sequence)
+                .withValue(COLUMN_ETAG, eTag);
+    }
+
+
+    /* custom queries */
+
+    public void updateFileNameAndUID(String uid) throws CalendarStorageException {
+        try {
+            String newFileName = uid + ".ics";
+
+            ContentValues values = new ContentValues(2);
+            values.put(Tasks._SYNC_ID, newFileName);
+            values.put(COLUMN_UID, uid);
+            taskList.provider.client.update(taskSyncURI(), values, null, null);
+
+            fileName = newFileName;
+            if (task != null)
+                task.uid = uid;
+
+        } catch (RemoteException e) {
+            throw new CalendarStorageException("Couldn't update UID", e);
+        }
+    }
+
+    @Override
+    public void clearDirty(String eTag) throws CalendarStorageException {
+        try {
+            ContentValues values = new ContentValues(2);
+            values.put(Tasks._DIRTY, 0);
+            values.put(COLUMN_ETAG, eTag);
+            if (task != null)
+                values.put(COLUMN_SEQUENCE, task.sequence);
+            taskList.provider.client.update(taskSyncURI(), values, null, null);
+
+            this.eTag = eTag;
+        } catch (RemoteException e) {
+            throw new CalendarStorageException("Couldn't update _DIRTY/ETag/SEQUENCE", e);
+        }
+    }
+
+
+    static class Factory implements AndroidTaskFactory {
+        static final Factory INSTANCE = new Factory();
+
+        @Override
+        public LocalTask newInstance(AndroidTaskList taskList, long id, ContentValues baseInfo) {
+            return new LocalTask(taskList, id, baseInfo);
+        }
+
+        @Override
+        public LocalTask newInstance(AndroidTaskList taskList, Task task) {
+            return new LocalTask(taskList, task, null, null);
+        }
+
+        @Override
+        public LocalTask[] newArray(int size) {
+            return new LocalTask[size];
+        }
+    }
+}

app/src/main/java/at/bitfire/davdroid/resource/LocalTaskList.java

@@ -0,0 +1,167 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.resource;
+
+import android.accounts.Account;
+import android.content.ContentValues;
+import android.content.Context;
+import android.database.Cursor;
+import android.net.Uri;
+import android.os.Build;
+import android.os.RemoteException;
+import android.support.annotation.NonNull;
+import android.text.TextUtils;
+
+import org.dmfs.provider.tasks.TaskContract.TaskLists;
+import org.dmfs.provider.tasks.TaskContract.Tasks;
+
+import java.io.FileNotFoundException;
+
+import at.bitfire.davdroid.DavUtils;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.ical4android.AndroidTaskList;
+import at.bitfire.ical4android.AndroidTaskListFactory;
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.ical4android.TaskProvider;
+import lombok.Cleanup;
+
+public class LocalTaskList extends AndroidTaskList implements LocalCollection {
+
+    public static final int defaultColor = 0xFFC3EA6E;     // "DAVdroid green"
+
+    public static final String COLUMN_CTAG = TaskLists.SYNC_VERSION;
+
+    static String[] BASE_INFO_COLUMNS = new String[] {
+            Tasks._ID,
+            Tasks._SYNC_ID,
+            LocalTask.COLUMN_ETAG
+    };
+
+    // can be cached, because after installing OpenTasks, you have to re-install DAVdroid anyway
+    private static Boolean tasksProviderAvailable;
+
+
+    @Override
+    protected String[] taskBaseInfoColumns() {
+        return BASE_INFO_COLUMNS;
+    }
+
+
+    protected LocalTaskList(Account account, TaskProvider provider, long id) {
+        super(account, provider, LocalTask.Factory.INSTANCE, id);
+    }
+
+    public static Uri create(Account account, TaskProvider provider, CollectionInfo info) throws CalendarStorageException {
+        ContentValues values = valuesFromCollectionInfo(info, true);
+        values.put(TaskLists.OWNER, account.name);
+        values.put(TaskLists.SYNC_ENABLED, 1);
+        values.put(TaskLists.VISIBLE, 1);
+        return create(account, provider, values);
+    }
+
+    public void update(CollectionInfo info, boolean updateColor) throws CalendarStorageException {
+        update(valuesFromCollectionInfo(info, updateColor));
+    }
+
+    private static ContentValues valuesFromCollectionInfo(CollectionInfo info, boolean withColor) {
+        ContentValues values = new ContentValues();
+        values.put(TaskLists._SYNC_ID, info.url);
+        values.put(TaskLists.LIST_NAME, !TextUtils.isEmpty(info.displayName) ? info.displayName : DavUtils.lastSegmentOfUrl(info.url));
+
+        if (withColor)
+            values.put(TaskLists.LIST_COLOR, info.color != null ? info.color : defaultColor);
+
+        return values;
+    }
+
+
+    @Override
+    public LocalTask[] getAll() throws CalendarStorageException {
+        return (LocalTask[])queryTasks(null, null);
+    }
+
+    @Override
+    public LocalTask[] getDeleted() throws CalendarStorageException {
+        return (LocalTask[])queryTasks(Tasks._DELETED + "!=0", null);
+    }
+
+    @Override
+    public LocalTask[] getWithoutFileName() throws CalendarStorageException {
+        return (LocalTask[])queryTasks(Tasks._SYNC_ID + " IS NULL", null);
+    }
+
+    @Override
+    public LocalResource[] getDirty() throws CalendarStorageException, FileNotFoundException {
+        LocalTask[] tasks = (LocalTask[])queryTasks(Tasks._DIRTY + "!=0", null);
+        if (tasks != null)
+        for (LocalTask task : tasks) {
+            if (task.getTask().sequence == null)    // sequence has not been assigned yet (i.e. this task was just locally created)
+                task.getTask().sequence = 0;
+            else
+                task.getTask().sequence++;
+        }
+        return tasks;
+    }
+
+
+    @Override
+    @SuppressWarnings("Recycle")
+    public String getCTag() throws CalendarStorageException {
+        try {
+            @Cleanup Cursor cursor = provider.client.query(taskListSyncUri(), new String[] { COLUMN_CTAG }, null, null, null);
+            if (cursor != null && cursor.moveToNext())
+                return cursor.getString(0);
+        } catch (RemoteException e) {
+            throw new CalendarStorageException("Couldn't read local (last known) CTag", e);
+        }
+        return null;
+    }
+
+    @Override
+    public void setCTag(String cTag) throws CalendarStorageException {
+        try {
+            ContentValues values = new ContentValues(1);
+            values.put(COLUMN_CTAG, cTag);
+            provider.client.update(taskListSyncUri(), values, null, null);
+        } catch (RemoteException e) {
+            throw new CalendarStorageException("Couldn't write local (last known) CTag", e);
+        }
+    }
+
+
+    // helpers
+
+    public static boolean tasksProviderAvailable(@NonNull Context context) {
+        if (tasksProviderAvailable != null)
+            return tasksProviderAvailable;
+        else {
+            if (Build.VERSION.SDK_INT >= 23)
+                return context.getPackageManager().resolveContentProvider(TaskProvider.ProviderName.OpenTasks.authority, 0) != null;
+            else {
+                @Cleanup TaskProvider provider = TaskProvider.acquire(context.getContentResolver(), TaskProvider.ProviderName.OpenTasks);
+                return tasksProviderAvailable = (provider != null);
+            }
+        }
+    }
+
+
+    public static class Factory implements AndroidTaskListFactory {
+        public static final Factory INSTANCE = new Factory();
+
+        @Override
+        public AndroidTaskList newInstance(Account account, TaskProvider provider, long id) {
+            return new LocalTaskList(account, provider, id);
+        }
+
+        @Override
+        public AndroidTaskList[] newArray(int size) {
+            return new LocalTaskList[size];
+        }
+    }
+}

app/src/main/java/at/bitfire/davdroid/syncadapter/AccountAuthenticatorService.java

@@ -1,10 +1,10 @@
-/*******************************************************************************
- * Copyright (c) 2014 Ricki Hirner (bitfire web engineering).
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the GNU Public License v3.0
  * which accompanies this distribution, and is available at
  * http://www.gnu.org/licenses/gpl.html
- ******************************************************************************/
+ */
 package at.bitfire.davdroid.syncadapter;
 
 import android.accounts.AbstractAccountAuthenticator;
@@ -18,6 +18,8 @@ import android.content.Intent;
 import android.os.Bundle;
 import android.os.IBinder;
 
+import at.bitfire.davdroid.ui.setup.LoginActivity;
+
 public class AccountAuthenticatorService extends Service {
 	private static AccountAuthenticator accountAuthenticator;
 
@@ -36,7 +38,7 @@ public class AccountAuthenticatorService extends Service {
 	
 	
 	private static class AccountAuthenticator extends AbstractAccountAuthenticator {
-		Context context;
+		final Context context;
 		
 		public AccountAuthenticator(Context context) {
 			super(context);
@@ -46,7 +48,7 @@ public class AccountAuthenticatorService extends Service {
 		@Override
 		public Bundle addAccount(AccountAuthenticatorResponse response, String accountType, String authTokenType,
 				String[] requiredFeatures, Bundle options) throws NetworkErrorException {
-			Intent intent = new Intent(context, AddAccountActivity.class);
+			Intent intent = new Intent(context, LoginActivity.class);
 			intent.putExtra(AccountManager.KEY_ACCOUNT_AUTHENTICATOR_RESPONSE, response);
 			Bundle bundle = new Bundle();
 			bundle.putParcelable(AccountManager.KEY_INTENT, intent);
@@ -54,8 +56,7 @@ public class AccountAuthenticatorService extends Service {
 		}
 
 		@Override
-		public Bundle confirmCredentials(AccountAuthenticatorResponse response, Account account, Bundle options)
-				throws NetworkErrorException {
+		public Bundle confirmCredentials(AccountAuthenticatorResponse response, Account account, Bundle options) throws NetworkErrorException {
 			return null;
 		}
 
@@ -64,9 +65,8 @@ public class AccountAuthenticatorService extends Service {
 			return null;
 		}
 
-		@Override
-		public Bundle getAuthToken(AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options)
-				throws NetworkErrorException {
+        @Override
+		public Bundle getAuthToken(AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options) throws NetworkErrorException {
 			return null;
 		}
 
@@ -76,14 +76,12 @@ public class AccountAuthenticatorService extends Service {
 		}
 
 		@Override
-		public Bundle hasFeatures(AccountAuthenticatorResponse response, Account account, String[] features)
-				throws NetworkErrorException {
+		public Bundle hasFeatures(AccountAuthenticatorResponse response, Account account, String[] features) throws NetworkErrorException {
 			return null;
 		}
 
 		@Override
-		public Bundle updateCredentials(AccountAuthenticatorResponse response, Account account, String authTokenType,
-				Bundle options) throws NetworkErrorException {
+		public Bundle updateCredentials(AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options) throws NetworkErrorException {
 			return null;
 		}
 	}

app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarSyncManager.java

@@ -0,0 +1,235 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.syncadapter;
+
+import android.accounts.Account;
+import android.content.Context;
+import android.content.SyncResult;
+import android.os.Bundle;
+
+import org.apache.commons.codec.Charsets;
+import org.apache.commons.lang3.StringUtils;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.Charset;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.logging.Level;
+
+import at.bitfire.dav4android.DavCalendar;
+import at.bitfire.dav4android.DavResource;
+import at.bitfire.dav4android.exception.DavException;
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.dav4android.property.CalendarData;
+import at.bitfire.dav4android.property.GetCTag;
+import at.bitfire.dav4android.property.GetContentType;
+import at.bitfire.dav4android.property.GetETag;
+import at.bitfire.davdroid.AccountSettings;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.ArrayUtils;
+import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.resource.LocalCalendar;
+import at.bitfire.davdroid.resource.LocalEvent;
+import at.bitfire.davdroid.resource.LocalResource;
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.ical4android.Event;
+import at.bitfire.ical4android.InvalidCalendarException;
+import at.bitfire.vcard4android.ContactsStorageException;
+import lombok.Cleanup;
+import okhttp3.HttpUrl;
+import okhttp3.MediaType;
+import okhttp3.RequestBody;
+import okhttp3.ResponseBody;
+
+/**
+ * Synchronization manager for CalDAV collections; handles events ({@code VEVENT}).
+ */
+public class CalendarSyncManager extends SyncManager {
+
+    protected static final int MAX_MULTIGET = 20;
+
+
+    public CalendarSyncManager(Context context, Account account, AccountSettings settings, Bundle extras, String authority, SyncResult result, LocalCalendar calendar) throws InvalidAccountException {
+        super(context, account, settings, extras, authority, result, "calendar/" + calendar.getId());
+        localCollection = calendar;
+    }
+
+    @Override
+    protected int notificationId() {
+        return Constants.NOTIFICATION_CALENDAR_SYNC;
+    }
+
+    @Override
+    protected String getSyncErrorTitle() {
+        return context.getString(R.string.sync_error_calendar, account.name);
+    }
+
+
+    @Override
+    protected void prepare() {
+        collectionURL = HttpUrl.parse(localCalendar().getName());
+        davCollection = new DavCalendar(httpClient, collectionURL);
+    }
+
+    @Override
+    protected void queryCapabilities() throws DavException, IOException, HttpException {
+        davCollection.propfind(0, GetCTag.NAME);
+    }
+
+    @Override
+    protected void prepareDirty() throws CalendarStorageException, ContactsStorageException {
+        super.prepareDirty();
+
+        localCalendar().processDirtyExceptions();
+    }
+
+    @Override
+    protected RequestBody prepareUpload(LocalResource resource) throws IOException, CalendarStorageException {
+        LocalEvent local = (LocalEvent)resource;
+        App.log.log(Level.FINE, "Preparing upload of event " + local.getFileName(), local.getEvent());
+
+        ByteArrayOutputStream os = new ByteArrayOutputStream();
+        local.getEvent().write(os);
+
+        return RequestBody.create(
+                DavCalendar.MIME_ICALENDAR,
+                os.toByteArray()
+        );
+    }
+
+    @Override
+    protected void listRemote() throws IOException, HttpException, DavException {
+        // calculate time range limits
+        Date limitStart = null;
+        Integer pastDays = settings.getTimeRangePastDays();
+        if (pastDays != null) {
+            Calendar calendar = Calendar.getInstance();
+            calendar.add(Calendar.DAY_OF_MONTH, -pastDays);
+            limitStart = calendar.getTime();
+        }
+
+        // fetch list of remote VEVENTs and build hash table to index file name
+        davCalendar().calendarQuery("VEVENT", limitStart, null);
+
+        remoteResources = new HashMap<>(davCollection.members.size());
+        for (DavResource iCal : davCollection.members) {
+            String fileName = iCal.fileName();
+            App.log.fine("Found remote VEVENT: " + fileName);
+            remoteResources.put(fileName, iCal);
+        }
+    }
+
+    @Override
+    protected void downloadRemote() throws IOException, HttpException, DavException, CalendarStorageException {
+        App.log.info("Downloading " + toDownload.size() + " events (" + MAX_MULTIGET + " at once)");
+
+        // download new/updated iCalendars from server
+        for (DavResource[] bunch : ArrayUtils.partition(toDownload.toArray(new DavResource[toDownload.size()]), MAX_MULTIGET)) {
+            if (Thread.interrupted())
+                return;
+            App.log.info("Downloading " + StringUtils.join(bunch, ", "));
+
+            if (bunch.length == 1) {
+                // only one contact, use GET
+                DavResource remote = bunch[0];
+
+                ResponseBody body = remote.get("text/calendar");
+
+                // CalDAV servers MUST return ETag on GET [https://tools.ietf.org/html/rfc4791#section-5.3.4]
+                GetETag eTag = (GetETag)remote.properties.get(GetETag.NAME);
+                if (eTag == null || StringUtils.isEmpty(eTag.eTag))
+                    throw new DavException("Received CalDAV GET response without ETag for " + remote.location);
+
+                Charset charset = Charsets.UTF_8;
+                MediaType contentType = body.contentType();
+                if (contentType != null)
+                    charset = contentType.charset(Charsets.UTF_8);
+
+                @Cleanup InputStream stream = body.byteStream();
+                processVEvent(remote.fileName(), eTag.eTag, stream, charset);
+
+            } else {
+                // multiple contacts, use multi-get
+                List<HttpUrl> urls = new LinkedList<>();
+                for (DavResource remote : bunch)
+                    urls.add(remote.location);
+                davCalendar().multiget(urls.toArray(new HttpUrl[urls.size()]));
+
+                // process multiget results
+                for (DavResource remote : davCollection.members) {
+                    String eTag;
+                    GetETag getETag = (GetETag)remote.properties.get(GetETag.NAME);
+                    if (getETag != null)
+                        eTag = getETag.eTag;
+                    else
+                        throw new DavException("Received multi-get response without ETag");
+
+                    Charset charset = Charsets.UTF_8;
+                    GetContentType getContentType = (GetContentType)remote.properties.get(GetContentType.NAME);
+                    if (getContentType != null && getContentType.type != null) {
+                        MediaType type = MediaType.parse(getContentType.type);
+                        if (type != null)
+                            charset = type.charset(Charsets.UTF_8);
+                    }
+
+                    CalendarData calendarData = (CalendarData)remote.properties.get(CalendarData.NAME);
+                    if (calendarData == null || calendarData.iCalendar == null)
+                        throw new DavException("Received multi-get response without address data");
+
+                    @Cleanup InputStream stream = new ByteArrayInputStream(calendarData.iCalendar.getBytes());
+                    processVEvent(remote.fileName(), eTag, stream, charset);
+                }
+            }
+        }
+    }
+
+
+    // helpers
+
+    private LocalCalendar localCalendar() { return ((LocalCalendar)localCollection); }
+    private DavCalendar davCalendar() { return (DavCalendar)davCollection; }
+
+    private void processVEvent(String fileName, String eTag, InputStream stream, Charset charset) throws IOException, CalendarStorageException {
+        Event[] events;
+        try {
+            events = Event.fromStream(stream, charset);
+        } catch (InvalidCalendarException e) {
+            App.log.log(Level.SEVERE, "Received invalid iCalendar, ignoring", e);
+            return;
+        }
+
+        if (events.length == 1) {
+            Event newData = events[0];
+
+            // delete local event, if it exists
+            LocalEvent localEvent = (LocalEvent)localResources.get(fileName);
+            if (localEvent != null) {
+                App.log.info("Updating " + fileName + " in local calendar");
+                localEvent.setETag(eTag);
+                localEvent.update(newData);
+                syncResult.stats.numUpdates++;
+            } else {
+                App.log.info("Adding " + fileName + " to local calendar");
+                localEvent = new LocalEvent(localCalendar(), newData, fileName, eTag);
+                localEvent.add();
+                syncResult.stats.numInserts++;
+            }
+        } else
+            App.log.severe("Received VCALENDAR with not exactly one VEVENT with UID, but without RECURRENCE-ID; ignoring " + fileName);
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarsSyncAdapterService.java

@@ -0,0 +1,148 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+package at.bitfire.davdroid.syncadapter;
+
+import android.accounts.Account;
+import android.content.AbstractThreadedSyncAdapter;
+import android.content.ContentProviderClient;
+import android.content.ContentResolver;
+import android.content.ContentValues;
+import android.content.Context;
+import android.content.SyncResult;
+import android.database.Cursor;
+import android.database.DatabaseUtils;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.os.Bundle;
+import android.provider.CalendarContract;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.logging.Level;
+
+import at.bitfire.davdroid.AccountSettings;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.davdroid.model.ServiceDB;
+import at.bitfire.davdroid.model.ServiceDB.Collections;
+import at.bitfire.davdroid.model.ServiceDB.Services;
+import at.bitfire.davdroid.resource.LocalCalendar;
+import at.bitfire.ical4android.CalendarStorageException;
+import lombok.Cleanup;
+
+public class CalendarsSyncAdapterService extends SyncAdapterService {
+
+    @Override
+    protected AbstractThreadedSyncAdapter syncAdapter() {
+        return new SyncAdapter(this);
+    }
+
+
+	private static class SyncAdapter extends SyncAdapterService.SyncAdapter {
+
+        public SyncAdapter(Context context) {
+            super(context);
+        }
+
+        @Override
+        public void onPerformSync(Account account, Bundle extras, String authority, ContentProviderClient provider, SyncResult syncResult) {
+            super.onPerformSync(account, extras, authority, provider, syncResult);
+
+            try {
+                AccountSettings settings = new AccountSettings(getContext(), account);
+                if (!extras.containsKey(ContentResolver.SYNC_EXTRAS_MANUAL) && !checkSyncConditions(settings))
+                    return;
+
+                updateLocalCalendars(provider, account, settings);
+
+                for (LocalCalendar calendar : (LocalCalendar[])LocalCalendar.find(account, provider, LocalCalendar.Factory.INSTANCE, CalendarContract.Calendars.SYNC_EVENTS + "!=0", null)) {
+                    App.log.info("Synchronizing calendar #"  + calendar.getId() + ", URL: " + calendar.getName());
+                    CalendarSyncManager syncManager = new CalendarSyncManager(getContext(), account, settings, extras, authority, syncResult, calendar);
+                    syncManager.performSync();
+                }
+            } catch (CalendarStorageException e) {
+                App.log.log(Level.SEVERE, "Couldn't enumerate local calendars", e);
+                syncResult.databaseError = true;
+            } catch (InvalidAccountException e) {
+                App.log.log(Level.SEVERE, "Couldn't get account settings", e);
+            }
+
+            App.log.info("Calendar sync complete");
+        }
+
+        private void updateLocalCalendars(ContentProviderClient provider, Account account, AccountSettings settings) throws CalendarStorageException {
+            SQLiteOpenHelper dbHelper = new ServiceDB.OpenHelper(getContext());
+            try {
+                // enumerate remote and local calendars
+                SQLiteDatabase db = dbHelper.getReadableDatabase();
+                Long service = getService(db, account);
+                Map<String, CollectionInfo> remote = remoteCalendars(db, service);
+
+                LocalCalendar[] local = (LocalCalendar[])LocalCalendar.find(account, provider, LocalCalendar.Factory.INSTANCE, null, null);
+
+                boolean updateColors = settings.getManageCalendarColors();
+
+                // delete obsolete local calendar
+                for (LocalCalendar calendar : local) {
+                    String url = calendar.getName();
+                    if (!remote.containsKey(url)) {
+                        App.log.fine("Deleting obsolete local calendar " + url);
+                        calendar.delete();
+                    } else {
+                        // remote CollectionInfo found for this local collection, update data
+                        CollectionInfo info = remote.get(url);
+                        App.log.fine("Updating local calendar " + url + " with " + info);
+                        calendar.update(info, updateColors);
+                        // we already have a local calendar for this remote collection, don't take into consideration anymore
+                        remote.remove(url);
+                    }
+                }
+
+                // create new local calendars
+                for (String url : remote.keySet()) {
+                    CollectionInfo info = remote.get(url);
+                    App.log.info("Adding local calendar list " + info);
+                    LocalCalendar.create(account, provider, info);
+                }
+            } finally {
+                dbHelper.close();
+            }
+        }
+
+        @Nullable
+        Long getService(@NonNull SQLiteDatabase db, @NonNull Account account) {
+            @Cleanup Cursor c = db.query(Services._TABLE, new String[] { Services.ID },
+                    Services.ACCOUNT_NAME + "=? AND " + Services.SERVICE + "=?", new String[] { account.name, Services.SERVICE_CALDAV }, null, null, null);
+            if (c.moveToNext())
+                return c.getLong(0);
+            else
+                return null;
+        }
+
+        @NonNull
+        private Map<String, CollectionInfo> remoteCalendars(@NonNull SQLiteDatabase db, Long service) {
+            Map<String, CollectionInfo> collections = new LinkedHashMap<>();
+            if (service != null) {
+                @Cleanup Cursor cursor = db.query(Collections._TABLE, null,
+                        Collections.SERVICE_ID + "=? AND " + Collections.SUPPORTS_VEVENT + "!=0 AND " + Collections.SYNC,
+                        new String[] { String.valueOf(service) }, null, null, null);
+                while (cursor.moveToNext()) {
+                    ContentValues values = new ContentValues();
+                    DatabaseUtils.cursorRowToContentValues(cursor, values);
+                    CollectionInfo info = CollectionInfo.fromDB(values);
+                    collections.put(info.url, info);
+                }
+            }
+            return collections;
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncAdapterService.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+package at.bitfire.davdroid.syncadapter;
+
+import android.accounts.Account;
+import android.content.AbstractThreadedSyncAdapter;
+import android.content.ContentProviderClient;
+import android.content.ContentResolver;
+import android.content.ContentValues;
+import android.content.Context;
+import android.content.SyncResult;
+import android.database.Cursor;
+import android.database.DatabaseUtils;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import java.util.logging.Level;
+
+import at.bitfire.davdroid.AccountSettings;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.davdroid.model.ServiceDB;
+import at.bitfire.davdroid.model.ServiceDB.Collections;
+import lombok.Cleanup;
+
+public class ContactsSyncAdapterService extends SyncAdapterService {
+
+    @Override
+    protected AbstractThreadedSyncAdapter syncAdapter() {
+        return new ContactsSyncAdapter(this);
+    }
+
+
+	private static class ContactsSyncAdapter extends SyncAdapter {
+
+        public ContactsSyncAdapter(Context context) {
+            super(context);
+        }
+
+        @Override
+        public void onPerformSync(Account account, Bundle extras, String authority, ContentProviderClient provider, SyncResult syncResult) {
+            super.onPerformSync(account, extras, authority, provider, syncResult);
+
+            SQLiteOpenHelper dbHelper = new ServiceDB.OpenHelper(getContext());
+            try {
+                AccountSettings settings = new AccountSettings(getContext(), account);
+                if (!extras.containsKey(ContentResolver.SYNC_EXTRAS_MANUAL) && !checkSyncConditions(settings))
+                    return;
+
+                SQLiteDatabase db = dbHelper.getReadableDatabase();
+                Long service = getService(db, account);
+                if (service != null) {
+                    CollectionInfo remote = remoteAddressBook(db, service);
+                    if (remote != null)
+                        try {
+                            ContactsSyncManager syncManager = new ContactsSyncManager(getContext(), account, settings, extras, authority, provider, syncResult, remote);
+                            syncManager.performSync();
+                        } catch(InvalidAccountException e) {
+                            App.log.log(Level.SEVERE, "Couldn't get account settings", e);
+                        }
+                    else
+                        App.log.info("No address book collection selected for synchronization");
+                } else
+                    App.log.info("No CardDAV service found in DB");
+            } catch (InvalidAccountException e) {
+                App.log.log(Level.SEVERE, "Couldn't get account settings", e);
+            } finally {
+                dbHelper.close();
+            }
+
+            App.log.info("Address book sync complete");
+        }
+
+        @Nullable
+        private Long getService(@NonNull SQLiteDatabase db, @NonNull Account account) {
+            @Cleanup Cursor c = db.query(ServiceDB.Services._TABLE, new String[] { ServiceDB.Services.ID },
+                    ServiceDB.Services.ACCOUNT_NAME + "=? AND " + ServiceDB.Services.SERVICE + "=?", new String[] { account.name, ServiceDB.Services.SERVICE_CARDDAV }, null, null, null);
+            if (c.moveToNext())
+                return c.getLong(0);
+            else
+                return null;
+        }
+
+        @Nullable
+        private CollectionInfo remoteAddressBook(@NonNull SQLiteDatabase db, long service) {
+            @Cleanup Cursor c = db.query(Collections._TABLE, null,
+                    Collections.SERVICE_ID + "=? AND " + Collections.SYNC, new String[] { String.valueOf(service) }, null, null, null);
+            if (c.moveToNext()) {
+                ContentValues values = new ContentValues();
+                DatabaseUtils.cursorRowToContentValues(c, values);
+                return CollectionInfo.fromDB(values);
+            } else
+                return null;
+        }
+
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncManager.java

@@ -0,0 +1,529 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.syncadapter;
+
+import android.accounts.Account;
+import android.content.ContentProviderClient;
+import android.content.ContentProviderOperation;
+import android.content.ContentUris;
+import android.content.ContentValues;
+import android.content.Context;
+import android.content.SyncResult;
+import android.database.Cursor;
+import android.os.Bundle;
+import android.os.RemoteException;
+import android.provider.ContactsContract;
+import android.provider.ContactsContract.Groups;
+import android.support.annotation.NonNull;
+import android.text.TextUtils;
+
+import org.apache.commons.codec.Charsets;
+import org.apache.commons.collections4.SetUtils;
+import org.apache.commons.lang3.StringUtils;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.Charset;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Set;
+import java.util.logging.Level;
+
+import at.bitfire.dav4android.DavAddressBook;
+import at.bitfire.dav4android.DavResource;
+import at.bitfire.dav4android.exception.DavException;
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.dav4android.property.AddressData;
+import at.bitfire.dav4android.property.GetCTag;
+import at.bitfire.dav4android.property.GetContentType;
+import at.bitfire.dav4android.property.GetETag;
+import at.bitfire.dav4android.property.SupportedAddressData;
+import at.bitfire.davdroid.AccountSettings;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.ArrayUtils;
+import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.HttpClient;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.davdroid.resource.LocalAddressBook;
+import at.bitfire.davdroid.resource.LocalContact;
+import at.bitfire.davdroid.resource.LocalGroup;
+import at.bitfire.davdroid.resource.LocalResource;
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.vcard4android.BatchOperation;
+import at.bitfire.vcard4android.Contact;
+import at.bitfire.vcard4android.ContactsStorageException;
+import at.bitfire.vcard4android.GroupMethod;
+import ezvcard.VCardVersion;
+import ezvcard.util.IOUtils;
+import lombok.Cleanup;
+import lombok.RequiredArgsConstructor;
+import okhttp3.HttpUrl;
+import okhttp3.MediaType;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.RequestBody;
+import okhttp3.Response;
+import okhttp3.ResponseBody;
+
+/**
+ * <p>Synchronization manager for CardDAV collections; handles contacts and groups.</p>
+ *
+ * <p></p>Group handling differs according to the {@link #groupMethod}. There are two basic methods to
+ * handle/manage groups:</p>
+ * <ul>
+ *     <li>{@code CATEGORIES}: groups memberships are attached to each contact and represented as
+ *     "category". When a group is dirty or has been deleted, all its members have to be set to
+ *     dirty, too (because they have to be uploaded without the respective category). This
+ *     is done in {@link #prepareDirty()}. Empty groups can be deleted without further processing,
+ *     which is done in {@link #postProcess()} because groups may become empty after downloading
+ *     updated remoted contacts.</li>
+ *     <li>Groups as separate VCards: individual and group contacts (with a list of member UIDs) are
+ *     distinguished. When a local group is dirty, its members don't need to be set to dirty.
+ *     <ol>
+ *         <li>However, when a contact is dirty, it has
+ *         to be checked whether its group memberships have changed. In this case, the respective
+ *         groups have to be set to dirty. For instance, if contact A is in group G and H, and then
+ *         group membership of G is removed, the contact will be set to dirty because of the changed
+ *         {@link android.provider.ContactsContract.CommonDataKinds.GroupMembership}. DAVdroid will
+ *         then have to check whether the group memberships have actually changed, and if so,
+ *         all affected groups have to be set to dirty. To detect changes in group memberships,
+ *         DAVdroid always mirrors all {@link android.provider.ContactsContract.CommonDataKinds.GroupMembership}
+ *         data rows in respective {@link at.bitfire.vcard4android.CachedGroupMembership} rows.
+ *         If the cached group memberships are not the same as the current group member ships, the
+ *         difference set (in our example G, because its in the cached memberships, but not in the
+ *         actual ones) is marked as dirty. This is done in {@link #prepareDirty()}.</li>
+ *         <li>When downloading remote contacts, groups (+ member information) may be received
+ *         by the actual members. Thus, the member lists have to be cached until all VCards
+ *         are received. This is done by caching the member UIDs of each group in
+ *         {@link LocalGroup#COLUMN_PENDING_MEMBERS}. In {@link #postProcess()},
+ *         these "pending memberships" are assigned to the actual contacs and then cleaned up.</li>
+ *     </ol>
+ * </ul>
+ */
+public class ContactsSyncManager extends SyncManager {
+    protected static final int MAX_MULTIGET = 10;
+
+    final private ContentProviderClient provider;
+    final private CollectionInfo remote;
+
+    private boolean hasVCard4;
+    private GroupMethod groupMethod;
+
+
+    public ContactsSyncManager(Context context, Account account, AccountSettings settings, Bundle extras, String authority, ContentProviderClient provider, SyncResult result, CollectionInfo remote) throws InvalidAccountException {
+        super(context, account, settings, extras, authority, result, "addressBook");
+        this.provider = provider;
+        this.remote = remote;
+    }
+
+    @Override
+    protected int notificationId() {
+        return Constants.NOTIFICATION_CONTACTS_SYNC;
+    }
+
+    @Override
+    protected String getSyncErrorTitle() {
+        return context.getString(R.string.sync_error_contacts, account.name);
+    }
+
+
+    @Override
+    protected void prepare() throws ContactsStorageException {
+        // prepare local address book
+        localCollection = new LocalAddressBook(account, provider);
+        LocalAddressBook localAddressBook = localAddressBook();
+
+        String url = remote.url;
+        String lastUrl = localAddressBook.getURL();
+        if (!url.equals(lastUrl)) {
+            App.log.info("Selected address book has changed from " + lastUrl + " to " + url + ", deleting all local contacts");
+            localAddressBook.deleteAll();
+        }
+
+        // set up Contacts Provider Settings
+        ContentValues values = new ContentValues(2);
+        values.put(ContactsContract.Settings.SHOULD_SYNC, 1);
+        values.put(ContactsContract.Settings.UNGROUPED_VISIBLE, 1);
+        localAddressBook.updateSettings(values);
+
+        collectionURL = HttpUrl.parse(url);
+        davCollection = new DavAddressBook(httpClient, collectionURL);
+    }
+
+    @Override
+    protected void queryCapabilities() throws DavException, IOException, HttpException {
+        // prepare remote address book
+        davCollection.propfind(0, SupportedAddressData.NAME, GetCTag.NAME);
+        SupportedAddressData supportedAddressData = (SupportedAddressData)davCollection.properties.get(SupportedAddressData.NAME);
+        hasVCard4 = supportedAddressData != null && supportedAddressData.hasVCard4();
+        App.log.info("Server advertises VCard/4 support: " + hasVCard4);
+
+        groupMethod = settings.getGroupMethod();
+        App.log.info("Contact group method: " + groupMethod);
+
+        localAddressBook().includeGroups = groupMethod == GroupMethod.GROUP_VCARDS;
+    }
+
+    @Override
+    protected void prepareDirty() throws CalendarStorageException, ContactsStorageException {
+        super.prepareDirty();
+
+        LocalAddressBook addressBook = localAddressBook();
+
+        if (groupMethod == GroupMethod.CATEGORIES) {
+            /* groups memberships are represented as contact CATEGORIES */
+
+            // groups with DELETED=1: set all members to dirty, then remove group
+            for (LocalGroup group : addressBook.getDeletedGroups()) {
+                App.log.fine("Finally removing group " + group);
+                // useless because Android deletes group memberships as soon as a group is set to DELETED:
+                // group.markMembersDirty();
+                group.delete();
+            }
+
+            // groups with DIRTY=1: mark all memberships as dirty, then clean DIRTY flag of group
+            for (LocalGroup group : addressBook.getDirtyGroups()) {
+                App.log.fine("Marking members of modified group " + group + " as dirty");
+                group.markMembersDirty();
+                group.clearDirty(null);
+            }
+        } else {
+            /* groups as separate VCards: there are group contacts and individual contacts */
+
+            // mark groups with changed members as dirty
+            BatchOperation batch = new BatchOperation(addressBook.provider);
+            for (LocalContact contact : addressBook.getDirtyContacts())
+                try {
+                    App.log.fine("Looking for changed group memberships of contact " + contact.getFileName());
+                    Set<Long>   cachedGroups = contact.getCachedGroupMemberships(),
+                                currentGroups = contact.getGroupMemberships();
+                    for (Long groupID : SetUtils.disjunction(cachedGroups, currentGroups)) {
+                        App.log.fine("Marking group as dirty: " + groupID);
+                        batch.enqueue(ContentProviderOperation
+                                .newUpdate(addressBook.syncAdapterURI(ContentUris.withAppendedId(Groups.CONTENT_URI, groupID)))
+                                .withValue(Groups.DIRTY, 1)
+                                .withYieldAllowed(true)
+                                .build()
+                        );
+                    }
+                } catch(FileNotFoundException ignored) {
+                }
+            batch.commit();
+        }
+    }
+
+    @Override
+    protected RequestBody prepareUpload(@NonNull LocalResource resource) throws IOException, ContactsStorageException {
+        final Contact contact;
+        if (resource instanceof LocalContact) {
+            LocalContact local = ((LocalContact)resource);
+            contact = local.getContact();
+
+            if (groupMethod == GroupMethod.CATEGORIES) {
+                // add groups as CATEGORIES
+                for (long groupID : local.getGroupMemberships()) {
+                    try {
+                        @Cleanup Cursor c = provider.query(
+                                localAddressBook().syncAdapterURI(ContentUris.withAppendedId(Groups.CONTENT_URI, groupID)),
+                                new String[] { Groups.TITLE },
+                                null, null,
+                                null
+                        );
+                        if (c != null && c.moveToNext()) {
+                            String title = c.getString(0);
+                            if (!TextUtils.isEmpty(title))
+                                contact.categories.add(title);
+                        }
+                    } catch(RemoteException e) {
+                        throw new ContactsStorageException("Couldn't find group for adding CATEGORIES", e);
+                    }
+                }
+            }
+        } else if (resource instanceof LocalGroup)
+            contact = ((LocalGroup)resource).getContact();
+        else
+            throw new IllegalArgumentException("Argument must be LocalContact or LocalGroup");
+
+        App.log.log(Level.FINE, "Preparing upload of VCard " + resource.getFileName(), contact);
+
+        ByteArrayOutputStream os = new ByteArrayOutputStream();
+        contact.write(hasVCard4 ? VCardVersion.V4_0 : VCardVersion.V3_0, groupMethod, settings.getVCardRFC6868(), os);
+
+        return RequestBody.create(
+                hasVCard4 ? DavAddressBook.MIME_VCARD4 : DavAddressBook.MIME_VCARD3_UTF8,
+                os.toByteArray()
+        );
+    }
+
+    @Override
+    protected void listRemote() throws IOException, HttpException, DavException {
+        // fetch list of remote VCards and build hash table to index file name
+
+        try {
+            davAddressBook().addressbookQuery();
+        } catch(HttpException e) {
+            /*  non-successful responses to CARDDAV:addressbook-query with empty filter, tested on 2015/10/21
+             *  fastmail.com                 403 Forbidden (DAV:error CARDDAV:supported-filter)
+             *  mailbox.org (OpenXchange)    400 Bad Request
+             *  SOGo                         207 Multi-status, but without entries       http://www.sogo.nu/bugs/view.php?id=3370
+             *  Zimbra ZCS                   500 Server Error                            https://bugzilla.zimbra.com/show_bug.cgi?id=101902
+             */
+            if (e.status == 400 || e.status == 403 || e.status == 500 || e.status == 501) {
+                App.log.log(Level.WARNING, "Server error on REPORT addressbook-query, falling back to PROPFIND", e);
+                davAddressBook().propfind(1, GetETag.NAME);
+            } else
+                // no defined fallback, pass through exception
+                throw e;
+        }
+
+        remoteResources = new HashMap<>(davCollection.members.size());
+        for (DavResource vCard : davCollection.members) {
+            String fileName = vCard.fileName();
+            App.log.fine("Found remote VCard: " + fileName);
+            remoteResources.put(fileName, vCard);
+        }
+    }
+
+    @Override
+    protected void downloadRemote() throws IOException, HttpException, DavException, ContactsStorageException {
+        App.log.info("Downloading " + toDownload.size() + " contacts (" + MAX_MULTIGET + " at once)");
+
+        // prepare downloader which may be used to download external resource like contact photos
+        Contact.Downloader downloader = new ResourceDownloader(collectionURL);
+
+        // download new/updated VCards from server
+        for (DavResource[] bunch : ArrayUtils.partition(toDownload.toArray(new DavResource[toDownload.size()]), MAX_MULTIGET)) {
+            if (Thread.interrupted())
+                return;
+
+            App.log.info("Downloading " + StringUtils.join(bunch, ", "));
+
+            if (bunch.length == 1) {
+                // only one contact, use GET
+                DavResource remote = bunch[0];
+
+                ResponseBody body = remote.get("text/vcard;version=4.0, text/vcard;charset=utf-8;q=0.8, text/vcard;q=0.5");
+
+                // CardDAV servers MUST return ETag on GET [https://tools.ietf.org/html/rfc6352#section-6.3.2.3]
+                GetETag eTag = (GetETag)remote.properties.get(GetETag.NAME);
+                if (eTag == null || StringUtils.isEmpty(eTag.eTag))
+                    throw new DavException("Received CardDAV GET response without ETag for " + remote.location);
+
+                Charset charset = Charsets.UTF_8;
+                MediaType contentType = body.contentType();
+                if (contentType != null)
+                    charset = contentType.charset(Charsets.UTF_8);
+
+                @Cleanup InputStream stream = body.byteStream();
+                processVCard(remote.fileName(), eTag.eTag, stream, charset, downloader);
+
+            } else {
+                // multiple contacts, use multi-get
+                List<HttpUrl> urls = new LinkedList<>();
+                for (DavResource remote : bunch)
+                    urls.add(remote.location);
+                davAddressBook().multiget(urls.toArray(new HttpUrl[urls.size()]), hasVCard4);
+
+                // process multiget results
+                for (DavResource remote : davCollection.members) {
+                    String eTag;
+                    GetETag getETag = (GetETag)remote.properties.get(GetETag.NAME);
+                    if (getETag != null)
+                        eTag = getETag.eTag;
+                    else
+                        throw new DavException("Received multi-get response without ETag");
+
+                    Charset charset = Charsets.UTF_8;
+                    GetContentType getContentType = (GetContentType)remote.properties.get(GetContentType.NAME);
+                    if (getContentType != null && getContentType.type != null) {
+                        MediaType type = MediaType.parse(getContentType.type);
+                        if (type != null)
+                            charset = type.charset(Charsets.UTF_8);
+                    }
+
+                    AddressData addressData = (AddressData)remote.properties.get(AddressData.NAME);
+                    if (addressData == null || addressData.vCard == null)
+                        throw new DavException("Received multi-get response without address data");
+
+                    @Cleanup InputStream stream = new ByteArrayInputStream(addressData.vCard.getBytes());
+                    processVCard(remote.fileName(), eTag, stream, charset, downloader);
+                }
+            }
+        }
+    }
+
+    @Override
+    protected void postProcess() throws CalendarStorageException, ContactsStorageException {
+        if (groupMethod == GroupMethod.CATEGORIES) {
+            /* VCard3 group handling: groups memberships are represented as contact CATEGORIES */
+
+            // remove empty groups
+            App.log.info("Removing empty groups");
+            localAddressBook().removeEmptyGroups();
+
+        } else {
+            /* VCard4 group handling: there are group contacts and individual contacts */
+            App.log.info("Assigning memberships of downloaded contact groups");
+            LocalGroup.applyPendingMemberships(localAddressBook());
+        }
+    }
+
+    @Override
+    protected void saveSyncState() throws CalendarStorageException, ContactsStorageException {
+        super.saveSyncState();
+        ((LocalAddressBook)localCollection).setURL(remote.url);
+    }
+
+
+    // helpers
+
+    private DavAddressBook davAddressBook() { return (DavAddressBook)davCollection; }
+    private LocalAddressBook localAddressBook() { return (LocalAddressBook)localCollection; }
+
+    private void processVCard(String fileName, String eTag, InputStream stream, Charset charset, Contact.Downloader downloader) throws IOException, ContactsStorageException {
+        App.log.info("Processing CardDAV resource " + fileName);
+        Contact[] contacts = Contact.fromStream(stream, charset, downloader);
+        if (contacts.length == 0) {
+            App.log.warning("Received VCard without data, ignoring");
+            return;
+        } else if (contacts.length > 1)
+            App.log.warning("Received multiple VCards, using first one");
+
+        final Contact newData = contacts[0];
+
+        if (groupMethod == GroupMethod.CATEGORIES && newData.group) {
+            groupMethod = GroupMethod.GROUP_VCARDS;
+            App.log.warning("Received group VCard although group method is CATEGORIES. Deleting all groups; new group method: " + groupMethod);
+            localAddressBook().removeGroups();
+            settings.setGroupMethod(groupMethod);
+        }
+
+        // update local contact, if it exists
+        LocalResource local = localResources.get(fileName);
+        if (local != null) {
+            App.log.log(Level.INFO, "Updating " + fileName + " in local address book", newData);
+
+            if (local instanceof LocalGroup && newData.group) {
+                // update group
+                LocalGroup group = (LocalGroup)local;
+                group.eTag = eTag;
+                group.updateFromServer(newData);
+                syncResult.stats.numUpdates++;
+
+            } else if (local instanceof LocalContact && !newData.group) {
+                // update contact
+                LocalContact contact = (LocalContact)local;
+                contact.eTag = eTag;
+                contact.update(newData);
+                syncResult.stats.numUpdates++;
+
+            } else {
+                // group has become an individual contact or vice versa
+                try {
+                    local.delete();
+                    local = null;
+                } catch(CalendarStorageException e) {
+                    // CalendarStorageException is not used by LocalGroup and LocalContact
+                }
+            }
+        }
+
+        if (local == null) {
+            if (newData.group) {
+                App.log.log(Level.INFO, "Creating local group", newData);
+                LocalGroup group = new LocalGroup(localAddressBook(), newData, fileName, eTag);
+                group.create();
+
+                local = group;
+            } else {
+                App.log.log(Level.INFO, "Creating local contact", newData);
+                LocalContact contact = new LocalContact(localAddressBook(), newData, fileName, eTag);
+                contact.create();
+
+                local = contact;
+            }
+            syncResult.stats.numInserts++;
+        }
+
+        if (groupMethod == GroupMethod.CATEGORIES && local instanceof LocalContact) {
+            // VCard3: update group memberships from CATEGORIES
+            LocalContact contact = (LocalContact)local;
+
+            BatchOperation batch = new BatchOperation(provider);
+            contact.removeGroupMemberships(batch);
+
+            for (String category : contact.getContact().categories) {
+                long groupID = localAddressBook().findOrCreateGroup(category);
+                contact.addToGroup(batch, groupID);
+            }
+
+            batch.commit();
+        }
+    }
+
+
+    // downloader helper class
+
+    @RequiredArgsConstructor
+    private class ResourceDownloader implements Contact.Downloader {
+        final HttpUrl baseUrl;
+
+        @Override
+        public byte[] download(String url, String accepts) {
+            HttpUrl httpUrl = HttpUrl.parse(url);
+
+            if (httpUrl == null) {
+                App.log.log(Level.SEVERE, "Invalid external resource URL", url);
+                return null;
+            }
+
+            String host = httpUrl.host();
+            if (host == null) {
+                App.log.log(Level.SEVERE, "External resource URL doesn't specify a host name", url);
+                return null;
+            }
+
+            OkHttpClient resourceClient = HttpClient.create();
+
+            // authenticate only against a certain host, and only upon request
+            resourceClient = HttpClient.addAuthentication(resourceClient, baseUrl.host(), settings.username(), settings.password());
+
+            // allow redirects
+            resourceClient = resourceClient.newBuilder()
+                    .followRedirects(true)
+                    .build();
+
+            try {
+                Response response = resourceClient.newCall(new Request.Builder()
+                        .get()
+                        .url(httpUrl)
+                        .build()).execute();
+
+                ResponseBody body = response.body();
+                if (body != null) {
+                    @Cleanup InputStream stream = body.byteStream();
+                    if (response.isSuccessful() && stream != null) {
+                        return IOUtils.toByteArray(stream);
+                    } else
+                        App.log.severe("Couldn't download external resource");
+                }
+            } catch(IOException e) {
+                App.log.log(Level.SEVERE, "Couldn't download external resource", e);
+            }
+            return null;
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/syncadapter/SyncAdapterService.java

@@ -0,0 +1,115 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.syncadapter;
+
+import android.accounts.Account;
+import android.app.Notification;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.app.Service;
+import android.content.AbstractThreadedSyncAdapter;
+import android.content.ContentProviderClient;
+import android.content.Context;
+import android.content.Intent;
+import android.content.SyncResult;
+import android.graphics.drawable.BitmapDrawable;
+import android.net.ConnectivityManager;
+import android.net.NetworkInfo;
+import android.net.wifi.WifiInfo;
+import android.net.wifi.WifiManager;
+import android.os.Bundle;
+import android.os.IBinder;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.v4.app.NotificationCompat;
+
+import java.util.logging.Level;
+
+import at.bitfire.davdroid.AccountSettings;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.ui.PermissionsActivity;
+
+public abstract class SyncAdapterService extends Service {
+
+    abstract protected AbstractThreadedSyncAdapter syncAdapter();
+
+    @Nullable
+    @Override
+    public IBinder onBind(Intent intent) {
+        return syncAdapter().getSyncAdapterBinder();
+    }
+
+
+    public static abstract class SyncAdapter extends AbstractThreadedSyncAdapter {
+
+        public SyncAdapter(Context context) {
+            super(context, false);
+        }
+
+        @Override
+        public void onPerformSync(Account account, Bundle extras, String authority, ContentProviderClient provider, SyncResult syncResult) {
+            App.log.info("Sync for " + authority + " has been initiated");
+
+            // required for dav4android (ServiceLoader)
+            Thread.currentThread().setContextClassLoader(getContext().getClassLoader());
+        }
+
+        @Override
+        public void onSecurityException(Account account, Bundle extras, String authority, SyncResult syncResult) {
+            App.log.log(Level.WARNING, "Security exception when opening content provider for " +  authority);
+            syncResult.databaseError = true;
+
+            Intent intent = new Intent(getContext(), PermissionsActivity.class);
+            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
+
+            Notification notify = new NotificationCompat.Builder(getContext())
+                    .setSmallIcon(R.drawable.ic_error_light)
+                    .setLargeIcon(((BitmapDrawable)getContext().getResources().getDrawable(R.drawable.ic_launcher)).getBitmap())
+                    .setContentTitle(getContext().getString(R.string.sync_error_permissions))
+                    .setContentText(getContext().getString(R.string.sync_error_permissions_text))
+                    .setContentIntent(PendingIntent.getActivity(getContext(), 0, intent, PendingIntent.FLAG_CANCEL_CURRENT))
+                    .setCategory(NotificationCompat.CATEGORY_ERROR)
+                    .setLocalOnly(true)
+                    .build();
+            NotificationManager nm = (NotificationManager)getContext().getSystemService(NOTIFICATION_SERVICE);
+            nm.notify(Constants.NOTIFICATION_PERMISSIONS, notify);
+        }
+
+        protected boolean checkSyncConditions(@NonNull AccountSettings settings) {
+            if (settings.getSyncWifiOnly()) {
+                ConnectivityManager cm = (ConnectivityManager)getContext().getSystemService(CONNECTIVITY_SERVICE);
+                NetworkInfo network = cm.getActiveNetworkInfo();
+                if (network == null) {
+                    App.log.info("No network available, stopping");
+                    return false;
+                }
+                if (network.getType() != ConnectivityManager.TYPE_WIFI || !network.isConnected()) {
+                    App.log.info("Not on connected WiFi, stopping");
+                    return false;
+                }
+
+                String onlySSID = settings.getSyncWifiOnlySSID();
+                if (onlySSID != null) {
+                    onlySSID = "\"" + onlySSID + "\"";
+                    WifiManager wifi = (WifiManager)getContext().getSystemService(WIFI_SERVICE);
+                    WifiInfo info = wifi.getConnectionInfo();
+                    if (info == null || !onlySSID.equals(info.getSSID())) {
+                        App.log.info("Connected to wrong WiFi network (" + info.getSSID() + ", required: " + onlySSID + "), ignoring");
+                        return false;
+                    }
+                }
+            }
+            return true;
+        }
+
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/syncadapter/SyncManager.java

@@ -0,0 +1,448 @@
+    /*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+package at.bitfire.davdroid.syncadapter;
+
+import android.accounts.Account;
+import android.annotation.TargetApi;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.content.ContentResolver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.SyncResult;
+import android.graphics.drawable.BitmapDrawable;
+import android.net.Uri;
+import android.os.Bundle;
+import android.support.v7.app.NotificationCompat;
+import android.text.TextUtils;
+
+import java.io.IOException;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+import java.util.logging.Level;
+
+import at.bitfire.dav4android.DavResource;
+import at.bitfire.dav4android.exception.ConflictException;
+import at.bitfire.dav4android.exception.DavException;
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.dav4android.exception.PreconditionFailedException;
+import at.bitfire.dav4android.exception.ServiceUnavailableException;
+import at.bitfire.dav4android.exception.UnauthorizedException;
+import at.bitfire.dav4android.property.GetCTag;
+import at.bitfire.dav4android.property.GetETag;
+import at.bitfire.davdroid.AccountSettings;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.HttpClient;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.resource.LocalCollection;
+import at.bitfire.davdroid.resource.LocalResource;
+import at.bitfire.davdroid.ui.AccountSettingsActivity;
+import at.bitfire.davdroid.ui.DebugInfoActivity;
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.vcard4android.ContactsStorageException;
+import okhttp3.HttpUrl;
+import okhttp3.OkHttpClient;
+import okhttp3.RequestBody;
+
+abstract public class SyncManager {
+
+    protected final int SYNC_PHASE_PREPARE = 0,
+                        SYNC_PHASE_QUERY_CAPABILITIES = 1,
+                        SYNC_PHASE_PROCESS_LOCALLY_DELETED = 2,
+                        SYNC_PHASE_PREPARE_DIRTY = 3,
+                        SYNC_PHASE_UPLOAD_DIRTY = 4,
+                        SYNC_PHASE_CHECK_SYNC_STATE = 5,
+                        SYNC_PHASE_LIST_LOCAL = 6,
+                        SYNC_PHASE_LIST_REMOTE = 7,
+                        SYNC_PHASE_COMPARE_LOCAL_REMOTE = 8,
+                        SYNC_PHASE_DOWNLOAD_REMOTE = 9,
+                        SYNC_PHASE_POST_PROCESSING = 10,
+                        SYNC_PHASE_SAVE_SYNC_STATE = 11;
+
+    protected final NotificationManager notificationManager;
+    protected final String uniqueCollectionId;
+
+    protected final Context context;
+    protected final Account account;
+    protected final Bundle extras;
+    protected final String authority;
+    protected final SyncResult syncResult;
+
+    protected final AccountSettings settings;
+    protected LocalCollection localCollection;
+
+    protected OkHttpClient httpClient;
+    protected HttpUrl collectionURL;
+    protected DavResource davCollection;
+
+
+    /** remote CTag at the time of {@link #listRemote()} */
+    protected String remoteCTag = null;
+
+    /** sync-able resources in the local collection, as enumerated by {@link #listLocal()} */
+    protected Map<String, LocalResource> localResources;
+
+    /** sync-able resources in the remote collection, as enumerated by {@link #listRemote()} */
+    protected Map<String, DavResource> remoteResources;
+
+    /** resources which have changed on the server, as determined by {@link #compareLocalRemote()} */
+    protected Set<DavResource> toDownload;
+
+
+
+    public SyncManager(Context context, Account account, AccountSettings settings, Bundle extras, String authority, SyncResult syncResult, String uniqueCollectionId) throws InvalidAccountException {
+        this.context = context;
+        this.account = account;
+        this.settings = settings;
+        this.extras = extras;
+        this.authority = authority;
+        this.syncResult = syncResult;
+
+        // create HttpClient with given logger
+        httpClient = HttpClient.create(context, account);
+
+        // dismiss previous error notifications
+        this.uniqueCollectionId = uniqueCollectionId;
+        notificationManager = (NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE);
+        notificationManager.cancel(uniqueCollectionId, notificationId());
+    }
+
+    protected abstract int notificationId();
+    protected abstract String getSyncErrorTitle();
+
+    @TargetApi(21)
+    public void performSync() {
+        int syncPhase = SYNC_PHASE_PREPARE;
+        try {
+            App.log.info("Preparing synchronization");
+            prepare();
+
+            if (Thread.interrupted())
+                return;
+            syncPhase = SYNC_PHASE_QUERY_CAPABILITIES;
+            App.log.info("Querying capabilities");
+            queryCapabilities();
+
+            syncPhase = SYNC_PHASE_PROCESS_LOCALLY_DELETED;
+            App.log.info("Processing locally deleted entries");
+            processLocallyDeleted();
+
+            if (Thread.interrupted())
+                return;
+            syncPhase = SYNC_PHASE_PREPARE_DIRTY;
+            App.log.info("Locally preparing dirty entries");
+            prepareDirty();
+
+            syncPhase = SYNC_PHASE_UPLOAD_DIRTY;
+            App.log.info("Uploading dirty entries");
+            uploadDirty();
+
+            syncPhase = SYNC_PHASE_CHECK_SYNC_STATE;
+            App.log.info("Checking sync state");
+            if (checkSyncState()) {
+                syncPhase = SYNC_PHASE_LIST_LOCAL;
+                App.log.info("Listing local entries");
+                listLocal();
+
+                if (Thread.interrupted())
+                    return;
+                syncPhase = SYNC_PHASE_LIST_REMOTE;
+                App.log.info("Listing remote entries");
+                listRemote();
+
+                if (Thread.interrupted())
+                    return;
+                syncPhase = SYNC_PHASE_COMPARE_LOCAL_REMOTE;
+                App.log.info("Comparing local/remote entries");
+                compareLocalRemote();
+
+                syncPhase = SYNC_PHASE_DOWNLOAD_REMOTE;
+                App.log.info("Downloading remote entries");
+                downloadRemote();
+
+                syncPhase = SYNC_PHASE_POST_PROCESSING;
+                App.log.info("Post-processing");
+                postProcess();
+
+                syncPhase = SYNC_PHASE_SAVE_SYNC_STATE;
+                App.log.info("Saving sync state");
+                saveSyncState();
+            } else
+                App.log.info("Remote collection didn't change, skipping remote sync");
+
+        } catch (IOException|ServiceUnavailableException e) {
+            App.log.log(Level.WARNING, "I/O exception during sync, trying again later", e);
+            syncResult.stats.numIoExceptions++;
+
+            if (e instanceof ServiceUnavailableException) {
+                Date retryAfter = ((ServiceUnavailableException) e).retryAfter;
+                if (retryAfter != null) {
+                    // how many seconds to wait? getTime() returns ms, so divide by 1000
+                    syncResult.delayUntil = (retryAfter.getTime() - new Date().getTime()) / 1000;
+                }
+            }
+
+        } catch(Exception|OutOfMemoryError e) {
+            final int messageString;
+
+            if (e instanceof UnauthorizedException) {
+                App.log.log(Level.SEVERE, "Not authorized anymore", e);
+                messageString = R.string.sync_error_unauthorized;
+                syncResult.stats.numAuthExceptions++;
+            } else if (e instanceof HttpException || e instanceof DavException) {
+                App.log.log(Level.SEVERE, "HTTP/DAV Exception during sync", e);
+                messageString = R.string.sync_error_http_dav;
+                syncResult.stats.numParseExceptions++;
+            } else if (e instanceof CalendarStorageException || e instanceof ContactsStorageException) {
+                App.log.log(Level.SEVERE, "Couldn't access local storage", e);
+                messageString = R.string.sync_error_local_storage;
+                syncResult.databaseError = true;
+            } else {
+                App.log.log(Level.SEVERE, "Unknown sync error", e);
+                messageString = R.string.sync_error;
+                syncResult.stats.numParseExceptions++;
+            }
+
+            final Intent detailsIntent;
+            if (e instanceof UnauthorizedException) {
+                detailsIntent = new Intent(context, AccountSettingsActivity.class);
+                detailsIntent.putExtra(AccountSettingsActivity.EXTRA_ACCOUNT, account);
+            } else {
+                detailsIntent = new Intent(context, DebugInfoActivity.class);
+                detailsIntent.putExtra(DebugInfoActivity.KEY_THROWABLE, e);
+                detailsIntent.putExtra(DebugInfoActivity.KEY_ACCOUNT, account);
+                detailsIntent.putExtra(DebugInfoActivity.KEY_AUTHORITY, authority);
+                detailsIntent.putExtra(DebugInfoActivity.KEY_PHASE, syncPhase);
+            }
+
+            // to make the PendingIntent unique
+            detailsIntent.setData(Uri.parse("uri://" + getClass().getName() + "/" + uniqueCollectionId));
+
+            NotificationCompat.Builder builder = new NotificationCompat.Builder(context);
+            builder .setSmallIcon(R.drawable.ic_error_light)
+                    .setLargeIcon(((BitmapDrawable)context.getResources().getDrawable(R.drawable.ic_launcher)).getBitmap())
+                    .setContentTitle(getSyncErrorTitle())
+                    .setContentIntent(PendingIntent.getActivity(context, 0, detailsIntent, PendingIntent.FLAG_CANCEL_CURRENT))
+                    .setCategory(NotificationCompat.CATEGORY_ERROR)
+                    .setLocalOnly(true);
+
+            try {
+                String[] phases = context.getResources().getStringArray(R.array.sync_error_phases);
+                String message = context.getString(messageString, phases[syncPhase]);
+                builder.setContentText(message);
+            } catch (IndexOutOfBoundsException ex) {
+                // should never happen
+            }
+
+            notificationManager.notify(uniqueCollectionId, notificationId(), builder.build());
+        }
+    }
+
+
+    abstract protected void prepare() throws ContactsStorageException;
+
+    abstract protected void queryCapabilities() throws IOException, HttpException, DavException, CalendarStorageException, ContactsStorageException;
+
+    /**
+     * Process locally deleted entries (DELETE them on the server as well).
+     * Checks Thread.interrupted() before each request to allow quick sync cancellation.
+     */
+    protected void processLocallyDeleted() throws CalendarStorageException, ContactsStorageException {
+        // Remove locally deleted entries from server (if they have a name, i.e. if they were uploaded before),
+        // but only if they don't have changed on the server. Then finally remove them from the local address book.
+        LocalResource[] localList = localCollection.getDeleted();
+        for (LocalResource local : localList) {
+            if (Thread.interrupted())
+                return;
+
+            final String fileName = local.getFileName();
+            if (!TextUtils.isEmpty(fileName)) {
+                App.log.info(fileName + " has been deleted locally -> deleting from server");
+                try {
+                    new DavResource(httpClient, collectionURL.newBuilder().addPathSegment(fileName).build())
+                            .delete(local.getETag());
+                } catch (IOException|HttpException e) {
+                    App.log.warning("Couldn't delete " + fileName + " from server; ignoring (may be downloaded again)");
+                }
+            } else
+                App.log.info("Removing local record #" + local.getId() + " which has been deleted locally and was never uploaded");
+            local.delete();
+            syncResult.stats.numDeletes++;
+        }
+    }
+
+    protected void prepareDirty() throws CalendarStorageException, ContactsStorageException {
+        // assign file names and UIDs to new contacts so that we can use the file name as an index
+        App.log.info("Looking for contacts/groups without file name");
+        for (LocalResource local : localCollection.getWithoutFileName()) {
+            String uuid = UUID.randomUUID().toString();
+            App.log.fine("Found local record #" + local.getId() + " without file name; assigning file name/UID based on " + uuid);
+            local.updateFileNameAndUID(uuid);
+        }
+    }
+
+    abstract protected RequestBody prepareUpload(LocalResource resource) throws IOException, CalendarStorageException, ContactsStorageException;
+
+    /**
+     * Uploads dirty records to the server, using a PUT request for each record.
+     * Checks Thread.interrupted() before each request to allow quick sync cancellation.
+     */
+    protected void uploadDirty() throws IOException, HttpException, CalendarStorageException, ContactsStorageException {
+        // upload dirty contacts
+        for (LocalResource local : localCollection.getDirty()) {
+            if (Thread.interrupted())
+                return;
+
+            final String fileName = local.getFileName();
+
+            DavResource remote = new DavResource(httpClient, collectionURL.newBuilder().addPathSegment(fileName).build());
+
+            // generate entity to upload (VCard, iCal, whatever)
+            RequestBody body = prepareUpload(local);
+
+            try {
+                if (local.getETag() == null) {
+                    App.log.info("Uploading new record " + fileName);
+                    remote.put(body, null, true);
+                } else {
+                    App.log.info("Uploading locally modified record " + fileName);
+                    remote.put(body, local.getETag(), false);
+                }
+            } catch (ConflictException|PreconditionFailedException e) {
+                // we can't interact with the user to resolve the conflict, so we treat 409 like 412
+                App.log.log(Level.INFO, "Resource has been modified on the server before upload, ignoring", e);
+            }
+
+            String eTag = null;
+            GetETag newETag = (GetETag) remote.properties.get(GetETag.NAME);
+            if (newETag != null) {
+                eTag = newETag.eTag;
+                App.log.fine("Received new ETag=" + eTag + " after uploading");
+            } else
+                App.log.fine("Didn't receive new ETag after uploading, setting to null");
+
+            local.clearDirty(eTag);
+        }
+    }
+
+    /**
+     * Checks the current sync state (e.g. CTag) and whether synchronization from remote is required.
+     * @return <ul>
+     *      <li><code>true</code>   if the remote collection has changed, i.e. synchronization from remote is required</li>
+     *      <li><code>false</code>  if the remote collection hasn't changed</li>
+     * </ul>
+     */
+    protected boolean checkSyncState() throws CalendarStorageException, ContactsStorageException {
+        // check CTag (ignore on manual sync)
+        GetCTag getCTag = (GetCTag)davCollection.properties.get(GetCTag.NAME);
+        if (getCTag != null)
+            remoteCTag = getCTag.cTag;
+
+        String localCTag = null;
+        if (extras.containsKey(ContentResolver.SYNC_EXTRAS_MANUAL))
+            App.log.info("Manual sync, ignoring CTag");
+        else
+            localCTag = localCollection.getCTag();
+
+        if (remoteCTag != null && remoteCTag.equals(localCTag)) {
+            App.log.info("Remote collection didn't change (CTag=" + remoteCTag + "), no need to query children");
+            return false;
+        } else
+            return true;
+    }
+
+    /**
+     * Lists all local resources which should be taken into account for synchronization into {@link #localResources}.
+     */
+    protected void listLocal() throws CalendarStorageException, ContactsStorageException {
+        // fetch list of local contacts and build hash table to index file name
+        LocalResource[] localList = localCollection.getAll();
+        localResources = new HashMap<>(localList.length);
+        for (LocalResource resource : localList) {
+            App.log.fine("Found local resource: " + resource.getFileName());
+            localResources.put(resource.getFileName(), resource);
+        }
+    }
+
+    /**
+     * Lists all members of the remote collection which should be taken into account for synchronization into {@link #remoteResources}.
+     */
+    abstract protected void listRemote() throws IOException, HttpException, DavException;
+
+    /**
+     * Compares {@link #localResources} and {@link #remoteResources} by file name and ETag:
+     * <ul>
+     *     <li>Local resources which are not available in the remote collection (anymore) will be removed.</li>
+     *     <li>Resources whose remote ETag has changed will be added into {@link #toDownload}</li>
+     * </ul>
+     */
+    protected void compareLocalRemote() throws IOException, HttpException, DavException, CalendarStorageException, ContactsStorageException {
+        /* check which contacts
+           1. are not present anymore remotely -> delete immediately on local side
+           2. updated remotely -> add to downloadNames
+           3. added remotely  -> add to downloadNames
+         */
+        toDownload = new HashSet<>();
+        for (String localName : localResources.keySet()) {
+            DavResource remote = remoteResources.get(localName);
+            if (remote == null) {
+                App.log.info(localName + " is not on server anymore, deleting");
+                localResources.get(localName).delete();
+                syncResult.stats.numDeletes++;
+            } else {
+                // contact is still on server, check whether it has been updated remotely
+                GetETag getETag = (GetETag)remote.properties.get(GetETag.NAME);
+                if (getETag == null || getETag.eTag == null)
+                    throw new DavException("Server didn't provide ETag");
+                String localETag = localResources.get(localName).getETag(),
+                        remoteETag = getETag.eTag;
+                if (remoteETag.equals(localETag))
+                    syncResult.stats.numSkippedEntries++;
+                else {
+                    App.log.info(localName + " has been changed on server (current ETag=" + remoteETag + ", last known ETag=" + localETag + ")");
+                    toDownload.add(remote);
+                }
+
+                // remote entry has been seen, remove from list
+                remoteResources.remove(localName);
+            }
+        }
+
+        // add all unseen (= remotely added) remote contacts
+        if (!remoteResources.isEmpty()) {
+            App.log.info("New resources have been found on the server: " + TextUtils.join(", ", remoteResources.keySet()));
+            toDownload.addAll(remoteResources.values());
+        }
+    }
+
+    /**
+     * Downloads the remote resources in {@link #toDownload} and stores them locally.
+     * Must check Thread.interrupted() periodically to allow quick sync cancellation.
+     */
+    abstract protected void downloadRemote() throws IOException, HttpException, DavException, ContactsStorageException, CalendarStorageException;
+
+    /**
+     * For post-processing of entries, for instance assigning groups.
+     */
+    protected void postProcess() throws CalendarStorageException, ContactsStorageException {
+    }
+
+    protected void saveSyncState() throws CalendarStorageException, ContactsStorageException {
+        /* Save sync state (CTag). It doesn't matter if it has changed during the sync process
+           (for instance, because another client has uploaded changes), because this will simply
+           cause all remote entries to be listed at the next sync. */
+        App.log.info("Saving CTag=" + remoteCTag);
+        localCollection.setCTag(remoteCTag);
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncAdapterService.java

@@ -0,0 +1,155 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+package at.bitfire.davdroid.syncadapter;
+
+import android.accounts.Account;
+import android.content.AbstractThreadedSyncAdapter;
+import android.content.ContentProviderClient;
+import android.content.ContentResolver;
+import android.content.ContentValues;
+import android.content.Context;
+import android.content.SyncResult;
+import android.database.Cursor;
+import android.database.DatabaseUtils;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import org.dmfs.provider.tasks.TaskContract;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.logging.Level;
+
+import at.bitfire.davdroid.AccountSettings;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.davdroid.model.ServiceDB;
+import at.bitfire.davdroid.model.ServiceDB.Collections;
+import at.bitfire.davdroid.model.ServiceDB.Services;
+import at.bitfire.davdroid.resource.LocalTaskList;
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.ical4android.TaskProvider;
+import lombok.Cleanup;
+
+/**
+ * Synchronization manager for CalDAV collections; handles tasks ({@code VTODO}).
+ */
+public class TasksSyncAdapterService extends SyncAdapterService {
+
+    @Override
+    protected AbstractThreadedSyncAdapter syncAdapter() {
+        return new SyncAdapter(this);
+    }
+
+
+	private static class SyncAdapter extends SyncAdapterService.SyncAdapter {
+
+        public SyncAdapter(Context context) {
+            super(context);
+        }
+
+        @Override
+        public void onPerformSync(Account account, Bundle extras, String authority, ContentProviderClient providerClient, SyncResult syncResult) {
+            super.onPerformSync(account, extras, authority, providerClient, syncResult);
+
+            try {
+                @Cleanup TaskProvider provider = TaskProvider.acquire(getContext().getContentResolver(), TaskProvider.ProviderName.OpenTasks);
+                if (provider == null)
+                    throw new CalendarStorageException("Couldn't access OpenTasks provider");
+
+                AccountSettings settings = new AccountSettings(getContext(), account);
+                if (!extras.containsKey(ContentResolver.SYNC_EXTRAS_MANUAL) && !checkSyncConditions(settings))
+                    return;
+
+                updateLocalTaskLists(provider, account, settings);
+
+                for (LocalTaskList taskList : (LocalTaskList[])LocalTaskList.find(account, provider, LocalTaskList.Factory.INSTANCE, TaskContract.TaskLists.SYNC_ENABLED + "!=0", null)) {
+                    App.log.info("Synchronizing task list #" + taskList.getId() + " [" + taskList.getSyncId() + "]");
+                    TasksSyncManager syncManager = new TasksSyncManager(getContext(), account, settings, extras, authority, provider, syncResult, taskList);
+                    syncManager.performSync();
+                }
+            } catch (CalendarStorageException e) {
+                App.log.log(Level.SEVERE, "Couldn't enumerate local task lists", e);
+            } catch (InvalidAccountException e) {
+                App.log.log(Level.SEVERE, "Couldn't get account settings", e);
+            }
+
+            App.log.info("Task sync complete");
+        }
+
+        private void updateLocalTaskLists(TaskProvider provider, Account account, AccountSettings settings) throws CalendarStorageException {
+            SQLiteOpenHelper dbHelper = new ServiceDB.OpenHelper(getContext());
+            try {
+                // enumerate remote and local task lists
+                SQLiteDatabase db = dbHelper.getReadableDatabase();
+                Long service = getService(db, account);
+                Map<String, CollectionInfo> remote = remoteTaskLists(db, service);
+                LocalTaskList[] local = (LocalTaskList[])LocalTaskList.find(account, provider, LocalTaskList.Factory.INSTANCE, null, null);
+
+                boolean updateColors = settings.getManageCalendarColors();
+
+                // delete obsolete local task lists
+                for (LocalTaskList list : local) {
+                    String url = list.getSyncId();
+                    if (!remote.containsKey(url)) {
+                        App.log.fine("Deleting obsolete local task list" + url);
+                        list.delete();
+                    } else {
+                        // remote CollectionInfo found for this local collection, update data
+                        CollectionInfo info = remote.get(url);
+                        App.log.fine("Updating local task list " + url + " with " + info);
+                        list.update(info, updateColors);
+                        // we already have a local task list for this remote collection, don't take into consideration anymore
+                        remote.remove(url);
+                    }
+                }
+
+                // create new local task lists
+                for (String url : remote.keySet()) {
+                    CollectionInfo info = remote.get(url);
+                    App.log.info("Adding local task list " + info);
+                    LocalTaskList.create(account, provider, info);
+                }
+            } finally {
+                dbHelper.close();
+            }
+        }
+
+        @Nullable
+        Long getService(@NonNull SQLiteDatabase db, @NonNull Account account) {
+            @Cleanup Cursor c = db.query(Services._TABLE, new String[] { Services.ID },
+                    Services.ACCOUNT_NAME + "=? AND " + Services.SERVICE + "=?", new String[] { account.name, Services.SERVICE_CALDAV }, null, null, null);
+            if (c.moveToNext())
+                return c.getLong(0);
+            else
+                return null;
+        }
+
+        @NonNull
+        private Map<String, CollectionInfo> remoteTaskLists(@NonNull SQLiteDatabase db, Long service) {
+            Map<String, CollectionInfo> collections = new LinkedHashMap<>();
+            if (service != null) {
+                @Cleanup Cursor cursor = db.query(Collections._TABLE, null,
+                        Collections.SERVICE_ID + "=? AND " + Collections.SUPPORTS_VTODO + "!=0 AND " + Collections.SYNC,
+                        new String[] { String.valueOf(service) }, null, null, null);
+                while (cursor.moveToNext()) {
+                    ContentValues values = new ContentValues();
+                    DatabaseUtils.cursorRowToContentValues(cursor, values);
+                    CollectionInfo info = CollectionInfo.fromDB(values);
+                    collections.put(info.url, info);
+                }
+            }
+            return collections;
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncManager.java

@@ -0,0 +1,217 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.syncadapter;
+
+import android.accounts.Account;
+import android.content.Context;
+import android.content.SyncResult;
+import android.os.Bundle;
+
+import org.apache.commons.codec.Charsets;
+import org.apache.commons.lang3.StringUtils;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.Charset;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.logging.Level;
+
+import at.bitfire.dav4android.DavCalendar;
+import at.bitfire.dav4android.DavResource;
+import at.bitfire.dav4android.exception.DavException;
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.dav4android.property.CalendarData;
+import at.bitfire.dav4android.property.GetCTag;
+import at.bitfire.dav4android.property.GetContentType;
+import at.bitfire.dav4android.property.GetETag;
+import at.bitfire.davdroid.AccountSettings;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.ArrayUtils;
+import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.resource.LocalResource;
+import at.bitfire.davdroid.resource.LocalTask;
+import at.bitfire.davdroid.resource.LocalTaskList;
+import at.bitfire.ical4android.CalendarStorageException;
+import at.bitfire.ical4android.InvalidCalendarException;
+import at.bitfire.ical4android.Task;
+import at.bitfire.ical4android.TaskProvider;
+import lombok.Cleanup;
+import okhttp3.HttpUrl;
+import okhttp3.MediaType;
+import okhttp3.RequestBody;
+import okhttp3.ResponseBody;
+
+public class TasksSyncManager extends SyncManager {
+
+    protected static final int MAX_MULTIGET = 30;
+
+    final protected TaskProvider provider;
+
+
+    public TasksSyncManager(Context context, Account account, AccountSettings settings, Bundle extras, String authority, TaskProvider provider, SyncResult result, LocalTaskList taskList) throws InvalidAccountException {
+        super(context, account, settings, extras, authority, result, "taskList/" + taskList.getId());
+        this.provider = provider;
+        localCollection = taskList;
+    }
+
+    @Override
+    protected int notificationId() {
+        return Constants.NOTIFICATION_TASK_SYNC;
+    }
+
+    @Override
+    protected String getSyncErrorTitle() {
+        return context.getString(R.string.sync_error_tasks, account.name);
+    }
+
+
+    @Override
+    protected void prepare() {
+        collectionURL = HttpUrl.parse(localTaskList().getSyncId());
+        davCollection = new DavCalendar(httpClient, collectionURL);
+    }
+
+    @Override
+    protected void queryCapabilities() throws DavException, IOException, HttpException {
+        davCollection.propfind(0, GetCTag.NAME);
+    }
+
+    @Override
+    protected RequestBody prepareUpload(LocalResource resource) throws IOException, CalendarStorageException {
+        LocalTask local = (LocalTask)resource;
+        App.log.log(Level.FINE, "Preparing upload of task " + local.getFileName(), local.getTask() );
+
+        ByteArrayOutputStream os = new ByteArrayOutputStream();
+        local.getTask().write(os);
+
+        return RequestBody.create(
+                DavCalendar.MIME_ICALENDAR,
+                os.toByteArray()
+        );
+    }
+
+    @Override
+    protected void listRemote() throws IOException, HttpException, DavException {
+        // fetch list of remote VTODOs and build hash table to index file name
+        davCalendar().calendarQuery("VTODO", null, null);
+        remoteResources = new HashMap<>(davCollection.members.size());
+        for (DavResource vCard : davCollection.members) {
+            String fileName = vCard.fileName();
+            App.log.fine("Found remote VTODO: " + fileName);
+            remoteResources.put(fileName, vCard);
+        }
+    }
+
+    @Override
+    protected void downloadRemote() throws IOException, HttpException, DavException, CalendarStorageException {
+        App.log.info("Downloading " + toDownload.size() + " tasks (" + MAX_MULTIGET + " at once)");
+
+        // download new/updated iCalendars from server
+        for (DavResource[] bunch : ArrayUtils.partition(toDownload.toArray(new DavResource[toDownload.size()]), MAX_MULTIGET)) {
+            if (Thread.interrupted())
+                return;
+
+            App.log.info("Downloading " + StringUtils.join(bunch, ", "));
+
+            if (bunch.length == 1) {
+                // only one contact, use GET
+                DavResource remote = bunch[0];
+
+                ResponseBody body = remote.get("text/calendar");
+
+                // CalDAV servers MUST return ETag on GET [https://tools.ietf.org/html/rfc4791#section-5.3.4]
+                GetETag eTag = (GetETag)remote.properties.get(GetETag.NAME);
+                if (eTag == null || StringUtils.isEmpty(eTag.eTag))
+                    throw new DavException("Received CalDAV GET response without ETag for " + remote.location);
+
+                Charset charset = Charsets.UTF_8;
+                MediaType contentType = body.contentType();
+                if (contentType != null)
+                    charset = contentType.charset(Charsets.UTF_8);
+
+                @Cleanup InputStream stream = body.byteStream();
+                processVTodo(remote.fileName(), eTag.eTag, stream, charset);
+
+            } else {
+                // multiple contacts, use multi-get
+                List<HttpUrl> urls = new LinkedList<>();
+                for (DavResource remote : bunch)
+                    urls.add(remote.location);
+                davCalendar().multiget(urls.toArray(new HttpUrl[urls.size()]));
+
+                // process multiget results
+                for (DavResource remote : davCollection.members) {
+                    String eTag;
+                    GetETag getETag = (GetETag)remote.properties.get(GetETag.NAME);
+                    if (getETag != null)
+                        eTag = getETag.eTag;
+                    else
+                        throw new DavException("Received multi-get response without ETag");
+
+                    Charset charset = Charsets.UTF_8;
+                    GetContentType getContentType = (GetContentType)remote.properties.get(GetContentType.NAME);
+                    if (getContentType != null && getContentType.type != null) {
+                        MediaType type = MediaType.parse(getContentType.type);
+                        if (type != null)
+                            charset = type.charset(Charsets.UTF_8);
+                    }
+
+                    CalendarData calendarData = (CalendarData)remote.properties.get(CalendarData.NAME);
+                    if (calendarData == null || calendarData.iCalendar == null)
+                        throw new DavException("Received multi-get response without address data");
+
+                    @Cleanup InputStream stream = new ByteArrayInputStream(calendarData.iCalendar.getBytes());
+                    processVTodo(remote.fileName(), eTag, stream, charset);
+                }
+            }
+        }
+    }
+
+
+    // helpers
+
+    private LocalTaskList localTaskList() { return ((LocalTaskList)localCollection); }
+    private DavCalendar davCalendar() { return (DavCalendar)davCollection; }
+
+    private void processVTodo(String fileName, String eTag, InputStream stream, Charset charset) throws IOException, CalendarStorageException {
+        Task[] tasks;
+        try {
+            tasks = Task.fromStream(stream, charset);
+        } catch (InvalidCalendarException e) {
+            App.log.log(Level.SEVERE, "Received invalid iCalendar, ignoring", e);
+            return;
+        }
+
+        if (tasks.length == 1) {
+            Task newData = tasks[0];
+
+            // update local task, if it exists
+            LocalTask localTask = (LocalTask)localResources.get(fileName);
+            if (localTask != null) {
+                App.log.info("Updating " + fileName + " in local tasklist");
+                localTask.setETag(eTag);
+                localTask.update(newData);
+                syncResult.stats.numUpdates++;
+            } else {
+                App.log.info("Adding " + fileName + " to local task list");
+                localTask = new LocalTask(localTaskList(), newData, fileName, eTag);
+                localTask.add();
+                syncResult.stats.numInserts++;
+            }
+        } else
+            App.log.severe("Received VCALENDAR with not exactly one VTODO; ignoring " + fileName);
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/AboutActivity.java

@@ -0,0 +1,220 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.annotation.SuppressLint;
+import android.content.Context;
+import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.support.design.widget.TabLayout;
+import android.support.v4.app.Fragment;
+import android.support.v4.app.FragmentManager;
+import android.support.v4.app.FragmentPagerAdapter;
+import android.support.v4.app.LoaderManager;
+import android.support.v4.content.AsyncTaskLoader;
+import android.support.v4.content.Loader;
+import android.support.v4.view.ViewPager;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.widget.Toolbar;
+import android.text.Html;
+import android.text.Spanned;
+import android.text.util.Linkify;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+
+import org.apache.commons.lang3.time.DateFormatUtils;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.logging.Level;
+
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.BuildConfig;
+import at.bitfire.davdroid.R;
+import ezvcard.Ezvcard;
+import ezvcard.util.IOUtils;
+import lombok.Cleanup;
+import lombok.RequiredArgsConstructor;
+
+public class AboutActivity extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_about);
+
+        setSupportActionBar((Toolbar)findViewById(R.id.toolbar));
+        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+
+        ViewPager viewPager = (ViewPager)findViewById(R.id.viewpager);
+        viewPager.setAdapter(new TabsAdapter(getSupportFragmentManager()));
+
+        TabLayout tabLayout = (TabLayout)findViewById(R.id.tabs);
+        tabLayout.setupWithViewPager(viewPager);
+    }
+
+
+    @RequiredArgsConstructor
+    private static class ComponentInfo {
+        final String title, version, website, copyright;
+        final int licenseInfo;
+        final String licenseTextFile;
+    }
+
+    private final static ComponentInfo components[] = {
+            new ComponentInfo(
+                    "DAVdroid", BuildConfig.VERSION_NAME, "https://davdroid.bitfire.at",
+                    DateFormatUtils.format(BuildConfig.buildTime, "yyyy") + " Ricki Hirner, Bernhard Stockmann (bitfire web engineering)",
+                    R.string.about_license_info_no_warranty, "gpl-3.0-standalone.html"
+            ), new ComponentInfo(
+                    "AmbilWarna", null, "https://github.com/yukuku/ambilwarna",
+                    "Yuku", R.string.about_license_info_no_warranty, "apache2.html"
+            ), new ComponentInfo(
+                    "Apache Commons", null, "http://commons.apache.org/",
+                    "Apache Software Foundation", R.string.about_license_info_no_warranty, "apache2.html"
+            ), new ComponentInfo(
+                    "dnsjava", null, "http://dnsjava.org/",
+                    "Brian Wellington", R.string.about_license_info_no_warranty, "bsd.html"
+            ), new ComponentInfo(
+                    "ez-vcard", Ezvcard.VERSION, "https://github.com/mangstadt/ez-vcard",
+                    "Michael Angstadt", R.string.about_license_info_no_warranty, "bsd.html"
+            ), new ComponentInfo(
+                    "ical4j", "2.x", "https://ical4j.github.io/",
+                    "Ben Fortuna", R.string.about_license_info_no_warranty, "bsd-3clause.html"
+            ), new ComponentInfo(
+                    "MemorizingTrustManager", null, "https://github.com/ge0rg/MemorizingTrustManager",
+                    "Georg Lukas", R.string.about_license_info_no_warranty, "mit.html"
+            ), new ComponentInfo(
+                    "OkHttp", null, "https://square.github.io/okhttp/",
+                    "Square, Inc.", R.string.about_license_info_no_warranty, "apache2.html"
+            ), new ComponentInfo(
+                    "Project Lombok", null, "https://projectlombok.org/",
+                    "The Project Lombok Authors", R.string.about_license_info_no_warranty, "mit.html"
+            )
+    };
+
+
+    private static class TabsAdapter extends FragmentPagerAdapter {
+        public TabsAdapter(FragmentManager fm) {
+            super(fm);
+        }
+
+        @Override
+        public int getCount() {
+            return components.length;
+        }
+
+        @Override
+        public CharSequence getPageTitle(int position) {
+            return components[position].title;
+        }
+
+        @Override
+        public Fragment getItem(int position) {
+            return ComponentFragment.instantiate(position);
+        }
+    }
+
+    public static class ComponentFragment extends Fragment implements LoaderManager.LoaderCallbacks<Spanned> {
+        private static final String
+                KEY_POSITION = "position",
+                KEY_FILE_NAME = "fileName";
+
+        public static ComponentFragment instantiate(int position) {
+            ComponentFragment frag = new ComponentFragment();
+            Bundle args = new Bundle(1);
+            args.putInt(KEY_POSITION, position);
+            frag.setArguments(args);
+            return frag;
+        }
+
+        @Nullable
+        @Override
+        @SuppressLint("SetTextI18n")
+        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+            ComponentInfo info = components[getArguments().getInt(KEY_POSITION)];
+
+            View v = inflater.inflate(R.layout.about_component, container, false);
+
+            TextView tv = (TextView)v.findViewById(R.id.title);
+            tv.setText(info.title + (info.version != null ? (" " + info.version) : ""));
+
+            tv = (TextView)v.findViewById(R.id.website);
+            tv.setAutoLinkMask(Linkify.WEB_URLS);
+            tv.setText(info.website);
+
+            tv = (TextView)v.findViewById(R.id.copyright);
+            tv.setText("© " + info.copyright);
+
+            tv = (TextView)v.findViewById(R.id.license_info);
+            tv.setText(info.licenseInfo);
+
+            // load and format license text
+            Bundle args = new Bundle(1);
+            args.putString(KEY_FILE_NAME, info.licenseTextFile);
+            getLoaderManager().initLoader(0, args, this);
+
+            return v;
+        }
+
+        @Override
+        public Loader<Spanned> onCreateLoader(int id, Bundle args) {
+            return new LicenseLoader(getContext(), args.getString(KEY_FILE_NAME));
+        }
+
+        @Override
+        public void onLoadFinished(Loader<Spanned> loader, Spanned license) {
+            if (getView() != null) {
+                TextView tv = (TextView)getView().findViewById(R.id.license_text);
+                if (tv != null) {
+                    tv.setAutoLinkMask(Linkify.EMAIL_ADDRESSES | Linkify.WEB_URLS);
+                    tv.setText(license);
+                }
+            }
+        }
+
+        @Override
+        public void onLoaderReset(Loader<Spanned> loader) {
+        }
+    }
+
+    private static class LicenseLoader extends AsyncTaskLoader<Spanned> {
+        final String fileName;
+        Spanned content;
+
+        LicenseLoader(Context context, String fileName) {
+            super(context);
+            this.fileName = fileName;
+        }
+
+        @Override
+        protected void onStartLoading() {
+            if (content == null)
+                forceLoad();
+            else
+                deliverResult(content);
+        }
+
+        @Override
+        public Spanned loadInBackground() {
+            App.log.fine("Loading license file " + fileName);
+            try {
+                @Cleanup InputStream is = getContext().getResources().getAssets().open(fileName);
+                byte[] raw = IOUtils.toByteArray(is);
+                return content = Html.fromHtml(new String(raw));
+            } catch (IOException e) {
+                App.log.log(Level.SEVERE, "Couldn't read license file", e);
+                return null;
+            }
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/AccountActivity.java

@@ -0,0 +1,566 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.accounts.Account;
+import android.accounts.AccountManager;
+import android.accounts.AccountManagerCallback;
+import android.accounts.AccountManagerFuture;
+import android.accounts.AuthenticatorException;
+import android.accounts.OperationCanceledException;
+import android.app.LoaderManager;
+import android.content.AsyncTaskLoader;
+import android.content.ComponentName;
+import android.content.ContentResolver;
+import android.content.ContentValues;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.Intent;
+import android.content.Loader;
+import android.content.ServiceConnection;
+import android.database.Cursor;
+import android.database.DatabaseUtils;
+import android.database.sqlite.SQLiteDatabase;
+import android.graphics.drawable.Drawable;
+import android.os.Build;
+import android.os.Bundle;
+import android.os.IBinder;
+import android.provider.CalendarContract;
+import android.provider.ContactsContract;
+import android.support.annotation.NonNull;
+import android.support.design.widget.Snackbar;
+import android.support.v7.app.AlertDialog;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.widget.CardView;
+import android.support.v7.widget.Toolbar;
+import android.text.TextUtils;
+import android.view.LayoutInflater;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.AbsListView;
+import android.widget.AdapterView;
+import android.widget.ArrayAdapter;
+import android.widget.CheckBox;
+import android.widget.ListView;
+import android.widget.PopupMenu;
+import android.widget.ProgressBar;
+import android.widget.RadioButton;
+import android.widget.TextView;
+
+import org.apache.commons.lang3.BooleanUtils;
+
+import java.io.IOException;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.logging.Level;
+
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.DavService;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.davdroid.model.ServiceDB;
+import at.bitfire.davdroid.model.ServiceDB.Collections;
+import at.bitfire.davdroid.model.ServiceDB.OpenHelper;
+import at.bitfire.davdroid.model.ServiceDB.Services;
+import at.bitfire.ical4android.TaskProvider;
+import lombok.Cleanup;
+
+public class AccountActivity extends AppCompatActivity implements Toolbar.OnMenuItemClickListener, PopupMenu.OnMenuItemClickListener, LoaderManager.LoaderCallbacks<AccountActivity.AccountInfo> {
+    public static final String EXTRA_ACCOUNT = "account";
+
+    private Account account;
+    private AccountInfo accountInfo;
+
+    ListView listCalDAV, listCardDAV;
+    Toolbar tbCardDAV, tbCalDAV;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        account = getIntent().getParcelableExtra(EXTRA_ACCOUNT);
+        setTitle(account.name);
+
+        setContentView(R.layout.activity_account);
+
+        Drawable icMenu = Build.VERSION.SDK_INT >= 21 ? getDrawable(R.drawable.ic_menu_light) :
+                getResources().getDrawable(R.drawable.ic_menu_light);
+
+        // CardDAV toolbar
+        tbCardDAV = (Toolbar)findViewById(R.id.carddav_menu);
+        tbCardDAV.setOverflowIcon(icMenu);
+        tbCardDAV.inflateMenu(R.menu.carddav_actions);
+        tbCardDAV.setOnMenuItemClickListener(this);
+
+        // CalDAV toolbar
+        tbCalDAV = (Toolbar)findViewById(R.id.caldav_menu);
+        tbCalDAV.setOverflowIcon(icMenu);
+        tbCalDAV.inflateMenu(R.menu.caldav_actions);
+        tbCalDAV.setOnMenuItemClickListener(this);
+
+        // load CardDAV/CalDAV collections
+        getLoaderManager().initLoader(0, getIntent().getExtras(), this);
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        getMenuInflater().inflate(R.menu.activity_account, menu);
+        return true;
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        switch (item.getItemId()) {
+            case R.id.sync_now:
+                requestSync();
+                break;
+            case R.id.settings:
+                Intent intent = new Intent(this, AccountSettingsActivity.class);
+                intent.putExtra(AccountSettingsActivity.EXTRA_ACCOUNT, account);
+                startActivity(intent);
+                break;
+            case R.id.delete_account:
+                new AlertDialog.Builder(AccountActivity.this)
+                        .setIcon(R.drawable.ic_error_dark)
+                        .setTitle(R.string.account_delete_confirmation_title)
+                        .setMessage(R.string.account_delete_confirmation_text)
+                        .setNegativeButton(android.R.string.no, null)
+                        .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int which) {
+                                deleteAccount();
+                            }
+                        })
+                        .show();
+                break;
+            default:
+                return super.onOptionsItemSelected(item);
+        }
+        return true;
+    }
+
+    @Override
+    public boolean onMenuItemClick(MenuItem item) {
+        Intent intent;
+        switch (item.getItemId()) {
+            case R.id.refresh_address_books:
+                if (accountInfo.carddav != null) {
+                    intent = new Intent(this, DavService.class);
+                    intent.setAction(DavService.ACTION_REFRESH_COLLECTIONS);
+                    intent.putExtra(DavService.EXTRA_DAV_SERVICE_ID, accountInfo.carddav.id);
+                    startService(intent);
+                }
+                break;
+            case R.id.create_address_book:
+                intent = new Intent(this, CreateAddressBookActivity.class);
+                intent.putExtra(CreateAddressBookActivity.EXTRA_ACCOUNT, account);
+                startActivity(intent);
+                break;
+            case R.id.refresh_calendars:
+                if (accountInfo.caldav != null) {
+                    intent = new Intent(this, DavService.class);
+                    intent.setAction(DavService.ACTION_REFRESH_COLLECTIONS);
+                    intent.putExtra(DavService.EXTRA_DAV_SERVICE_ID, accountInfo.caldav.id);
+                    startService(intent);
+                }
+                break;
+            case R.id.create_calendar:
+                intent = new Intent(this, CreateCalendarActivity.class);
+                intent.putExtra(CreateCalendarActivity.EXTRA_ACCOUNT, account);
+                startActivity(intent);
+                break;
+        }
+        return false;
+    }
+
+
+    private AdapterView.OnItemClickListener onItemClickListener = new AdapterView.OnItemClickListener() {
+        @Override
+        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
+            final ListView list = (ListView)parent;
+            final ArrayAdapter<CollectionInfo> adapter = (ArrayAdapter)list.getAdapter();
+            final CollectionInfo info = adapter.getItem(position);
+
+            boolean nowChecked = !info.selected;
+
+            if (list.getChoiceMode() == AbsListView.CHOICE_MODE_SINGLE)
+                // clear all other checked items
+                for (int i = adapter.getCount()-1; i >= 0; i--)
+                    adapter.getItem(i).selected = false;
+
+            OpenHelper dbHelper = new OpenHelper(AccountActivity.this);
+            try {
+                SQLiteDatabase db = dbHelper.getWritableDatabase();
+                db.beginTransactionNonExclusive();
+
+                if (list.getChoiceMode() == AbsListView.CHOICE_MODE_SINGLE) {
+                    // disable all other collections
+                    ContentValues values = new ContentValues(1);
+                    values.put(Collections.SYNC, 0);
+                    db.update(Collections._TABLE, values, Collections.SERVICE_ID + "=?", new String[] { String.valueOf(info.serviceID) });
+                }
+
+                ContentValues values = new ContentValues(1);
+                values.put(Collections.SYNC, nowChecked ? 1 : 0);
+                db.update(Collections._TABLE, values, Collections.ID + "=?", new String[] { String.valueOf(info.id) });
+
+                db.setTransactionSuccessful();
+                db.endTransaction();
+
+                info.selected = nowChecked;
+                adapter.notifyDataSetChanged();
+            } finally {
+                dbHelper.close();
+            }
+        }
+    };
+
+    private AdapterView.OnItemLongClickListener onItemLongClickListener = new AdapterView.OnItemLongClickListener() {
+        @Override
+        public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
+            final ListView list = (ListView)parent;
+            final ArrayAdapter<CollectionInfo> adapter = (ArrayAdapter)list.getAdapter();
+            final CollectionInfo info = adapter.getItem(position);
+
+            PopupMenu popup = new PopupMenu(AccountActivity.this, view);
+            popup.inflate(R.menu.account_collection_operations);
+            popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
+                @Override
+                public boolean onMenuItemClick(MenuItem item) {
+                    switch (item.getItemId()) {
+                        case R.id.delete_collection:
+                            DeleteCollectionFragment.ConfirmDeleteCollectionFragment.newInstance(account, info).show(getSupportFragmentManager(), null);
+                            break;
+                    }
+                    return true;
+                }
+            });
+            popup.show();
+
+            // long click was handled
+            return true;
+        }
+    };
+
+
+    /* LOADERS AND LOADED DATA */
+
+    protected static class AccountInfo {
+        ServiceInfo carddav, caldav;
+
+        public static class ServiceInfo {
+            long id;
+            boolean refreshing;
+
+            boolean hasHomeSets;
+            List<CollectionInfo> collections;
+        }
+    }
+
+    @Override
+    public Loader<AccountInfo> onCreateLoader(int id, Bundle args) {
+        return new AccountLoader(this, account.name);
+    }
+
+    public void reload() {
+        getLoaderManager().restartLoader(0, getIntent().getExtras(), this);
+    }
+
+    @Override
+    public void onLoadFinished(Loader<AccountInfo> loader, final AccountInfo info) {
+        accountInfo = info;
+
+        if (accountInfo == null) {
+            // account doesn't exist anymore
+            finish();
+            return;
+        }
+
+        CardView card = (CardView)findViewById(R.id.carddav);
+        if (info.carddav != null) {
+            ProgressBar progress = (ProgressBar)findViewById(R.id.carddav_refreshing);
+            progress.setVisibility(info.carddav.refreshing ? View.VISIBLE : View.GONE);
+
+            listCardDAV = (ListView)findViewById(R.id.address_books);
+            listCardDAV.setEnabled(!info.carddav.refreshing);
+            listCardDAV.setAlpha(info.carddav.refreshing ? 0.5f : 1);
+
+            tbCardDAV.getMenu().findItem(R.id.create_address_book).setEnabled(info.carddav.hasHomeSets);
+
+            AddressBookAdapter adapter = new AddressBookAdapter(this);
+            adapter.addAll(info.carddav.collections);
+            listCardDAV.setAdapter(adapter);
+            listCardDAV.setOnItemClickListener(onItemClickListener);
+            listCardDAV.setOnItemLongClickListener(onItemLongClickListener);
+        } else
+            card.setVisibility(View.GONE);
+
+        card = (CardView)findViewById(R.id.caldav);
+        if (info.caldav != null) {
+            ProgressBar progress = (ProgressBar)findViewById(R.id.caldav_refreshing);
+            progress.setVisibility(info.caldav.refreshing ? View.VISIBLE : View.GONE);
+
+            listCalDAV = (ListView)findViewById(R.id.calendars);
+            listCalDAV.setEnabled(!info.caldav.refreshing);
+            listCalDAV.setAlpha(info.caldav.refreshing ? 0.5f : 1);
+
+            tbCalDAV.getMenu().findItem(R.id.create_calendar).setEnabled(info.caldav.hasHomeSets);
+
+            final CalendarAdapter adapter = new CalendarAdapter(this);
+            adapter.addAll(info.caldav.collections);
+            listCalDAV.setAdapter(adapter);
+            listCalDAV.setOnItemClickListener(onItemClickListener);
+            listCalDAV.setOnItemLongClickListener(onItemLongClickListener);
+        } else
+            card.setVisibility(View.GONE);
+    }
+
+    @Override
+    public void onLoaderReset(Loader<AccountInfo> loader) {
+        if (listCardDAV != null)
+            listCardDAV.setAdapter(null);
+
+        if (listCalDAV != null)
+            listCalDAV.setAdapter(null);
+    }
+
+
+    private static class AccountLoader extends AsyncTaskLoader<AccountInfo> implements DavService.RefreshingStatusListener, ServiceConnection {
+        private final String accountName;
+        private final OpenHelper dbHelper;
+        private DavService.InfoBinder davService;
+
+        public AccountLoader(Context context, String accountName) {
+            super(context);
+            this.accountName = accountName;
+            dbHelper = new OpenHelper(context);
+        }
+
+        @Override
+        protected void onStartLoading() {
+            getContext().bindService(new Intent(getContext(), DavService.class), this, Context.BIND_AUTO_CREATE);
+        }
+
+        @Override
+        protected void onStopLoading() {
+            davService.removeRefreshingStatusListener(this);
+            getContext().unbindService(this);
+        }
+
+        @Override
+        public void onServiceConnected(ComponentName name, IBinder service) {
+            davService = (DavService.InfoBinder)service;
+            davService.addRefreshingStatusListener(this, false);
+
+            forceLoad();
+        }
+
+        @Override
+        public void onServiceDisconnected(ComponentName name) {
+            davService = null;
+        }
+
+        @Override
+        public void onDavRefreshStatusChanged(long id, boolean refreshing) {
+            forceLoad();
+        }
+
+        @Override
+        public AccountInfo loadInBackground() {
+            AccountInfo info = new AccountInfo();
+            try {
+                SQLiteDatabase db = dbHelper.getReadableDatabase();
+
+                @Cleanup Cursor cursor = db.query(
+                        Services._TABLE,
+                        new String[] { Services.ID, Services.SERVICE },
+                        Services.ACCOUNT_NAME + "=?", new String[] { accountName },
+                        null, null, null);
+
+                if (cursor.getCount() == 0)
+                    // no services, account not useable
+                    return null;
+
+                while (cursor.moveToNext()) {
+                    long id = cursor.getLong(0);
+                    String service = cursor.getString(1);
+                    if (Services.SERVICE_CARDDAV.equals(service)) {
+                        info.carddav = new AccountInfo.ServiceInfo();
+                        info.carddav.id = id;
+                        info.carddav.refreshing = davService.isRefreshing(id);
+                        info.carddav.hasHomeSets = hasHomeSets(db, id);
+                        info.carddav.collections = readCollections(db, id);
+
+                    } else if (Services.SERVICE_CALDAV.equals(service)) {
+                        info.caldav = new AccountInfo.ServiceInfo();
+                        info.caldav.id = id;
+                        info.caldav.refreshing = davService.isRefreshing(id);
+                        info.caldav.hasHomeSets = hasHomeSets(db, id);
+                        info.caldav.collections = readCollections(db, id);
+                    }
+                }
+            } finally {
+                dbHelper.close();
+            }
+            return info;
+        }
+
+        private boolean hasHomeSets(@NonNull SQLiteDatabase db, long service) {
+            @Cleanup Cursor cursor = db.query(ServiceDB.HomeSets._TABLE, null, ServiceDB.HomeSets.SERVICE_ID + "=?",
+                    new String[] { String.valueOf(service) }, null, null, null);
+            return cursor.getCount() > 0;
+        }
+
+        private List<CollectionInfo> readCollections(@NonNull SQLiteDatabase db, long service) {
+            List<CollectionInfo> collections = new LinkedList<>();
+            @Cleanup Cursor cursor = db.query(Collections._TABLE, null, Collections.SERVICE_ID + "=?",
+                    new String[] { String.valueOf(service) }, null, null, Collections.SUPPORTS_VEVENT + " DESC," + Collections.DISPLAY_NAME);
+            while (cursor.moveToNext()) {
+                ContentValues values = new ContentValues();
+                DatabaseUtils.cursorRowToContentValues(cursor, values);
+                collections.add(CollectionInfo.fromDB(values));
+            }
+            return collections;
+        }
+    }
+
+
+    /* LIST ADAPTERS */
+
+    public static class AddressBookAdapter extends ArrayAdapter<CollectionInfo> {
+        public AddressBookAdapter(Context context) {
+            super(context, R.layout.account_carddav_item);
+        }
+
+        @Override
+        public View getView(int position, View v, ViewGroup parent) {
+            if (v == null)
+                v = LayoutInflater.from(getContext()).inflate(R.layout.account_carddav_item, parent, false);
+
+            final CollectionInfo info = getItem(position);
+
+            RadioButton checked = (RadioButton)v.findViewById(R.id.checked);
+            checked.setChecked(info.selected);
+
+            TextView tv = (TextView)v.findViewById(R.id.title);
+            tv.setText(TextUtils.isEmpty(info.displayName) ? info.url : info.displayName);
+
+            tv = (TextView)v.findViewById(R.id.description);
+            if (TextUtils.isEmpty(info.description))
+                tv.setVisibility(View.GONE);
+            else {
+                tv.setVisibility(View.VISIBLE);
+                tv.setText(info.description);
+            }
+
+            tv = (TextView)v.findViewById(R.id.read_only);
+            tv.setVisibility(info.readOnly ? View.VISIBLE : View.GONE);
+
+            return v;
+        }
+    }
+
+    public static class CalendarAdapter extends ArrayAdapter<CollectionInfo> {
+        public CalendarAdapter(Context context) {
+            super(context, R.layout.account_caldav_item);
+        }
+
+        @Override
+        public View getView(final int position, View v, ViewGroup parent) {
+            if (v == null)
+                v = LayoutInflater.from(getContext()).inflate(R.layout.account_caldav_item, parent, false);
+
+            final CollectionInfo info = getItem(position);
+
+            CheckBox checked = (CheckBox)v.findViewById(R.id.checked);
+            checked.setChecked(info.selected);
+
+            View vColor = v.findViewById(R.id.color);
+            if (info.color != null) {
+                vColor.setVisibility(View.VISIBLE);
+                vColor.setBackgroundColor(info.color);
+            } else
+                vColor.setVisibility(View.GONE);
+
+            TextView tv = (TextView)v.findViewById(R.id.title);
+            tv.setText(TextUtils.isEmpty(info.displayName) ? info.url : info.displayName);
+
+            tv = (TextView)v.findViewById(R.id.description);
+            if (TextUtils.isEmpty(info.description))
+                tv.setVisibility(View.GONE);
+            else {
+                tv.setVisibility(View.VISIBLE);
+                tv.setText(info.description);
+            }
+
+            tv = (TextView)v.findViewById(R.id.read_only);
+            tv.setVisibility(info.readOnly ? View.VISIBLE : View.GONE);
+
+            tv = (TextView)v.findViewById(R.id.events);
+            tv.setVisibility(BooleanUtils.isTrue(info.supportsVEVENT) ? View.VISIBLE : View.GONE);
+
+            tv = (TextView)v.findViewById(R.id.tasks);
+            tv.setVisibility(BooleanUtils.isTrue(info.supportsVTODO) ? View.VISIBLE : View.GONE);
+
+            return v;
+        }
+    }
+
+
+    /* USER ACTIONS */
+
+    private void deleteAccount() {
+        AccountManager accountManager = AccountManager.get(this);
+
+        if (Build.VERSION.SDK_INT >= 22)
+            accountManager.removeAccount(account, this, new AccountManagerCallback<Bundle>() {
+                @Override
+                public void run(AccountManagerFuture<Bundle> future) {
+                    try {
+                        if (future.getResult().getBoolean(AccountManager.KEY_BOOLEAN_RESULT))
+                            finish();
+                    } catch(OperationCanceledException|IOException|AuthenticatorException e) {
+                        App.log.log(Level.SEVERE, "Couldn't remove account", e);
+                    }
+                }
+            }, null);
+        else
+            accountManager.removeAccount(account, new AccountManagerCallback<Boolean>() {
+                @Override
+                public void run(AccountManagerFuture<Boolean> future) {
+                    try {
+                        if (future.getResult())
+                            finish();
+                    } catch (OperationCanceledException|IOException|AuthenticatorException e) {
+                        App.log.log(Level.SEVERE, "Couldn't remove account", e);
+                    }
+                }
+            }, null);
+    }
+
+    private void requestSync() {
+        String authorities[] = {
+                ContactsContract.AUTHORITY,
+                CalendarContract.AUTHORITY,
+                TaskProvider.ProviderName.OpenTasks.authority
+        };
+
+        for (String authority : authorities) {
+            Bundle extras = new Bundle();
+            extras.putBoolean(ContentResolver.SYNC_EXTRAS_MANUAL, true);        // manual sync
+            extras.putBoolean(ContentResolver.SYNC_EXTRAS_EXPEDITED, true);     // run immediately (don't queue)
+            ContentResolver.requestSync(account, authority, extras);
+        }
+
+        Snackbar.make(findViewById(R.id.parent), R.string.account_synchronizing_now, Snackbar.LENGTH_LONG).show();
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/AccountListFragment.java

@@ -0,0 +1,133 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.accounts.Account;
+import android.accounts.AccountManager;
+import android.accounts.OnAccountsUpdateListener;
+import android.content.Context;
+import android.content.Intent;
+import android.os.Bundle;
+import android.support.v4.app.ListFragment;
+import android.support.v4.app.LoaderManager;
+import android.support.v4.content.AsyncTaskLoader;
+import android.support.v4.content.Loader;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.AbsListView;
+import android.widget.AdapterView;
+import android.widget.ArrayAdapter;
+import android.widget.ListView;
+import android.widget.TextView;
+
+import at.bitfire.davdroid.AccountsChangedReceiver;
+import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.R;
+
+public class AccountListFragment extends ListFragment implements LoaderManager.LoaderCallbacks<Account[]>, AdapterView.OnItemClickListener {
+
+    @Override
+    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        setListAdapter(new AccountListAdapter(getContext()));
+
+        return inflater.inflate(R.layout.account_list, container, false);
+    }
+
+    @Override
+    public void onViewCreated(View view, Bundle savedInstanceState) {
+        super.onViewCreated(view, savedInstanceState);
+        getLoaderManager().initLoader(0, getArguments(), this);
+
+        ListView list = getListView();
+        list.setOnItemClickListener(this);
+        list.setChoiceMode(AbsListView.CHOICE_MODE_SINGLE);
+    }
+
+    @Override
+    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
+        Account account = (Account)getListAdapter().getItem(position);
+
+        Intent intent = new Intent(getContext(), AccountActivity.class);
+        intent.putExtra(AccountActivity.EXTRA_ACCOUNT, account);
+        startActivity(intent);
+    }
+
+
+    // loader
+
+    @Override
+    public Loader<Account[]> onCreateLoader(int id, Bundle args) {
+        return new AccountLoader(getContext());
+    }
+
+    @Override
+    public void onLoadFinished(Loader<Account[]> loader, Account[] accounts) {
+        AccountListAdapter adapter = (AccountListAdapter)getListAdapter();
+        adapter.clear();
+        adapter.addAll(accounts);
+    }
+
+    @Override
+    public void onLoaderReset(Loader<Account[]> loader) {
+        ((AccountListAdapter)getListAdapter()).clear();
+    }
+
+    private static class AccountLoader extends AsyncTaskLoader<Account[]> implements OnAccountsUpdateListener {
+        private final AccountManager accountManager;
+
+        public AccountLoader(Context context) {
+            super(context);
+            accountManager = AccountManager.get(context);
+        }
+
+        @Override
+        protected void onStartLoading() {
+            AccountsChangedReceiver.registerListener(this, true);
+        }
+
+        @Override
+        protected void onStopLoading() {
+            AccountsChangedReceiver.unregisterListener(this);
+        }
+
+        @Override
+        public void onAccountsUpdated(Account[] accounts) {
+            forceLoad();
+        }
+
+        @Override
+        public Account[] loadInBackground() {
+            return accountManager.getAccountsByType(Constants.ACCOUNT_TYPE);
+        }
+    }
+
+
+    // list adapter
+
+    static class AccountListAdapter extends ArrayAdapter<Account> {
+        public AccountListAdapter(Context context) {
+            super(context, R.layout.account_list_item);
+        }
+
+        @Override
+        public View getView(int position, View v, ViewGroup parent) {
+            if (v == null)
+                v = LayoutInflater.from(getContext()).inflate(R.layout.account_list_item, parent, false);
+
+            Account account = getItem(position);
+
+            TextView tv = (TextView)v.findViewById(R.id.account_name);
+            tv.setText(account.name);
+
+            return v;
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/AccountSettingsActivity.java

@@ -0,0 +1,296 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.accounts.Account;
+import android.content.Intent;
+import android.os.Bundle;
+import android.provider.CalendarContract;
+import android.provider.ContactsContract;
+import android.support.v4.app.NavUtils;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.preference.EditTextPreference;
+import android.support.v7.preference.ListPreference;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceFragmentCompat;
+import android.support.v7.preference.SwitchPreferenceCompat;
+import android.text.TextUtils;
+import android.view.MenuItem;
+
+import java.util.logging.Level;
+
+import at.bitfire.davdroid.AccountSettings;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.R;
+import at.bitfire.ical4android.TaskProvider;
+import at.bitfire.vcard4android.GroupMethod;
+
+public class AccountSettingsActivity extends AppCompatActivity {
+    public final static String EXTRA_ACCOUNT = "account";
+
+    private Account account;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        account = getIntent().getParcelableExtra(EXTRA_ACCOUNT);
+        setTitle(getString(R.string.settings_title, account.name));
+
+        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+
+        if (savedInstanceState == null)
+            getSupportFragmentManager().beginTransaction()
+                    .replace(android.R.id.content, AccountSettingsFragment.instantiate(this, AccountSettingsFragment.class.getName(), getIntent().getExtras()))
+                    .commit();
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        if (item.getItemId() == android.R.id.home) {
+            Intent intent = new Intent(this, AccountActivity.class);
+            intent.putExtra(AccountActivity.EXTRA_ACCOUNT, account);
+            NavUtils.navigateUpTo(this, intent);
+            return true;
+        } else
+            return false;
+    }
+
+
+    public static class AccountSettingsFragment extends PreferenceFragmentCompat {
+        Account account;
+
+        @Override
+        public void onCreate(Bundle savedInstanceState) {
+            super.onCreate(savedInstanceState);
+
+            account = getArguments().getParcelable(EXTRA_ACCOUNT);
+            refresh();
+        }
+
+        @Override
+        public void onCreatePreferences(Bundle bundle, String s) {
+            addPreferencesFromResource(R.xml.settings_account);
+        }
+
+        public void refresh() {
+            final AccountSettings settings;
+
+            try {
+                settings = new AccountSettings(getActivity(), account);
+            } catch(InvalidAccountException e) {
+                App.log.log(Level.INFO, "Account is invalid or doesn't exist (anymore)", e);
+                getActivity().finish();
+                return;
+            }
+
+            // category: authentication
+            final EditTextPreference prefUserName = (EditTextPreference)findPreference("username");
+            prefUserName.setSummary(settings.username());
+            prefUserName.setText(settings.username());
+            prefUserName.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                @Override
+                public boolean onPreferenceChange(Preference preference, Object newValue) {
+                    settings.username((String)newValue);
+                    refresh();
+                    return false;
+                }
+            });
+
+            final EditTextPreference prefPassword = (EditTextPreference)findPreference("password");
+            prefPassword.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                @Override
+                public boolean onPreferenceChange(Preference preference, Object newValue) {
+                    settings.password((String)newValue);
+                    refresh();
+                    return false;
+                }
+            });
+
+            final SwitchPreferenceCompat prefPreemptive = (SwitchPreferenceCompat)findPreference("preemptive");
+            prefPreemptive.setChecked(settings.preemptiveAuth());
+            prefPreemptive.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                @Override
+                public boolean onPreferenceChange(Preference preference, Object newValue) {
+                    settings.preemptiveAuth((Boolean)newValue);
+                    refresh();
+                    return false;
+                }
+            });
+
+            // category: synchronization
+            final ListPreference prefSyncContacts = (ListPreference)findPreference("sync_interval_contacts");
+            final Long syncIntervalContacts = settings.getSyncInterval(ContactsContract.AUTHORITY);
+            if (syncIntervalContacts != null) {
+                prefSyncContacts.setValue(syncIntervalContacts.toString());
+                if (syncIntervalContacts == AccountSettings.SYNC_INTERVAL_MANUALLY)
+                    prefSyncContacts.setSummary(R.string.settings_sync_summary_manually);
+                else
+                    prefSyncContacts.setSummary(getString(R.string.settings_sync_summary_periodically, syncIntervalContacts / 60));
+                prefSyncContacts.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                    @Override
+                    public boolean onPreferenceChange(Preference preference, Object newValue) {
+                        settings.setSyncInterval(ContactsContract.AUTHORITY, Long.parseLong((String)newValue));
+                        refresh();
+                        return false;
+                    }
+                });
+            } else {
+                prefSyncContacts.setEnabled(false);
+                prefSyncContacts.setSummary(R.string.settings_sync_summary_not_available);
+            }
+
+            final ListPreference prefSyncCalendars = (ListPreference)findPreference("sync_interval_calendars");
+            final Long syncIntervalCalendars = settings.getSyncInterval(CalendarContract.AUTHORITY);
+            if (syncIntervalCalendars != null) {
+                prefSyncCalendars.setValue(syncIntervalCalendars.toString());
+                if (syncIntervalCalendars == AccountSettings.SYNC_INTERVAL_MANUALLY)
+                    prefSyncCalendars.setSummary(R.string.settings_sync_summary_manually);
+                else
+                    prefSyncCalendars.setSummary(getString(R.string.settings_sync_summary_periodically, syncIntervalCalendars / 60));
+                prefSyncCalendars.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                    @Override
+                    public boolean onPreferenceChange(Preference preference, Object newValue) {
+                        settings.setSyncInterval(CalendarContract.AUTHORITY, Long.parseLong((String)newValue));
+                        refresh();
+                        return false;
+                    }
+                });
+            } else {
+                prefSyncCalendars.setEnabled(false);
+                prefSyncCalendars.setSummary(R.string.settings_sync_summary_not_available);
+            }
+
+            final ListPreference prefSyncTasks = (ListPreference)findPreference("sync_interval_tasks");
+            final Long syncIntervalTasks = settings.getSyncInterval(TaskProvider.ProviderName.OpenTasks.authority);
+            if (syncIntervalTasks != null) {
+                prefSyncTasks.setValue(syncIntervalTasks.toString());
+                if (syncIntervalTasks == AccountSettings.SYNC_INTERVAL_MANUALLY)
+                    prefSyncTasks.setSummary(R.string.settings_sync_summary_manually);
+                else
+                    prefSyncTasks.setSummary(getString(R.string.settings_sync_summary_periodically, syncIntervalTasks / 60));
+                prefSyncTasks.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                    @Override
+                    public boolean onPreferenceChange(Preference preference, Object newValue) {
+                        settings.setSyncInterval(TaskProvider.ProviderName.OpenTasks.authority, Long.parseLong((String)newValue));
+                        refresh();
+                        return false;
+                    }
+                });
+            } else {
+                prefSyncTasks.setEnabled(false);
+                prefSyncTasks.setSummary(R.string.settings_sync_summary_not_available);
+            }
+
+            final SwitchPreferenceCompat prefWifiOnly = (SwitchPreferenceCompat)findPreference("sync_wifi_only");
+            prefWifiOnly.setChecked(settings.getSyncWifiOnly());
+            prefWifiOnly.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                @Override
+                public boolean onPreferenceChange(Preference preference, Object wifiOnly) {
+                    settings.setSyncWiFiOnly((Boolean)wifiOnly);
+                    refresh();
+                    return false;
+                }
+            });
+
+            final EditTextPreference prefWifiOnlySSID = (EditTextPreference)findPreference("sync_wifi_only_ssid");
+            final String onlySSID = settings.getSyncWifiOnlySSID();
+            prefWifiOnlySSID.setText(onlySSID);
+            if (onlySSID != null)
+                prefWifiOnlySSID.setSummary(getString(R.string.settings_sync_wifi_only_ssid_on, onlySSID));
+            else
+                prefWifiOnlySSID.setSummary(R.string.settings_sync_wifi_only_ssid_off);
+            prefWifiOnlySSID.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                @Override
+                public boolean onPreferenceChange(Preference preference, Object newValue) {
+                    String ssid = (String)newValue;
+                    settings.setSyncWifiOnlySSID(!TextUtils.isEmpty(ssid) ? ssid : null);
+                    refresh();
+                    return false;
+                }
+            });
+
+            // category: CardDAV
+            final SwitchPreferenceCompat prefRFC6868 = (SwitchPreferenceCompat)findPreference("vcard_rfc6868");
+            if (syncIntervalContacts != null) {
+                prefRFC6868.setChecked(settings.getVCardRFC6868());
+                prefRFC6868.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                    @Override
+                    public boolean onPreferenceChange(Preference preference, Object o) {
+                        settings.setVCardRFC6868((Boolean)o);
+                        refresh();
+                        return false;
+                    }
+                });
+            } else
+                prefRFC6868.setEnabled(false);
+
+            final ListPreference prefGroupMethod = (ListPreference)findPreference("contact_group_method");
+            if (syncIntervalContacts != null) {
+                prefGroupMethod.setValue(settings.getGroupMethod().name());
+                prefGroupMethod.setSummary(prefGroupMethod.getEntry());
+                prefGroupMethod.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                    @Override
+                    public boolean onPreferenceChange(Preference preference, Object o) {
+                        String name = (String)o;
+                        settings.setGroupMethod(GroupMethod.valueOf(name));
+                        refresh();
+                        return false;
+                    }
+                });
+            } else
+                prefGroupMethod.setEnabled(false);
+
+            // category: CalDAV
+            final EditTextPreference prefTimeRangePastDays = (EditTextPreference)findPreference("time_range_past_days");
+            if (syncIntervalCalendars != null) {
+                Integer pastDays = settings.getTimeRangePastDays();
+                if (pastDays != null) {
+                    prefTimeRangePastDays.setText(pastDays.toString());
+                    prefTimeRangePastDays.setSummary(getResources().getQuantityString(R.plurals.settings_sync_time_range_past_days, pastDays, pastDays));
+                } else {
+                    prefTimeRangePastDays.setText(null);
+                    prefTimeRangePastDays.setSummary(R.string.settings_sync_time_range_past_none);
+                }
+                prefTimeRangePastDays.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                    @Override
+                    public boolean onPreferenceChange(Preference preference, Object newValue) {
+                        int days;
+                        try {
+                            days = Integer.parseInt((String)newValue);
+                        } catch(NumberFormatException ignored) {
+                            days = -1;
+                        }
+                        settings.setTimeRangePastDays(days < 0 ? null : days);
+                        refresh();
+                        return false;
+                    }
+                });
+            } else
+                prefTimeRangePastDays.setEnabled(false);
+
+            final SwitchPreferenceCompat prefManageColors = (SwitchPreferenceCompat)findPreference("manage_calendar_colors");
+            if (syncIntervalCalendars != null || syncIntervalTasks != null) {
+                prefManageColors.setChecked(settings.getManageCalendarColors());
+                prefManageColors.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                    @Override
+                    public boolean onPreferenceChange(Preference preference, Object newValue) {
+                        settings.setManageCalendarColors((Boolean)newValue);
+                        refresh();
+                        return false;
+                    }
+                });
+            } else
+                prefManageColors.setEnabled(false);
+
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/AccountsActivity.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.content.Intent;
+import android.net.Uri;
+import android.os.Build;
+import android.os.Bundle;
+import android.support.design.widget.FloatingActionButton;
+import android.support.design.widget.NavigationView;
+import android.support.v4.app.FragmentTransaction;
+import android.support.v4.view.GravityCompat;
+import android.support.v4.widget.DrawerLayout;
+import android.support.v7.app.ActionBarDrawerToggle;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.widget.Toolbar;
+import android.view.MenuItem;
+import android.view.View;
+
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.BuildConfig;
+import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.ui.setup.LoginActivity;
+
+public class AccountsActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_accounts);
+
+        Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar);
+        setSupportActionBar(toolbar);
+
+        FloatingActionButton fab = (FloatingActionButton)findViewById(R.id.fab);
+        fab.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                startActivity(new Intent(AccountsActivity.this, LoginActivity.class));
+            }
+        });
+
+        DrawerLayout drawer = (DrawerLayout)findViewById(R.id.drawer_layout);
+        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
+                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
+        drawer.setDrawerListener(toggle);
+        toggle.syncState();
+
+        NavigationView navigationView = (NavigationView)findViewById(R.id.nav_view);
+        navigationView.setNavigationItemSelectedListener(this);
+        navigationView.setItemIconTintList(null);
+
+        if (savedInstanceState == null && !getPackageName().equals(getCallingPackage())) {
+            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
+            for (StartupDialogFragment fragment : StartupDialogFragment.getStartupDialogs(this))
+                ft.add(fragment, null);
+            ft.commit();
+        }
+    }
+
+    @Override
+    public void onBackPressed() {
+        DrawerLayout drawer = (DrawerLayout)findViewById(R.id.drawer_layout);
+        if (drawer.isDrawerOpen(GravityCompat.START))
+            drawer.closeDrawer(GravityCompat.START);
+        else
+            super.onBackPressed();
+    }
+
+    @Override
+    public boolean onNavigationItemSelected(MenuItem item) {
+        switch (item.getItemId()) {
+            case R.id.nav_about:
+                startActivity(new Intent(this, AboutActivity.class));
+                break;
+            case R.id.nav_app_settings:
+                startActivity(new Intent(this, AppSettingsActivity.class));
+                break;
+            case R.id.nav_twitter:
+                startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("https://twitter.com/davdroidapp")));
+                break;
+            case R.id.nav_website:
+                startActivity(new Intent(Intent.ACTION_VIEW, Constants.webUri));
+                break;
+            case R.id.nav_faq:
+                startActivity(new Intent(Intent.ACTION_VIEW, Constants.webUri.buildUpon().appendEncodedPath("faq/").build()));
+                break;
+            case R.id.nav_forums:
+                startActivity(new Intent(Intent.ACTION_VIEW, Constants.webUri.buildUpon().appendEncodedPath("forums/").build()));
+                break;
+            case R.id.nav_donate:
+                if (BuildConfig.FLAVOR != App.FLAVOR_GOOGLE_PLAY)
+                    startActivity(new Intent(Intent.ACTION_VIEW, Constants.webUri.buildUpon().appendEncodedPath("donate/").build()));
+                break;
+        }
+
+        DrawerLayout drawer = (DrawerLayout)findViewById(R.id.drawer_layout);
+        drawer.closeDrawer(GravityCompat.START);
+        return true;
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/AppSettingsActivity.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.support.design.widget.Snackbar;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceFragmentCompat;
+import android.support.v7.preference.SwitchPreferenceCompat;
+
+import java.security.KeyStoreException;
+import java.util.Enumeration;
+import java.util.logging.Level;
+
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.model.ServiceDB;
+import at.bitfire.davdroid.model.Settings;
+import de.duenndns.ssl.MemorizingTrustManager;
+import lombok.Cleanup;
+
+public class AppSettingsActivity extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        if (savedInstanceState == null) {
+            getSupportFragmentManager().beginTransaction()
+                    .replace(android.R.id.content, new SettingsFragment())
+                    .commit();
+        }
+    }
+
+
+    public static class SettingsFragment extends PreferenceFragmentCompat {
+        Preference prefResetHints,
+                    prefResetCertificates;
+        SwitchPreferenceCompat prefLogToExternalStorage;
+
+        @Override
+        public void onCreatePreferences(Bundle bundle, String s) {
+            addPreferencesFromResource(R.xml.settings_app);
+
+            prefResetHints = findPreference("reset_hints");
+            prefResetCertificates = findPreference("reset_certificates");
+
+            @Cleanup ServiceDB.OpenHelper dbHelper = new ServiceDB.OpenHelper(getContext());
+            Settings settings = new Settings(dbHelper.getReadableDatabase());
+            prefLogToExternalStorage = (SwitchPreferenceCompat)findPreference("log_to_external_storage");
+            prefLogToExternalStorage.setChecked(settings.getBoolean(App.LOG_TO_EXTERNAL_STORAGE, false));
+        }
+
+        @Override
+        public boolean onPreferenceTreeClick(Preference preference) {
+            if (preference == prefResetHints)
+                resetHints();
+            else if (preference == prefResetCertificates)
+                resetCertificates();
+            else if (preference == prefLogToExternalStorage)
+                setExternalLogging(((SwitchPreferenceCompat)preference).isChecked());
+            else
+                return false;
+            return true;
+        }
+
+        private void resetHints() {
+            @Cleanup ServiceDB.OpenHelper dbHelper = new ServiceDB.OpenHelper(getContext());
+            Settings settings = new Settings(dbHelper.getWritableDatabase());
+            settings.remove(StartupDialogFragment.HINT_GOOGLE_PLAY_ACCOUNTS_REMOVED);
+            settings.remove(StartupDialogFragment.HINT_OPENTASKS_NOT_INSTALLED);
+            Snackbar.make(getView(), R.string.app_settings_reset_hints_success, Snackbar.LENGTH_LONG).show();
+        }
+
+        private void resetCertificates() {
+            MemorizingTrustManager mtm = App.getMemorizingTrustManager();
+
+            int deleted = 0;
+            Enumeration<String> iterator = mtm.getCertificates();
+            while (iterator.hasMoreElements())
+                try {
+                    mtm.deleteCertificate(iterator.nextElement());
+                    deleted++;
+                } catch (KeyStoreException e) {
+                    App.log.log(Level.SEVERE, "Couldn't distrust certificate", e);
+                }
+            Snackbar.make(getView(), getResources().getQuantityString(R.plurals.app_settings_reset_trusted_certificates_success, deleted, deleted), Snackbar.LENGTH_LONG).show();
+        }
+
+        private void setExternalLogging(boolean externalLogging) {
+            @Cleanup ServiceDB.OpenHelper dbHelper = new ServiceDB.OpenHelper(getContext());
+            Settings settings = new Settings(dbHelper.getWritableDatabase());
+            settings.putBoolean(App.LOG_TO_EXTERNAL_STORAGE, externalLogging);
+
+            // reinitialize logger of default process
+            App app = (App)getContext().getApplicationContext();
+            app.reinitLogger();
+
+            // reinitialize logger of :sync process
+            getContext().sendBroadcast(new Intent("at.bitfire.davdroid.REINIT_LOGGER"));
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/CreateAddressBookActivity.java

@@ -0,0 +1,161 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.accounts.Account;
+import android.content.Context;
+import android.content.Intent;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.os.Bundle;
+import android.support.v4.app.LoaderManager;
+import android.support.v4.app.NavUtils;
+import android.support.v4.content.AsyncTaskLoader;
+import android.support.v4.content.Loader;
+import android.support.v7.app.AppCompatActivity;
+import android.text.TextUtils;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.widget.ArrayAdapter;
+import android.widget.EditText;
+import android.widget.Spinner;
+
+import org.apache.commons.lang3.StringUtils;
+
+import java.util.LinkedList;
+import java.util.List;
+import java.util.UUID;
+
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.davdroid.model.ServiceDB;
+import lombok.Cleanup;
+import okhttp3.HttpUrl;
+
+public class CreateAddressBookActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<CreateAddressBookActivity.AccountInfo> {
+    public static final String EXTRA_ACCOUNT = "account";
+
+    protected Account account;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        account = getIntent().getParcelableExtra(EXTRA_ACCOUNT);
+
+        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+        setContentView(R.layout.activity_create_address_book);
+
+        getSupportLoaderManager().initLoader(0, getIntent().getExtras(), this);
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        getMenuInflater().inflate(R.menu.activity_create_collection, menu);
+        return true;
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        if (item.getItemId() == android.R.id.home) {
+            Intent intent = new Intent(this, AccountActivity.class);
+            intent.putExtra(AccountActivity.EXTRA_ACCOUNT, account);
+            NavUtils.navigateUpTo(this, intent);
+            return true;
+        }
+        return false;
+    }
+
+    public void onCreateCollection(MenuItem item) {
+        boolean ok = true;
+        CollectionInfo info = new CollectionInfo();
+
+        Spinner spinner = (Spinner)findViewById(R.id.home_sets);
+        String homeSet = (String)spinner.getSelectedItem();
+
+        EditText edit = (EditText)findViewById(R.id.display_name);
+        info.displayName = edit.getText().toString();
+        if (TextUtils.isEmpty(info.displayName)) {
+            edit.setError(getString(R.string.create_collection_display_name_required));
+            ok = false;
+        }
+
+        edit = (EditText)findViewById(R.id.description);
+        info.description = StringUtils.trimToNull(edit.getText().toString());
+
+        if (ok) {
+            info.type = CollectionInfo.Type.ADDRESS_BOOK;
+            info.url = HttpUrl.parse(homeSet).resolve(UUID.randomUUID().toString() + "/").toString();
+            CreateCollectionFragment.newInstance(account, info).show(getSupportFragmentManager(), null);
+        }
+    }
+
+
+    @Override
+    public Loader<AccountInfo> onCreateLoader(int id, Bundle args) {
+        return new AccountInfoLoader(this, account);
+    }
+
+    @Override
+    public void onLoadFinished(Loader<AccountInfo> loader, AccountInfo info) {
+        if (info != null) {
+            Spinner spinner = (Spinner)findViewById(R.id.home_sets);
+            spinner.setAdapter(new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, info.homeSets));
+        }
+    }
+
+    @Override
+    public void onLoaderReset(Loader<AccountInfo> loader) {
+    }
+
+    protected static class AccountInfo {
+        List<String> homeSets = new LinkedList<>();
+    }
+
+    protected static class AccountInfoLoader extends AsyncTaskLoader<AccountInfo> {
+        private final Account account;
+        private final ServiceDB.OpenHelper dbHelper;
+
+        public AccountInfoLoader(Context context, Account account) {
+            super(context);
+            this.account = account;
+            dbHelper = new ServiceDB.OpenHelper(context);
+        }
+
+        @Override
+        protected void onStartLoading() {
+            forceLoad();
+        }
+
+        @Override
+        public AccountInfo loadInBackground() {
+            final AccountInfo info = new AccountInfo();
+
+            // find DAV service and home sets
+            SQLiteDatabase db = dbHelper.getReadableDatabase();
+            try {
+                @Cleanup Cursor cursorService = db.query(ServiceDB.Services._TABLE, new String[] { ServiceDB.Services.ID },
+                        ServiceDB.Services.ACCOUNT_NAME + "=? AND " + ServiceDB.Services.SERVICE + "=?",
+                        new String[] { account.name, ServiceDB.Services.SERVICE_CARDDAV }, null, null, null);
+                if (!cursorService.moveToNext())
+                    return null;
+                String strServiceID = cursorService.getString(0);
+
+                @Cleanup Cursor cursorHomeSets = db.query(ServiceDB.HomeSets._TABLE, new String[] { ServiceDB.HomeSets.URL },
+                        ServiceDB.HomeSets.SERVICE_ID + "=?", new String[] { strServiceID }, null, null, null);
+                while (cursorHomeSets.moveToNext())
+                    info.homeSets.add(cursorHomeSets.getString(0));
+            } finally {
+                dbHelper.close();
+            }
+
+            return info;
+        }
+    }
+}

app/src/main/java/at/bitfire/davdroid/ui/CreateCalendarActivity.java

@@ -0,0 +1,222 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.accounts.Account;
+import android.content.Context;
+import android.content.Intent;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.graphics.drawable.ColorDrawable;
+import android.os.Bundle;
+import android.support.v4.app.LoaderManager;
+import android.support.v4.app.NavUtils;
+import android.support.v4.content.AsyncTaskLoader;
+import android.support.v4.content.Loader;
+import android.support.v7.app.AppCompatActivity;
+import android.text.TextUtils;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.view.View;
+import android.widget.ArrayAdapter;
+import android.widget.EditText;
+import android.widget.RadioGroup;
+import android.widget.Spinner;
+
+import net.fortuna.ical4j.model.Calendar;
+
+import org.apache.commons.lang3.StringUtils;
+
+import java.util.LinkedList;
+import java.util.List;
+import java.util.TimeZone;
+import java.util.UUID;
+
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.davdroid.model.ServiceDB;
+import at.bitfire.ical4android.DateUtils;
+import lombok.Cleanup;
+import okhttp3.HttpUrl;
+import yuku.ambilwarna.AmbilWarnaDialog;
+
+public class CreateCalendarActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<CreateCalendarActivity.AccountInfo> {
+    public static final String EXTRA_ACCOUNT = "account";
+
+    protected Account account;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        account = getIntent().getExtras().getParcelable(EXTRA_ACCOUNT);
+
+        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+
+        setContentView(R.layout.activity_create_calendar);
+        final View colorSquare = findViewById(R.id.color);
+        colorSquare.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                new AmbilWarnaDialog(CreateCalendarActivity.this, ((ColorDrawable)colorSquare.getBackground()).getColor(), true, new AmbilWarnaDialog.OnAmbilWarnaListener() {
+                    @Override
+                    public void onCancel(AmbilWarnaDialog dialog) {
+                    }
+
+                    @Override
+                    public void onOk(AmbilWarnaDialog dialog, int color) {
+                        colorSquare.setBackgroundColor(color);
+                    }
+                }).show();
+            }
+        });
+
+        getSupportLoaderManager().initLoader(0, null, this);
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        getMenuInflater().inflate(R.menu.activity_create_collection, menu);
+        return true;
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        if (item.getItemId() == android.R.id.home) {
+            Intent intent = new Intent(this, AccountActivity.class);
+            intent.putExtra(AccountActivity.EXTRA_ACCOUNT, account);
+            NavUtils.navigateUpTo(this, intent);
+            return true;
+        }
+        return false;
+    }
+
+    public void onCreateCollection(MenuItem item) {
+        boolean ok = true;
+        CollectionInfo info = new CollectionInfo();
+
+        Spinner spinner = (Spinner)findViewById(R.id.home_sets);
+        String homeSet = (String)spinner.getSelectedItem();
+
+        EditText edit = (EditText)findViewById(R.id.display_name);
+        info.displayName = edit.getText().toString();
+        if (TextUtils.isEmpty(info.displayName)) {
+            edit.setError(getString(R.string.create_collection_display_name_required));
+            ok = false;
+        }
+
+        edit = (EditText)findViewById(R.id.description);
+        info.description = StringUtils.trimToNull(edit.getText().toString());
+
+        View view = findViewById(R.id.color);
+        info.color = ((ColorDrawable)view.getBackground()).getColor();
+
+        spinner = (Spinner)findViewById(R.id.time_zone);
+        net.fortuna.ical4j.model.TimeZone tz = DateUtils.tzRegistry.getTimeZone((String)spinner.getSelectedItem());
+        if (tz != null) {
+            Calendar cal = new Calendar();
+            cal.getComponents().add(tz.getVTimeZone());
+            info.timeZone = cal.toString();
+        }
+
+        RadioGroup typeGroup = (RadioGroup)findViewById(R.id.type);
+        switch (typeGroup.getCheckedRadioButtonId()) {
+            case R.id.type_events:
+                info.supportsVEVENT = true;
+                break;
+            case R.id.type_tasks:
+                info.supportsVTODO = true;
+                break;
+            case R.id.type_events_and_tasks:
+                info.supportsVEVENT = true;
+                info.supportsVTODO = true;
+                break;
+        }
+
+        if (ok) {
+            info.type = CollectionInfo.Type.CALENDAR;
+            info.url = HttpUrl.parse(homeSet).resolve(UUID.randomUUID().toString() + "/").toString();
+            CreateCollectionFragment.newInstance(account, info).show(getSupportFragmentManager(), null);
+        }
+    }
+
+
+    @Override
+    public Loader<AccountInfo> onCreateLoader(int id, Bundle args) {
+        return new AccountInfoLoader(this, account);
+    }
+
+    @Override
+    public void onLoadFinished(Loader<AccountInfo> loader, AccountInfo info) {
+        Spinner spinner = (Spinner)findViewById(R.id.time_zone);
+        String[] timeZones = TimeZone.getAvailableIDs();
+        spinner.setAdapter(new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, timeZones));
+        // select system time zone
+        String defaultTimeZone = TimeZone.getDefault().getID();
+        for (int i = 0; i < timeZones.length; i++)
+            if (timeZones[i].equals(defaultTimeZone)) {
+                spinner.setSelection(i);
+                break;
+            }
+
+        if (info != null) {
+            spinner = (Spinner)findViewById(R.id.home_sets);
+            spinner.setAdapter(new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, info.homeSets));
+        }
+    }
+
+    @Override
+    public void onLoaderReset(Loader<AccountInfo> loader) {
+    }
+
+    protected static class AccountInfo {
+        List<String> homeSets = new LinkedList<>();
+    }
+
+    protected static class AccountInfoLoader extends AsyncTaskLoader<AccountInfo> {
+        private final Account account;
+        private final ServiceDB.OpenHelper dbHelper;
+
+        public AccountInfoLoader(Context context, Account account) {
+            super(context);
+            this.account = account;
+            dbHelper = new ServiceDB.OpenHelper(context);
+        }
+
+        @Override
+        protected void onStartLoading() {
+            forceLoad();
+        }
+
+        @Override
+        public AccountInfo loadInBackground() {
+            final AccountInfo info = new AccountInfo();
+
+            // find DAV service and home sets
+            SQLiteDatabase db = dbHelper.getReadableDatabase();
+            try {
+                @Cleanup Cursor cursorService = db.query(ServiceDB.Services._TABLE, new String[] { ServiceDB.Services.ID },
+                        ServiceDB.Services.ACCOUNT_NAME + "=? AND " + ServiceDB.Services.SERVICE + "=?",
+                        new String[] { account.name, ServiceDB.Services.SERVICE_CALDAV }, null, null, null);
+                if (!cursorService.moveToNext())
+                    return null;
+                String strServiceID = cursorService.getString(0);
+
+                @Cleanup Cursor cursorHomeSets = db.query(ServiceDB.HomeSets._TABLE, new String[] { ServiceDB.HomeSets.URL },
+                        ServiceDB.HomeSets.SERVICE_ID + "=?", new String[] { strServiceID }, null, null, null);
+                while (cursorHomeSets.moveToNext())
+                    info.homeSets.add(cursorHomeSets.getString(0));
+            } finally {
+                dbHelper.close();
+            }
+
+            return info;
+        }
+    }
+}

app/src/main/java/at/bitfire/davdroid/ui/CreateCollectionFragment.java

@@ -0,0 +1,252 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.accounts.Account;
+import android.app.Activity;
+import android.app.Dialog;
+import android.app.ProgressDialog;
+import android.content.ContentValues;
+import android.content.Context;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v4.app.DialogFragment;
+import android.support.v4.app.LoaderManager;
+import android.support.v4.content.AsyncTaskLoader;
+import android.support.v4.content.Loader;
+
+import org.apache.commons.lang3.BooleanUtils;
+import org.xmlpull.v1.XmlSerializer;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.logging.Level;
+
+import at.bitfire.dav4android.DavResource;
+import at.bitfire.dav4android.XmlUtils;
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.DavUtils;
+import at.bitfire.davdroid.HttpClient;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.davdroid.model.ServiceDB;
+import lombok.Cleanup;
+import okhttp3.HttpUrl;
+import okhttp3.OkHttpClient;
+
+public class CreateCollectionFragment extends DialogFragment implements LoaderManager.LoaderCallbacks<Exception> {
+    private static final String
+            ARG_ACCOUNT = "account",
+            ARG_COLLECTION_INFO = "collectionInfo";
+
+    protected Account account;
+    protected CollectionInfo info;
+
+    public static CreateCollectionFragment newInstance(Account account, CollectionInfo info) {
+        CreateCollectionFragment frag = new CreateCollectionFragment();
+        Bundle args = new Bundle(2);
+        args.putParcelable(ARG_ACCOUNT, account);
+        args.putSerializable(ARG_COLLECTION_INFO, info);
+        frag.setArguments(args);
+        return frag;
+    }
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        account = getArguments().getParcelable(ARG_ACCOUNT);
+        info = (CollectionInfo)getArguments().getSerializable(ARG_COLLECTION_INFO);
+
+        getLoaderManager().initLoader(0, null, this);
+    }
+
+    @NonNull
+    @Override
+    public Dialog onCreateDialog(Bundle savedInstanceState) {
+        ProgressDialog progress = new ProgressDialog(getContext());
+        progress.setTitle(R.string.create_collection_creating);
+        progress.setMessage(getString(R.string.please_wait));
+        progress.setIndeterminate(true);
+        progress.setCanceledOnTouchOutside(false);
+        setCancelable(false);
+        return progress;
+    }
+
+
+    @Override
+    public Loader<Exception> onCreateLoader(int id, Bundle args) {
+        return new CreateCollectionLoader(getContext(), account, info);
+    }
+
+    @Override
+    public void onLoadFinished(Loader<Exception> loader, Exception exception) {
+        dismissAllowingStateLoss();
+
+        Activity parent = getActivity();
+        if (parent != null) {
+            if (exception != null)
+                getFragmentManager().beginTransaction()
+                        .add(ExceptionInfoFragment.newInstance(exception, account), null)
+                        .commitAllowingStateLoss();
+            else
+                parent.finish();
+        }
+
+    }
+
+    @Override
+    public void onLoaderReset(Loader<Exception> loader) {
+    }
+
+
+    protected static class CreateCollectionLoader extends AsyncTaskLoader<Exception> {
+        final Account account;
+        final CollectionInfo info;
+
+        public CreateCollectionLoader(Context context, Account account, CollectionInfo info) {
+            super(context);
+            this.account = account;
+            this.info = info;
+        }
+
+        @Override
+        protected void onStartLoading() {
+            forceLoad();
+        }
+
+        @Override
+        public Exception loadInBackground() {
+            StringWriter writer = new StringWriter();
+            try {
+                XmlSerializer serializer = XmlUtils.newSerializer();
+                serializer.setOutput(writer);
+                serializer.startDocument("UTF-8", null);
+                serializer.setPrefix("", XmlUtils.NS_WEBDAV);
+                serializer.setPrefix("CAL", XmlUtils.NS_CALDAV);
+                serializer.setPrefix("CARD", XmlUtils.NS_CARDDAV);
+
+                serializer.startTag(XmlUtils.NS_WEBDAV, "mkcol");
+                    serializer.startTag(XmlUtils.NS_WEBDAV, "set");
+                        serializer.startTag(XmlUtils.NS_WEBDAV, "prop");
+                            serializer.startTag(XmlUtils.NS_WEBDAV, "resourcetype");
+                                serializer.startTag(XmlUtils.NS_WEBDAV, "collection");
+                                serializer.endTag(XmlUtils.NS_WEBDAV, "collection");
+                                if (info.type == CollectionInfo.Type.ADDRESS_BOOK) {
+                                    serializer.startTag(XmlUtils.NS_CARDDAV, "addressbook");
+                                    serializer.endTag(XmlUtils.NS_CARDDAV, "addressbook");
+                                } else if (info.type == CollectionInfo.Type.CALENDAR) {
+                                    serializer.startTag(XmlUtils.NS_CALDAV, "calendar");
+                                    serializer.endTag(XmlUtils.NS_CALDAV, "calendar");
+                                }
+                            serializer.endTag(XmlUtils.NS_WEBDAV, "resourcetype");
+                            if (info.displayName != null) {
+                                serializer.startTag(XmlUtils.NS_WEBDAV, "displayname");
+                                    serializer.text(info.displayName);
+                                serializer.endTag(XmlUtils.NS_WEBDAV, "displayname");
+                            }
+
+                            // addressbook-specific properties
+                            if (info.type == CollectionInfo.Type.ADDRESS_BOOK) {
+                                if (info.description != null) {
+                                    serializer.startTag(XmlUtils.NS_CARDDAV, "addressbook-description");
+                                    serializer.text(info.description);
+                                    serializer.endTag(XmlUtils.NS_CARDDAV, "addressbook-description");
+                                }
+                            }
+
+                            // calendar-specific properties
+                            if (info.type == CollectionInfo.Type.CALENDAR) {
+                                if (info.description != null) {
+                                    serializer.startTag(XmlUtils.NS_CALDAV, "calendar-description");
+                                    serializer.text(info.description);
+                                    serializer.endTag(XmlUtils.NS_CALDAV, "calendar-description");
+                                }
+
+                                if (info.color != null) {
+                                    serializer.startTag(XmlUtils.NS_APPLE_ICAL, "calendar-color");
+                                    serializer.text(DavUtils.ARGBtoCalDAVColor(info.color));
+                                    serializer.endTag(XmlUtils.NS_APPLE_ICAL, "calendar-color");
+                                }
+
+                                if (info.timeZone != null) {
+                                    serializer.startTag(XmlUtils.NS_CALDAV, "calendar-timezone");
+                                    serializer.cdsect(info.timeZone);
+                                    serializer.endTag(XmlUtils.NS_CALDAV, "calendar-timezone");
+                                }
+
+                                serializer.startTag(XmlUtils.NS_CALDAV, "supported-calendar-component-set");
+                                if (BooleanUtils.isTrue(info.supportsVEVENT)) {
+                                    serializer.startTag(XmlUtils.NS_CALDAV, "comp");
+                                    serializer.attribute(null, "name", "VEVENT");
+                                    serializer.endTag(XmlUtils.NS_CALDAV, "comp");
+                                }
+                                if (BooleanUtils.isTrue(info.supportsVTODO)) {
+                                    serializer.startTag(XmlUtils.NS_CALDAV, "comp");
+                                    serializer.attribute(null, "name", "VTODO");
+                                    serializer.endTag(XmlUtils.NS_CALDAV, "comp");
+                                }
+                                serializer.endTag(XmlUtils.NS_CALDAV, "supported-calendar-component-set");
+                            }
+
+                        serializer.endTag(XmlUtils.NS_WEBDAV, "prop");
+                    serializer.endTag(XmlUtils.NS_WEBDAV, "set");
+                serializer.endTag(XmlUtils.NS_WEBDAV, "mkcol");
+                serializer.endDocument();
+            } catch (IOException e) {
+                App.log.log(Level.SEVERE, "Couldn't assemble Extended MKCOL request", e);
+            }
+
+            ServiceDB.OpenHelper dbHelper = new ServiceDB.OpenHelper(getContext());
+
+            try {
+                OkHttpClient client = HttpClient.create(getContext(), account);
+                DavResource collection = new DavResource(client, HttpUrl.parse(info.url));
+
+                // create collection on remote server
+                collection.mkCol(writer.toString());
+
+                // now insert collection into database:
+                SQLiteDatabase db = dbHelper.getWritableDatabase();
+
+                // 1. find service ID
+                String serviceType;
+                if (info.type == CollectionInfo.Type.ADDRESS_BOOK)
+                    serviceType = ServiceDB.Services.SERVICE_CARDDAV;
+                else if (info.type == CollectionInfo.Type.CALENDAR)
+                    serviceType = ServiceDB.Services.SERVICE_CALDAV;
+                else
+                    throw new IllegalArgumentException("Collection must be an address book or calendar");
+                @Cleanup Cursor c = db.query(ServiceDB.Services._TABLE, new String[] { ServiceDB.Services.ID },
+                        ServiceDB.Services.ACCOUNT_NAME + "=? AND " + ServiceDB.Services.SERVICE + "=?",
+                        new String[] { account.name, serviceType }, null, null, null
+                );
+                if (!c.moveToNext())
+                    throw new IllegalStateException();
+                long serviceID = c.getLong(0);
+
+                // 2. add collection to service
+                ContentValues values = info.toDB();
+                values.put(ServiceDB.Collections.SERVICE_ID, serviceID);
+                db.insert(ServiceDB.Collections._TABLE, null, values);
+            } catch(InvalidAccountException|IOException|HttpException|IllegalStateException e) {
+                return e;
+            } finally {
+                dbHelper.close();
+            }
+
+            return null;
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/DebugInfoActivity.java

@@ -0,0 +1,256 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.accounts.Account;
+import android.accounts.AccountManager;
+import android.app.LoaderManager;
+import android.content.AsyncTaskLoader;
+import android.content.ContentResolver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.Loader;
+import android.content.pm.PackageManager;
+import android.net.Uri;
+import android.os.Build;
+import android.os.Bundle;
+import android.provider.CalendarContract;
+import android.provider.ContactsContract;
+import android.support.v7.app.AppCompatActivity;
+import android.text.TextUtils;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.widget.TextView;
+
+import org.apache.commons.lang3.exception.ExceptionUtils;
+import org.apache.commons.lang3.text.WordUtils;
+
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.util.Date;
+import java.util.logging.Level;
+
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.davdroid.AccountSettings;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.BuildConfig;
+import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.model.ServiceDB;
+import lombok.Cleanup;
+
+public class DebugInfoActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<String> {
+    public static final String
+            KEY_THROWABLE = "throwable",
+            KEY_LOGS = "logs",
+            KEY_ACCOUNT = "account",
+            KEY_AUTHORITY = "authority",
+            KEY_PHASE = "phase";
+
+    private static final int MAX_INLINE_REPORT_LENGTH = 8000;
+
+    TextView tvReport;
+    String report;
+
+    File reportFile;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        setContentView(R.layout.activity_debug_info);
+        tvReport = (TextView)findViewById(R.id.text_report);
+
+        getLoaderManager().initLoader(0, getIntent().getExtras(), this);
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        getMenuInflater().inflate(R.menu.activity_debug_info, menu);
+        return true;
+    }
+
+
+    public void onShare(MenuItem item) {
+        if (!TextUtils.isEmpty(report)) {
+            Intent sendIntent = new Intent();
+            sendIntent.setAction(Intent.ACTION_SEND);
+            sendIntent.setType("text/plain");
+            sendIntent.putExtra(Intent.EXTRA_SUBJECT, "DAVdroid debug info");
+
+            boolean inline = false;
+
+            if (report.length() > MAX_INLINE_REPORT_LENGTH)
+                // report is too long for inline text, send it as an attachment
+                try {
+                    reportFile = File.createTempFile("davdroid-debug", ".txt", getExternalCacheDir());
+                    App.log.fine("Writing debug info to " + reportFile.getAbsolutePath());
+                    FileWriter writer = new FileWriter(reportFile);
+                    writer.write(report);
+                    writer.close();
+
+                    sendIntent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(reportFile));
+                } catch (IOException e) {
+                    // let's hope the report is < 1 MB (Android IPC limit)
+                    inline = true;
+                }
+            else
+                inline = true;
+
+            if (inline)
+                sendIntent.putExtra(Intent.EXTRA_TEXT, report);
+
+            startActivity(sendIntent);
+        }
+    }
+
+
+    @Override
+    public Loader<String> onCreateLoader(int id, Bundle args) {
+        return new ReportLoader(this, args);
+    }
+
+    @Override
+    public void onLoadFinished(Loader<String> loader, String data) {
+        if (data != null)
+            tvReport.setText(report = data);
+    }
+
+    @Override
+    public void onLoaderReset(Loader<String> loader) {
+    }
+
+
+    static class ReportLoader extends AsyncTaskLoader<String> {
+
+        final Bundle extras;
+
+        public ReportLoader(Context context, Bundle extras) {
+            super(context);
+            this.extras = extras;
+        }
+
+        @Override
+        protected void onStartLoading() {
+            forceLoad();
+        }
+
+        @Override
+        public String loadInBackground() {
+            Throwable throwable = null;
+            String  logs = null,
+                    authority = null;
+            Account account = null;
+            int phase = -1;
+
+            if (extras != null) {
+                throwable = (Throwable)extras.getSerializable(KEY_THROWABLE);
+                logs = extras.getString(KEY_LOGS);
+                account = extras.getParcelable(KEY_ACCOUNT);
+                authority = extras.getString(KEY_AUTHORITY);
+                phase = extras.getInt(KEY_PHASE, -1);
+            }
+
+            StringBuilder report = new StringBuilder();
+
+            // begin with most specific information
+
+            if (phase != -1)
+                report.append("SYNCHRONIZATION INFO\nSynchronization phase: ").append(phase).append("\n");
+            if (account != null)
+                report.append("Account name: ").append(account.name).append("\n");
+            if (authority != null)
+                report.append("Authority: ").append(authority).append("\n");
+
+            if (throwable instanceof HttpException) {
+                HttpException http = (HttpException)throwable;
+                if (http.request != null)
+                    report.append("\nHTTP REQUEST:\n").append(http.request).append("\n\n");
+                if (http.response != null)
+                    report.append("HTTP RESPONSE:\n").append(http.response).append("\n");
+            }
+
+            if (throwable != null)
+                report  .append("\nEXCEPTION:\n")
+                        .append(ExceptionUtils.getStackTrace(throwable));
+
+            if (logs != null)
+                report.append("\nLOGS:\n").append(logs).append("\n");
+
+            try {
+                PackageManager pm = getContext().getPackageManager();
+                String installedFrom = pm.getInstallerPackageName(BuildConfig.APPLICATION_ID);
+                if (TextUtils.isEmpty(installedFrom))
+                    installedFrom = "APK (directly)";
+                boolean workaroundInstalled = false;
+                try {
+                    workaroundInstalled = pm.getPackageInfo("at.bitfire.davdroid.jbworkaround", 0) != null;
+                } catch(PackageManager.NameNotFoundException ignored) {}
+                report.append("\nSOFTWARE INFORMATION\n" +
+                                "DAVdroid version: ").append(BuildConfig.VERSION_NAME).append(" (").append(BuildConfig.VERSION_CODE).append(") ").append(new Date(BuildConfig.buildTime)).append("\n")
+                                .append("Installed from: ").append(installedFrom).append("\n")
+                                .append("JB Workaround installed: ").append(workaroundInstalled ? "yes" : "no").append("\n\n");
+            } catch(Exception ex) {
+                App.log.log(Level.SEVERE, "Couldn't get software information", ex);
+            }
+
+            report.append(
+                    "CONFIGURATION\n" +
+                    "System-wide synchronization: ").append(ContentResolver.getMasterSyncAutomatically() ? "automatically" : "manually").append("\n");
+            AccountManager accountManager = AccountManager.get(getContext());
+            for (Account acct : accountManager.getAccountsByType(Constants.ACCOUNT_TYPE))
+                try {
+                    AccountSettings settings = new AccountSettings(getContext(), acct);
+                    report.append("Account: ").append(acct.name).append("\n" +
+                                  "  Address book sync. interval: ").append(syncStatus(settings, ContactsContract.AUTHORITY)).append("\n" +
+                                  "  Calendar     sync. interval: ").append(syncStatus(settings, CalendarContract.AUTHORITY)).append("\n" +
+                                  "  OpenTasks    sync. interval: ").append(syncStatus(settings, "org.dmfs.tasks")).append("\n" +
+                                  "  Preemptive auth: ").append(settings.preemptiveAuth()).append("\n" +
+                                  "  WiFi only: ").append(settings.getSyncWifiOnly());
+                    if (settings.getSyncWifiOnlySSID() != null)
+                        report.append(", SSID: ").append(settings.getSyncWifiOnlySSID());
+                    report.append("\n  [CardDAV] Contact group method: ").append(settings.getGroupMethod())
+                          .append("\n            RFC 6868 encoding: ").append(settings.getVCardRFC6868())
+                          .append("\n  [CalDAV] Time range (past days): ").append(settings.getTimeRangePastDays())
+                          .append("\n           Manage calendar colors: ").append(settings.getManageCalendarColors())
+                          .append("\n");
+                } catch(InvalidAccountException e) {
+                    report.append(acct).append(" is invalid (unsupported settings version) or does not exist\n");
+                }
+            report.append("\n");
+
+            report.append("SQLITE DUMP\n");
+            @Cleanup ServiceDB.OpenHelper dbHelper = new ServiceDB.OpenHelper(getContext());
+            dbHelper.dump(report);
+            report.append("\n");
+
+            try {
+                report.append(
+                        "SYSTEM INFORMATION\n" +
+                                "Android version: ").append(Build.VERSION.RELEASE).append(" (").append(Build.DISPLAY).append(")\n" +
+                                "Device: ").append(WordUtils.capitalize(Build.MANUFACTURER)).append(" ").append(Build.MODEL).append(" (").append(Build.DEVICE).append(")\n\n"
+                );
+            } catch(Exception ex) {
+                App.log.log(Level.SEVERE, "Couldn't get system details", ex);
+            }
+
+            return report.toString();
+        }
+
+        protected String syncStatus(AccountSettings settings, String authority) {
+            Long interval = settings.getSyncInterval(authority);
+            return interval != null ?
+                    (interval == AccountSettings.SYNC_INTERVAL_MANUALLY ? "manually" : interval/60 + " min") :
+                    "—";
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/DeleteCollectionFragment.java

@@ -0,0 +1,172 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.accounts.Account;
+import android.app.Activity;
+import android.app.Dialog;
+import android.app.ProgressDialog;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.database.sqlite.SQLiteDatabase;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v4.app.DialogFragment;
+import android.support.v4.app.LoaderManager;
+import android.support.v4.content.AsyncTaskLoader;
+import android.support.v4.content.Loader;
+import android.support.v7.app.AlertDialog;
+import android.text.TextUtils;
+
+import java.io.IOException;
+
+import at.bitfire.dav4android.DavResource;
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.davdroid.HttpClient;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.davdroid.model.ServiceDB;
+import okhttp3.HttpUrl;
+import okhttp3.OkHttpClient;
+
+public class DeleteCollectionFragment extends DialogFragment implements LoaderManager.LoaderCallbacks<Exception> {
+    protected static final String
+            ARG_ACCOUNT = "account",
+            ARG_COLLECTION_INFO = "collectionInfo";
+
+    protected Account account;
+    protected CollectionInfo collectionInfo;
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        getLoaderManager().initLoader(0, getArguments(), this);
+    }
+
+    @NonNull
+    @Override
+    public Dialog onCreateDialog(Bundle savedInstanceState) {
+        ProgressDialog progress = new ProgressDialog(getContext());
+        progress.setTitle(R.string.delete_collection_deleting_collection);
+        progress.setMessage(getString(R.string.please_wait));
+        progress.setIndeterminate(true);
+        progress.setCanceledOnTouchOutside(false);
+        setCancelable(false);
+        return progress;
+    }
+
+
+    @Override
+    public Loader<Exception> onCreateLoader(int id, Bundle args) {
+        account = args.getParcelable(ARG_ACCOUNT);
+        collectionInfo = (CollectionInfo)args.getSerializable(ARG_COLLECTION_INFO);
+        return new DeleteCollectionLoader(getContext(), account, collectionInfo);
+    }
+
+    @Override
+    public void onLoadFinished(Loader loader, Exception exception) {
+        dismissAllowingStateLoss();
+
+        if (exception != null)
+            getFragmentManager().beginTransaction()
+                    .add(ExceptionInfoFragment.newInstance(exception, account), null)
+                    .commitAllowingStateLoss();
+        else {
+            Activity activity = getActivity();
+            if (activity instanceof AccountActivity)
+                ((AccountActivity)activity).reload();
+        }
+    }
+
+    @Override
+    public void onLoaderReset(Loader loader) {
+    }
+
+
+    protected static class DeleteCollectionLoader extends AsyncTaskLoader<Exception> {
+        final Account account;
+        final CollectionInfo collectionInfo;
+        final ServiceDB.OpenHelper dbHelper;
+
+        public DeleteCollectionLoader(Context context, Account account, CollectionInfo collectionInfo) {
+            super(context);
+            this.account = account;
+            this.collectionInfo = collectionInfo;
+            dbHelper = new ServiceDB.OpenHelper(getContext());
+        }
+
+        @Override
+        protected void onStartLoading() {
+            forceLoad();
+        }
+
+        @Override
+        public Exception loadInBackground() {
+            try {
+                OkHttpClient httpClient = HttpClient.create(getContext(), account);
+                DavResource collection = new DavResource(httpClient, HttpUrl.parse(collectionInfo.url));
+
+                // delete collection from server
+                collection.delete(null);
+
+                // delete collection locally
+                SQLiteDatabase db = dbHelper.getWritableDatabase();
+                db.delete(ServiceDB.Collections._TABLE, ServiceDB.Collections.ID + "=?", new String[] { String.valueOf(collectionInfo.id) });
+
+                return null;
+            } catch (InvalidAccountException|IOException|HttpException e) {
+                return e;
+            } finally {
+                dbHelper.close();
+            }
+        }
+    }
+
+
+    public static class ConfirmDeleteCollectionFragment extends DialogFragment {
+
+        public static ConfirmDeleteCollectionFragment newInstance(Account account, CollectionInfo collectionInfo) {
+            ConfirmDeleteCollectionFragment frag = new ConfirmDeleteCollectionFragment();
+            Bundle args = new Bundle(2);
+            args.putParcelable(ARG_ACCOUNT, account);
+            args.putSerializable(ARG_COLLECTION_INFO, collectionInfo);
+            frag.setArguments(args);
+            return frag;
+        }
+
+        @NonNull
+        @Override
+        public Dialog onCreateDialog(Bundle savedInstanceState) {
+            CollectionInfo collectionInfo = (CollectionInfo)getArguments().getSerializable(ARG_COLLECTION_INFO);
+            String name = TextUtils.isEmpty(collectionInfo.displayName) ? collectionInfo.url : collectionInfo.displayName;
+
+            return new AlertDialog.Builder(getContext())
+                    .setTitle(R.string.delete_collection_confirm_title)
+                    .setMessage(getString(R.string.delete_collection_confirm_warning, name))
+                    .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
+                        @Override
+                        public void onClick(DialogInterface dialog, int which) {
+                            DialogFragment frag = new DeleteCollectionFragment();
+                            frag.setArguments(getArguments());
+                            frag.show(getFragmentManager(), null);
+                        }
+                    })
+                    .setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {
+                        @Override
+                        public void onClick(DialogInterface dialog, int which) {
+                            dismiss();
+                        }
+                    })
+                    .create();
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/ExceptionInfoFragment.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.accounts.Account;
+import android.app.Dialog;
+import android.content.DialogInterface;
+import android.content.Intent;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v4.app.DialogFragment;
+import android.support.v7.app.AlertDialog;
+
+import java.io.IOException;
+
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.davdroid.R;
+
+public class ExceptionInfoFragment extends DialogFragment {
+    protected static final String
+            ARG_ACCOUNT = "account",
+            ARG_EXCEPTION = "exception";
+
+    public static ExceptionInfoFragment newInstance(@NonNull Exception exception, Account account) {
+        ExceptionInfoFragment frag = new ExceptionInfoFragment();
+        Bundle args = new Bundle(1);
+        args.putSerializable(ARG_EXCEPTION, exception);
+        args.putParcelable(ARG_ACCOUNT, account);
+        frag.setArguments(args);
+        return frag;
+    }
+
+    @NonNull
+    @Override
+    public Dialog onCreateDialog(Bundle savedInstanceState) {
+        Bundle args = getArguments();
+        final Exception exception = (Exception)args.getSerializable(ARG_EXCEPTION);
+        final Account account = args.getParcelable(ARG_ACCOUNT);
+
+        int title = R.string.exception;
+        if (exception instanceof HttpException)
+            title = R.string.exception_httpexception;
+        else if (exception instanceof IOException)
+            title = R.string.exception_ioexception;
+
+        Dialog dialog = new AlertDialog.Builder(getContext())
+                .setIcon(R.drawable.ic_error_dark)
+                .setTitle(title)
+                .setMessage(exception.getClass().getCanonicalName() + "\n" + exception.getLocalizedMessage())
+                .setNegativeButton(R.string.exception_show_details, new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int which) {
+                        Intent intent = new Intent(getContext(), DebugInfoActivity.class);
+                        intent.putExtra(DebugInfoActivity.KEY_THROWABLE, exception);
+                        if (account != null)
+                            intent.putExtra(DebugInfoActivity.KEY_ACCOUNT, account);
+                        startActivity(intent);
+                    }
+                })
+                .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int which) {
+                    }
+                })
+                .create();
+        setCancelable(false);
+        return dialog;
+    }
+}

app/src/main/java/at/bitfire/davdroid/ui/PermissionsActivity.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.Manifest;
+import android.app.NotificationManager;
+import android.content.pm.PackageManager;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.v4.app.ActivityCompat;
+import android.support.v7.app.AppCompatActivity;
+import android.view.View;
+
+import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.resource.LocalTaskList;
+
+public class PermissionsActivity extends AppCompatActivity {
+
+    public static final String
+            PERMISSION_READ_TASKS = "org.dmfs.permission.READ_TASKS",
+            PERMISSION_WRITE_TASKS = "org.dmfs.permission.WRITE_TASKS";
+
+    @Override
+    protected void onCreate(@Nullable Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_permissions);
+}
+
+    @Override
+    protected void onResume() {
+        super.onResume();
+        refresh();
+    }
+
+    protected void refresh() {
+        boolean noCalendarPermissions =
+                ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_CALENDAR) != PackageManager.PERMISSION_GRANTED ||
+                ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_CALENDAR) != PackageManager.PERMISSION_GRANTED;
+        findViewById(R.id.calendar_permissions).setVisibility(noCalendarPermissions ? View.VISIBLE : View.GONE);
+
+        boolean noContactsPermissions =
+                ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS) != PackageManager.PERMISSION_GRANTED ||
+                ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_CONTACTS) != PackageManager.PERMISSION_GRANTED;
+        findViewById(R.id.contacts_permissions).setVisibility(noContactsPermissions ? View.VISIBLE : View.GONE);
+
+        boolean noTaskPermissions;
+        if (LocalTaskList.tasksProviderAvailable(this)) {
+            noTaskPermissions =
+                    ActivityCompat.checkSelfPermission(this, PERMISSION_READ_TASKS) != PackageManager.PERMISSION_GRANTED ||
+                    ActivityCompat.checkSelfPermission(this, PERMISSION_WRITE_TASKS) != PackageManager.PERMISSION_GRANTED;
+            findViewById(R.id.opentasks_permissions).setVisibility(noTaskPermissions ? View.VISIBLE : View.GONE);
+        } else {
+            findViewById(R.id.opentasks_permissions).setVisibility(View.GONE);
+            noTaskPermissions = false;
+        }
+
+        if (!noCalendarPermissions && !noContactsPermissions && !noTaskPermissions) {
+            NotificationManager nm = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
+            nm.cancel(Constants.NOTIFICATION_PERMISSIONS);
+
+            finish();
+        }
+    }
+
+    public void requestCalendarPermissions(View v) {
+        ActivityCompat.requestPermissions(this, new String[] {
+                Manifest.permission.READ_CALENDAR,
+                Manifest.permission.WRITE_CALENDAR
+        }, 0);
+    }
+
+    public void requestContactsPermissions(View v) {
+        ActivityCompat.requestPermissions(this, new String[] {
+                Manifest.permission.READ_CONTACTS,
+                Manifest.permission.WRITE_CONTACTS
+        }, 0);
+    }
+
+    public void requestOpenTasksPermissions(View v) {
+        ActivityCompat.requestPermissions(this, new String[] {
+                PERMISSION_READ_TASKS,
+                PERMISSION_WRITE_TASKS
+        }, 0);
+    }
+
+    @Override
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
+        refresh();
+    }
+}

app/src/main/java/at/bitfire/davdroid/ui/StartupDialogFragment.java

@@ -0,0 +1,216 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui;
+
+import android.app.Dialog;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.graphics.drawable.Drawable;
+import android.net.Uri;
+import android.os.Build;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v4.app.DialogFragment;
+import android.support.v7.app.AlertDialog;
+
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.logging.Level;
+
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.BuildConfig;
+import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.model.ServiceDB;
+import at.bitfire.davdroid.model.Settings;
+import at.bitfire.davdroid.resource.LocalTaskList;
+import lombok.Cleanup;
+
+public class StartupDialogFragment extends DialogFragment {
+    public static final String
+            HINT_GOOGLE_PLAY_ACCOUNTS_REMOVED = "hint_GooglePlayAccountsRemoved",
+            HINT_OPENTASKS_NOT_INSTALLED = "hint_OpenTasksNotInstalled";
+
+    private static final String ARGS_MODE = "mode";
+
+    enum Mode {
+        DEVELOPMENT_VERSION,
+        FDROID_DONATE,
+        GOOGLE_PLAY_ACCOUNTS_REMOVED,
+        OPENTASKS_NOT_INSTALLED
+    }
+
+    public static StartupDialogFragment[] getStartupDialogs(Context context) {
+        List<StartupDialogFragment> dialogs = new LinkedList<>();
+
+        @Cleanup ServiceDB.OpenHelper dbHelper = new ServiceDB.OpenHelper(context);
+        Settings settings  = new Settings(dbHelper.getReadableDatabase());
+
+        if (BuildConfig.VERSION_NAME.contains("-alpha") || BuildConfig.VERSION_NAME.contains("-beta") || BuildConfig.VERSION_NAME.contains("-rc"))
+            dialogs.add(StartupDialogFragment.instantiate(Mode.DEVELOPMENT_VERSION));
+        else {
+            // store-specific information
+            if (BuildConfig.FLAVOR == App.FLAVOR_GOOGLE_PLAY) {
+                // Play store
+                if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP &&    // only on Android <5
+                    settings.getBoolean(HINT_GOOGLE_PLAY_ACCOUNTS_REMOVED, true))      // and only when "Don't show again" hasn't been clicked yet
+                    dialogs.add(StartupDialogFragment.instantiate(Mode.GOOGLE_PLAY_ACCOUNTS_REMOVED));
+            } else {
+                // other stores
+                final String installedFrom = installedFrom(context);
+                if (installedFrom == null || installedFrom.startsWith("org.fdroid"))
+                    dialogs.add(StartupDialogFragment.instantiate(Mode.FDROID_DONATE));
+            }
+        }
+
+        // OpenTasks information
+        if (!LocalTaskList.tasksProviderAvailable(context) &&
+                settings.getBoolean(HINT_OPENTASKS_NOT_INSTALLED, true))
+            dialogs.add(StartupDialogFragment.instantiate(Mode.OPENTASKS_NOT_INSTALLED));
+
+        Collections.reverse(dialogs);
+        return dialogs.toArray(new StartupDialogFragment[dialogs.size()]);
+    }
+
+    public static StartupDialogFragment instantiate(Mode mode) {
+        StartupDialogFragment frag = new StartupDialogFragment();
+        Bundle args = new Bundle(1);
+        args.putString(ARGS_MODE, mode.name());
+        frag.setArguments(args);
+        return frag;
+    }
+
+    @NonNull
+    @Override
+    public Dialog onCreateDialog(Bundle savedInstanceState) {
+        setCancelable(false);
+
+        final ServiceDB.OpenHelper dbHelper = new ServiceDB.OpenHelper(getContext());
+
+        Mode mode = Mode.valueOf(getArguments().getString(ARGS_MODE));
+        switch (mode) {
+            case DEVELOPMENT_VERSION:
+                return new AlertDialog.Builder(getActivity())
+                        .setIcon(R.drawable.ic_launcher)
+                        .setTitle(R.string.startup_development_version)
+                        .setMessage(R.string.startup_development_version_message)
+                        .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int which) {
+                            }
+                        })
+                        .setNeutralButton(R.string.startup_development_version_give_feedback, new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int which) {
+                                startActivity(new Intent(Intent.ACTION_VIEW, Constants.webUri.buildUpon().appendEncodedPath("forums/").build()));
+                            }
+                        })
+                        .create();
+
+            case FDROID_DONATE:
+                if (BuildConfig.FLAVOR != App.FLAVOR_GOOGLE_PLAY)
+                    return new AlertDialog.Builder(getActivity())
+                            .setIcon(R.drawable.ic_launcher)
+                            .setTitle(R.string.startup_donate)
+                            .setMessage(R.string.startup_donate_message)
+                            .setPositiveButton(R.string.startup_donate_now, new DialogInterface.OnClickListener() {
+                                @Override
+                                public void onClick(DialogInterface dialog, int which) {
+                                    startActivity(new Intent(Intent.ACTION_VIEW, Constants.webUri.buildUpon().appendEncodedPath("donate/").build()));
+                                }
+                            })
+                            .setNegativeButton(R.string.startup_donate_later, new DialogInterface.OnClickListener() {
+                                @Override
+                                public void onClick(DialogInterface dialog, int which) {
+                                }
+                            })
+                            .create();
+                else
+                    throw new IllegalArgumentException();
+
+            case GOOGLE_PLAY_ACCOUNTS_REMOVED:
+                Drawable icon = null;
+                try {
+                    icon = getContext().getPackageManager().getApplicationIcon("com.android.vending").getCurrent();
+                } catch (PackageManager.NameNotFoundException e) {
+                    App.log.log(Level.WARNING, "Can't load Play Store icon", e);
+                }
+                return new AlertDialog.Builder(getActivity())
+                        .setIcon(icon)
+                        .setTitle(R.string.startup_google_play_accounts_removed)
+                        .setMessage(R.string.startup_google_play_accounts_removed_message)
+                        .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int which) {
+                            }
+                        })
+                        .setNeutralButton(R.string.startup_google_play_accounts_removed_more_info, new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int which) {
+                                Intent intent = new Intent(Intent.ACTION_VIEW, Constants.webUri.buildUpon().appendEncodedPath("faq/").build());
+                                getContext().startActivity(intent);
+                            }
+                        })
+                        .setNegativeButton(R.string.startup_dont_show_again, new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int which) {
+                                Settings settings = new Settings(dbHelper.getWritableDatabase());
+                                settings.putBoolean(HINT_GOOGLE_PLAY_ACCOUNTS_REMOVED, false);
+                            }
+                        })
+                        .create();
+
+            case OPENTASKS_NOT_INSTALLED:
+                StringBuilder builder = new StringBuilder(getString(R.string.startup_opentasks_not_installed_message));
+                if (Build.VERSION.SDK_INT < 23)
+                    builder.append("\n\n").append(getString(R.string.startup_opentasks_reinstall_davdroid));
+                return new AlertDialog.Builder(getActivity())
+                        .setIcon(R.drawable.ic_alarm_on_dark)
+                        .setTitle(R.string.startup_opentasks_not_installed)
+                        .setMessage(builder.toString())
+                        .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int which) {
+                            }
+                        })
+                        .setNeutralButton(R.string.startup_opentasks_not_installed_install, new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int which) {
+                                Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=org.dmfs.tasks"));
+                                if (intent.resolveActivity(getContext().getPackageManager()) != null)
+                                    getContext().startActivity(intent);
+                                else
+                                    App.log.warning("No market app available, can't install OpenTasks");
+                            }
+                        })
+                        .setNegativeButton(R.string.startup_dont_show_again, new DialogInterface.OnClickListener() {
+                            @Override
+                            public void onClick(DialogInterface dialog, int which) {
+                                Settings settings = new Settings(dbHelper.getWritableDatabase());
+                                settings.putBoolean(HINT_OPENTASKS_NOT_INSTALLED, false);
+                            }
+                        })
+                        .create();
+        }
+
+        throw new IllegalArgumentException(/* illegal mode argument */);
+    }
+
+    private static String installedFrom(Context context) {
+        try {
+            return context.getPackageManager().getInstallerPackageName(context.getPackageName());
+        } catch(IllegalArgumentException e) {
+            return null;
+        }
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/setup/AccountDetailsFragment.java

@@ -0,0 +1,208 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui.setup;
+
+import android.accounts.Account;
+import android.accounts.AccountManager;
+import android.content.ContentResolver;
+import android.content.ContentValues;
+import android.content.Intent;
+import android.database.sqlite.SQLiteDatabase;
+import android.os.Build;
+import android.os.Bundle;
+import android.provider.CalendarContract;
+import android.provider.ContactsContract;
+import android.support.design.widget.Snackbar;
+import android.support.v4.app.Fragment;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Button;
+import android.widget.EditText;
+import android.widget.Spinner;
+
+import java.net.URI;
+import java.util.logging.Level;
+
+import at.bitfire.davdroid.AccountSettings;
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.DavService;
+import at.bitfire.davdroid.InvalidAccountException;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.model.CollectionInfo;
+import at.bitfire.davdroid.model.ServiceDB.Collections;
+import at.bitfire.davdroid.model.ServiceDB.HomeSets;
+import at.bitfire.davdroid.model.ServiceDB.OpenHelper;
+import at.bitfire.davdroid.model.ServiceDB.Services;
+import at.bitfire.davdroid.resource.LocalTaskList;
+import at.bitfire.ical4android.TaskProvider;
+import at.bitfire.vcard4android.GroupMethod;
+import lombok.Cleanup;
+
+public class AccountDetailsFragment extends Fragment {
+
+    private static final String KEY_CONFIG = "config";
+    private static final int DEFAULT_SYNC_INTERVAL = 4 * 3600;  // 4 hours
+
+    Spinner spnrGroupMethod;
+
+
+    public static AccountDetailsFragment newInstance(DavResourceFinder.Configuration config) {
+        AccountDetailsFragment frag = new AccountDetailsFragment();
+        Bundle args = new Bundle(1);
+        args.putSerializable(KEY_CONFIG, config);
+        frag.setArguments(args);
+        return frag;
+    }
+
+
+    @Override
+    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        final View v = inflater.inflate(R.layout.login_account_details, container, false);
+
+        Button btnBack = (Button)v.findViewById(R.id.back);
+        btnBack.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                getFragmentManager().popBackStack();
+            }
+        });
+
+        DavResourceFinder.Configuration config = (DavResourceFinder.Configuration)getArguments().getSerializable(KEY_CONFIG);
+
+        final EditText editName = (EditText)v.findViewById(R.id.account_name);
+        editName.setText(config.userName);
+
+        // CardDAV-specific
+        v.findViewById(R.id.carddav).setVisibility(config.cardDAV != null ? View.VISIBLE : View.GONE);
+        spnrGroupMethod = (Spinner)v.findViewById(R.id.contact_group_method);
+
+        Button btnCreate = (Button)v.findViewById(R.id.create_account);
+        btnCreate.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                String name = editName.getText().toString();
+                if (name.isEmpty())
+                    editName.setError(getString(R.string.login_account_name_required));
+                else {
+                    if (createAccount(name, (DavResourceFinder.Configuration)getArguments().getSerializable(KEY_CONFIG)))
+                        getActivity().finish();
+                    else
+                        Snackbar.make(v, R.string.login_account_not_created, Snackbar.LENGTH_LONG).show();
+                }
+            }
+        });
+
+        return v;
+    }
+
+    protected boolean createAccount(String accountName, DavResourceFinder.Configuration config) {
+        Account account = new Account(accountName, Constants.ACCOUNT_TYPE);
+
+        // create Android account
+        Bundle userData = AccountSettings.initialUserData(config.userName, config.preemptive);
+        App.log.log(Level.INFO, "Creating Android account with initial config", new Object[] { account, userData });
+
+        AccountManager accountManager = AccountManager.get(getContext());
+        if (!accountManager.addAccountExplicitly(account, config.password, userData))
+            return false;
+
+        // add entries for account to service DB
+        App.log.log(Level.INFO, "Writing account configuration to database", config);
+        @Cleanup OpenHelper dbHelper = new OpenHelper(getContext());
+        SQLiteDatabase db = dbHelper.getWritableDatabase();
+        try {
+            AccountSettings settings = new AccountSettings(getContext(), account);
+
+            Intent refreshIntent = new Intent(getActivity(), DavService.class);
+            refreshIntent.setAction(DavService.ACTION_REFRESH_COLLECTIONS);
+
+            if (config.cardDAV != null) {
+                // insert CardDAV service
+                long id = insertService(db, accountName, Services.SERVICE_CARDDAV, config.cardDAV);
+
+                // start CardDAV service detection (refresh collections)
+                refreshIntent.putExtra(DavService.EXTRA_DAV_SERVICE_ID, id);
+                getActivity().startService(refreshIntent);
+
+                // initial CardDAV account settings
+                int idx = spnrGroupMethod.getSelectedItemPosition();
+                String groupMethodName = getResources().getStringArray(R.array.settings_contact_group_method_values)[idx];
+                settings.setGroupMethod(GroupMethod.valueOf(groupMethodName));
+
+                // enable contact sync
+                ContentResolver.setIsSyncable(account, ContactsContract.AUTHORITY, 1);
+                settings.setSyncInterval(ContactsContract.AUTHORITY, DEFAULT_SYNC_INTERVAL);
+            } else
+                // disable contact sync when CardDAV is not available
+                ContentResolver.setIsSyncable(account, ContactsContract.AUTHORITY, 0);
+
+            if (config.calDAV != null) {
+                // insert CalDAV service
+                long id = insertService(db, accountName, Services.SERVICE_CALDAV, config.calDAV);
+
+                // start CalDAV service detection (refresh collections)
+                refreshIntent.putExtra(DavService.EXTRA_DAV_SERVICE_ID, id);
+                getActivity().startService(refreshIntent);
+
+                // enable calendar sync
+                ContentResolver.setIsSyncable(account, CalendarContract.AUTHORITY, 1);
+                settings.setSyncInterval(CalendarContract.AUTHORITY, DEFAULT_SYNC_INTERVAL);
+
+                // enable task sync, if possible
+                if (Build.VERSION.SDK_INT >= 23 || LocalTaskList.tasksProviderAvailable(getContext())) {
+                    ContentResolver.setIsSyncable(account, TaskProvider.ProviderName.OpenTasks.authority, 1);
+                    settings.setSyncInterval(TaskProvider.ProviderName.OpenTasks.authority, DEFAULT_SYNC_INTERVAL);
+                } else
+                    // Android <6 only: disable OpenTasks sync forever when OpenTasks is not installed
+                    // because otherwise, there will be a non-catchable SecurityException as soon as OpenTasks is installed
+                    ContentResolver.setIsSyncable(account, TaskProvider.ProviderName.OpenTasks.authority, 0);
+            } else {
+                // disable calendar and task sync when CalDAV is not available
+                ContentResolver.setIsSyncable(account, CalendarContract.AUTHORITY, 0);
+                ContentResolver.setIsSyncable(account, TaskProvider.ProviderName.OpenTasks.authority, 0);
+            }
+
+        } catch(InvalidAccountException e) {
+            App.log.log(Level.SEVERE, "Couldn't access account settings", e);
+        }
+
+        return true;
+    }
+
+    protected long insertService(SQLiteDatabase db, String accountName, String service, DavResourceFinder.Configuration.ServiceInfo info) {
+        ContentValues values = new ContentValues();
+
+        // insert service
+        values.put(Services.ACCOUNT_NAME, accountName);
+        values.put(Services.SERVICE, service);
+        if (info.principal != null)
+            values.put(Services.PRINCIPAL, info.principal.toString());
+        long serviceID = db.insertWithOnConflict(Services._TABLE, null, values, SQLiteDatabase.CONFLICT_REPLACE);
+
+        // insert home sets
+        for (URI homeSet : info.homeSets) {
+            values.clear();
+            values.put(HomeSets.SERVICE_ID, serviceID);
+            values.put(HomeSets.URL, homeSet.toString());
+            db.insertWithOnConflict(HomeSets._TABLE, null, values, SQLiteDatabase.CONFLICT_REPLACE);
+        }
+
+        // insert collections
+        for (CollectionInfo collection : info.collections.values()) {
+            values = collection.toDB();
+            values.put(Collections.SERVICE_ID, serviceID);
+            db.insertWithOnConflict(Collections._TABLE, null, values, SQLiteDatabase.CONFLICT_REPLACE);
+        }
+
+        return serviceID;
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/setup/DavResourceFinder.java

@@ -0,0 +1,383 @@
+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+package at.bitfire.davdroid.ui.setup;
+
+import android.content.Context;
+import android.support.annotation.NonNull;
+
+import org.xbill.DNS.Lookup;
+import org.xbill.DNS.Record;
+import org.xbill.DNS.SRVRecord;
+import org.xbill.DNS.TXTRecord;
+import org.xbill.DNS.Type;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.net.URI;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import at.bitfire.dav4android.DavResource;
+import at.bitfire.dav4android.UrlUtils;
+import at.bitfire.dav4android.exception.DavException;
+import at.bitfire.dav4android.exception.HttpException;
+import at.bitfire.dav4android.exception.NotFoundException;
+import at.bitfire.dav4android.property.AddressbookDescription;
+import at.bitfire.dav4android.property.AddressbookHomeSet;
+import at.bitfire.dav4android.property.CalendarColor;
+import at.bitfire.dav4android.property.CalendarDescription;
+import at.bitfire.dav4android.property.CalendarHomeSet;
+import at.bitfire.dav4android.property.CalendarTimezone;
+import at.bitfire.dav4android.property.CurrentUserPrincipal;
+import at.bitfire.dav4android.property.CurrentUserPrivilegeSet;
+import at.bitfire.dav4android.property.DisplayName;
+import at.bitfire.dav4android.property.ResourceType;
+import at.bitfire.dav4android.property.SupportedCalendarComponentSet;
+import at.bitfire.davdroid.HttpClient;
+import at.bitfire.davdroid.log.StringHandler;
+import at.bitfire.davdroid.model.CollectionInfo;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+import okhttp3.HttpUrl;
+import okhttp3.OkHttpClient;
+
+public class DavResourceFinder {
+    public enum Service {
+        CALDAV("caldav"),
+        CARDDAV("carddav");
+
+        final String name;
+        Service(String name) { this.name = name;}
+        @Override public String toString() { return name; }
+    }
+
+    protected final Context context;
+    protected final LoginCredentials credentials;
+
+    protected final Logger log;
+    protected final StringHandler logBuffer = new StringHandler();
+    protected OkHttpClient httpClient;
+
+    public DavResourceFinder(@NonNull Context context, @NonNull LoginCredentials credentials) {
+		this.context = context;
+        this.credentials = credentials;
+
+        log = Logger.getLogger("davdroid.DavResourceFinder");
+        log.setLevel(Level.FINEST);
+        log.addHandler(logBuffer);
+
+        httpClient = HttpClient.create(log);
+        httpClient = HttpClient.addAuthentication(httpClient, credentials.userName, credentials.password, credentials.authPreemptive);
+	}
+
+
+    public Configuration findInitialConfiguration() {
+        final Configuration.ServiceInfo
+                cardDavConfig = findInitialConfiguration(Service.CARDDAV),
+                calDavConfig = findInitialConfiguration(Service.CALDAV);
+
+        return new Configuration(
+                credentials.userName, credentials.password, credentials.authPreemptive,
+                cardDavConfig, calDavConfig,
+                logBuffer.toString()
+        );
+    }
+
+    protected Configuration.ServiceInfo findInitialConfiguration(@NonNull Service service) {
+        // user-given base URI (either mailto: URI or http(s):// URL)
+        final URI baseURI = credentials.uri;
+
+        // domain for service discovery
+        String discoveryFQDN = null;
+
+        // put discovered information here
+        final Configuration.ServiceInfo config = new Configuration.ServiceInfo();
+        log.info("Finding initial " + service.name + " service configuration");
+
+        if ("http".equalsIgnoreCase(baseURI.getScheme()) || "https".equalsIgnoreCase(baseURI.getScheme())) {
+            final HttpUrl baseURL = HttpUrl.get(baseURI);
+
+            // remember domain for service discovery
+            // try service discovery only for https:// URLs because only secure service discovery is implemented
+            if ("https".equalsIgnoreCase(baseURL.scheme()))
+                discoveryFQDN = baseURI.getHost();
+
+            checkUserGivenURL(baseURL, service, config);
+
+            if (config.principal == null)
+                try {
+                    config.principal = getCurrentUserPrincipal(baseURL.resolve("/.well-known/" + service.name), service);
+                } catch (IOException|HttpException|DavException e) {
+                    log.log(Level.FINE, "Well-known URL detection failed", e);
+                }
+
+        } else if ("mailto".equalsIgnoreCase(baseURI.getScheme())) {
+            String mailbox = baseURI.getSchemeSpecificPart();
+
+            int posAt = mailbox.lastIndexOf("@");
+            if (posAt != -1)
+                discoveryFQDN = mailbox.substring(posAt + 1);
+        }
+
+        // Step 2: If user-given URL didn't reveal a principal, search for it: SERVICE DISCOVERY
+        if (config.principal == null && discoveryFQDN != null) {
+            log.info("No principal found at user-given URL, trying to discover");
+            try {
+                config.principal = discoverPrincipalUrl(discoveryFQDN, service);
+            } catch (IOException|HttpException|DavException e) {
+                log.log(Level.FINE, service.name + " service discovery failed", e);
+            }
+        }
+
+        // return config or null if config doesn't contain useful information
+        boolean serviceAvailable = config.principal != null || !config.homeSets.isEmpty() || !config.collections.isEmpty();
+        return serviceAvailable ? config : null;
+    }
+
+    protected void checkUserGivenURL(@NonNull HttpUrl baseURL, @NonNull Service service, @NonNull Configuration.ServiceInfo config) {
+        log.info("Checking user-given URL: " + baseURL.toString());
+
+        HttpUrl principal = null;
+        try {
+            DavResource davBase = new DavResource(httpClient, baseURL, log);
+
+            if (service == Service.CARDDAV) {
+                davBase.propfind(0,
+                        ResourceType.NAME, DisplayName.NAME, AddressbookDescription.NAME,
+                        AddressbookHomeSet.NAME,
+                        CurrentUserPrincipal.NAME
+                );
+                rememberIfAddressBookOrHomeset(davBase, config);
+
+            } else if (service == Service.CALDAV) {
+                davBase.propfind(0,
+                        ResourceType.NAME, DisplayName.NAME, CalendarColor.NAME, CalendarDescription.NAME, CalendarTimezone.NAME, CurrentUserPrivilegeSet.NAME, SupportedCalendarComponentSet.NAME,
+                        CalendarHomeSet.NAME,
+                        CurrentUserPrincipal.NAME
+                );
+                rememberIfCalendarOrHomeset(davBase, config);
+            }
+
+            // check for current-user-principal
+            CurrentUserPrincipal currentUserPrincipal = (CurrentUserPrincipal)davBase.properties.get(CurrentUserPrincipal.NAME);
+            if (currentUserPrincipal != null && currentUserPrincipal.href != null)
+                principal = davBase.location.resolve(currentUserPrincipal.href);
+
+            // check for resource type "principal"
+            if (principal == null) {
+                ResourceType resourceType = (ResourceType)davBase.properties.get(ResourceType.NAME);
+                if (resourceType != null && resourceType.types.contains(ResourceType.PRINCIPAL))
+                    principal = davBase.location;
+            }
+
+            // If a principal has been detected successfully, ensure that it provides the required service.
+            if (principal != null && providesService(principal, service))
+                config.principal = principal.uri();
+
+        } catch (IOException|HttpException|DavException e) {
+            log.log(Level.FINE, "PROPFIND/OPTIONS on user-given URL failed", e);
+        }
+    }
+
+    /**
+     * If #dav is an address book or an address book home set, it will added to
+     * config.collections or config.homesets. Only evaluates already known properties,
+     * does not call dav.propfind()! URLs will be stored with trailing "/".
+     * @param dav       resource whose properties are evaluated
+     * @param config    structure where the address book (collection) and/or home set is stored into (if found)
+     */
+    protected void rememberIfAddressBookOrHomeset(@NonNull DavResource dav, @NonNull Configuration.ServiceInfo config) {
+        // Is the collection an address book?
+        ResourceType resourceType = (ResourceType)dav.properties.get(ResourceType.NAME);
+        if (resourceType != null && resourceType.types.contains(ResourceType.ADDRESSBOOK)) {
+            dav.location = UrlUtils.withTrailingSlash(dav.location);
+            log.info("Found address book at " + dav.location);
+            config.collections.put(dav.location.uri(), CollectionInfo.fromDavResource(dav));
+        }
+
+        // Does the collection refer to address book homesets?
+        AddressbookHomeSet homeSets = (AddressbookHomeSet)dav.properties.get(AddressbookHomeSet.NAME);
+        if (homeSets != null)
+            for (String href : homeSets.hrefs) {
+                HttpUrl location = UrlUtils.withTrailingSlash(dav.location.resolve(href));
+                log.info("Found addressbook home-set at " + location);
+                config.homeSets.add(location.uri());
+            }
+    }
+
+    protected void rememberIfCalendarOrHomeset(@NonNull DavResource dav, @NonNull Configuration.ServiceInfo config) {
+        // Is the collection a calendar collection?
+        ResourceType resourceType = (ResourceType)dav.properties.get(ResourceType.NAME);
+        if (resourceType != null && resourceType.types.contains(ResourceType.CALENDAR)) {
+            dav.location = UrlUtils.withTrailingSlash(dav.location);
+            log.info("Found calendar collection at " + dav.location);
+            config.collections.put(dav.location.uri(), CollectionInfo.fromDavResource(dav));
+        }
+
+        // Does the collection refer to calendar homesets?
+        CalendarHomeSet homeSets = (CalendarHomeSet)dav.properties.get(CalendarHomeSet.NAME);
+        if (homeSets != null)
+            for (String href : homeSets.hrefs)
+                config.homeSets.add(UrlUtils.withTrailingSlash(dav.location.resolve(href)).uri());
+    }
+
+
+    protected boolean providesService(HttpUrl url, Service service) throws IOException {
+        DavResource davPrincipal = new DavResource(httpClient, url, log);
+        try {
+            davPrincipal.options();
+
+            if ((service == Service.CARDDAV && davPrincipal.capabilities.contains("addressbook")) ||
+                (service == Service.CALDAV && davPrincipal.capabilities.contains("calendar-access")))
+                return true;
+
+        } catch (HttpException|DavException e) {
+            log.log(Level.SEVERE, "Couldn't detect services on " + url, e);
+        }
+        return false;
+    }
+
+
+    /**
+     * Try to find the principal URL by performing service discovery on a given domain name.
+     * Only secure services (caldavs, carddavs) will be discovered!
+     * @param domain         domain name, e.g. "icloud.com"
+     * @param service        service to discover (CALDAV or CARDDAV)
+     * @return principal URL, or null if none found
+     */
+    protected URI discoverPrincipalUrl(@NonNull String domain, @NonNull Service service) throws IOException, HttpException, DavException {
+        String scheme;
+        String fqdn;
+        Integer port = 443;
+        List<String> paths = new LinkedList<>();     // there may be multiple paths to try
+
+        final String query = "_" + service.name + "s._tcp." + domain;
+        log.fine("Looking up SRV records for " + query);
+        Record[] records = new Lookup(query, Type.SRV).run();
+        if (records != null && records.length >= 1) {
+            // choose SRV record to use (query may return multiple SRV records)
+            SRVRecord srv = selectSRVRecord(records);
+
+            scheme = "https";
+            fqdn = srv.getTarget().toString(true);
+            port = srv.getPort();
+            log.info("Found " + service + " service at https://" + fqdn + ":" + port);
+
+        } else {
+            // no SRV records, try domain name as FQDN
+            log.info("Didn't find " + service + " service, trying at https://" + domain + ":" + port);
+
+            scheme = "https";
+            fqdn = domain;
+        }
+
+        // look for TXT record too (for initial context path)
+        records = new Lookup(query, Type.TXT).run();
+        if (records != null)
+            for (Record record : records)
+                if (record instanceof TXTRecord)
+                    for (String segment : (List<String>)((TXTRecord)record).getStrings())
+                        if (segment.startsWith("path=")) {
+                            paths.add(segment.substring(5));
+                            log.info("Found TXT record; initial context path=" + paths);
+                            break;
+                        }
+
+        // if there's TXT record and if it it's wrong, try well-known
+        paths.add("/.well-known/" + service.name);
+        // if this fails, too, try "/"
+        paths.add("/");
+
+        for (String path : paths)
+            try {
+                HttpUrl initialContextPath = new HttpUrl.Builder()
+                        .scheme(scheme)
+                        .host(fqdn).port(port)
+                        .encodedPath(path)
+                        .build();
+
+                log.info("Trying to determine principal from initial context path=" + initialContextPath);
+                URI principal = getCurrentUserPrincipal(initialContextPath, service);
+
+                if (principal != null)
+                    return principal;
+            } catch(NotFoundException|IllegalArgumentException e) {
+                log.log(Level.WARNING, "No resource found", e);
+            }
+        return null;
+    }
+
+    /**
+     * Queries a given URL for current-user-principal
+     * @param url       URL to query with PROPFIND (Depth: 0)
+     * @param service   required service (may be null, in which case no service check is done)
+     * @return          current-user-principal URL that provides required service, or null if none
+     */
+    public URI getCurrentUserPrincipal(HttpUrl url, Service service) throws IOException, HttpException, DavException {
+        DavResource dav = new DavResource(httpClient, url, log);
+        dav.propfind(0, CurrentUserPrincipal.NAME);
+
+        CurrentUserPrincipal currentUserPrincipal = (CurrentUserPrincipal)dav.properties.get(CurrentUserPrincipal.NAME);
+        if (currentUserPrincipal != null && currentUserPrincipal.href != null) {
+            HttpUrl principal = dav.location.resolve(currentUserPrincipal.href);
+            if (principal != null) {
+                log.info("Found current-user-principal: " + principal);
+
+                // service check
+                if (service != null && !providesService(principal, service)) {
+                    log.info(principal + " doesn't provide required " + service + " service");
+                    principal = null;
+                }
+
+                return principal != null ? principal.uri() : null;
+            }
+        }
+        return null;
+    }
+
+
+    // helpers
+
+	private SRVRecord selectSRVRecord(Record[] records) {
+		if (records.length > 1)
+			log.warning("Multiple SRV records not supported yet; using first one");
+		return (SRVRecord)records[0];
+	}
+
+
+    // data classes
+
+    @RequiredArgsConstructor
+    @ToString(exclude="logs")
+    public static class Configuration implements Serializable {
+        // We have to use URI here because HttpUrl is not serializable!
+
+        @ToString
+        public static class ServiceInfo implements Serializable {
+            public URI principal;
+            public final Set<URI> homeSets = new HashSet<>();
+            public final Map<URI, CollectionInfo> collections = new HashMap<>();
+        }
+
+        public final String userName, password;
+        public final boolean preemptive;
+
+        public final ServiceInfo cardDAV;
+        public final ServiceInfo calDAV;
+
+        public final String logs;
+
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/setup/DetectConfigurationFragment.java

@@ -0,0 +1,145 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui.setup;
+
+import android.app.Dialog;
+import android.app.ProgressDialog;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.Intent;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v4.app.DialogFragment;
+import android.support.v4.app.LoaderManager;
+import android.support.v4.content.AsyncTaskLoader;
+import android.support.v4.content.Loader;
+import android.support.v7.app.AlertDialog;
+
+import at.bitfire.davdroid.App;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.ui.DebugInfoActivity;
+import at.bitfire.davdroid.ui.setup.DavResourceFinder.Configuration;
+
+public class DetectConfigurationFragment extends DialogFragment implements LoaderManager.LoaderCallbacks<Configuration> {
+    protected static final String ARG_LOGIN_CREDENTIALS = "credentials";
+
+    public static DetectConfigurationFragment newInstance(LoginCredentials credentials) {
+        DetectConfigurationFragment frag = new DetectConfigurationFragment();
+        Bundle args = new Bundle(1);
+        args.putParcelable(ARG_LOGIN_CREDENTIALS, credentials);
+        frag.setArguments(args);
+        return frag;
+    }
+
+    @NonNull
+    @Override
+    public Dialog onCreateDialog(Bundle savedInstanceState) {
+        ProgressDialog progress = new ProgressDialog(getActivity());
+        progress.setTitle(R.string.login_configuration_detection);
+        progress.setMessage(getString(R.string.login_querying_server));
+        progress.setIndeterminate(true);
+        progress.setCanceledOnTouchOutside(false);
+        setCancelable(false);
+        return progress;
+    }
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        getLoaderManager().initLoader(0, getArguments(), this);
+    }
+
+    @Override
+    public Loader<Configuration> onCreateLoader(int id, Bundle args) {
+        return new ServerConfigurationLoader(getContext(), (LoginCredentials)args.getParcelable(ARG_LOGIN_CREDENTIALS));
+    }
+
+    @Override
+    public void onLoadFinished(Loader<Configuration> loader, Configuration data) {
+        if (data != null) {
+            if (data.calDAV == null && data.cardDAV == null)
+                // no service found: show error message
+                getFragmentManager().beginTransaction()
+                        .add(NothingDetectedFragment.newInstance(data.logs), null)
+                        .commitAllowingStateLoss();
+            else
+                // service found: continue
+                getFragmentManager().beginTransaction()
+                        .replace(android.R.id.content, AccountDetailsFragment.newInstance(data))
+                        .addToBackStack(null)
+                        .commitAllowingStateLoss();
+        } else
+            App.log.severe("Configuration detection failed");
+
+        dismissAllowingStateLoss();
+    }
+
+    @Override
+    public void onLoaderReset(Loader<Configuration> loader) {
+    }
+
+
+    public static class NothingDetectedFragment extends DialogFragment {
+        private static String KEY_LOGS = "logs";
+
+        public static NothingDetectedFragment newInstance(String logs) {
+            Bundle args = new Bundle();
+            args.putString(KEY_LOGS, logs);
+            NothingDetectedFragment fragment = new NothingDetectedFragment();
+            fragment.setArguments(args);
+            return fragment;
+        }
+
+        @Override
+        @NonNull
+        public Dialog onCreateDialog(Bundle savedInstanceState) {
+            return new AlertDialog.Builder(getActivity())
+                    .setTitle(R.string.login_configuration_detection)
+                    .setIcon(R.drawable.ic_error_dark)
+                    .setMessage(R.string.login_no_caldav_carddav)
+                    .setNeutralButton(R.string.login_view_logs, new DialogInterface.OnClickListener() {
+                        @Override
+                        public void onClick(DialogInterface dialog, int which) {
+                            Intent intent = new Intent(getActivity(), DebugInfoActivity.class);
+                            intent.putExtra(DebugInfoActivity.KEY_LOGS, getArguments().getString(KEY_LOGS));
+                            startActivity(intent);
+                        }
+                    })
+                    .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                        @Override
+                        public void onClick(DialogInterface dialog, int which) {
+                            // dismiss
+                        }
+                    })
+                    .create();
+        }
+    }
+
+    static class ServerConfigurationLoader extends AsyncTaskLoader<Configuration> {
+        final Context context;
+        final LoginCredentials credentials;
+
+        public ServerConfigurationLoader(Context context, LoginCredentials credentials) {
+            super(context);
+            this.context = context;
+            this.credentials = credentials;
+        }
+
+        @Override
+        protected void onStartLoading() {
+            forceLoad();
+        }
+
+        @Override
+        public Configuration loadInBackground() {
+            return new DavResourceFinder(context, credentials).findInitialConfiguration();
+        }
+    }
+}

app/src/main/java/at/bitfire/davdroid/ui/setup/LoginActivity.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui.setup;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.support.v7.app.AppCompatActivity;
+import android.view.Menu;
+import android.view.MenuItem;
+
+import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.R;
+
+public class LoginActivity extends AppCompatActivity {
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        if (savedInstanceState == null)
+            // first call, add fragment
+            getSupportFragmentManager().beginTransaction()
+                    .replace(android.R.id.content, new LoginCredentialsFragment())
+                    .commit();
+
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        getMenuInflater().inflate(R.menu.activity_login, menu);
+        return true;
+    }
+
+    public void showHelp(MenuItem item) {
+        startActivity(new Intent(Intent.ACTION_VIEW, Constants.webUri.buildUpon().appendEncodedPath("configuration/").build()));
+    }
+}

app/src/main/java/at/bitfire/davdroid/ui/setup/LoginCredentials.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui.setup;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import java.net.URI;
+
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+public class LoginCredentials implements Parcelable {
+    public final URI uri;
+    public final String userName, password;
+    public final boolean authPreemptive;
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(Parcel dest, int flags) {
+        dest.writeSerializable(uri);
+        dest.writeString(userName);
+        dest.writeString(password);
+        dest.writeValue(authPreemptive);
+    }
+
+    public static final Creator CREATOR = new Creator<LoginCredentials>() {
+        @Override
+        public LoginCredentials createFromParcel(Parcel source) {
+            return new LoginCredentials(
+                    (URI)source.readSerializable(),
+                    source.readString(), source.readString(),
+                    (boolean)source.readValue(null)
+            );
+        }
+
+        @Override
+        public LoginCredentials[] newArray(int size) {
+            return new LoginCredentials[size];
+        }
+    };
+}

app/src/main/java/at/bitfire/davdroid/ui/setup/LoginCredentialsFragment.java

@@ -0,0 +1,168 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui.setup;
+
+import android.net.Uri;
+import android.os.Bundle;
+import android.support.v4.app.Fragment;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Button;
+import android.widget.CheckBox;
+import android.widget.CompoundButton;
+import android.widget.EditText;
+import android.widget.LinearLayout;
+import android.widget.RadioButton;
+
+import org.apache.commons.lang3.StringUtils;
+
+import java.net.IDN;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.logging.Level;
+
+import at.bitfire.dav4android.Constants;
+import at.bitfire.davdroid.R;
+import at.bitfire.davdroid.ui.widget.EditPassword;
+
+public class LoginCredentialsFragment extends Fragment implements CompoundButton.OnCheckedChangeListener {
+
+    RadioButton radioUseEmail;
+    LinearLayout emailDetails;
+    EditText editEmailAddress;
+    EditPassword editEmailPassword;
+
+    RadioButton radioUseURL;
+    LinearLayout urlDetails;
+    EditText editBaseURL, editUserName;
+    EditPassword editUrlPassword;
+    CheckBox checkPreemptiveAuth;
+
+
+    @Override
+    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+        View v = inflater.inflate(R.layout.login_credentials_fragment, container, false);
+
+        radioUseEmail = (RadioButton)v.findViewById(R.id.login_type_email);
+        emailDetails = (LinearLayout)v.findViewById(R.id.login_type_email_details);
+        editEmailAddress = (EditText)v.findViewById(R.id.email_address);
+        editEmailPassword = (EditPassword)v.findViewById(R.id.email_password);
+
+        radioUseURL = (RadioButton)v.findViewById(R.id.login_type_url);
+        urlDetails = (LinearLayout)v.findViewById(R.id.login_type_url_details);
+        editBaseURL = (EditText)v.findViewById(R.id.base_url);
+        editUserName = (EditText)v.findViewById(R.id.user_name);
+        editUrlPassword = (EditPassword)v.findViewById(R.id.url_password);
+        checkPreemptiveAuth = (CheckBox)v.findViewById(R.id.preemptive_auth);
+
+        radioUseEmail.setOnCheckedChangeListener(this);
+        radioUseURL.setOnCheckedChangeListener(this);
+
+        if (savedInstanceState == null)
+            radioUseEmail.setChecked(true);
+
+        final Button login = (Button)v.findViewById(R.id.login);
+        login.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                LoginCredentials credentials = validateLoginData();
+                if (credentials != null)
+                    DetectConfigurationFragment.newInstance(credentials).show(getFragmentManager(), null);
+            }
+        });
+
+        return v;
+    }
+
+    @Override
+    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+        if (isChecked) {
+            boolean loginByEmail = buttonView == radioUseEmail;
+            emailDetails.setVisibility(loginByEmail ? View.VISIBLE : View.GONE);
+            urlDetails.setVisibility(loginByEmail ? View.GONE : View.VISIBLE);
+            (loginByEmail ? editEmailAddress : editBaseURL).requestFocus();
+        }
+    }
+
+    protected LoginCredentials validateLoginData() {
+        if (radioUseEmail.isChecked()) {
+            URI uri = null;
+            boolean valid = true;
+
+            String email = editEmailAddress.getText().toString();
+            if (!email.matches(".+@.+")) {
+                editEmailAddress.setError(getString(R.string.login_email_address_error));
+                valid = false;
+            } else
+                try {
+                    uri = new URI("mailto", email, null);
+                } catch (URISyntaxException e) {
+                    editEmailAddress.setError(e.getLocalizedMessage());
+                    valid = false;
+                }
+
+            String password = editEmailPassword.getText().toString();
+            if (password.isEmpty()) {
+                editEmailPassword.setError(getString(R.string.login_password_required));
+                valid = false;
+            }
+
+            return valid ? new LoginCredentials(uri, email, password, true) : null;
+
+        } else if (radioUseURL.isChecked()) {
+            URI uri = null;
+            boolean valid = true;
+
+            Uri baseUrl = Uri.parse(editBaseURL.getText().toString());
+            String scheme = baseUrl.getScheme();
+            if ("https".equalsIgnoreCase(scheme) || "http".equalsIgnoreCase(scheme)) {
+                String host = baseUrl.getHost();
+                if (StringUtils.isEmpty(host)) {
+                    editBaseURL.setError(getString(R.string.login_url_host_name_required));
+                    valid = false;
+                } else
+                    try {
+                        host = IDN.toASCII(host);
+                    } catch(IllegalArgumentException e) {
+                        Constants.log.log(Level.WARNING, "Host name not conforming to RFC 3490", e);
+                    }
+
+                String path = baseUrl.getEncodedPath();
+                int port = baseUrl.getPort();
+                try {
+                    uri = new URI(baseUrl.getScheme(), null, host, port, path, null, null);
+                } catch (URISyntaxException e) {
+                    editBaseURL.setError(e.getLocalizedMessage());
+                    valid = false;
+                }
+            } else {
+                editBaseURL.setError(getString(R.string.login_url_must_be_http_or_https));
+                valid = false;
+            }
+
+            String userName = editUserName.getText().toString();
+            if (userName.isEmpty()) {
+                editUserName.setError(getString(R.string.login_user_name_required));
+                valid = false;
+            }
+
+            String password = editUrlPassword.getText().toString();
+            if (password.isEmpty()) {
+                editUrlPassword.setError(getString(R.string.login_password_required));
+                valid = false;
+            }
+
+            return valid ? new LoginCredentials(uri, userName, password, checkPreemptiveAuth.isChecked()) : null;
+        }
+
+        return null;
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/widget/EditPassword.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui.widget;
+
+import android.content.Context;
+import android.text.Editable;
+import android.util.AttributeSet;
+import android.view.inputmethod.EditorInfo;
+import android.widget.CheckBox;
+import android.widget.CompoundButton;
+import android.widget.EditText;
+import android.widget.LinearLayout;
+
+import at.bitfire.davdroid.R;
+
+public class EditPassword extends LinearLayout {
+    private static final String NS_ANDROID = "http://schemas.android.com/apk/res/android";
+
+    EditText editPassword;
+
+    public EditPassword(Context context) {
+        super(context, null);
+    }
+
+    public EditPassword(Context context, AttributeSet attrs) {
+        super(context, attrs);
+
+        inflate(context, R.layout.edit_password, this);
+
+        editPassword = (EditText)findViewById(R.id.password);
+        editPassword.setHint(attrs.getAttributeResourceValue(NS_ANDROID, "hint", 0));
+        editPassword.setText(attrs.getAttributeValue(NS_ANDROID, "text"));
+
+        CheckBox checkShowPassword = (CheckBox)findViewById(R.id.show_password);
+        checkShowPassword.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+                int inputType = editPassword.getInputType() & ~EditorInfo.TYPE_MASK_VARIATION;
+                inputType |= isChecked ? EditorInfo.TYPE_TEXT_VARIATION_VISIBLE_PASSWORD : EditorInfo.TYPE_TEXT_VARIATION_PASSWORD;
+                editPassword.setInputType(inputType);
+            }
+        });
+    }
+
+    public Editable getText() {
+        return editPassword.getText();
+    }
+
+    public void setError(CharSequence error) {
+        editPassword.setError(error);
+    }
+
+    public void setText(CharSequence text) {
+        editPassword.setText(text);
+    }
+
+}

app/src/main/java/at/bitfire/davdroid/ui/widget/MaximizedListView.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.davdroid.ui.widget;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.ListAdapter;
+import android.widget.ListView;
+
+public class MaximizedListView extends ListView {
+
+    public MaximizedListView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
+
+        int widthMode = MeasureSpec.getMode(widthMeasureSpec),
+            widthSize = MeasureSpec.getSize(widthMeasureSpec),
+            heightMode = MeasureSpec.getMode(heightMeasureSpec),
+            heightSize = MeasureSpec.getSize(heightMeasureSpec);
+
+        int width = 0, height = 0;
+
+        if (widthMode == MeasureSpec.EXACTLY || widthMode == MeasureSpec.AT_MOST)
+            width = widthSize;
+
+        if (heightMode == MeasureSpec.EXACTLY)
+            height = heightSize;
+        else {
+            ListAdapter listAdapter = getAdapter();
+            if (listAdapter != null) {
+                int widthSpec = View.MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY);
+                for (int i = 0; i < listAdapter.getCount(); i++) {
+                    View listItem = listAdapter.getView(i, null, this);
+                    listItem.measure(widthSpec, View.MeasureSpec.UNSPECIFIED);
+                    height += listItem.getMeasuredHeight();
+                }
+                height += getDividerHeight() * (listAdapter.getCount() - 1);
+            }
+        }
+
+        setMeasuredDimension(width, height);
+    }
+
+}

app/src/main/lombok.config

@@ -0,0 +1,2 @@
+lombok.addGeneratedAnnotation = false
+lombok.anyConstructor.suppressConstructorProperties = true

app/src/main/res/color/buttontext.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:state_enabled="false" android:color="@android:color/darker_gray" />
+    <item android:color="@android:color/black" />
+</selector>

app/src/main/res/drawable/ic_account_circle_white.xml

@@ -0,0 +1,17 @@
+<!--
+  ~ Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="48dp"
+        android:height="48dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FFFFFFFF"
+        android:pathData="M12,2C6.48,2 2,6.48 2,12s4.48,10 10,10 10,-4.48 10,-10S17.52,2 12,2zm0,3c1.66,0 3,1.34 3,3s-1.34,3 -3,3 -3,-1.34 -3,-3 1.34,-3 3,-3zm0,14.2c-2.5,0 -4.71,-1.28 -6,-3.22 0.03,-1.99 4,-3.08 6,-3.08 1.99,0 5.97,1.09 6,3.08 -1.29,1.94 -3.5,3.22 -6,3.22z"/>
+</vector>

app/src/main/res/drawable/ic_add_light.xml

@@ -0,0 +1,17 @@
+<!--
+  ~ Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FFFFFFFF"
+        android:pathData="M19,13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/>
+</vector>

app/src/main/res/drawable/ic_alarm_on_dark.xml

@@ -0,0 +1,13 @@
+<!--
+  ~ Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<vector android:alpha="0.54" android:height="32dp"
+    android:viewportHeight="24.0" android:viewportWidth="24.0"
+    android:width="32dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#FF000000" android:pathData="M22,5.72l-4.6,-3.86 -1.29,1.53 4.6,3.86L22,5.72zM7.88,3.39L6.6,1.86 2,5.71l1.29,1.53 4.59,-3.85zM12,4c-4.97,0 -9,4.03 -9,9s4.02,9 9,9c4.97,0 9,-4.03 9,-9s-4.03,-9 -9,-9zm0,16c-3.87,0 -7,-3.13 -7,-7s3.13,-7 7,-7 7,3.13 7,7 -3.13,7 -7,7zm-1.46,-5.47L8.41,12.4l-1.06,1.06 3.18,3.18 6,-6 -1.06,-1.06 -4.93,4.95z"/>
+</vector>

app/src/main/res/drawable/ic_attach_money_dark.xml

@@ -0,0 +1,13 @@
+<!--
+  ~ Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<vector android:alpha="0.54" android:height="24dp"
+    android:viewportHeight="24.0" android:viewportWidth="24.0"
+    android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#FF000000" android:pathData="M11.8,10.9c-2.27,-0.59 -3,-1.2 -3,-2.15 0,-1.09 1.01,-1.85 2.7,-1.85 1.78,0 2.44,0.85 2.5,2.1h2.21c-0.07,-1.72 -1.12,-3.3 -3.21,-3.81V3h-3v2.16c-1.94,0.42 -3.5,1.68 -3.5,3.61 0,2.31 1.91,3.46 4.7,4.13 2.5,0.6 3,1.48 3,2.41 0,0.69 -0.49,1.79 -2.7,1.79 -2.06,0 -2.87,-0.92 -2.98,-2.1h-2.2c0.12,2.19 1.76,3.42 3.68,3.83V21h3v-2.15c1.95,-0.37 3.5,-1.5 3.5,-3.55 0,-2.84 -2.43,-3.81 -4.7,-4.4z"/>
+</vector>

app/src/main/res/drawable/ic_error_dark.xml

@@ -0,0 +1,18 @@
+<!--
+  ~ Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0"
+        android:alpha="0.54" >
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M12,2C6.48,2 2,6.48 2,12s4.48,10 10,10 10,-4.48 10,-10S17.52,2 12,2zm1,15h-2v-2h2v2zm0,-4h-2V7h2v6z"/>
+</vector>

app/src/main/res/drawable/ic_error_light.xml

@@ -0,0 +1,17 @@
+<!--
+  ~ Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FFFFFFFF"
+        android:pathData="M12,2C6.48,2 2,6.48 2,12s4.48,10 10,10 10,-4.48 10,-10S17.52,2 12,2zm1,15h-2v-2h2v2zm0,-4h-2V7h2v6z"/>
+</vector>

app/src/main/res/drawable/ic_event_light.xml

@@ -0,0 +1,17 @@
+<!--
+  ~ Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FFFFFFFF"
+        android:pathData="M17,12h-5v5h5v-5zM16,1v2H8V1H6v2H5c-1.11,0 -1.99,0.9 -1.99,2L3,19c0,1.1 0.89,2 2,2h14c1.1,0 2,-0.9 2,-2V5c0,-1.1 -0.9,-2 -2,-2h-1V1h-2zm3,18H5V8h14v11z"/>
+</vector>

app/src/main/res/drawable/ic_forum_dark.xml

@@ -0,0 +1,18 @@
+<!--
+  ~ Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0"
+        android:alpha="0.54" >
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M21,6h-2v9H6v2c0,0.55 0.45,1 1,1h11l4,4V7c0,-0.55 -0.45,-1 -1,-1zm-4,6V3c0,-0.55 -0.45,-1 -1,-1H3c-0.55,0 -1,0.45 -1,1v14l4,-4h10c0.55,0 1,-0.45 1,-1z"/>
+</vector>

app/src/main/res/drawable/ic_help_dark.xml

@@ -0,0 +1,18 @@
+<!--
+  ~ Copyright © 2013 – 2016 Ricki Hirner (bitfire web engineering).
+  ~ All rights reserved. This program and the accompanying materials
+  ~ are made available under the terms of the GNU Public License v3.0
+  ~ which accompanies this distribution, and is available at
+  ~ http://www.gnu.org/licenses/gpl.html
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0"
+        android:alpha="0.54" >
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M12,2C6.48,2 2,6.48 2,12s4.48,10 10,10 10,-4.48 10,-10S17.52,2 12,2zm1,17h-2v-2h2v2zm2.07,-7.75l-0.9,0.92C13.45,12.9 13,13.5 13,15h-2v-0.5c0,-1.1 0.45,-2.1 1.17,-2.83l1.24,-1.26c0.37,-0.36 0.59,-0.86 0.59,-1.41 0,-1.1 -0.9,-2 -2,-2s-2,0.9 -2,2H8c0,-2.21 1.79,-4 4,-4s4,1.79 4,4c0,0.88 -0.36,1.68 -0.93,2.25z"/>
+</vector>

app/src/main/res/drawable/ic_home_dark.xml

@@ -0,0 +1,5 @@
+<vector android:alpha="0.54" android:height="24dp"
+    android:viewportHeight="24.0" android:viewportWidth="24.0"
+    android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#FF000000" android:pathData="M10,20v-6h4v6h5v-8h3L12,3 2,12h3v8z"/>
+</vector>