Cancel syncs for calendar, tasks, and contacts separately

* Disable pending sync indicator on Android 14+

* Disable forever pending sync workaround on Android 14+

.github/dependabot.yml

@@ -8,4 +8,7 @@ updates:
     schedule:
       interval: "weekly"
     commit-message:
-      prefix: "[CI] "
+      prefix: "[CI] "
+    groups:
+      ci-actions:
+        patterns: ["*"]

.github/workflows/codeql.yml

@@ -28,8 +28,8 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
-    - uses: actions/setup-java@v4
+      uses: actions/checkout@v5
+    - uses: actions/setup-java@v5
       with:
         distribution: temurin
         java-version: 21

.github/workflows/release.yml

@@ -19,8 +19,8 @@ jobs:
       discussions: write
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-java@v4
+      - uses: actions/checkout@v5
+      - uses: actions/setup-java@v5
         with:
           distribution: temurin
           java-version: 21

.github/workflows/test-dev.yml

@@ -15,8 +15,8 @@ jobs:
     if: ${{ github.ref == 'refs/heads/main-ose' }}
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-java@v4
+      - uses: actions/checkout@v5
+      - uses: actions/setup-java@v5
         with:
           distribution: temurin
           java-version: 21
@@ -35,8 +35,8 @@ jobs:
     name: Lint and unit tests
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-java@v4
+      - uses: actions/checkout@v5
+      - uses: actions/setup-java@v5
         with:
           distribution: temurin
           java-version: 21
@@ -56,8 +56,8 @@ jobs:
     name: Instrumented tests
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-java@v4
+      - uses: actions/checkout@v5
+      - uses: actions/setup-java@v5
         with:
           distribution: temurin
           java-version: 21

app/build.gradle.kts

@@ -19,10 +19,10 @@ android {
     defaultConfig {
         applicationId = "at.bitfire.davdroid"
 
-        versionCode = 405020002
-        versionName = "4.5.2"
+        versionCode = 405040002
+        versionName = "4.5.4-rc.1"
 
-        setProperty("archivesBaseName", "davx5-ose-$versionName")
+        base.archivesName = "davx5-ose-$versionName"
 
         minSdk = 24        // Android 7.0
         targetSdk = 36     // Android 16
@@ -188,7 +188,6 @@ dependencies {
     implementation(libs.dnsjava)
     implementation(libs.guava)
     implementation(libs.mikepenz.aboutLibraries)
-    implementation(libs.nsk90.kstatemachine)
     implementation(libs.okhttp.base)
     implementation(libs.okhttp.brotli)
     implementation(libs.okhttp.logging)

app/src/androidTest/kotlin/at/bitfire/davdroid/Dav4jvmTest.kt

@@ -1,20 +0,0 @@
-/*
- * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
- */
-
-package at.bitfire.davdroid
-
-import android.util.Xml
-import at.bitfire.dav4jvm.XmlUtils
-import org.junit.Assert.assertTrue
-import org.junit.Test
-
-class Dav4jvmTest {
-
-    @Test
-    fun test_Dav4jvm_XmlUtils_NewPullParser_RelaxedParsing() {
-        val parser = XmlUtils.newPullParser()
-        assertTrue(parser.getFeature(Xml.FEATURE_RELAXED))
-    }
-
-}

app/src/androidTest/kotlin/at/bitfire/davdroid/ExternalLibrariesTest.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid
+
+import android.util.Xml
+import at.bitfire.dav4jvm.XmlUtils
+import okhttp3.HttpUrl.Companion.toHttpUrl
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class ExternalLibrariesTest {
+
+    @Test
+    fun test_Dav4jvm_XmlUtils_NewPullParser_RelaxedParsing() {
+        val parser = XmlUtils.newPullParser()
+        assertTrue(parser.getFeature(Xml.FEATURE_RELAXED))
+    }
+
+    @Test
+    fun testOkhttpHttpUrl_PublicSuffixList() {
+        // HttpUrl.topPrivateDomain() requires okhttp's internal PublicSuffixList.
+        // In Android, loading the PublicSuffixList is done over AndroidX startup.
+        // This test verifies that everything is working.
+        assertEquals("example.com", "http://example.com".toHttpUrl().topPrivateDomain())
+    }
+
+}

app/src/androidTest/kotlin/at/bitfire/davdroid/HiltTestRunner.kt

@@ -10,7 +10,6 @@ import android.os.Build
 import android.os.Bundle
 import androidx.test.runner.AndroidJUnitRunner
 import at.bitfire.davdroid.di.TestCoroutineDispatchersModule
-import at.bitfire.davdroid.sync.SyncAdapterService
 import at.bitfire.davdroid.test.BuildConfig
 import at.bitfire.synctools.log.LogcatHandler
 import dagger.hilt.android.testing.HiltTestApplication
@@ -36,9 +35,6 @@ class HiltTestRunner : AndroidJUnitRunner() {
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.P)
             throw AssertionError("MockK requires Android P [https://mockk.io/ANDROID.html]")
 
-        // disable sync adapters
-        SyncAdapterService.syncActive.set(false)
-
         // set main dispatcher for tests (especially runTest)
         TestCoroutineDispatchersModule.initMainDispatcher()
     }

app/src/androidTest/kotlin/at/bitfire/davdroid/db/migration/DatabaseMigrationTest.kt

@@ -44,6 +44,11 @@ abstract class DatabaseMigrationTest(
     /**
      * Used for testing the migration process from [toVersion]-1 to [toVersion].
      *
+     * Note: SQLite's foreign key constraint enforcement is not enabled in tests. We need
+     * to enable it ourselves using setting "PRAGMA foreign_keys=ON" directly after opening
+     * a new database connection (works per connection). In tests it's usually more practical
+     * not to do so, however. In production database connections room enables it for us.
+     *
      * @param prepare      Callback to prepare the database. Will be run with database schema in version [toVersion] - 1.
      * @param validate     Callback to validate the migration result. Will be run with database schema in version [toVersion].
      */
@@ -61,6 +66,8 @@ abstract class DatabaseMigrationTest(
         // Prepare the database with the initial version.
         val dbName = "test"
         helper.createDatabase(dbName, version = toVersion - 1).apply {
+            // We could enable foreign key constraint enforcement here
+            // by setting "PRAGMA foreign_keys=ON".
             prepare(this)
             close()
         }

app/src/androidTest/kotlin/at/bitfire/davdroid/di/FakeSyncAdapterModule.kt

@@ -0,0 +1,20 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.di
+
+import at.bitfire.davdroid.sync.FakeSyncAdapter
+import at.bitfire.davdroid.sync.adapter.SyncAdapter
+import at.bitfire.davdroid.sync.adapter.SyncAdapterImpl
+import dagger.Binds
+import dagger.Module
+import dagger.hilt.components.SingletonComponent
+import dagger.hilt.testing.TestInstallIn
+
+@Module
+@TestInstallIn(components = [SingletonComponent::class], replaces = [SyncAdapterImpl.RealSyncAdapterModule::class])
+abstract class FakeSyncAdapterModule {
+    @Binds
+    abstract fun provide(impl: FakeSyncAdapter): SyncAdapter
+}

app/src/androidTest/kotlin/at/bitfire/davdroid/resource/LocalAddressBookTest.kt

@@ -29,6 +29,7 @@ import org.junit.Rule
 import org.junit.Test
 import java.io.FileNotFoundException
 import java.util.LinkedList
+import java.util.Optional
 import javax.inject.Inject
 
 @HiltAndroidTest
@@ -98,7 +99,7 @@ class LocalAddressBookTest {
             val id = ContentUris.parseId(uri)
 
             // make sure it's not dirty
-            localGroup.clearDirty(null, null, null)
+            localGroup.clearDirty(Optional.empty(), null, null)
             assertFalse("Group is dirty before moving", isGroupDirty(addressBook, id))
 
             // rename address book
@@ -127,7 +128,7 @@ class LocalAddressBookTest {
      */
     fun isContactDirty(adddressBook: LocalAddressBook, id: Long): Boolean {
         val uri = ContentUris.withAppendedId(adddressBook.rawContactsSyncUri(), id)
-        provider!!.query(uri, arrayOf(ContactsContract.RawContacts.DIRTY), null, null, null)?.use { cursor ->
+        provider.query(uri, arrayOf(ContactsContract.RawContacts.DIRTY), null, null, null)?.use { cursor ->
             if (cursor.moveToFirst())
                 return cursor.getInt(0) != 0
         }
@@ -143,7 +144,7 @@ class LocalAddressBookTest {
      */
     fun isGroupDirty(adddressBook: LocalAddressBook, id: Long): Boolean {
         val uri = ContentUris.withAppendedId(adddressBook.groupsSyncUri(), id)
-        provider!!.query(uri, arrayOf(ContactsContract.Groups.DIRTY), null, null, null)?.use { cursor ->
+        provider.query(uri, arrayOf(ContactsContract.Groups.DIRTY), null, null, null)?.use { cursor ->
             if (cursor.moveToFirst())
                 return cursor.getInt(0) != 0
         }

app/src/androidTest/kotlin/at/bitfire/davdroid/resource/LocalCalendarTest.kt

@@ -8,15 +8,18 @@ import android.accounts.Account
 import android.content.ContentProviderClient
 import android.content.ContentUris
 import android.content.ContentValues
+import android.content.Entity
 import android.provider.CalendarContract
 import android.provider.CalendarContract.ACCOUNT_TYPE_LOCAL
 import android.provider.CalendarContract.Events
+import androidx.core.content.contentValuesOf
 import androidx.test.platform.app.InstrumentationRegistry
-import at.bitfire.ical4android.AndroidEvent
 import at.bitfire.ical4android.Event
 import at.bitfire.ical4android.util.MiscUtils.asSyncAdapter
 import at.bitfire.ical4android.util.MiscUtils.closeCompat
+import at.bitfire.synctools.storage.calendar.AndroidCalendar
 import at.bitfire.synctools.storage.calendar.AndroidCalendarProvider
+import at.bitfire.synctools.storage.calendar.AndroidEvent2
 import at.bitfire.synctools.test.InitCalendarProviderRule
 import dagger.hilt.android.testing.HiltAndroidRule
 import dagger.hilt.android.testing.HiltAndroidTest
@@ -26,6 +29,8 @@ import net.fortuna.ical4j.model.property.RecurrenceId
 import net.fortuna.ical4j.model.property.Status
 import org.junit.After
 import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertNull
 import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
@@ -45,6 +50,7 @@ class LocalCalendarTest {
     lateinit var localCalendarFactory: LocalCalendar.Factory
 
     private val account = Account("LocalCalendarTest", ACCOUNT_TYPE_LOCAL)
+    private lateinit var androidCalendar: AndroidCalendar
     private lateinit var client: ContentProviderClient
     private lateinit var calendar: LocalCalendar
 
@@ -56,12 +62,13 @@ class LocalCalendarTest {
         client = context.contentResolver.acquireContentProviderClient(CalendarContract.AUTHORITY)!!
 
         val provider = AndroidCalendarProvider(account, client)
-        calendar = localCalendarFactory.create(provider.createAndGetCalendar(ContentValues()))
+        androidCalendar = provider.createAndGetCalendar(ContentValues())
+        calendar = localCalendarFactory.create(androidCalendar)
     }
 
     @After
     fun tearDown() {
-        calendar.androidCalendar.delete()
+        androidCalendar.delete()
         client.closeCompat()
     }
 
@@ -92,9 +99,15 @@ class LocalCalendarTest {
                 status = Status.VEVENT_CANCELLED
             })
         }
-        val localEvent = AndroidEvent(calendar.androidCalendar, event, "filename.ics", null, null, LocalResource.FLAG_REMOTELY_PRESENT)
-        localEvent.add()
-        val eventId = localEvent.id!!
+        calendar.add(
+            event = event,
+            fileName = "filename.ics",
+            eTag = null,
+            scheduleTag = null,
+            flags = LocalResource.FLAG_REMOTELY_PRESENT
+        )
+        val localEvent = calendar.findByName("filename.ics")!!
+        val eventId = localEvent.id
 
         // set event as dirty
         client.update(ContentUris.withAppendedId(Events.CONTENT_URI.asSyncAdapter(account), eventId), ContentValues(1).apply {
@@ -122,26 +135,102 @@ class LocalCalendarTest {
             summary = "Event with 3 instances"
             rRules.add(RRule("FREQ=DAILY;COUNT=3"))
         }
-        val localEvent = AndroidEvent(calendar.androidCalendar, event, "filename.ics", null, null, LocalResource.FLAG_REMOTELY_PRESENT)
-        localEvent.add()
-        val eventId = localEvent.id!!
+        calendar.add(
+            event = event,
+            fileName = "filename.ics",
+            eTag = null,
+            scheduleTag = null,
+            flags = LocalResource.FLAG_REMOTELY_PRESENT
+        )
+        val localEvent = calendar.findByName("filename.ics")!!
+        val eventUrl = androidCalendar.eventUri(localEvent.id)
 
         // set event as dirty
-        client.update(ContentUris.withAppendedId(Events.CONTENT_URI.asSyncAdapter(account), eventId), ContentValues(1).apply {
-            put(Events.DIRTY, 1)
-        }, null, null)
+        client.update(eventUrl, contentValuesOf(
+            Events.DIRTY to 1
+        ), null, null)
 
         // this method should mark the event as deleted
         calendar.deleteDirtyEventsWithoutInstances()
 
         // verify that event is not marked as deleted
-        client.query(
-            ContentUris.withAppendedId(Events.CONTENT_URI.asSyncAdapter(account), eventId),
-            arrayOf(Events.DELETED), null, null, null
-        )!!.use { cursor ->
+        client.query(eventUrl, arrayOf(Events.DELETED), null, null, null)!!.use { cursor ->
             cursor.moveToNext()
             assertEquals(0, cursor.getInt(0))
         }
     }
 
+    /**
+     * Verifies that [LocalCalendar.removeNotDirtyMarked] works as expected.
+     * @param contentValues values to set on the event. Required:
+     * - [Events._ID]
+     * - [Events.DIRTY]
+     */
+    private fun testRemoveNotDirtyMarked(contentValues: ContentValues) {
+        val id = androidCalendar.addEvent(Entity(
+            contentValuesOf(
+                Events.CALENDAR_ID to androidCalendar.id,
+                Events.DTSTART to System.currentTimeMillis(),
+                Events.DTEND to System.currentTimeMillis(),
+                Events.TITLE to "Some Event",
+                AndroidEvent2.COLUMN_FLAGS to 123
+            ).apply { putAll(contentValues) }
+        ))
+
+        calendar.removeNotDirtyMarked(123)
+
+        assertNull(androidCalendar.getEvent(id))
+    }
+
+    @Test
+    fun testRemoveNotDirtyMarked_IdLargerThanIntMaxValue() = testRemoveNotDirtyMarked(
+        contentValuesOf(Events._ID to Int.MAX_VALUE.toLong() + 10, Events.DIRTY to 0)
+    )
+
+    @Test
+    fun testRemoveNotDirtyMarked_DirtyIs0() = testRemoveNotDirtyMarked(
+        contentValuesOf(Events._ID to 1, Events.DIRTY to 0)
+    )
+
+    @Test
+    fun testRemoveNotDirtyMarked_DirtyNull() = testRemoveNotDirtyMarked(
+        contentValuesOf(Events._ID to 1, Events.DIRTY to null)
+    )
+
+    /**
+     * Verifies that [LocalCalendar.markNotDirty] works as expected.
+     * @param contentValues values to set on the event. Required:
+     * - [Events.DIRTY]
+     */
+    private fun testMarkNotDirty(contentValues: ContentValues) {
+        val id = androidCalendar.addEvent(Entity(
+            contentValuesOf(
+                Events.CALENDAR_ID to androidCalendar.id,
+                Events._ID to 1,
+                Events.DTSTART to System.currentTimeMillis(),
+                Events.DTEND to System.currentTimeMillis(),
+                Events.TITLE to "Some Event",
+                AndroidEvent2.COLUMN_FLAGS to 123
+            ).apply { putAll(contentValues) }
+        ))
+
+        val updated = calendar.markNotDirty(321)
+        assertEquals(1, updated)
+        assertEquals(321, androidCalendar.getEvent(id)?.flags)
+    }
+
+    @Test
+    fun test_markNotDirty_DirtyIs0() = testMarkNotDirty(
+        contentValuesOf(
+            Events.DIRTY to 0
+        )
+    )
+
+    @Test
+    fun test_markNotDirty_DirtyIsNull() = testMarkNotDirty(
+        contentValuesOf(
+            Events.DIRTY to null
+        )
+    )
+
 }

app/src/androidTest/kotlin/at/bitfire/davdroid/resource/LocalEventTest.kt

@@ -14,7 +14,6 @@ import android.provider.CalendarContract.ACCOUNT_TYPE_LOCAL
 import android.provider.CalendarContract.Events
 import androidx.test.platform.app.InstrumentationRegistry
 import androidx.test.rule.GrantPermissionRule
-import at.bitfire.ical4android.AndroidEvent
 import at.bitfire.ical4android.Event
 import at.bitfire.ical4android.util.MiscUtils.closeCompat
 import at.bitfire.synctools.storage.calendar.AndroidCalendarProvider
@@ -74,8 +73,15 @@ class LocalEventTest {
             dtStart = DtStart("20220120T010203Z")
             summary = "Event without uid"
         }
-        val localEvent = LocalEvent(AndroidEvent(calendar.androidCalendar, event, null))
-        localEvent.add()    // save it to calendar storage
+
+        calendar.add(
+            event = event,
+            fileName = "filename.ics",
+            eTag = null,
+            scheduleTag = null,
+            flags = LocalResource.FLAG_REMOTELY_PRESENT
+        )
+        val localEvent = calendar.findByName("filename.ics")!!
 
         // prepare for upload - this should generate a new random uuid, returned as filename
         val fileNameWithSuffix = localEvent.prepareForUpload()
@@ -102,8 +108,14 @@ class LocalEventTest {
             summary = "Event with normal uid"
             uid = "some-event@hostname.tld"     // old UID format, UUID would be new format
         }
-        val localEvent = LocalEvent(AndroidEvent(calendar.androidCalendar, event, null))
-        localEvent.add() // save it to calendar storage
+        calendar.add(
+            event = event,
+            fileName = "filename.ics",
+            eTag = null,
+            scheduleTag = null,
+            flags = LocalResource.FLAG_REMOTELY_PRESENT
+        )
+        val localEvent = calendar.findByName("filename.ics")!!
 
         // prepare for upload - this should use the UID for the file name
         val fileNameWithSuffix = localEvent.prepareForUpload()
@@ -129,8 +141,14 @@ class LocalEventTest {
             summary = "Event with funny uid"
             uid = "https://www.example.com/events/asdfewfe-cxyb-ewrws-sadfrwerxyvser-asdfxye-"
         }
-        val localEvent = LocalEvent(AndroidEvent(calendar.androidCalendar, event, null))
-        localEvent.add() // save it to calendar storage
+        calendar.add(
+            event = event,
+            fileName = "filename.ics",
+            eTag = null,
+            scheduleTag = null,
+            flags = LocalResource.FLAG_REMOTELY_PRESENT
+        )
+        val localEvent = calendar.findByName("filename.ics")!!
 
         // prepare for upload - this should generate a new random uuid, returned as filename
         val fileNameWithSuffix = localEvent.prepareForUpload()
@@ -181,8 +199,14 @@ class LocalEventTest {
                 status = Status.VEVENT_CANCELLED
             })
         }
-        val localEvent = LocalEvent(AndroidEvent(calendar.androidCalendar, event, "filename.ics", null, null, LocalResource.FLAG_REMOTELY_PRESENT))
-        localEvent.add()
+        calendar.add(
+            event = event,
+            fileName = "filename.ics",
+            eTag = null,
+            scheduleTag = null,
+            flags = LocalResource.FLAG_REMOTELY_PRESENT
+        )
+        val localEvent = calendar.findByName("filename.ics")!!
         val eventId = localEvent.id!!
 
         // set event as dirty
@@ -210,8 +234,14 @@ class LocalEventTest {
             summary = "Event with 3 instances"
             rRules.add(RRule("FREQ=DAILY;COUNT=3"))
         }
-        val localEvent = LocalEvent(AndroidEvent(calendar.androidCalendar, event, "filename.ics", null, null, LocalResource.FLAG_REMOTELY_PRESENT))
-        localEvent.add()
+        calendar.add(
+            event = event,
+            fileName = "filename.ics",
+            eTag = null,
+            scheduleTag = null,
+            flags = LocalResource.FLAG_REMOTELY_PRESENT
+        )
+        val localEvent = calendar.findByName("filename.ics")!!
         val eventId = localEvent.id!!
 
         // set event as dirty

app/src/androidTest/kotlin/at/bitfire/davdroid/resource/LocalGroupTest.kt

@@ -32,6 +32,7 @@ import org.junit.BeforeClass
 import org.junit.ClassRule
 import org.junit.Rule
 import org.junit.Test
+import java.util.Optional
 import javax.inject.Inject
 
 @HiltAndroidTest
@@ -164,7 +165,7 @@ class LocalGroupTest {
                 }
             )
 
-            group.clearDirty(null, null)
+            group.clearDirty(Optional.empty(), null)
 
             // check cached group membership
             ab.provider!!.query(
@@ -200,7 +201,7 @@ class LocalGroupTest {
                 }
             )
 
-            group.clearDirty(null, null)
+            group.clearDirty(Optional.empty(), null)
 
             // cached group membership should be gone
             ab.provider!!.query(

app/src/androidTest/kotlin/at/bitfire/davdroid/resource/LocalTestAddressBook.kt

@@ -10,7 +10,7 @@ import android.content.Context
 import at.bitfire.davdroid.repository.DavCollectionRepository
 import at.bitfire.davdroid.repository.DavServiceRepository
 import at.bitfire.davdroid.settings.AccountSettings
-import at.bitfire.davdroid.sync.SyncFrameworkIntegration
+import at.bitfire.davdroid.sync.adapter.SyncFrameworkIntegration
 import at.bitfire.vcard4android.GroupMethod
 import dagger.assisted.Assisted
 import dagger.assisted.AssistedFactory

app/src/androidTest/kotlin/at/bitfire/davdroid/servicedetection/CollectionListRefresherTest.kt

@@ -1,749 +0,0 @@
-/*
- * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
- */
-
-package at.bitfire.davdroid.servicedetection
-
-import android.security.NetworkSecurityPolicy
-import at.bitfire.davdroid.db.AppDatabase
-import at.bitfire.davdroid.db.Collection
-import at.bitfire.davdroid.db.HomeSet
-import at.bitfire.davdroid.db.Principal
-import at.bitfire.davdroid.db.Service
-import at.bitfire.davdroid.network.HttpClient
-import at.bitfire.davdroid.settings.Settings
-import at.bitfire.davdroid.settings.SettingsManager
-import dagger.hilt.android.testing.BindValue
-import dagger.hilt.android.testing.HiltAndroidRule
-import dagger.hilt.android.testing.HiltAndroidTest
-import io.mockk.every
-import io.mockk.impl.annotations.MockK
-import io.mockk.junit4.MockKRule
-import kotlinx.coroutines.test.runTest
-import okhttp3.mockwebserver.Dispatcher
-import okhttp3.mockwebserver.MockResponse
-import okhttp3.mockwebserver.MockWebServer
-import okhttp3.mockwebserver.RecordedRequest
-import org.junit.After
-import org.junit.Assert.assertEquals
-import org.junit.Assert.assertFalse
-import org.junit.Assert.assertTrue
-import org.junit.Assume
-import org.junit.Before
-import org.junit.Rule
-import org.junit.Test
-import java.util.logging.Logger
-import javax.inject.Inject
-
-@HiltAndroidTest
-class CollectionListRefresherTest {
-
-    @Inject
-    lateinit var db: AppDatabase
-
-    @Inject
-    lateinit var httpClientBuilder: HttpClient.Builder
-
-    @Inject
-    lateinit var logger: Logger
-
-    @Inject
-    lateinit var refresherFactory: CollectionListRefresher.Factory
-
-    @BindValue
-    @MockK(relaxed = true)
-    lateinit var settings: SettingsManager
-
-    @get:Rule
-    val hiltRule = HiltAndroidRule(this)
-
-    @get:Rule
-    val mockKRule = MockKRule(this)
-
-    private lateinit var client: HttpClient
-    private lateinit var mockServer: MockWebServer
-    private lateinit var service: Service
-
-    @Before
-    fun setUp() {
-        hiltRule.inject()
-
-        // Start mock web server
-        mockServer = MockWebServer().apply {
-            dispatcher = TestDispatcher(logger)
-            start()
-        }
-
-        // build HTTP client
-        client = httpClientBuilder.build()
-        Assume.assumeTrue(NetworkSecurityPolicy.getInstance().isCleartextTrafficPermitted)
-
-        // insert test service
-        val serviceId = db.serviceDao().insertOrReplace(
-            Service(id = 0, accountName = "test", type = Service.TYPE_CARDDAV, principal = null)
-        )
-        service = db.serviceDao().get(serviceId)!!
-    }
-
-    @After
-    fun tearDown() {
-        client.close()
-        mockServer.shutdown()
-    }
-
-
-    @Test
-    fun testDiscoverHomesets() {
-        val baseUrl = mockServer.url(PATH_CARDDAV + SUBPATH_PRINCIPAL)
-
-        // Query home sets
-        refresherFactory.create(service, client.okHttpClient).discoverHomesets(baseUrl)
-
-        // Check home set has been saved correctly to database
-        val savedHomesets = db.homeSetDao().getByService(service.id)
-        assertEquals(2, savedHomesets.size)
-
-        // Home set from current-user-principal
-        val personalHomeset = savedHomesets[1]
-        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL/"), personalHomeset.url)
-        assertEquals(service.id, personalHomeset.serviceId)
-        // personal should be true for homesets detected at first query of current-user-principal (Even if they occur in a group principal as well!!!)
-        assertEquals(true, personalHomeset.personal)
-
-        // Home set found in a group principal
-        val groupHomeset = savedHomesets[0]
-        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_HOMESET_NON_PERSONAL/"), groupHomeset.url)
-        assertEquals(service.id, groupHomeset.serviceId)
-        // personal should be false for homesets not detected at the first query of current-user-principal (IE. in groups)
-        assertEquals(false, groupHomeset.personal)
-    }
-
-
-    // refreshHomesetsAndTheirCollections
-
-    @Test
-    fun refreshHomesetsAndTheirCollections_addsNewCollection() = runTest {
-        // save homeset in DB
-        val homesetId = db.homeSetDao().insert(
-            HomeSet(id=0, service.id, true, mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL"))
-        )
-
-        // Refresh
-        refresherFactory.create(service, client.okHttpClient).refreshHomesetsAndTheirCollections()
-
-        // Check the collection defined in homeset is now in the database
-        assertEquals(
-            Collection(
-                1,
-                service.id,
-                homesetId,
-                1, // will have gotten an owner too
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
-                displayName = "My Contacts",
-                description = "My Contacts Description"
-            ),
-            db.collectionDao().getByService(service.id).first()
-        )
-    }
-
-    @Test
-    fun refreshHomesetsAndTheirCollections_updatesExistingCollection() {
-        // save "old" collection in DB
-        val collectionId = db.collectionDao().insertOrUpdateByUrl(
-            Collection(
-                0,
-                service.id,
-                null,
-                null,
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
-                displayName = "My Contacts",
-                description = "My Contacts Description"
-            )
-        )
-
-        // Refresh
-        refresherFactory.create(service, client.okHttpClient).refreshHomesetsAndTheirCollections()
-
-        // Check the collection got updated
-        assertEquals(
-            Collection(
-                collectionId,
-                service.id,
-                null,
-                null,
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
-                displayName = "My Contacts",
-                description = "My Contacts Description"
-            ),
-            db.collectionDao().get(collectionId)
-        )
-    }
-
-    @Test
-    fun refreshHomesetsAndTheirCollections_preservesCollectionFlags() {
-        // save "old" collection in DB - with set flags
-        val collectionId = db.collectionDao().insertOrUpdateByUrl(
-            Collection(
-                0,
-                service.id,
-                null,
-                null,
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
-                displayName = "My Contacts",
-                description = "My Contacts Description",
-                forceReadOnly = true,
-                sync = true
-            )
-        )
-
-        // Refresh
-        refresherFactory.create(service, client.okHttpClient).refreshHomesetsAndTheirCollections()
-
-        // Check the collection got updated
-        assertEquals(
-            Collection(
-                collectionId,
-                service.id,
-                null,
-                null,
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
-                displayName = "My Contacts",
-                description = "My Contacts Description",
-                forceReadOnly = true,
-                sync = true
-            ),
-            db.collectionDao().get(collectionId)
-        )
-    }
-
-    @Test
-    fun refreshHomesetsAndTheirCollections_marksRemovedCollectionsAsHomeless() {
-        // save homeset in DB - which is empty (zero address books) on the serverside
-        val homesetId = db.homeSetDao().insert(
-            HomeSet(id=0, service.id, true, mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_HOMESET_EMPTY"))
-        )
-
-        // place collection in DB - as part of the homeset
-        val collectionId = db.collectionDao().insertOrUpdateByUrl(
-            Collection(
-                0,
-                service.id,
-                homesetId,
-                null,
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/")
-            )
-        )
-
-        // Refresh - should mark collection as homeless, because serverside homeset is empty.
-        refresherFactory.create(service, client.okHttpClient).refreshHomesetsAndTheirCollections()
-
-        // Check the collection, is now marked as homeless
-        assertEquals(null, db.collectionDao().get(collectionId)!!.homeSetId)
-    }
-
-    @Test
-    fun refreshHomesetsAndTheirCollections_addsOwnerUrls() {
-        // save a homeset in DB
-        val homesetId = db.homeSetDao().insert(
-            HomeSet(id=0, service.id, true, mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL"))
-        )
-
-        // place collection in DB - as part of the homeset
-        val collectionId = db.collectionDao().insertOrUpdateByUrl(
-            Collection(
-                0,
-                service.id,
-                homesetId, // part of above home set
-                null,
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/")
-            )
-        )
-
-        // Refresh - homesets and their collections
-        assertEquals(0, db.principalDao().getByService(service.id).size)
-        refresherFactory.create(service, client.okHttpClient).refreshHomesetsAndTheirCollections()
-
-        // Check principal saved and the collection was updated with its reference
-        val principals = db.principalDao().getByService(service.id)
-        assertEquals(1, principals.size)
-        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL"), principals[0].url)
-        assertEquals(null, principals[0].displayName)
-        assertEquals(
-            principals[0].id,
-            db.collectionDao().get(collectionId)!!.ownerId
-        )
-    }
-
-
-    // refreshHomelessCollections
-
-    @Test
-    fun refreshHomelessCollections_updatesExistingCollection() {
-        // place homeless collection in DB
-        val collectionId = db.collectionDao().insertOrUpdateByUrl(
-            Collection(
-                0,
-                service.id,
-                null,
-                null,
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
-            )
-        )
-
-        // Refresh
-        refresherFactory.create(service, client.okHttpClient).refreshHomelessCollections()
-
-        // Check the collection got updated - with display name and description
-        assertEquals(
-            Collection(
-                collectionId,
-                service.id,
-                null,
-                1, // will have gotten an owner too
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
-                displayName = "My Contacts",
-                description = "My Contacts Description"
-            ),
-            db.collectionDao().get(collectionId)
-        )
-    }
-
-    @Test
-    fun refreshHomelessCollections_deletesInaccessibleCollections() {
-        // place homeless collection in DB - it is also inaccessible
-        val collectionId = db.collectionDao().insertOrUpdateByUrl(
-            Collection(
-                0,
-                service.id,
-                null,
-                null,
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_INACCESSIBLE")
-            )
-        )
-
-        // Refresh - should delete collection
-        refresherFactory.create(service, client.okHttpClient).refreshHomelessCollections()
-
-        // Check the collection got deleted
-        assertEquals(null, db.collectionDao().get(collectionId))
-    }
-
-    @Test
-    fun refreshHomelessCollections_addsOwnerUrls() {
-        // place homeless collection in DB
-        val collectionId = db.collectionDao().insertOrUpdateByUrl(
-            Collection(
-                0,
-                service.id,
-                null,
-                null,
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
-            )
-        )
-
-        // Refresh homeless collections
-        assertEquals(0, db.principalDao().getByService(service.id).size)
-        refresherFactory.create(service, client.okHttpClient).refreshHomelessCollections()
-
-        // Check principal saved and the collection was updated with its reference
-        val principals = db.principalDao().getByService(service.id)
-        assertEquals(1, principals.size)
-        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL"), principals[0].url)
-        assertEquals(null, principals[0].displayName)
-        assertEquals(
-            principals[0].id,
-            db.collectionDao().get(collectionId)!!.ownerId
-        )
-    }
-
-
-    // refreshPrincipals
-
-    @Test
-    fun refreshPrincipals_inaccessiblePrincipal() {
-        // place principal without display name in db
-        val principalId = db.principalDao().insert(
-            Principal(
-                0,
-                service.id,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL_INACCESSIBLE"), // no trailing slash
-                null // no display name for now
-            )
-        )
-        // add an associated collection - as the principal is rightfully removed otherwise
-        db.collectionDao().insertOrUpdateByUrl(
-            Collection(
-                0,
-                service.id,
-                null,
-                principalId, // create association with principal
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"), // with trailing slash
-            )
-        )
-
-        // Refresh principals
-        refresherFactory.create(service, client.okHttpClient).refreshPrincipals()
-
-        // Check principal was not updated
-        val principals = db.principalDao().getByService(service.id)
-        assertEquals(1, principals.size)
-        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL_INACCESSIBLE"), principals[0].url)
-        assertEquals(null, principals[0].displayName)
-    }
-
-    @Test
-    fun refreshPrincipals_updatesPrincipal() {
-        // place principal without display name in db
-        val principalId = db.principalDao().insert(
-            Principal(
-                0,
-                service.id,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL"), // no trailing slash
-                null // no display name for now
-            )
-        )
-        // add an associated collection - as the principal is rightfully removed otherwise
-        db.collectionDao().insertOrUpdateByUrl(
-            Collection(
-                0,
-                service.id,
-                null,
-                principalId, // create association with principal
-                Collection.TYPE_ADDRESSBOOK,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"), // with trailing slash
-            )
-        )
-
-        // Refresh principals
-        refresherFactory.create(service, client.okHttpClient).refreshPrincipals()
-
-        // Check principal now got a display name
-        val principals = db.principalDao().getByService(service.id)
-        assertEquals(1, principals.size)
-        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL"), principals[0].url)
-        assertEquals("Mr. Wobbles", principals[0].displayName)
-    }
-
-    @Test
-    fun refreshPrincipals_deletesPrincipalsWithoutCollections() {
-        // place principal without collections in DB
-        db.principalDao().insert(
-            Principal(
-                0,
-                service.id,
-                mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL_WITHOUT_COLLECTIONS/")
-            )
-        )
-
-        // Refresh principals - detecting it does not own collections
-        refresherFactory.create(service, client.okHttpClient).refreshPrincipals()
-
-        // Check principal was deleted
-        val principals = db.principalDao().getByService(service.id)
-        assertEquals(0, principals.size)
-    }
-
-    // Others
-
-    @Test
-    fun shouldPreselect_none() {
-        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_NONE
-        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns ""
-
-        val collection = Collection(
-            0,
-            service.id,
-            0,
-            type = Collection.TYPE_ADDRESSBOOK,
-            url = mockServer.url("/addressbook-homeset/addressbook/")
-        )
-        val homesets = listOf(
-            HomeSet(
-                id = 0,
-                serviceId = service.id,
-                personal = true,
-                url = mockServer.url("/addressbook-homeset/")
-            )
-        )
-
-        val refresher = refresherFactory.create(service, client.okHttpClient)
-        assertFalse(refresher.shouldPreselect(collection, homesets))
-    }
-
-    @Test
-    fun shouldPreselect_all() {
-        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_ALL
-        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns ""
-
-        val collection = Collection(
-            0,
-            service.id,
-            0,
-            type = Collection.TYPE_ADDRESSBOOK,
-            url = mockServer.url("/addressbook-homeset/addressbook/")
-        )
-        val homesets = listOf(
-            HomeSet(
-                id = 0,
-                serviceId = service.id,
-                personal = false,
-                url = mockServer.url("/addressbook-homeset/")
-            )
-        )
-
-        val refresher = refresherFactory.create(service, client.okHttpClient)
-        assertTrue(refresher.shouldPreselect(collection, homesets))
-    }
-
-    @Test
-    fun shouldPreselect_all_blacklisted() {
-        val url = mockServer.url("/addressbook-homeset/addressbook/")
-
-        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_ALL
-        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns url.toString()
-
-        val collection = Collection(
-            id = 0,
-            serviceId = service.id,
-            homeSetId = 0,
-            type = Collection.TYPE_ADDRESSBOOK,
-            url = url
-        )
-        val homesets = listOf(
-            HomeSet(
-                id = 0,
-                serviceId = service.id,
-                personal = false,
-                url = mockServer.url("/addressbook-homeset/")
-            )
-        )
-
-        val refresher = refresherFactory.create(service, client.okHttpClient)
-        assertFalse(refresher.shouldPreselect(collection, homesets))
-    }
-
-    @Test
-    fun shouldPreselect_personal_notPersonal() {
-        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_PERSONAL
-        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns ""
-
-        val collection = Collection(
-            id = 0,
-            serviceId = service.id,
-            homeSetId = 0,
-            type = Collection.TYPE_ADDRESSBOOK,
-            url = mockServer.url("/addressbook-homeset/addressbook/")
-        )
-        val homesets = listOf(
-            HomeSet(
-                id = 0,
-                serviceId = service.id,
-                personal = false,
-                url = mockServer.url("/addressbook-homeset/")
-            )
-        )
-
-        val refresher = refresherFactory.create(service, client.okHttpClient)
-        assertFalse(refresher.shouldPreselect(collection, homesets))
-    }
-
-    @Test
-    fun shouldPreselect_personal_isPersonal() {
-        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_PERSONAL
-        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns ""
-
-        val collection = Collection(
-            0,
-            service.id,
-            0,
-            type = Collection.TYPE_ADDRESSBOOK,
-            url = mockServer.url("/addressbook-homeset/addressbook/")
-        )
-        val homesets = listOf(
-            HomeSet(
-                id = 0,
-                serviceId = service.id,
-                personal = true,
-                url = mockServer.url("/addressbook-homeset/")
-            )
-        )
-
-        val refresher = refresherFactory.create(service, client.okHttpClient)
-        assertTrue(refresher.shouldPreselect(collection, homesets))
-    }
-
-    @Test
-    fun shouldPreselect_personal_isPersonalButBlacklisted() {
-        val collectionUrl = mockServer.url("/addressbook-homeset/addressbook/")
-
-        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_PERSONAL
-        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns collectionUrl.toString()
-
-        val collection = Collection(
-            id = 0,
-            serviceId = service.id,
-            homeSetId = 0,
-            type = Collection.TYPE_ADDRESSBOOK,
-            url = collectionUrl
-        )
-        val homesets = listOf(
-            HomeSet(
-                id = 0,
-                serviceId = service.id,
-                personal = true,
-                url = mockServer.url("/addressbook-homeset/")
-            )
-        )
-
-        val refresher = refresherFactory.create(service, client.okHttpClient)
-        assertFalse(refresher.shouldPreselect(collection, homesets))
-    }
-
-
-    companion object {
-
-        private const val PATH_CALDAV = "/caldav"
-        private const val PATH_CARDDAV = "/carddav"
-
-        private const val SUBPATH_PRINCIPAL = "/principal"
-        private const val SUBPATH_PRINCIPAL_INACCESSIBLE = "/inaccessible-principal"
-        private const val SUBPATH_PRINCIPAL_WITHOUT_COLLECTIONS = "/principal2"
-        private const val SUBPATH_GROUPPRINCIPAL_0 = "/groups/0"
-        private const val SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL = "/addressbooks-homeset"
-        private const val SUBPATH_ADDRESSBOOK_HOMESET_NON_PERSONAL = "/addressbooks-homeset-non-personal"
-        private const val SUBPATH_ADDRESSBOOK_HOMESET_EMPTY = "/addressbooks-homeset-empty"
-        private const val SUBPATH_ADDRESSBOOK = "/addressbooks/my-contacts"
-        private const val SUBPATH_ADDRESSBOOK_INACCESSIBLE = "/addressbooks/inaccessible-contacts"
-
-    }
-
-    class TestDispatcher(
-        private val logger: Logger
-    ): Dispatcher() {
-
-        override fun dispatch(request: RecordedRequest): MockResponse {
-            val path = request.path!!.trimEnd('/')
-
-            if (request.method.equals("PROPFIND", true)) {
-                val properties = when (path) {
-                    PATH_CALDAV,
-                    PATH_CARDDAV ->
-                        "<current-user-principal>" +
-                        "   <href>$path${SUBPATH_PRINCIPAL}</href>" +
-                        "</current-user-principal>"
-
-                    PATH_CARDDAV + SUBPATH_PRINCIPAL ->
-                        "<resourcetype><principal/></resourcetype>" +
-                        "<displayname>Mr. Wobbles</displayname>" +
-                        "<CARD:addressbook-home-set>" +
-                        "   <href>${PATH_CARDDAV}${SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL}</href>" +
-                        "</CARD:addressbook-home-set>" +
-                        "<group-membership>" +
-                        "   <href>${PATH_CARDDAV}${SUBPATH_GROUPPRINCIPAL_0}</href>" +
-                        "</group-membership>"
-
-                    PATH_CARDDAV + SUBPATH_PRINCIPAL_WITHOUT_COLLECTIONS ->
-                        "<CARD:addressbook-home-set>" +
-                        "   <href>${PATH_CARDDAV}${SUBPATH_ADDRESSBOOK_HOMESET_EMPTY}</href>" +
-                        "</CARD:addressbook-home-set>" +
-                        "<displayname>Mr. Wobbles Jr.</displayname>"
-
-                    PATH_CARDDAV + SUBPATH_GROUPPRINCIPAL_0 ->
-                        "<resourcetype><principal/></resourcetype>" +
-                        "<displayname>All address books</displayname>" +
-                        "<CARD:addressbook-home-set>" +
-                        "   <href>${PATH_CARDDAV}${SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL}</href>" +
-                        "   <href>${PATH_CARDDAV}${SUBPATH_ADDRESSBOOK_HOMESET_NON_PERSONAL}</href>" +
-                        "</CARD:addressbook-home-set>"
-
-                    PATH_CARDDAV + SUBPATH_ADDRESSBOOK,
-                    PATH_CARDDAV + SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL ->
-                        "<resourcetype>" +
-                        "   <collection/>" +
-                        "   <CARD:addressbook/>" +
-                        "</resourcetype>" +
-                        "<displayname>My Contacts</displayname>" +
-                        "<CARD:addressbook-description>My Contacts Description</CARD:addressbook-description>" +
-                        "<owner>" +
-                        "   <href>${PATH_CARDDAV + SUBPATH_PRINCIPAL}</href>" +
-                        "</owner>"
-
-                    PATH_CARDDAV + SUBPATH_ADDRESSBOOK_HOMESET_NON_PERSONAL ->
-                        "<resourcetype>" +
-                        "   <collection/>" +
-                        "   <CARD:addressbook/>" +
-                        "</resourcetype>" +
-                        "<displayname>Freds Contacts (not mine)</displayname>" +
-                        "<CARD:addressbook-description>Not personal contacts</CARD:addressbook-description>" +
-                        "<owner>" +
-                        "   <href>${PATH_CARDDAV + SUBPATH_PRINCIPAL}</href>" + // OK, user is allowed to own non-personal contacts
-                        "</owner>"
-
-                    PATH_CALDAV + SUBPATH_PRINCIPAL ->
-                        "<CAL:calendar-user-address-set>" +
-                        "  <href>urn:unknown-entry</href>" +
-                        "  <href>mailto:email1@example.com</href>" +
-                        "  <href>mailto:email2@example.com</href>" +
-                        "</CAL:calendar-user-address-set>"
-
-                    SUBPATH_ADDRESSBOOK_HOMESET_EMPTY -> ""
-
-                    else -> ""
-                }
-
-                var responseBody = ""
-                var responseCode = 207
-                when (path) {
-                    PATH_CARDDAV + SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL ->
-                        responseBody =
-                            "<multistatus xmlns='DAV:' xmlns:CARD='urn:ietf:params:xml:ns:carddav' xmlns:CAL='urn:ietf:params:xml:ns:caldav'>" +
-                            "<response>" +
-                            "   <href>${PATH_CARDDAV + SUBPATH_ADDRESSBOOK}</href>" +
-                            "   <propstat><prop>" +
-                                    properties +
-                            "   </prop></propstat>" +
-                            "   <status>HTTP/1.1 200 OK</status>" +
-                            "</response>" +
-                            "</multistatus>"
-
-                    PATH_CARDDAV + SUBPATH_PRINCIPAL_INACCESSIBLE,
-                    PATH_CARDDAV + SUBPATH_ADDRESSBOOK_INACCESSIBLE ->
-                        responseCode = 404
-
-                    else ->
-                        responseBody =
-                            "<multistatus xmlns='DAV:' xmlns:CARD='urn:ietf:params:xml:ns:carddav' xmlns:CAL='urn:ietf:params:xml:ns:caldav'>" +
-                            "<response>" +
-                            "   <href>$path</href>" +
-                            "   <propstat><prop>"+
-                                    properties +
-                            "   </prop></propstat>" +
-                            "</response>" +
-                            "</multistatus>"
-                }
-
-                logger.info("Queried: $path")
-                logger.info("Response: $responseBody")
-                return MockResponse()
-                    .setResponseCode(responseCode)
-                    .setBody(responseBody)
-            }
-
-            return MockResponse().setResponseCode(404)
-        }
-
-    }
-
-}

app/src/androidTest/kotlin/at/bitfire/davdroid/servicedetection/CollectionsWithoutHomeSetRefresherTest.kt

@@ -0,0 +1,222 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.servicedetection
+
+import android.security.NetworkSecurityPolicy
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.db.Collection
+import at.bitfire.davdroid.db.Service
+import at.bitfire.davdroid.network.HttpClient
+import at.bitfire.davdroid.settings.SettingsManager
+import dagger.hilt.android.testing.BindValue
+import dagger.hilt.android.testing.HiltAndroidRule
+import dagger.hilt.android.testing.HiltAndroidTest
+import io.mockk.impl.annotations.MockK
+import io.mockk.junit4.MockKRule
+import okhttp3.mockwebserver.Dispatcher
+import okhttp3.mockwebserver.MockResponse
+import okhttp3.mockwebserver.MockWebServer
+import okhttp3.mockwebserver.RecordedRequest
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assume
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import java.util.logging.Logger
+import javax.inject.Inject
+
+@HiltAndroidTest
+class CollectionsWithoutHomeSetRefresherTest {
+
+    @get:Rule
+    val hiltRule = HiltAndroidRule(this)
+
+    @get:Rule
+    val mockKRule = MockKRule(this)
+
+    @Inject
+    lateinit var db: AppDatabase
+
+    @Inject
+    lateinit var httpClientBuilder: HttpClient.Builder
+
+    @Inject
+    lateinit var logger: Logger
+
+    @Inject
+    lateinit var refresherFactory: CollectionsWithoutHomeSetRefresher.Factory
+
+    @BindValue
+    @MockK(relaxed = true)
+    lateinit var settings: SettingsManager
+
+    private lateinit var client: HttpClient
+    private lateinit var mockServer: MockWebServer
+    private lateinit var service: Service
+
+    @Before
+    fun setUp() {
+        hiltRule.inject()
+
+        // Start mock web server
+        mockServer = MockWebServer().apply {
+            dispatcher = TestDispatcher(logger)
+            start()
+        }
+
+        // build HTTP client
+        client = httpClientBuilder.build()
+        Assume.assumeTrue(NetworkSecurityPolicy.getInstance().isCleartextTrafficPermitted)
+
+        // insert test service
+        val serviceId = db.serviceDao().insertOrReplace(
+            Service(id = 0, accountName = "test", type = Service.TYPE_CARDDAV, principal = null)
+        )
+        service = db.serviceDao().get(serviceId)!!
+    }
+
+    @After
+    fun tearDown() {
+        client.close()
+        mockServer.shutdown()
+    }
+
+
+    // refreshCollectionsWithoutHomeSet
+
+    @Test
+    fun refreshCollectionsWithoutHomeSet_updatesExistingCollection() {
+        // place homeless collection in DB
+        val collectionId = db.collectionDao().insertOrUpdateByUrl(
+            Collection(
+                0,
+                service.id,
+                null,
+                null,
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
+            )
+        )
+
+        // Refresh
+        refresherFactory.create(service, client.okHttpClient).refreshCollectionsWithoutHomeSet()
+
+        // Check the collection got updated - with display name and description
+        assertEquals(
+            Collection(
+                collectionId,
+                service.id,
+                null,
+                1, // will have gotten an owner too
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
+                displayName = "My Contacts",
+                description = "My Contacts Description"
+            ),
+            db.collectionDao().get(collectionId)
+        )
+    }
+
+    @Test
+    fun refreshCollectionsWithoutHomeSet_deletesInaccessibleCollectionsWithoutHomeSet() {
+        // place homeless collection in DB - it is also inaccessible
+        val collectionId = db.collectionDao().insertOrUpdateByUrl(
+            Collection(
+                0,
+                service.id,
+                null,
+                null,
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_INACCESSIBLE")
+            )
+        )
+
+        // Refresh - should delete collection
+        refresherFactory.create(service, client.okHttpClient).refreshCollectionsWithoutHomeSet()
+
+        // Check the collection got deleted
+        assertEquals(null, db.collectionDao().get(collectionId))
+    }
+
+    @Test
+    fun refreshCollectionsWithoutHomeSet_addsOwnerUrls() {
+        // place homeless collection in DB
+        val collectionId = db.collectionDao().insertOrUpdateByUrl(
+            Collection(
+                0,
+                service.id,
+                null,
+                null,
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
+            )
+        )
+
+        // Refresh homeless collections
+        assertEquals(0, db.principalDao().getByService(service.id).size)
+        refresherFactory.create(service, client.okHttpClient).refreshCollectionsWithoutHomeSet()
+
+        // Check principal saved and the collection was updated with its reference
+        val principals = db.principalDao().getByService(service.id)
+        assertEquals(1, principals.size)
+        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL"), principals[0].url)
+        assertEquals(null, principals[0].displayName)
+        assertEquals(
+            principals[0].id,
+            db.collectionDao().get(collectionId)!!.ownerId
+        )
+    }
+
+
+    companion object {
+        private const val PATH_CARDDAV = "/carddav"
+        private const val SUBPATH_PRINCIPAL = "/principal"
+        private const val SUBPATH_ADDRESSBOOK = "/addressbooks/my-contacts"
+        private const val SUBPATH_ADDRESSBOOK_INACCESSIBLE = "/addressbooks/inaccessible-contacts"
+    }
+
+    class TestDispatcher(
+        private val logger: Logger
+    ): Dispatcher() {
+
+        override fun dispatch(request: RecordedRequest): MockResponse {
+            val path = request.path!!.trimEnd('/')
+            logger.info("${request.method} on $path")
+
+            if (request.method.equals("PROPFIND", true)) {
+                val properties = when (path) {
+                    PATH_CARDDAV + SUBPATH_ADDRESSBOOK ->
+                        "<resourcetype>" +
+                        "   <collection/>" +
+                        "   <CARD:addressbook/>" +
+                        "</resourcetype>" +
+                        "<displayname>My Contacts</displayname>" +
+                        "<CARD:addressbook-description>My Contacts Description</CARD:addressbook-description>" +
+                        "<owner>" +
+                        "   <href>${PATH_CARDDAV + SUBPATH_PRINCIPAL}</href>" +
+                        "</owner>"
+
+                    else -> ""
+                }
+
+                return MockResponse()
+                    .setResponseCode(207)
+                    .setBody("<multistatus xmlns='DAV:' xmlns:CARD='urn:ietf:params:xml:ns:carddav' xmlns:CAL='urn:ietf:params:xml:ns:caldav'>" +
+                            "<response>" +
+                            "   <href>$path</href>" +
+                            "   <propstat><prop>"+
+                            properties +
+                            "   </prop></propstat>" +
+                            "</response>" +
+                            "</multistatus>")
+            }
+
+            return MockResponse().setResponseCode(404)
+        }
+
+    }
+
+}

app/src/androidTest/kotlin/at/bitfire/davdroid/servicedetection/HomeSetRefresherTest.kt

@@ -0,0 +1,473 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.servicedetection
+
+import android.security.NetworkSecurityPolicy
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.db.Collection
+import at.bitfire.davdroid.db.HomeSet
+import at.bitfire.davdroid.db.Service
+import at.bitfire.davdroid.network.HttpClient
+import at.bitfire.davdroid.settings.Settings
+import at.bitfire.davdroid.settings.SettingsManager
+import dagger.hilt.android.testing.BindValue
+import dagger.hilt.android.testing.HiltAndroidRule
+import dagger.hilt.android.testing.HiltAndroidTest
+import io.mockk.every
+import io.mockk.impl.annotations.MockK
+import io.mockk.junit4.MockKRule
+import junit.framework.TestCase.assertFalse
+import junit.framework.TestCase.assertTrue
+import kotlinx.coroutines.test.runTest
+import okhttp3.mockwebserver.Dispatcher
+import okhttp3.mockwebserver.MockResponse
+import okhttp3.mockwebserver.MockWebServer
+import okhttp3.mockwebserver.RecordedRequest
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assume
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import java.util.logging.Logger
+import javax.inject.Inject
+
+@HiltAndroidTest
+class HomeSetRefresherTest {
+
+    @get:Rule
+    val hiltRule = HiltAndroidRule(this)
+
+    @get:Rule
+    val mockKRule = MockKRule(this)
+
+    @Inject
+    lateinit var db: AppDatabase
+
+    @Inject
+    lateinit var httpClientBuilder: HttpClient.Builder
+
+    @Inject
+    lateinit var logger: Logger
+
+    @Inject
+    lateinit var homeSetRefresherFactory: HomeSetRefresher.Factory
+
+    @BindValue
+    @MockK(relaxed = true)
+    lateinit var settings: SettingsManager
+
+    private lateinit var client: HttpClient
+    private lateinit var mockServer: MockWebServer
+    private lateinit var service: Service
+
+    @Before
+    fun setUp() {
+        hiltRule.inject()
+
+        // Start mock web server
+        mockServer = MockWebServer().apply {
+            dispatcher = TestDispatcher(logger)
+            start()
+        }
+
+        // build HTTP client
+        client = httpClientBuilder.build()
+        Assume.assumeTrue(NetworkSecurityPolicy.getInstance().isCleartextTrafficPermitted)
+
+        // insert test service
+        val serviceId = db.serviceDao().insertOrReplace(
+            Service(id = 0, accountName = "test", type = Service.TYPE_CARDDAV, principal = null)
+        )
+        service = db.serviceDao().get(serviceId)!!
+    }
+
+    @After
+    fun tearDown() {
+        client.close()
+        mockServer.shutdown()
+    }
+
+
+    // refreshHomesetsAndTheirCollections
+
+    @Test
+    fun refreshHomesetsAndTheirCollections_addsNewCollection() = runTest {
+        // save homeset in DB
+        val homesetId = db.homeSetDao().insert(
+            HomeSet(id = 0, service.id, true, mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL"))
+        )
+
+        // Refresh
+        homeSetRefresherFactory.create(service, client.okHttpClient)
+            .refreshHomesetsAndTheirCollections()
+
+        // Check the collection defined in homeset is now in the database
+        assertEquals(
+            Collection(
+                1,
+                service.id,
+                homesetId,
+                1, // will have gotten an owner too
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
+                displayName = "My Contacts",
+                description = "My Contacts Description"
+            ),
+            db.collectionDao().getByService(service.id).first()
+        )
+    }
+
+    @Test
+    fun refreshHomesetsAndTheirCollections_updatesExistingCollection() {
+        // save "old" collection in DB
+        val collectionId = db.collectionDao().insertOrUpdateByUrl(
+            Collection(
+                0,
+                service.id,
+                null,
+                null,
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
+                displayName = "My Contacts",
+                description = "My Contacts Description"
+            )
+        )
+
+        // Refresh
+        homeSetRefresherFactory.create(service, client.okHttpClient).refreshHomesetsAndTheirCollections()
+
+        // Check the collection got updated
+        assertEquals(
+            Collection(
+                collectionId,
+                service.id,
+                null,
+                null,
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
+                displayName = "My Contacts",
+                description = "My Contacts Description"
+            ),
+            db.collectionDao().get(collectionId)
+        )
+    }
+
+    @Test
+    fun refreshHomesetsAndTheirCollections_preservesCollectionFlags() {
+        // save "old" collection in DB - with set flags
+        val collectionId = db.collectionDao().insertOrUpdateByUrl(
+            Collection(
+                0,
+                service.id,
+                null,
+                null,
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
+                displayName = "My Contacts",
+                description = "My Contacts Description",
+                forceReadOnly = true,
+                sync = true
+            )
+        )
+
+        // Refresh
+        homeSetRefresherFactory.create(service, client.okHttpClient).refreshHomesetsAndTheirCollections()
+
+        // Check the collection got updated
+        assertEquals(
+            Collection(
+                collectionId,
+                service.id,
+                null,
+                null,
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"),
+                displayName = "My Contacts",
+                description = "My Contacts Description",
+                forceReadOnly = true,
+                sync = true
+            ),
+            db.collectionDao().get(collectionId)
+        )
+    }
+
+    @Test
+    fun refreshHomesetsAndTheirCollections_marksRemovedCollectionsAsHomeless() {
+        // save homeset in DB - which is empty (zero address books) on the serverside
+        val homesetId = db.homeSetDao().insert(
+            HomeSet(id = 0, service.id, true, mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_HOMESET_EMPTY"))
+        )
+
+        // place collection in DB - as part of the homeset
+        val collectionId = db.collectionDao().insertOrUpdateByUrl(
+            Collection(
+                0,
+                service.id,
+                homesetId,
+                null,
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/")
+            )
+        )
+
+        // Refresh - should mark collection as homeless, because serverside homeset is empty.
+        homeSetRefresherFactory.create(service, client.okHttpClient).refreshHomesetsAndTheirCollections()
+
+        // Check the collection, is now marked as homeless
+        assertEquals(null, db.collectionDao().get(collectionId)!!.homeSetId)
+    }
+
+    @Test
+    fun refreshHomesetsAndTheirCollections_addsOwnerUrls() {
+        // save a homeset in DB
+        val homesetId = db.homeSetDao().insert(
+            HomeSet(id = 0, service.id, true, mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL"))
+        )
+
+        // place collection in DB - as part of the homeset
+        val collectionId = db.collectionDao().insertOrUpdateByUrl(
+            Collection(
+                0,
+                service.id,
+                homesetId, // part of above home set
+                null,
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/")
+            )
+        )
+
+        // Refresh - homesets and their collections
+        assertEquals(0, db.principalDao().getByService(service.id).size)
+        homeSetRefresherFactory.create(service, client.okHttpClient).refreshHomesetsAndTheirCollections()
+
+        // Check principal saved and the collection was updated with its reference
+        val principals = db.principalDao().getByService(service.id)
+        assertEquals(1, principals.size)
+        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL"), principals[0].url)
+        assertEquals(null, principals[0].displayName)
+        assertEquals(
+            principals[0].id,
+            db.collectionDao().get(collectionId)!!.ownerId
+        )
+    }
+
+
+    // other
+
+    @Test
+    fun shouldPreselect_none() {
+        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_NONE
+        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns ""
+
+        val collection = Collection(
+            0,
+            service.id,
+            0,
+            type = Collection.TYPE_ADDRESSBOOK,
+            url = mockServer.url("/addressbook-homeset/addressbook/")
+        )
+        val homesets = listOf(
+            HomeSet(
+                id = 0,
+                serviceId = service.id,
+                personal = true,
+                url = mockServer.url("/addressbook-homeset/")
+            )
+        )
+
+        val refresher = homeSetRefresherFactory.create(service, client.okHttpClient)
+        assertFalse(refresher.shouldPreselect(collection, homesets))
+    }
+
+    @Test
+    fun shouldPreselect_all() {
+        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_ALL
+        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns ""
+
+        val collection = Collection(
+            0,
+            service.id,
+            0,
+            type = Collection.TYPE_ADDRESSBOOK,
+            url = mockServer.url("/addressbook-homeset/addressbook/")
+        )
+        val homesets = listOf(
+            HomeSet(
+                id = 0,
+                serviceId = service.id,
+                personal = false,
+                url = mockServer.url("/addressbook-homeset/")
+            )
+        )
+
+        val refresher = homeSetRefresherFactory.create(service, client.okHttpClient)
+        assertTrue(refresher.shouldPreselect(collection, homesets))
+    }
+
+    @Test
+    fun shouldPreselect_all_blacklisted() {
+        val url = mockServer.url("/addressbook-homeset/addressbook/")
+
+        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_ALL
+        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns url.toString()
+
+        val collection = Collection(
+            id = 0,
+            serviceId = service.id,
+            homeSetId = 0,
+            type = Collection.TYPE_ADDRESSBOOK,
+            url = url
+        )
+        val homesets = listOf(
+            HomeSet(
+                id = 0,
+                serviceId = service.id,
+                personal = false,
+                url = mockServer.url("/addressbook-homeset/")
+            )
+        )
+
+        val refresher = homeSetRefresherFactory.create(service, client.okHttpClient)
+        assertFalse(refresher.shouldPreselect(collection, homesets))
+    }
+
+    @Test
+    fun shouldPreselect_personal_notPersonal() {
+        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_PERSONAL
+        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns ""
+
+        val collection = Collection(
+            id = 0,
+            serviceId = service.id,
+            homeSetId = 0,
+            type = Collection.TYPE_ADDRESSBOOK,
+            url = mockServer.url("/addressbook-homeset/addressbook/")
+        )
+        val homesets = listOf(
+            HomeSet(
+                id = 0,
+                serviceId = service.id,
+                personal = false,
+                url = mockServer.url("/addressbook-homeset/")
+            )
+        )
+
+        val refresher = homeSetRefresherFactory.create(service, client.okHttpClient)
+        assertFalse(refresher.shouldPreselect(collection, homesets))
+    }
+
+    @Test
+    fun shouldPreselect_personal_isPersonal() {
+        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_PERSONAL
+        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns ""
+
+        val collection = Collection(
+            0,
+            service.id,
+            0,
+            type = Collection.TYPE_ADDRESSBOOK,
+            url = mockServer.url("/addressbook-homeset/addressbook/")
+        )
+        val homesets = listOf(
+            HomeSet(
+                id = 0,
+                serviceId = service.id,
+                personal = true,
+                url = mockServer.url("/addressbook-homeset/")
+            )
+        )
+
+        val refresher = homeSetRefresherFactory.create(service, client.okHttpClient)
+        assertTrue(refresher.shouldPreselect(collection, homesets))
+    }
+
+    @Test
+    fun shouldPreselect_personal_isPersonalButBlacklisted() {
+        val collectionUrl = mockServer.url("/addressbook-homeset/addressbook/")
+
+        every { settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS) } returns Settings.PRESELECT_COLLECTIONS_PERSONAL
+        every { settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED) } returns collectionUrl.toString()
+
+        val collection = Collection(
+            id = 0,
+            serviceId = service.id,
+            homeSetId = 0,
+            type = Collection.TYPE_ADDRESSBOOK,
+            url = collectionUrl
+        )
+        val homesets = listOf(
+            HomeSet(
+                id = 0,
+                serviceId = service.id,
+                personal = true,
+                url = mockServer.url("/addressbook-homeset/")
+            )
+        )
+
+        val refresher = homeSetRefresherFactory.create(service, client.okHttpClient)
+        assertFalse(refresher.shouldPreselect(collection, homesets))
+    }
+
+
+    companion object {
+
+        private const val PATH_CARDDAV = "/carddav"
+
+        private const val SUBPATH_PRINCIPAL = "/principal"
+        private const val SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL = "/addressbooks-homeset"
+        private const val SUBPATH_ADDRESSBOOK_HOMESET_EMPTY = "/addressbooks-homeset-empty"
+        private const val SUBPATH_ADDRESSBOOK = "/addressbooks/my-contacts"
+
+    }
+
+    class TestDispatcher(
+        private val logger: Logger
+    ) : Dispatcher() {
+
+        override fun dispatch(request: RecordedRequest): MockResponse {
+            val path = request.path!!.trimEnd('/')
+
+            if (request.method.equals("PROPFIND", true)) {
+                val properties = when (path) {
+
+                    PATH_CARDDAV + SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL ->
+                        "<resourcetype>" +
+                                "   <collection/>" +
+                                "   <CARD:addressbook/>" +
+                                "</resourcetype>" +
+                                "<displayname>My Contacts</displayname>" +
+                                "<CARD:addressbook-description>My Contacts Description</CARD:addressbook-description>" +
+                                "<owner>" +
+                                "   <href>${PATH_CARDDAV + SUBPATH_PRINCIPAL}</href>" +
+                                "</owner>"
+
+                    SUBPATH_ADDRESSBOOK_HOMESET_EMPTY -> ""
+
+                    else -> ""
+                }
+
+                logger.info("Queried: $path")
+                return MockResponse()
+                    .setResponseCode(207)
+                    .setBody(
+                        "<multistatus xmlns='DAV:' xmlns:CARD='urn:ietf:params:xml:ns:carddav' xmlns:CAL='urn:ietf:params:xml:ns:caldav'>" +
+                                "<response>" +
+                                "   <href>${PATH_CARDDAV + SUBPATH_ADDRESSBOOK}</href>" +
+                                "   <propstat><prop>" +
+                                properties +
+                                "   </prop></propstat>" +
+                                "   <status>HTTP/1.1 200 OK</status>" +
+                                "</response>" +
+                                "</multistatus>"
+                    )
+            }
+
+            return MockResponse().setResponseCode(404)
+        }
+
+    }
+
+}

app/src/androidTest/kotlin/at/bitfire/davdroid/servicedetection/PrincipalsRefresherTest.kt

@@ -0,0 +1,236 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.servicedetection
+
+import android.security.NetworkSecurityPolicy
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.db.Collection
+import at.bitfire.davdroid.db.Principal
+import at.bitfire.davdroid.db.Service
+import at.bitfire.davdroid.network.HttpClient
+import at.bitfire.davdroid.settings.SettingsManager
+import dagger.hilt.android.testing.BindValue
+import dagger.hilt.android.testing.HiltAndroidRule
+import dagger.hilt.android.testing.HiltAndroidTest
+import io.mockk.impl.annotations.MockK
+import io.mockk.junit4.MockKRule
+import junit.framework.TestCase.assertEquals
+import okhttp3.mockwebserver.Dispatcher
+import okhttp3.mockwebserver.MockResponse
+import okhttp3.mockwebserver.MockWebServer
+import okhttp3.mockwebserver.RecordedRequest
+import org.junit.After
+import org.junit.Assume
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import java.util.logging.Logger
+import javax.inject.Inject
+
+@HiltAndroidTest
+class PrincipalsRefresherTest {
+
+    @Inject
+    lateinit var db: AppDatabase
+
+    @Inject
+    lateinit var httpClientBuilder: HttpClient.Builder
+
+    @Inject
+    lateinit var logger: Logger
+
+    @Inject
+    lateinit var principalsRefresher: PrincipalsRefresher.Factory
+
+    @BindValue
+    @MockK(relaxed = true)
+    lateinit var settings: SettingsManager
+
+    @get:Rule
+    val hiltRule = HiltAndroidRule(this)
+
+    @get:Rule
+    val mockKRule = MockKRule(this)
+
+    private lateinit var client: HttpClient
+    private lateinit var mockServer: MockWebServer
+    private lateinit var service: Service
+
+    @Before
+    fun setUp() {
+        hiltRule.inject()
+
+        // Start mock web server
+        mockServer = MockWebServer().apply {
+            dispatcher = TestDispatcher(logger)
+            start()
+        }
+
+        // build HTTP client
+        client = httpClientBuilder.build()
+        Assume.assumeTrue(NetworkSecurityPolicy.getInstance().isCleartextTrafficPermitted)
+
+        // insert test service
+        val serviceId = db.serviceDao().insertOrReplace(
+            Service(id = 0, accountName = "test", type = Service.TYPE_CARDDAV, principal = null)
+        )
+        service = db.serviceDao().get(serviceId)!!
+    }
+
+    @After
+    fun tearDown() {
+        client.close()
+        mockServer.shutdown()
+    }
+
+
+    @Test
+    fun refreshPrincipals_inaccessiblePrincipal() {
+        // place principal without display name in db
+        val principalId = db.principalDao().insert(
+            Principal(
+                0,
+                service.id,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL_INACCESSIBLE"), // no trailing slash
+                null // no display name for now
+            )
+        )
+        // add an associated collection - as the principal is rightfully removed otherwise
+        db.collectionDao().insertOrUpdateByUrl(
+            Collection(
+                0,
+                service.id,
+                null,
+                principalId, // create association with principal
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"), // with trailing slash
+            )
+        )
+
+        // Refresh principals
+        principalsRefresher.create(service, client.okHttpClient).refreshPrincipals()
+
+        // Check principal was not updated
+        val principals = db.principalDao().getByService(service.id)
+        assertEquals(1, principals.size)
+        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL_INACCESSIBLE"), principals[0].url)
+        assertEquals(null, principals[0].displayName)
+    }
+
+    @Test
+    fun refreshPrincipals_updatesPrincipal() {
+        // place principal without display name in db
+        val principalId = db.principalDao().insert(
+            Principal(
+                0,
+                service.id,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL"), // no trailing slash
+                null // no display name for now
+            )
+        )
+        // add an associated collection - as the principal is rightfully removed otherwise
+        db.collectionDao().insertOrUpdateByUrl(
+            Collection(
+                0,
+                service.id,
+                null,
+                principalId, // create association with principal
+                Collection.TYPE_ADDRESSBOOK,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK/"), // with trailing slash
+            )
+        )
+
+        // Refresh principals
+        principalsRefresher.create(service, client.okHttpClient).refreshPrincipals()
+
+        // Check principal now got a display name
+        val principals = db.principalDao().getByService(service.id)
+        assertEquals(1, principals.size)
+        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL"), principals[0].url)
+        assertEquals("Mr. Wobbles", principals[0].displayName)
+    }
+
+    @Test
+    fun refreshPrincipals_deletesPrincipalsWithoutCollections() {
+        // place principal without collections in DB
+        db.principalDao().insert(
+            Principal(
+                0,
+                service.id,
+                mockServer.url("$PATH_CARDDAV$SUBPATH_PRINCIPAL_WITHOUT_COLLECTIONS/")
+            )
+        )
+
+        // Refresh principals - detecting it does not own collections
+        principalsRefresher.create(service, client.okHttpClient).refreshPrincipals()
+
+        // Check principal was deleted
+        val principals = db.principalDao().getByService(service.id)
+        assertEquals(0, principals.size)
+    }
+
+
+    companion object {
+
+        private const val PATH_CARDDAV = "/carddav"
+
+        private const val SUBPATH_PRINCIPAL = "/principal"
+        private const val SUBPATH_PRINCIPAL_INACCESSIBLE = "/inaccessible-principal"
+        private const val SUBPATH_PRINCIPAL_WITHOUT_COLLECTIONS = "/principal2"
+        private const val SUBPATH_GROUPPRINCIPAL_0 = "/groups/0"
+        private const val SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL = "/addressbooks-homeset"
+        private const val SUBPATH_ADDRESSBOOK_HOMESET_EMPTY = "/addressbooks-homeset-empty"
+        private const val SUBPATH_ADDRESSBOOK = "/addressbooks/my-contacts"
+
+    }
+
+    class TestDispatcher(
+        private val logger: Logger
+    ) : Dispatcher() {
+
+        override fun dispatch(request: RecordedRequest): MockResponse {
+            val path = request.path!!.trimEnd('/')
+
+            if (request.method.equals("PROPFIND", true)) {
+                val properties = when (path) {
+
+                    PATH_CARDDAV + SUBPATH_PRINCIPAL ->
+                        "<resourcetype><principal/></resourcetype>" +
+                                "<displayname>Mr. Wobbles</displayname>" + "<CARD:addressbook-home-set>" + "   <href>${PATH_CARDDAV}${SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL}</href>" + "</CARD:addressbook-home-set>" + "<group-membership>" + "   <href>${PATH_CARDDAV}${SUBPATH_GROUPPRINCIPAL_0}</href>" +
+                                "</group-membership>"
+
+                    PATH_CARDDAV + SUBPATH_PRINCIPAL_WITHOUT_COLLECTIONS ->
+                        "<CARD:addressbook-home-set>" +
+                                "   <href>${PATH_CARDDAV}${SUBPATH_ADDRESSBOOK_HOMESET_EMPTY}</href>" +
+                                "</CARD:addressbook-home-set>" +
+                                "<displayname>Mr. Wobbles Jr.</displayname>"
+
+
+                    SUBPATH_ADDRESSBOOK_HOMESET_EMPTY -> ""
+
+                    else -> ""
+                }
+
+                logger.info("Queried: $path")
+                return MockResponse()
+                    .setResponseCode(207)
+                    .setBody(
+                        "<multistatus xmlns='DAV:' xmlns:CARD='urn:ietf:params:xml:ns:carddav' xmlns:CAL='urn:ietf:params:xml:ns:caldav'>" +
+                                "<response>" +
+                                "   <href>$path</href>" +
+                                "   <propstat><prop>" +
+                                properties +
+                                "   </prop></propstat>" +
+                                "</response>" +
+                                "</multistatus>"
+                    )
+            }
+
+            return MockResponse().setResponseCode(404)
+        }
+
+    }
+
+}

app/src/androidTest/kotlin/at/bitfire/davdroid/servicedetection/ServiceRefresherTest.kt

@@ -0,0 +1,163 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.servicedetection
+
+import android.security.NetworkSecurityPolicy
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.db.Service
+import at.bitfire.davdroid.network.HttpClient
+import dagger.hilt.android.testing.HiltAndroidRule
+import dagger.hilt.android.testing.HiltAndroidTest
+import okhttp3.mockwebserver.Dispatcher
+import okhttp3.mockwebserver.MockResponse
+import okhttp3.mockwebserver.MockWebServer
+import okhttp3.mockwebserver.RecordedRequest
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assume
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import java.util.logging.Logger
+import javax.inject.Inject
+
+@HiltAndroidTest
+class ServiceRefresherTest {
+
+    @get:Rule
+    val hiltRule = HiltAndroidRule(this)
+
+    @Inject
+    lateinit var db: AppDatabase
+
+    @Inject
+    lateinit var httpClientBuilder: HttpClient.Builder
+
+    @Inject
+    lateinit var logger: Logger
+
+    @Inject
+    lateinit var serviceRefresherFactory: ServiceRefresher.Factory
+
+    private lateinit var client: HttpClient
+    private lateinit var mockServer: MockWebServer
+    private lateinit var service: Service
+
+    @Before
+    fun setUp() {
+        hiltRule.inject()
+
+        // Start mock web server
+        mockServer = MockWebServer().apply {
+            dispatcher = TestDispatcher(logger)
+            start()
+        }
+
+        // build HTTP client
+        client = httpClientBuilder.build()
+        Assume.assumeTrue(NetworkSecurityPolicy.getInstance().isCleartextTrafficPermitted)
+
+        // insert test service
+        val serviceId = db.serviceDao().insertOrReplace(
+            Service(id = 0, accountName = "test", type = Service.TYPE_CARDDAV, principal = null)
+        )
+        service = db.serviceDao().get(serviceId)!!
+    }
+
+    @After
+    fun tearDown() {
+        client.close()
+        mockServer.shutdown()
+    }
+
+
+    @Test
+    fun testDiscoverHomesets() {
+        val baseUrl = mockServer.url(PATH_CARDDAV + SUBPATH_PRINCIPAL)
+
+        // Query home sets
+        serviceRefresherFactory.create(service, client.okHttpClient)
+            .discoverHomesets(baseUrl)
+
+        // Check home set has been saved correctly to database
+        val savedHomesets = db.homeSetDao().getByService(service.id)
+        assertEquals(2, savedHomesets.size)
+
+        // Home set from current-user-principal
+        val personalHomeset = savedHomesets[1]
+        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL/"), personalHomeset.url)
+        assertEquals(service.id, personalHomeset.serviceId)
+        // personal should be true for homesets detected at first query of current-user-principal (Even if they occur in a group principal as well!!!)
+        assertEquals(true, personalHomeset.personal)
+
+        // Home set found in a group principal
+        val groupHomeset = savedHomesets[0]
+        assertEquals(mockServer.url("$PATH_CARDDAV$SUBPATH_ADDRESSBOOK_HOMESET_NON_PERSONAL/"), groupHomeset.url)
+        assertEquals(service.id, groupHomeset.serviceId)
+        // personal should be false for homesets not detected at the first query of current-user-principal (IE. in groups)
+        assertEquals(false, groupHomeset.personal)
+    }
+
+
+    companion object {
+        private const val PATH_CARDDAV = "/carddav"
+
+        private const val SUBPATH_PRINCIPAL = "/principal"
+        private const val SUBPATH_GROUPPRINCIPAL_0 = "/groups/0"
+        private const val SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL = "/addressbooks-homeset"
+        private const val SUBPATH_ADDRESSBOOK_HOMESET_NON_PERSONAL = "/addressbooks-homeset-non-personal"
+
+    }
+
+    class TestDispatcher(
+        private val logger: Logger
+    ) : Dispatcher() {
+
+        override fun dispatch(request: RecordedRequest): MockResponse {
+            val path = request.path!!.trimEnd('/')
+            logger.info("Query: ${request.method} on $path ")
+
+            if (request.method.equals("PROPFIND", true)) {
+                val properties = when (path) {
+                    PATH_CARDDAV + SUBPATH_PRINCIPAL ->
+                        "<resourcetype><principal/></resourcetype>" +
+                                "<displayname>Mr. Wobbles</displayname>" +
+                                "<CARD:addressbook-home-set>" +
+                                "   <href>${PATH_CARDDAV}${SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL}</href>" +
+                                "</CARD:addressbook-home-set>" +
+                                "<group-membership>" +
+                                "   <href>${PATH_CARDDAV}${SUBPATH_GROUPPRINCIPAL_0}</href>" +
+                                "</group-membership>"
+
+                    PATH_CARDDAV + SUBPATH_GROUPPRINCIPAL_0 ->
+                        "<resourcetype><principal/></resourcetype>" +
+                                "<displayname>All address books</displayname>" +
+                                "<CARD:addressbook-home-set>" +
+                                "   <href>${PATH_CARDDAV}${SUBPATH_ADDRESSBOOK_HOMESET_PERSONAL}</href>" +
+                                "   <href>${PATH_CARDDAV}${SUBPATH_ADDRESSBOOK_HOMESET_NON_PERSONAL}</href>" +
+                                "</CARD:addressbook-home-set>"
+
+                    else -> ""
+                }
+                return MockResponse()
+                    .setResponseCode(207)
+                    .setBody(
+                        "<multistatus xmlns='DAV:' xmlns:CARD='urn:ietf:params:xml:ns:carddav' xmlns:CAL='urn:ietf:params:xml:ns:caldav'>" +
+                                "<response>" +
+                                "   <href>$path</href>" +
+                                "   <propstat><prop>" +
+                                properties +
+                                "   </prop></propstat>" +
+                                "</response>" +
+                                "</multistatus>"
+                    )
+            }
+
+            return MockResponse().setResponseCode(404)
+        }
+
+    }
+
+}

app/src/androidTest/kotlin/at/bitfire/davdroid/sync/AndroidSyncFrameworkTest.kt

@@ -0,0 +1,230 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.sync
+
+import android.accounts.Account
+import android.content.ContentResolver
+import android.content.Context
+import android.content.SyncRequest
+import android.os.Bundle
+import android.provider.CalendarContract
+import androidx.test.filters.SdkSuppress
+import at.bitfire.davdroid.sync.account.TestAccount
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.android.testing.HiltAndroidRule
+import dagger.hilt.android.testing.HiltAndroidTest
+import io.mockk.junit4.MockKRule
+import junit.framework.AssertionFailedError
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.withTimeout
+import org.junit.After
+import org.junit.AfterClass
+import org.junit.Before
+import org.junit.BeforeClass
+import org.junit.Rule
+import org.junit.Test
+import java.util.Collections
+import java.util.LinkedList
+import java.util.logging.Logger
+import javax.inject.Inject
+import kotlin.time.Duration.Companion.seconds
+
+@HiltAndroidTest
+class AndroidSyncFrameworkTest {
+
+    @get:Rule
+    val hiltRule = HiltAndroidRule(this)
+
+    @get:Rule
+    val mockkRule = MockKRule(this)
+
+    @Inject
+    @ApplicationContext
+    lateinit var context: Context
+
+    @Inject
+    lateinit var logger: Logger
+
+    lateinit var account: Account
+    val authority = CalendarContract.AUTHORITY
+
+    private lateinit var stateChangeListener: Any
+    private val recordedStates = Collections.synchronizedList(LinkedList<State>())
+
+    @Before
+    fun setUp() {
+        hiltRule.inject()
+
+        account = TestAccount.create()
+
+        // Enable sync globally and for the test account
+        ContentResolver.setIsSyncable(account, authority, 1)
+
+        // Remember states the sync framework reports as pairs of (sync pending, sync active).
+        recordedStates.clear()
+        onStatusChanged(0)      // record first entry (pending = false, active = false)
+        stateChangeListener = ContentResolver.addStatusChangeListener(
+            ContentResolver.SYNC_OBSERVER_TYPE_PENDING or ContentResolver.SYNC_OBSERVER_TYPE_ACTIVE,
+            ::onStatusChanged
+        )
+    }
+
+    @After
+    fun tearDown() {
+        ContentResolver.removeStatusChangeListener(stateChangeListener)
+        TestAccount.remove(account)
+    }
+
+
+    /**
+     * Correct behaviour of the sync framework on Android 13 and below.
+     * Pending state is correctly reflected
+     */
+    @SdkSuppress(maxSdkVersion = 33)
+    @Test
+    fun testVerifySyncAlwaysPending_correctBehaviour_android13() {
+        verifySyncStates(
+            listOf(
+                State(pending = false, active = false),                 // no sync pending or active
+                State(pending = true, active = false, optional = true), // sync becomes pending
+                State(pending = true, active = true),                   // ... and pending and active at the same time
+                State(pending = false, active = true),                  // ... and then only active
+                State(pending = false, active = false)                  // sync finished
+            )
+        )
+    }
+
+    /**
+     * Wrong behaviour of the sync framework on Android 14+.
+     * Pending state stays true forever (after initial run), active state behaves correctly
+     */
+    @SdkSuppress(minSdkVersion = 34 /*, maxSdkVersion = 36 */)
+    @Test
+    fun testVerifySyncAlwaysPending_wrongBehaviour_android14() {
+        verifySyncStates(
+            listOf(
+                State(pending = false, active = false),                 // no sync pending or active
+                State(pending = true, active = false, optional = true), // sync becomes pending
+                State(pending = true, active = true),                   // ... and pending and active at the same time
+                State(pending = true, active = false)                   // ... and finishes, but stays pending
+            )
+        )
+    }
+
+
+    // helpers
+
+    private fun syncRequest() = SyncRequest.Builder()
+        .setSyncAdapter(account, authority)
+        .syncOnce()
+        .setExtras(Bundle())    // needed for Android 9
+        .setExpedited(true)     // sync request will be scheduled at the front of the sync request queue
+        .setManual(true)        // equivalent of setting both SYNC_EXTRAS_IGNORE_SETTINGS and SYNC_EXTRAS_IGNORE_BACKOFF
+        .build()
+
+    /**
+     * Verifies that the given expected states match the recorded states.
+     */
+    private fun verifySyncStates(expectedStates: List<State>) = runBlocking {
+        // We use runBlocking for these tests because it uses the default dispatcher
+        // which does not auto-advance virtual time and we need real system time to
+        // test the sync framework behavior.
+
+        ContentResolver.requestSync(syncRequest())
+
+        // Even though the always-pending-bug is present on Android 14+, the sync active
+        // state behaves correctly, so we can record the state changes as pairs (pending,
+        // active) and expect a certain sequence of state pairs to verify the presence or
+        // absence of the bug on different Android versions.
+        withTimeout(60.seconds) { // Usually takes less than 30 seconds
+            while (recordedStates.size < expectedStates.size) {
+                // verify already known states
+                if (recordedStates.isNotEmpty())
+                    assertStatesEqual(expectedStates.subList(0, recordedStates.size), recordedStates)
+
+                delay(500) // avoid busy-waiting
+            }
+
+            assertStatesEqual(expectedStates, recordedStates)
+        }
+    }
+
+    /**
+     * Asserts whether [actualStates] and [expectedStates] are the same, under the condition
+     * that expected states with the [State.optional] flag can be skipped.
+     */
+    private fun assertStatesEqual(expectedStates: List<State>, actualStates: List<State>) {
+        fun fail() {
+            throw AssertionFailedError("Expected states=$expectedStates, actual=$actualStates")
+        }
+
+        // iterate through entries
+        val expectedIterator = expectedStates.iterator()
+        for (actual in actualStates) {
+            if (!expectedIterator.hasNext())
+                fail()
+            var expected = expectedIterator.next()
+
+            // skip optional expected entries if they don't match the actual entry
+            while (!actual.stateEquals(expected) && expected.optional) {
+                if (!expectedIterator.hasNext())
+                    fail()
+                expected = expectedIterator.next()
+            }
+
+            if (!actual.stateEquals(expected))
+                fail()
+        }
+    }
+
+
+    // SyncStatusObserver implementation and data class
+
+    fun onStatusChanged(which: Int) {
+        val state = State(
+            pending = ContentResolver.isSyncPending(account, authority),
+            active = ContentResolver.isSyncActive(account, authority)
+        )
+        synchronized(recordedStates) {
+            if (recordedStates.lastOrNull() != state) {
+                logger.info("$account syncState = $state")
+                recordedStates += state
+            }
+        }
+    }
+
+    data class State(
+        val pending: Boolean,
+        val active: Boolean,
+        val optional: Boolean = false
+    ) {
+        fun stateEquals(other: State) =
+            pending == other.pending && active == other.active
+    }
+
+
+    companion object {
+
+        var globalAutoSyncBeforeTest = false
+
+        @BeforeClass
+        @JvmStatic
+        fun before() {
+            globalAutoSyncBeforeTest = ContentResolver.getMasterSyncAutomatically()
+
+            // We'll request syncs explicitly and with SYNC_EXTRAS_IGNORE_SETTINGS
+            ContentResolver.setMasterSyncAutomatically(false)
+        }
+
+        @AfterClass
+        @JvmStatic
+        fun after() {
+            ContentResolver.setMasterSyncAutomatically(globalAutoSyncBeforeTest)
+        }
+
+    }
+
+}

app/src/androidTest/kotlin/at/bitfire/davdroid/sync/FakeSyncAdapter.kt

@@ -0,0 +1,51 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.sync
+
+import android.accounts.Account
+import android.content.AbstractThreadedSyncAdapter
+import android.content.ContentProviderClient
+import android.content.Context
+import android.content.SyncResult
+import android.os.Bundle
+import android.os.IBinder
+import at.bitfire.davdroid.sync.adapter.SyncAdapter
+import dagger.hilt.android.qualifiers.ApplicationContext
+import java.util.logging.Level
+import java.util.logging.Logger
+import javax.inject.Inject
+
+class FakeSyncAdapter @Inject constructor(
+    @ApplicationContext context: Context,
+    private val logger: Logger
+): AbstractThreadedSyncAdapter(context, true), SyncAdapter {
+
+    init {
+        logger.info("FakeSyncAdapter created")
+    }
+
+    override fun onPerformSync(account: Account, extras: Bundle, authority: String, provider: ContentProviderClient, syncResult: SyncResult) {
+        logger.log(
+            Level.INFO,
+            "onPerformSync(account=$account, extras=$extras, authority=$authority, syncResult=$syncResult)",
+            extras.keySet().map { key -> "extras[$key] = ${extras[key]}" }
+        )
+
+        // fake 5 sec sync
+        try {
+            Thread.sleep(5000)
+        } catch (_: InterruptedException) {
+            logger.info("onPerformSync($account) cancelled")
+        }
+
+        logger.info("onPerformSync($account) finished")
+    }
+
+
+    // SyncAdapter implementation and Hilt module
+
+    override fun getBinder(): IBinder = syncAdapterBinder
+
+}

app/src/androidTest/kotlin/at/bitfire/davdroid/sync/LocalTestResource.kt

@@ -5,6 +5,7 @@
 package at.bitfire.davdroid.sync
 
 import at.bitfire.davdroid.resource.LocalResource
+import java.util.Optional
 
 class LocalTestResource: LocalResource<Any> {
 
@@ -19,10 +20,10 @@ class LocalTestResource: LocalResource<Any> {
 
     override fun prepareForUpload() = "generated-file.txt"
 
-    override fun clearDirty(fileName: String?, eTag: String?, scheduleTag: String?) {
+    override fun clearDirty(fileName: Optional<String>, eTag: String?, scheduleTag: String?) {
         dirty = false
-        if (fileName != null)
-            this.fileName = fileName
+        if (fileName.isPresent)
+            this.fileName = fileName.get()
         this.eTag = eTag
         this.scheduleTag = scheduleTag
     }
@@ -31,9 +32,8 @@ class LocalTestResource: LocalResource<Any> {
         this.flags = flags
     }
 
-    override fun add() = throw NotImplementedError()
-    override fun update(data: Any) = throw NotImplementedError()
-    override fun delete() = throw NotImplementedError()
+    override fun update(data: Any, fileName: String?, eTag: String?, scheduleTag: String?, flags: Int) = throw NotImplementedError()
+    override fun deleteLocal() = throw NotImplementedError()
     override fun resetDeleted() = throw NotImplementedError()
 
 }

app/src/androidTest/kotlin/at/bitfire/davdroid/sync/SyncAdapterImplTest.kt

@@ -5,6 +5,7 @@
 package at.bitfire.davdroid.sync
 
 import android.accounts.Account
+import android.content.ContentResolver
 import android.content.Context
 import android.content.SyncResult
 import android.os.Bundle
@@ -13,17 +14,17 @@ import androidx.hilt.work.HiltWorkerFactory
 import androidx.work.WorkInfo
 import androidx.work.WorkManager
 import at.bitfire.davdroid.TestUtils
-import at.bitfire.davdroid.repository.DavCollectionRepository
-import at.bitfire.davdroid.repository.DavServiceRepository
-import at.bitfire.davdroid.settings.AccountSettings
 import at.bitfire.davdroid.sync.account.TestAccount
+import at.bitfire.davdroid.sync.adapter.SyncAdapterImpl
 import at.bitfire.davdroid.sync.worker.SyncWorkerManager
 import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.android.testing.BindValue
 import dagger.hilt.android.testing.HiltAndroidRule
 import dagger.hilt.android.testing.HiltAndroidTest
 import io.mockk.Awaits
 import io.mockk.coEvery
 import io.mockk.every
+import io.mockk.impl.annotations.MockK
 import io.mockk.junit4.MockKRule
 import io.mockk.just
 import io.mockk.mockk
@@ -39,36 +40,12 @@ import org.junit.After
 import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
-import org.junit.rules.Timeout
-import java.util.logging.Logger
 import javax.inject.Inject
+import javax.inject.Provider
 import kotlin.coroutines.cancellation.CancellationException
 
 @HiltAndroidTest
-class SyncAdapterServicesTest {
-
-    lateinit var account: Account
-
-    @Inject
-    lateinit var accountSettingsFactory: AccountSettings.Factory
-
-    @Inject
-    lateinit var collectionRepository: DavCollectionRepository
-
-    @Inject @ApplicationContext
-    lateinit var context: Context
-
-    @Inject
-    lateinit var logger: Logger
-
-    @Inject
-    lateinit var serviceRepository: DavServiceRepository
-
-    @Inject
-    lateinit var syncConditionsFactory: SyncConditions.Factory
-
-    @Inject
-    lateinit var workerFactory: HiltWorkerFactory
+class SyncAdapterImplTest {
 
     @get:Rule
     val hiltRule = HiltAndroidRule(this)
@@ -76,10 +53,21 @@ class SyncAdapterServicesTest {
     @get:Rule
     val mockkRule = MockKRule(this)
 
-    // test methods should run quickly and not wait 60 seconds for a sync timeout or something like that
-    @get:Rule
-    val timeoutRule: Timeout = Timeout.seconds(5)
+    @Inject @ApplicationContext
+    lateinit var context: Context
 
+    @Inject
+    lateinit var syncAdapterImplProvider: Provider<SyncAdapterImpl>
+
+    @BindValue @MockK
+    lateinit var syncWorkerManager: SyncWorkerManager
+
+    @Inject
+    lateinit var workerFactory: HiltWorkerFactory
+
+    lateinit var account: Account
+
+    private var masterSyncStateBeforeTest = ContentResolver.getMasterSyncAutomatically()
 
     @Before
     fun setUp() {
@@ -87,33 +75,23 @@ class SyncAdapterServicesTest {
         TestUtils.setUpWorkManager(context, workerFactory)
 
         account = TestAccount.create()
+
+        ContentResolver.setMasterSyncAutomatically(true)
+        ContentResolver.setSyncAutomatically(account, CalendarContract.AUTHORITY, true)
+        ContentResolver.setIsSyncable(account, CalendarContract.AUTHORITY, 1)
     }
 
     @After
     fun tearDown() {
+        ContentResolver.setMasterSyncAutomatically(masterSyncStateBeforeTest)
         TestAccount.remove(account)
     }
 
 
-    private fun syncAdapter(
-        syncWorkerManager: SyncWorkerManager
-    ): SyncAdapterService.SyncAdapter =
-        SyncAdapterService.SyncAdapter(
-            accountSettingsFactory = accountSettingsFactory,
-            collectionRepository = collectionRepository,
-            serviceRepository = serviceRepository,
-            context = context,
-            logger = logger,
-            syncConditionsFactory = syncConditionsFactory,
-            syncWorkerManager = syncWorkerManager
-        )
-
-
     @Test
     fun testSyncAdapter_onPerformSync_cancellation() = runTest {
-        val syncWorkerManager = mockk<SyncWorkerManager>()
-        val syncAdapter = syncAdapter(syncWorkerManager = syncWorkerManager)
         val workManager = WorkManager.getInstance(context)
+        val syncAdapter = syncAdapterImplProvider.get()
 
         mockkObject(workManager) {
             // don't actually create a worker
@@ -136,9 +114,8 @@ class SyncAdapterServicesTest {
 
     @Test
     fun testSyncAdapter_onPerformSync_returnsAfterTimeout() {
-        val syncWorkerManager = mockk<SyncWorkerManager>()
-        val syncAdapter = syncAdapter(syncWorkerManager = syncWorkerManager)
         val workManager = WorkManager.getInstance(context)
+        val syncAdapter = syncAdapterImplProvider.get()
 
         mockkObject(workManager) {
             // don't actually create a worker
@@ -158,9 +135,8 @@ class SyncAdapterServicesTest {
 
     @Test
     fun testSyncAdapter_onPerformSync_runsInTime() {
-        val syncWorkerManager = mockk<SyncWorkerManager>()
-        val syncAdapter = syncAdapter(syncWorkerManager = syncWorkerManager)
         val workManager = WorkManager.getInstance(context)
+        val syncAdapter = syncAdapterImplProvider.get()
 
         mockkObject(workManager) {
             // don't actually create a worker
@@ -179,4 +155,4 @@ class SyncAdapterServicesTest {
         }
     }
 
-}
+}

app/src/androidTest/kotlin/at/bitfire/davdroid/sync/SyncerTest.kt

@@ -189,7 +189,7 @@ class SyncerTest {
         override val authority: String
             get() = throw NotImplementedError()
 
-        override fun acquireContentProvider(): ContentProviderClient? {
+        override fun acquireContentProvider(throwOnMissingPermissions: Boolean): ContentProviderClient? {
             throw NotImplementedError()
         }
 

app/src/androidTest/kotlin/at/bitfire/davdroid/webdav/WebDavMountRepositoryTest.kt

@@ -6,11 +6,11 @@ package at.bitfire.davdroid.webdav
 
 import dagger.hilt.android.testing.HiltAndroidRule
 import dagger.hilt.android.testing.HiltAndroidTest
+import junit.framework.TestCase.assertEquals
 import kotlinx.coroutines.test.runTest
 import okhttp3.mockwebserver.MockResponse
 import okhttp3.mockwebserver.MockWebServer
-import org.junit.Assert.assertFalse
-import org.junit.Assert.assertTrue
+import org.junit.Assert.assertNull
 import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
@@ -36,7 +36,7 @@ class WebDavMountRepositoryTest {
     @Test
     fun testHasWebDav_NoDavHeader() = runTest {
         web.enqueue(MockResponse().setResponseCode(200))
-        assertFalse(repository.hasWebDav(url, null))
+        assertNull(repository.hasWebDav(url, null))
     }
 
     @Test
@@ -44,7 +44,7 @@ class WebDavMountRepositoryTest {
         web.enqueue(MockResponse()
             .setResponseCode(200)
             .addHeader("DAV: 1"))
-        assertTrue(repository.hasWebDav(url, null))
+        assertEquals(url, repository.hasWebDav(url, null))
     }
 
     @Test
@@ -52,7 +52,7 @@ class WebDavMountRepositoryTest {
         web.enqueue(MockResponse()
             .setResponseCode(200)
             .addHeader("DAV: 1, 2"))
-        assertTrue(repository.hasWebDav(url, null))
+        assertEquals(url,repository.hasWebDav(url, null))
     }
 
     @Test
@@ -60,7 +60,7 @@ class WebDavMountRepositoryTest {
         web.enqueue(MockResponse()
             .setResponseCode(200)
             .addHeader("DAV: 1, 3"))
-        assertTrue(repository.hasWebDav(url, null))
+        assertEquals(url,repository.hasWebDav(url, null))
     }
 
 }

app/src/androidTest/kotlin/at/bitfire/davdroid/webdav/operation/QueryChildDocumentsOperationTest.kt

@@ -2,7 +2,7 @@
  * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
  */
 
-package at.bitfire.davdroid.webdav
+package at.bitfire.davdroid.webdav.operation
 
 import android.content.Context
 import android.security.NetworkSecurityPolicy
@@ -14,6 +14,7 @@ import dagger.hilt.android.qualifiers.ApplicationContext
 import dagger.hilt.android.testing.HiltAndroidRule
 import dagger.hilt.android.testing.HiltAndroidTest
 import io.mockk.junit4.MockKRule
+import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.test.runTest
 import okhttp3.mockwebserver.Dispatcher
 import okhttp3.mockwebserver.MockResponse
@@ -29,29 +30,7 @@ import java.util.logging.Logger
 import javax.inject.Inject
 
 @HiltAndroidTest
-class DavDocumentsProviderTest {
-
-    companion object {
-        private const val PATH_WEBDAV_ROOT = "/webdav"
-    }
-
-    @Inject @ApplicationContext
-    lateinit var context: Context
-
-    @Inject
-    lateinit var credentialsStore: CredentialsStore
-    
-    @Inject
-    lateinit var davDocumentsActorFactory: DavDocumentsProvider.DavDocumentsActor.Factory
-
-    @Inject
-    lateinit var httpClientBuilder: HttpClient.Builder
-    
-    @Inject
-    lateinit var db: AppDatabase
-
-    @Inject
-    lateinit var testDispatcher: TestDispatcher
+class QueryChildDocumentsOperationTest {
 
     @get:Rule
     val hiltRule = HiltAndroidRule(this)
@@ -59,13 +38,32 @@ class DavDocumentsProviderTest {
     @get:Rule
     val mockkRule = MockKRule(this)
 
+    @Inject @ApplicationContext
+    lateinit var context: Context
+
+    @Inject
+    lateinit var db: AppDatabase
+
+    @Inject
+    lateinit var operation: QueryChildDocumentsOperation
+
+    @Inject
+    lateinit var httpClientBuilder: HttpClient.Builder
+
+    @Inject
+    lateinit var testDispatcher: TestDispatcher
+
     private lateinit var server: MockWebServer
     private lateinit var client: HttpClient
 
+    private lateinit var mount: WebDavMount
+    private lateinit var rootDocument: WebDavDocument
+
     @Before
     fun setUp() {
         hiltRule.inject()
 
+        // create server and client
         server = MockWebServer().apply {
             dispatcher = testDispatcher
             start()
@@ -75,50 +73,49 @@ class DavDocumentsProviderTest {
 
         // mock server delivers HTTP without encryption
         assertTrue(NetworkSecurityPolicy.getInstance().isCleartextTrafficPermitted)
+
+        // create WebDAV mount and root document in DB
+        runBlocking {
+            val mountId = db.webDavMountDao().insert(WebDavMount(0, "Cat food storage", server.url(PATH_WEBDAV_ROOT)))
+            mount = db.webDavMountDao().getById(mountId)
+            rootDocument = db.webDavDocumentDao().getOrCreateRoot(mount)
+        }
     }
 
     @After
     fun tearDown() {
         client.close()
         server.shutdown()
+
+        runBlocking {
+            db.webDavMountDao().deleteAsync(mount)
+        }
     }
 
 
     @Test
     fun testDoQueryChildren_insert() = runTest {
-        // Create parent and root in database
-        val id = db.webDavMountDao().insert(WebDavMount(0, "Cat food storage", server.url(PATH_WEBDAV_ROOT)))
-        val webDavMount = db.webDavMountDao().getById(id)
-        val parent = db.webDavDocumentDao().getOrCreateRoot(webDavMount)
-
         // Query
-        val actor = davDocumentsActorFactory.create(
-            cookieStore = mutableMapOf(),
-            credentialsStore = credentialsStore
-        )
-        actor.queryChildren(parent)
+        operation.queryChildren(rootDocument)
 
         // Assert new children were inserted into db
-        assertEquals(3, db.webDavDocumentDao().getChildren(parent.id).size)
-        assertEquals("Library", db.webDavDocumentDao().getChildren(parent.id)[0].displayName)
-        assertEquals("MeowMeow_Cats.docx", db.webDavDocumentDao().getChildren(parent.id)[1].displayName)
-        assertEquals("Secret_Document.pages", db.webDavDocumentDao().getChildren(parent.id)[2].displayName)
+        assertEquals(3, db.webDavDocumentDao().getChildren(rootDocument.id).size)
+        assertEquals("Library", db.webDavDocumentDao().getChildren(rootDocument.id)[0].displayName)
+        assertEquals("MeowMeow_Cats.docx", db.webDavDocumentDao().getChildren(rootDocument.id)[1].displayName)
+        assertEquals("Secret_Document.pages", db.webDavDocumentDao().getChildren(rootDocument.id)[2].displayName)
     }
 
     @Test
     fun testDoQueryChildren_update() = runTest {
         // Create parent and root in database
-        val mountId = db.webDavMountDao().insert(WebDavMount(0, "Cat food storage", server.url(PATH_WEBDAV_ROOT)))
-        val webDavMount = db.webDavMountDao().getById(mountId)
-        val parent = db.webDavDocumentDao().getOrCreateRoot(webDavMount)
-        assertEquals("Cat food storage", db.webDavDocumentDao().get(parent.id)!!.displayName)
+        assertEquals("Cat food storage", db.webDavDocumentDao().get(rootDocument.id)!!.displayName)
 
         // Create a folder
         val folderId = db.webDavDocumentDao().insert(
             WebDavDocument(
                 0,
-                mountId,
-                parent.id,
+                mount.id,
+                rootDocument.id,
                 "My_Books",
                 true,
                 "My Books",
@@ -128,38 +125,25 @@ class DavDocumentsProviderTest {
         assertEquals("My Books", db.webDavDocumentDao().get(folderId)!!.displayName)
 
         // Query - should update the parent displayname and folder name
-        val actor = davDocumentsActorFactory.create(
-            cookieStore = mutableMapOf(),
-            credentialsStore = credentialsStore
-        )
-        actor.queryChildren(parent)
+        operation.queryChildren(rootDocument)
 
         // Assert parent and children were updated in database
-        assertEquals("Cats WebDAV", db.webDavDocumentDao().get(parent.id)!!.displayName)
-        assertEquals("Library", db.webDavDocumentDao().getChildren(parent.id)[0].name)
-        assertEquals("Library", db.webDavDocumentDao().getChildren(parent.id)[0].displayName)
+        assertEquals("Cats WebDAV", db.webDavDocumentDao().get(rootDocument.id)!!.displayName)
+        assertEquals("Library", db.webDavDocumentDao().getChildren(rootDocument.id)[0].name)
+        assertEquals("Library", db.webDavDocumentDao().getChildren(rootDocument.id)[0].displayName)
 
     }
 
     @Test
     fun testDoQueryChildren_delete() = runTest {
-        // Create parent and root in database
-        val mountId = db.webDavMountDao().insert(WebDavMount(0, "Cat food storage", server.url(PATH_WEBDAV_ROOT)))
-        val webDavMount = db.webDavMountDao().getById(mountId)
-        val parent = db.webDavDocumentDao().getOrCreateRoot(webDavMount)
-
         // Create a folder
         val folderId = db.webDavDocumentDao().insert(
-            WebDavDocument(0, mountId, parent.id, "deleteme", true, "Should be deleted")
+            WebDavDocument(0, mount.id, rootDocument.id, "deleteme", true, "Should be deleted")
         )
         assertEquals("deleteme", db.webDavDocumentDao().get(folderId)!!.name)
 
         // Query - discovers serverside deletion
-        val actor = davDocumentsActorFactory.create(
-            cookieStore = mutableMapOf(),
-            credentialsStore = credentialsStore
-        )
-        actor.queryChildren(parent)
+        operation.queryChildren(rootDocument)
 
         // Assert folder got deleted
         assertEquals(null, db.webDavDocumentDao().get(folderId))
@@ -167,26 +151,17 @@ class DavDocumentsProviderTest {
 
     @Test
     fun testDoQueryChildren_updateTwoDirectoriesSimultaneously() = runTest {
-        // Create root in database
-        val mountId = db.webDavMountDao().insert(WebDavMount(0, "Cat food storage", server.url(PATH_WEBDAV_ROOT)))
-        val webDavMount = db.webDavMountDao().getById(mountId)
-        val root = db.webDavDocumentDao().getOrCreateRoot(webDavMount)
-
         // Create two directories
-        val parent1Id = db.webDavDocumentDao().insert(WebDavDocument(0, mountId, root.id, "parent1", true))
-        val parent2Id = db.webDavDocumentDao().insert(WebDavDocument(0, mountId, root.id, "parent2", true))
+        val parent1Id = db.webDavDocumentDao().insert(WebDavDocument(0, mount.id, rootDocument.id, "parent1", true))
+        val parent2Id = db.webDavDocumentDao().insert(WebDavDocument(0, mount.id, rootDocument.id, "parent2", true))
         val parent1 = db.webDavDocumentDao().get(parent1Id)!!
         val parent2 = db.webDavDocumentDao().get(parent2Id)!!
         assertEquals("parent1", parent1.name)
         assertEquals("parent2", parent2.name)
 
         // Query - find children of two nodes simultaneously
-        val actor = davDocumentsActorFactory.create(
-            cookieStore = mutableMapOf(),
-            credentialsStore = credentialsStore
-        )
-        actor.queryChildren(parent1)
-        actor.queryChildren(parent2)
+        operation.queryChildren(parent1)
+        operation.queryChildren(parent2)
 
         // Assert the two folders names have changed
         assertEquals("childOne.txt", db.webDavDocumentDao().getChildren(parent1Id)[0].name)
@@ -214,7 +189,7 @@ class DavDocumentsProviderTest {
                     PATH_WEBDAV_ROOT to arrayOf(
                         Resource("",
                             "<resourcetype><collection/></resourcetype>" +
-                            "<displayname>Cats WebDAV</displayname>"
+                                    "<displayname>Cats WebDAV</displayname>"
                         ),
                         Resource("Secret_Document.pages",
                             "<displayname>Secret_Document.pages</displayname>",
@@ -224,7 +199,7 @@ class DavDocumentsProviderTest {
                         ),
                         Resource("Library",
                             "<resourcetype><collection/></resourcetype>" +
-                            "<displayname>Library</displayname>"
+                                    "<displayname>Library</displayname>"
                         )
                     ),
 
@@ -243,15 +218,15 @@ class DavDocumentsProviderTest {
                 val responses = propsMap[requestPath]?.joinToString { resource ->
                     "<response><href>$requestPath/${resource.name}</href><propstat><prop>" +
                             resource.props +
-                    "</prop></propstat></response>"
+                            "</prop></propstat></response>"
                 }
 
                 val multistatus =
                     "<multistatus xmlns='DAV:' " +
-                        "xmlns:CARD='urn:ietf:params:xml:ns:carddav' " +
-                        "xmlns:CAL='urn:ietf:params:xml:ns:caldav'>" +
-                        responses +
-                    "</multistatus>"
+                            "xmlns:CARD='urn:ietf:params:xml:ns:carddav' " +
+                            "xmlns:CAL='urn:ietf:params:xml:ns:caldav'>" +
+                            responses +
+                            "</multistatus>"
 
                 logger.info("Response: $multistatus")
                 return MockResponse()
@@ -264,4 +239,9 @@ class DavDocumentsProviderTest {
 
     }
 
+
+    companion object {
+        private const val PATH_WEBDAV_ROOT = "/webdav"
+    }
+
 }

app/src/main/AndroidManifest.xml

@@ -53,11 +53,19 @@
         tools:ignore="UnusedAttribute"
         android:supportsRtl="true">
 
-        <!-- required for Hilt/WorkManager integration -->
+        <!-- Required for Hilt/WorkManager integration. See
+        - https://developer.android.com/develop/background-work/background-tasks/persistent/configuration/custom-configuration#remove-default
+        - https://developer.android.com/training/dependency-injection/hilt-jetpack#workmanager
+        However, we must not disable AndroidX startup completely, as it's needed by other libraries like okhttp. -->
         <provider
             android:name="androidx.startup.InitializationProvider"
             android:authorities="${applicationId}.androidx-startup"
-            tools:node="remove">
+            android:exported="false"
+            tools:node="merge">
+            <meta-data
+                android:name="androidx.work.WorkManagerInitializer"
+                android:value="androidx.startup"
+                tools:node="remove" />
         </provider>
 
         <!-- Remove the node added by AppAuth (remove only from net.openid.appauth library, not from our flavor manifest files) -->
@@ -178,7 +186,7 @@
                 android:resource="@xml/account_authenticator"/>
         </service>
         <service
-            android:name=".sync.CalendarsSyncAdapterService"
+            android:name=".sync.adapter.CalendarsSyncAdapterService"
             android:exported="true"
             tools:ignore="ExportedService">
             <intent-filter>
@@ -189,7 +197,7 @@
                 android:resource="@xml/sync_calendars"/>
         </service>
         <service
-            android:name=".sync.JtxSyncAdapterService"
+            android:name=".sync.adapter.JtxSyncAdapterService"
             android:exported="true"
             tools:ignore="ExportedService">
             <intent-filter>
@@ -200,7 +208,7 @@
                 android:resource="@xml/sync_notes"/>
         </service>
         <service
-            android:name=".sync.OpenTasksSyncAdapterService"
+            android:name=".sync.adapter.OpenTasksSyncAdapterService"
             android:exported="true"
             tools:ignore="ExportedService">
             <intent-filter>
@@ -211,7 +219,7 @@
                 android:resource="@xml/sync_opentasks"/>
         </service>
         <service
-            android:name=".sync.TasksOrgSyncAdapterService"
+            android:name=".sync.adapter.TasksOrgSyncAdapterService"
             android:exported="true"
             tools:ignore="ExportedService">
             <intent-filter>
@@ -246,7 +254,7 @@
                 android:resource="@xml/account_authenticator_address_book"/>
         </service>
         <service
-            android:name=".sync.ContactsSyncAdapterService"
+            android:name=".sync.adapter.ContactsSyncAdapterService"
             android:exported="true"
             tools:ignore="ExportedService">
             <intent-filter>

app/src/main/kotlin/at/bitfire/davdroid/Constants.kt

@@ -3,7 +3,7 @@
  */
 package at.bitfire.davdroid
 
-import at.bitfire.ical4android.ical4jVersion
+import at.bitfire.synctools.icalendar.ical4jVersion
 import ezvcard.Ezvcard
 import net.fortuna.ical4j.model.property.ProdId
 

app/src/main/kotlin/at/bitfire/davdroid/db/AppDatabase.kt

@@ -35,6 +35,13 @@ import dagger.hilt.components.SingletonComponent
 import java.io.Writer
 import javax.inject.Singleton
 
+/**
+ * The app database. Managed via android jetpack room. Room provides an abstraction
+ * layer over SQLite.
+ *
+ * Note: In SQLite PRAGMA foreign_keys is off by default. Room activates it for
+ * production (non-test) databases.
+ */
 @Database(entities = [
     Service::class,
     HomeSet::class,

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalAddressBook.kt

@@ -23,9 +23,9 @@ import at.bitfire.davdroid.resource.LocalAddressBook.Companion.USER_DATA_READ_ON
 import at.bitfire.davdroid.resource.workaround.ContactDirtyVerifier
 import at.bitfire.davdroid.settings.AccountSettings
 import at.bitfire.davdroid.sync.SyncDataType
-import at.bitfire.davdroid.sync.SyncFrameworkIntegration
 import at.bitfire.davdroid.sync.account.SystemAccountUtils
 import at.bitfire.davdroid.sync.account.setAndVerifyUserData
+import at.bitfire.davdroid.sync.adapter.SyncFrameworkIntegration
 import at.bitfire.synctools.storage.BatchOperation
 import at.bitfire.synctools.storage.ContactsBatchOperation
 import at.bitfire.vcard4android.AndroidAddressBook
@@ -234,7 +234,7 @@ open class LocalAddressBook @AssistedInject constructor(
         if (syncInterval != null)
             syncFramework.enableSyncOnContentChange(addressBookAccount, ContactsContract.AUTHORITY)
         else
-            syncFramework.disableSyncAbility(addressBookAccount, ContactsContract.AUTHORITY)
+            syncFramework.disableSyncOnContentChange(addressBookAccount, ContactsContract.AUTHORITY)
     }
 
 

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalAddressBookStore.kt

@@ -78,8 +78,14 @@ class LocalAddressBookStore @Inject constructor(
         return sb.toString()
     }
 
-    override fun acquireContentProvider() =
+    override fun acquireContentProvider(throwOnMissingPermissions: Boolean) = try {
         context.contentResolver.acquireContentProviderClient(authority)
+    } catch (e: SecurityException) {
+        if (throwOnMissingPermissions)
+            throw e
+        else
+            /* return */ null
+    }
 
     override fun create(provider: ContentProviderClient, fromCollection: Collection): LocalAddressBook? {
         val service = serviceRepository.getBlocking(fromCollection.serviceId) ?: throw IllegalArgumentException("Couldn't fetch DB service from collection")

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalCalendar.kt

@@ -8,16 +8,18 @@ import android.content.ContentUris
 import android.provider.CalendarContract.Calendars
 import android.provider.CalendarContract.Events
 import androidx.core.content.contentValuesOf
-import at.bitfire.ical4android.AndroidEvent
+import at.bitfire.ical4android.Event
 import at.bitfire.ical4android.util.MiscUtils.asSyncAdapter
+import at.bitfire.synctools.mapping.calendar.LegacyAndroidEventBuilder2
 import at.bitfire.synctools.storage.BatchOperation
 import at.bitfire.synctools.storage.calendar.AndroidCalendar
+import at.bitfire.synctools.storage.calendar.AndroidEvent2
+import at.bitfire.synctools.storage.calendar.AndroidRecurringCalendar
 import at.bitfire.synctools.storage.calendar.CalendarBatchOperation
 import dagger.assisted.Assisted
 import dagger.assisted.AssistedFactory
 import dagger.assisted.AssistedInject
 import java.util.LinkedList
-import java.util.logging.Level
 import java.util.logging.Logger
 
 /**
@@ -26,16 +28,18 @@ import java.util.logging.Logger
  * [Calendars._SYNC_ID] corresponds to the database collection ID ([at.bitfire.davdroid.db.Collection.id]).
  */
 class LocalCalendar @AssistedInject constructor(
-    @Assisted val androidCalendar: AndroidCalendar,
+    @Assisted internal val androidCalendar: AndroidCalendar,
     private val logger: Logger
 ) : LocalCollection<LocalEvent> {
 
     @AssistedFactory
     interface Factory {
-        fun create(androidCalendar: AndroidCalendar): LocalCalendar
+        fun create(calendar: AndroidCalendar): LocalCalendar
     }
 
 
+    // properties
+
     override val dbCollectionId: Long?
         get() = androidCalendar.syncId?.toLongOrNull()
 
@@ -56,11 +60,29 @@ class LocalCalendar @AssistedInject constructor(
             androidCalendar.writeSyncState(state.toString())
         }
 
+    private val recurringCalendar = AndroidRecurringCalendar(androidCalendar)
 
-    override fun findDeleted() =
-        androidCalendar
-            .findEvents("${Events.DELETED} AND ${Events.ORIGINAL_ID} IS NULL", null)
-            .map { LocalEvent(it) }
+
+    fun add(event: Event, fileName: String, eTag: String?, scheduleTag: String?, flags: Int) {
+        val mapped = LegacyAndroidEventBuilder2(
+            calendar = androidCalendar,
+            event = event,
+            id = null,
+            syncId = fileName,
+            eTag = eTag,
+            scheduleTag = scheduleTag,
+            flags = flags
+        ).build()
+        recurringCalendar.addEventAndExceptions(mapped)
+    }
+
+    override fun findDeleted(): List<LocalEvent> {
+        val result = LinkedList<LocalEvent>()
+        androidCalendar.iterateEvents( "${Events.DELETED} AND ${Events.ORIGINAL_ID} IS NULL", null) { entity ->
+            result += LocalEvent(recurringCalendar, AndroidEvent2(androidCalendar, entity))
+        }
+        return result
+    }
 
     override fun findDirty(): List<LocalEvent> {
         val dirty = LinkedList<LocalEvent>()
@@ -70,62 +92,57 @@ class LocalCalendar @AssistedInject constructor(
          * When a calendar component is created, its sequence number is 0. It is monotonically incremented by the "Organizer's"
          * CUA each time the "Organizer" makes a significant revision to the calendar component.
          */
-        for (androidEvent in androidCalendar.findEvents("${Events.DIRTY} AND ${Events.ORIGINAL_ID} IS NULL", null)) {
-            val localEvent = LocalEvent(androidEvent)
-            try {
-                val event = requireNotNull(androidEvent.event)
-
-                val nonGroupScheduled = event.attendees.isEmpty()
-                val weAreOrganizer = localEvent.weAreOrganizer
-
-                val sequence = event.sequence
-                if (sequence == null)
-                    // sequence has not been assigned yet (i.e. this event was just locally created)
-                    event.sequence = 0
-                else if (nonGroupScheduled || weAreOrganizer)   // increase sequence
-                    event.sequence = sequence + 1
-
-            } catch(e: Exception) {
-                logger.log(Level.WARNING, "Couldn't check/increase sequence", e)
-            }
-            dirty += localEvent
+        androidCalendar.iterateEvents("${Events.DIRTY} AND ${Events.ORIGINAL_ID} IS NULL", null) { values ->
+            dirty += LocalEvent(recurringCalendar, AndroidEvent2(androidCalendar, values))
         }
 
         return dirty
     }
 
     override fun findByName(name: String) =
-        androidCalendar.findEvents("${Events._SYNC_ID}=?", arrayOf(name)).firstOrNull()?.let { LocalEvent(it) }
-
+        androidCalendar.findEvent("${Events._SYNC_ID}=? AND ${Events.ORIGINAL_SYNC_ID} IS null", arrayOf(name))?.let {
+            LocalEvent(recurringCalendar, it)
+        }
 
     override fun markNotDirty(flags: Int) =
-        androidCalendar.updateEvents(
-            contentValuesOf(AndroidEvent.COLUMN_FLAGS to flags),
-            "${Events.CALENDAR_ID}=? AND NOT ${Events.DIRTY} AND ${Events.ORIGINAL_ID} IS NULL",
+        androidCalendar.updateEventRows(
+            contentValuesOf(AndroidEvent2.COLUMN_FLAGS to flags),
+            // `dirty` can be 0, 1, or null. "NOT dirty" is not enough.
+            """
+                ${Events.CALENDAR_ID}=?
+                AND (${Events.DIRTY} IS NULL OR ${Events.DIRTY}=0)
+                AND ${Events.ORIGINAL_ID} IS NULL
+            """.trimIndent(),
             arrayOf(androidCalendar.id.toString())
         )
 
     override fun removeNotDirtyMarked(flags: Int): Int {
         // list all non-dirty events with the given flags and delete every row + its exceptions
         val batch = CalendarBatchOperation(androidCalendar.client)
-        androidCalendar.iterateEvents(
+        androidCalendar.iterateEventRows(
             arrayOf(Events._ID),
-            "${Events.CALENDAR_ID}=? AND NOT ${Events.DIRTY} AND ${Events.ORIGINAL_ID} IS NULL AND ${AndroidEvent.COLUMN_FLAGS}=?",
+            // `dirty` can be 0, 1, or null. "NOT dirty" is not enough.
+            """
+                ${Events.CALENDAR_ID}=?
+                AND (${Events.DIRTY} IS NULL OR ${Events.DIRTY}=0)
+                AND ${Events.ORIGINAL_ID} IS NULL
+                AND ${AndroidEvent2.COLUMN_FLAGS}=?
+            """.trimIndent(),
             arrayOf(androidCalendar.id.toString(), flags.toString())
         ) { values ->
-            val id = values.getAsInteger(Events._ID)
+            val id = values.getAsLong(Events._ID)
 
             // delete event and possible exceptions (content provider doesn't delete exceptions itself)
             batch += BatchOperation.CpoBuilder
-                .newDelete(Events.CONTENT_URI.asSyncAdapter(androidCalendar.account))
+                .newDelete(androidCalendar.eventsUri)
                 .withSelection("${Events._ID}=? OR ${Events.ORIGINAL_ID}=?", arrayOf(id.toString(), id.toString()))
         }
         return batch.commit()
     }
 
     override fun forgetETags() {
-        androidCalendar.updateEvents(
-            contentValuesOf(AndroidEvent.COLUMN_ETAG to null),
+        androidCalendar.updateEventRows(
+            contentValuesOf(AndroidEvent2.COLUMN_ETAG to null),
             "${Events.CALENDAR_ID}=?", arrayOf(androidCalendar.id.toString())
         )
     }
@@ -135,8 +152,8 @@ class LocalCalendar @AssistedInject constructor(
         // process deleted exceptions
         logger.info("Processing deleted exceptions")
 
-        androidCalendar.iterateEvents(
-            arrayOf(Events._ID, Events.ORIGINAL_ID, AndroidEvent.COLUMN_SEQUENCE),
+        androidCalendar.iterateEventRows(
+            arrayOf(Events._ID, Events.ORIGINAL_ID, AndroidEvent2.COLUMN_SEQUENCE),
             "${Events.CALENDAR_ID}=? AND ${Events.DELETED} AND ${Events.ORIGINAL_ID} IS NOT NULL",
             arrayOf(androidCalendar.id.toString())
         ) { values ->
@@ -148,12 +165,12 @@ class LocalCalendar @AssistedInject constructor(
             val batch = CalendarBatchOperation(androidCalendar.client)
 
             // enqueue: increase sequence of main event
-            val originalEventValues = androidCalendar.getEventValues(originalID, arrayOf(AndroidEvent.COLUMN_SEQUENCE))
-            val originalSequence = originalEventValues?.getAsInteger(AndroidEvent.COLUMN_SEQUENCE) ?: 0
+            val originalEventValues = androidCalendar.getEventRow(originalID, arrayOf(AndroidEvent2.COLUMN_SEQUENCE))
+            val originalSequence = originalEventValues?.getAsInteger(AndroidEvent2.COLUMN_SEQUENCE) ?: 0
 
             batch += BatchOperation.CpoBuilder
                 .newUpdate(ContentUris.withAppendedId(Events.CONTENT_URI, originalID).asSyncAdapter(androidCalendar.account))
-                .withValue(AndroidEvent.COLUMN_SEQUENCE, originalSequence + 1)
+                .withValue(AndroidEvent2.COLUMN_SEQUENCE, originalSequence + 1)
                 .withValue(Events.DIRTY, 1)
 
             // completely remove deleted exception
@@ -163,8 +180,8 @@ class LocalCalendar @AssistedInject constructor(
 
         // process dirty exceptions
         logger.info("Processing dirty exceptions")
-        androidCalendar.iterateEvents(
-            arrayOf(Events._ID, Events.ORIGINAL_ID, AndroidEvent.COLUMN_SEQUENCE),
+        androidCalendar.iterateEventRows(
+            arrayOf(Events._ID, Events.ORIGINAL_ID, AndroidEvent2.COLUMN_SEQUENCE),
             "${Events.CALENDAR_ID}=? AND ${Events.DIRTY} AND ${Events.ORIGINAL_ID} IS NOT NULL",
             arrayOf(androidCalendar.id.toString())
         ) { values ->
@@ -172,7 +189,7 @@ class LocalCalendar @AssistedInject constructor(
 
             val id = values.getAsLong(Events._ID)                   // can't be null (by definition)
             val originalID = values.getAsLong(Events.ORIGINAL_ID)   // can't be null (by query)
-            val sequence = values.getAsInteger(AndroidEvent.COLUMN_SEQUENCE) ?: 0
+            val sequence = values.getAsInteger(AndroidEvent2.COLUMN_SEQUENCE) ?: 0
 
             val batch = CalendarBatchOperation(androidCalendar.client)
 
@@ -184,7 +201,7 @@ class LocalCalendar @AssistedInject constructor(
             // enqueue: increase exception SEQUENCE and set DIRTY to 0
             batch += BatchOperation.CpoBuilder
                 .newUpdate(androidCalendar.eventUri(id))
-                .withValue(AndroidEvent.COLUMN_SEQUENCE, sequence + 1)
+                .withValue(AndroidEvent2.COLUMN_SEQUENCE, sequence + 1)
                 .withValue(Events.DIRTY, 0)
 
             batch.commit()
@@ -198,7 +215,7 @@ class LocalCalendar @AssistedInject constructor(
      */
     fun deleteDirtyEventsWithoutInstances() {
         // Iterate dirty main events without exceptions
-        androidCalendar.iterateEvents(
+        androidCalendar.iterateEventRows(
             arrayOf(Events._ID),
             "${Events.DIRTY} AND NOT ${Events.DELETED} AND ${Events.ORIGINAL_ID} IS NULL",
             null
@@ -211,7 +228,7 @@ class LocalCalendar @AssistedInject constructor(
             // delete event if there are no instances
             if (numEventInstances == 0) {
                 logger.fine("Marking event #$eventId without instances as deleted")
-                androidCalendar.updateEvent(eventId, contentValuesOf(Events.DELETED to 1))
+                androidCalendar.updateEventRow(eventId, contentValuesOf(Events.DELETED to 1))
             }
         }
     }

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalCalendarStore.kt

@@ -39,8 +39,14 @@ class LocalCalendarStore @Inject constructor(
     override val authority: String
         get() = CalendarContract.AUTHORITY
 
-    override fun acquireContentProvider() =
+    override fun acquireContentProvider(throwOnMissingPermissions: Boolean) = try {
         context.contentResolver.acquireContentProviderClient(authority)
+    } catch (e: SecurityException) {
+        if (throwOnMissingPermissions)
+            throw e
+        else
+            /* return */ null
+    }
 
     override fun create(client: ContentProviderClient, fromCollection: Collection): LocalCalendar? {
         val service = serviceRepository.getBlocking(fromCollection.serviceId) ?: throw IllegalArgumentException("Couldn't fetch DB service from collection")

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalCollection.kt

@@ -48,10 +48,8 @@ interface LocalCollection<out T: LocalResource<*>> {
      */
     fun findByName(name: String): T?
 
-
     /**
-     * Sets the [LocalEvent.COLUMN_FLAGS] value for entries which are not dirty ([Events.DIRTY] is 0)
-     * and have an [Events.ORIGINAL_ID] of null.
+     * Updates the flags value for entries which are not dirty.
      *
      * @param flags    value of flags to set (for instance, [LocalResource.FLAG_REMOTELY_PRESENT]])
      *
@@ -60,8 +58,7 @@ interface LocalCollection<out T: LocalResource<*>> {
     fun markNotDirty(flags: Int): Int
 
     /**
-     * Removes entries which are not dirty ([Events.DIRTY] is 0 and an [Events.ORIGINAL_ID] is null) with
-     * a given flag combination.
+     * Removes entries which are not dirty with a given flag combination.
      *
      * @param flags    exact flags value to remove entries with (for instance, if this is [LocalResource.FLAG_REMOTELY_PRESENT]],
      *                 all entries with exactly this flag will be removed)
@@ -76,4 +73,4 @@ interface LocalCollection<out T: LocalResource<*>> {
      */
     fun forgetETags()
 
-}
+}

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalContact.kt

@@ -23,13 +23,13 @@ import at.bitfire.vcard4android.AndroidContactFactory
 import at.bitfire.vcard4android.CachedGroupMembership
 import at.bitfire.vcard4android.Contact
 import java.io.FileNotFoundException
+import java.util.Optional
 import java.util.UUID
 import kotlin.jvm.optionals.getOrNull
 
 class LocalContact: AndroidContact, LocalAddress {
 
     companion object {
-
         const val COLUMN_FLAGS = ContactsContract.RawContacts.SYNC4
         const val COLUMN_HASHCODE = ContactsContract.RawContacts.SYNC3
     }
@@ -40,9 +40,8 @@ class LocalContact: AndroidContact, LocalAddress {
     internal val cachedGroupMemberships = HashSet<Long>()
     internal val groupMemberships = HashSet<Long>()
 
-    override var scheduleTag: String?
+    override val scheduleTag: String?
         get() = null
-        set(_) = throw NotImplementedError()
 
     override var flags: Int = 0
 
@@ -90,13 +89,13 @@ class LocalContact: AndroidContact, LocalAddress {
         _contact = null
     }
 
-    override fun clearDirty(fileName: String?, eTag: String?, scheduleTag: String?) {
+    override fun clearDirty(fileName: Optional<String>, eTag: String?, scheduleTag: String?) {
         if (scheduleTag != null)
             throw IllegalArgumentException("Contacts must not have a Schedule-Tag")
 
         val values = ContentValues(4)
-        if (fileName != null)
-            values.put(COLUMN_FILENAME, fileName)
+        if (fileName.isPresent)
+            values.put(COLUMN_FILENAME, fileName.get())
         values.put(COLUMN_ETAG, eTag)
         values.put(ContactsContract.RawContacts.DIRTY, 0)
 
@@ -105,21 +104,25 @@ class LocalContact: AndroidContact, LocalAddress {
 
         addressBook.provider!!.update(rawContactSyncURI(), values, null, null)
 
-        if (fileName != null)
-            this.fileName = fileName
+        if (fileName.isPresent)
+            this.fileName = fileName.get()
         this.eTag = eTag
     }
 
-    override fun resetDeleted() {
-        val values = contentValuesOf(ContactsContract.Groups.DELETED to 0)
-        addressBook.provider!!.update(rawContactSyncURI(), values, null, null)
-    }
-
     fun resetDirty() {
         val values = contentValuesOf(ContactsContract.RawContacts.DIRTY to 0)
         addressBook.provider!!.update(rawContactSyncURI(), values, null, null)
     }
 
+    override fun update(data: Contact, fileName: String?, eTag: String?, scheduleTag: String?, flags: Int) {
+        this.fileName = fileName
+        this.eTag = eTag
+        this.flags = flags
+
+        // processes this.{fileName, eTag, flags} and resets DIRTY flag
+        update(data)
+    }
+
     override fun updateFlags(flags: Int) {
         val values = contentValuesOf(COLUMN_FLAGS to flags)
         addressBook.provider!!.update(rawContactSyncURI(), values, null, null)
@@ -127,6 +130,15 @@ class LocalContact: AndroidContact, LocalAddress {
         this.flags = flags
     }
 
+    override fun deleteLocal() {
+        delete()
+    }
+
+    override fun resetDeleted() {
+        val values = contentValuesOf(ContactsContract.Groups.DELETED to 0)
+        addressBook.provider!!.update(rawContactSyncURI(), values, null, null)
+    }
+
 
     fun addToGroup(batch: ContactsBatchOperation, groupID: Long) {
         batch += BatchOperation.CpoBuilder

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalDataStore.kt

@@ -25,16 +25,19 @@ interface LocalDataStore<T: LocalCollection<*>> {
      *
      * **The caller is responsible for closing the content provider client!**
      *
-     * @return the content provider client, or `null` if the content provider could not be acquired
+     * @param throwOnMissingPermissions If `true`, the function will throw [SecurityException] if permissions are not granted.
+     *
+     * @return the content provider client, or `null` if the content provider could not be acquired (or permissions are not
+     * granted and [throwOnMissingPermissions] is `false`)
      *
      * @throws SecurityException on missing permissions
      */
-    fun acquireContentProvider(): ContentProviderClient?
+    fun acquireContentProvider(throwOnMissingPermissions: Boolean = false): ContentProviderClient?
 
     /**
      * Creates a new local collection from the given (remote) collection info.
      *
-     * @param provider       the content provider client
+     * @param client        the content provider client
      * @param fromCollection collection info
      *
      * @return the new local collection, or `null` if creation failed
@@ -46,7 +49,7 @@ interface LocalDataStore<T: LocalCollection<*>> {
      * [Collection] entry.
      *
      * @param account  the account that the data store is associated with
-     * @param provider the content provider client
+     * @param client   the content provider client
      *
      * @return a list of all local collections
      */
@@ -55,7 +58,7 @@ interface LocalDataStore<T: LocalCollection<*>> {
     /**
      * Updates the local collection with the data from the given (remote) collection info.
      *
-     * @param provider        the content provider client
+     * @param client          the content provider client
      * @param localCollection the local collection to update
      * @param fromCollection  collection info
      */

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalEvent.kt

@@ -4,50 +4,110 @@
 
 package at.bitfire.davdroid.resource
 
-import android.content.ContentValues
 import android.provider.CalendarContract.Events
 import androidx.core.content.contentValuesOf
-import at.bitfire.ical4android.AndroidEvent
 import at.bitfire.ical4android.Event
+import at.bitfire.ical4android.LegacyAndroidCalendar
+import at.bitfire.synctools.mapping.calendar.LegacyAndroidEventBuilder2
+import at.bitfire.synctools.storage.LocalStorageException
+import at.bitfire.synctools.storage.calendar.AndroidEvent2
+import at.bitfire.synctools.storage.calendar.AndroidRecurringCalendar
+import java.util.Optional
 import java.util.UUID
 
 class LocalEvent(
-    val androidEvent: AndroidEvent
+    val recurringCalendar: AndroidRecurringCalendar,
+    val androidEvent: AndroidEvent2
 ) : LocalResource<Event> {
 
-    // LocalResource implementation
-
-    override val id: Long?
+    override val id: Long
         get() = androidEvent.id
 
-    override var fileName: String?
+    override val fileName: String?
         get() = androidEvent.syncId
-        private set(value) {
-            androidEvent.syncId = value
-        }
 
-    override var eTag: String?
+    override val eTag: String?
         get() = androidEvent.eTag
-        set(value) { androidEvent.eTag = value }
 
-    override var scheduleTag: String?
+    override val scheduleTag: String?
         get() = androidEvent.scheduleTag
-        set(value) { androidEvent.scheduleTag = value }
 
     override val flags: Int
         get() = androidEvent.flags
 
-    override fun add() = androidEvent.add()
 
-    override fun update(data: Event) = androidEvent.update(data)
-
-    override fun delete() = androidEvent.delete()
+    override fun update(data: Event, fileName: String?, eTag: String?, scheduleTag: String?, flags: Int) {
+        val eventAndExceptions = LegacyAndroidEventBuilder2(
+            calendar = androidEvent.calendar,
+            event = data,
+            id = id,
+            syncId = fileName,
+            eTag = eTag,
+            scheduleTag = scheduleTag,
+            flags = flags
+        ).build()
+        recurringCalendar.updateEventAndExceptions(id, eventAndExceptions)
+    }
 
 
-    // other methods
+    private var _event: Event? = null
+    /**
+     * Retrieves the event from the content provider and converts it to a legacy data object.
+     *
+     * Caches the result: the content provider is only queried at the first call and then
+     * this method always returns the same object.
+     *
+     * @throws LocalStorageException    if there is no local event with the ID from [androidEvent]
+     */
+    @Synchronized
+    fun getCachedEvent(): Event {
+        _event?.let { return it }
 
-    val weAreOrganizer
-        get() = androidEvent.event!!.isOrganizer == true
+        val legacyCalendar = LegacyAndroidCalendar(androidEvent.calendar)
+        val event = legacyCalendar.getEvent(androidEvent.id)
+            ?: throw LocalStorageException("Event ${androidEvent.id} not found")
+
+        _event = event
+        return event
+    }
+
+    /**
+     * Generates the [Event] that should actually be uploaded:
+     *
+     * 1. Takes the [getCachedEvent].
+     * 2. Calculates the new SEQUENCE.
+     *
+     * _Note: This method currently modifies the object returned by [getCachedEvent], but
+     * this may change in the future._
+     *
+     * @return data object that should be used for uploading
+     */
+    fun eventToUpload(): Event {
+        val event = getCachedEvent()
+
+        val nonGroupScheduled = event.attendees.isEmpty()
+        val weAreOrganizer = event.isOrganizer == true
+
+        // Increase sequence (event.sequence null/non-null behavior is defined by the Event, see KDoc of event.sequence):
+        // - If it's null, the event has just been created in the database, so we can start with SEQUENCE:0 (default).
+        // - If it's non-null, the event already exists on the server, so increase by one.
+        val sequence = event.sequence
+        if (sequence != null && (nonGroupScheduled || weAreOrganizer))
+            event.sequence = sequence + 1
+
+        return event
+    }
+
+    /**
+     * Updates the SEQUENCE of the event in the content provider.
+     *
+     * @param sequence  new sequence value
+     */
+    fun updateSequence(sequence: Int?) {
+        androidEvent.update(contentValuesOf(
+            AndroidEvent2.COLUMN_SEQUENCE to sequence
+        ))
+    }
 
 
     /**
@@ -58,16 +118,16 @@ class LocalEvent(
      */
     override fun prepareForUpload(): String {
         // make sure that UID is set
-        val uid: String = androidEvent.event!!.uid ?: run {
+        val uid: String = getCachedEvent().uid ?: run {
             // generate new UID
             val newUid = UUID.randomUUID().toString()
 
-            // update in calendar provider
+            // persist to calendar provider
             val values = contentValuesOf(Events.UID_2445 to newUid)
             androidEvent.update(values)
 
-            // update this event
-            androidEvent.event?.uid = newUid
+            // update in cached event data object
+            getCachedEvent().uid = newUid
 
             newUid
         }
@@ -85,33 +145,31 @@ class LocalEvent(
             "${UUID.randomUUID()}.ics"      // UID would be dangerous as file name, use random UUID instead
     }
 
-
-    override fun clearDirty(fileName: String?, eTag: String?, scheduleTag: String?) {
-        val values = ContentValues(5)
-        if (fileName != null)
-            values.put(Events._SYNC_ID, fileName)
-        values.put(AndroidEvent.COLUMN_ETAG, eTag)
-        values.put(AndroidEvent.COLUMN_SCHEDULE_TAG, scheduleTag)
-        values.put(AndroidEvent.COLUMN_SEQUENCE, androidEvent.event!!.sequence)
-        values.put(Events.DIRTY, 0)
+    override fun clearDirty(fileName: Optional<String>, eTag: String?, scheduleTag: String?) {
+        val values = contentValuesOf(
+            Events.DIRTY to 0,
+            AndroidEvent2.COLUMN_ETAG to eTag,
+            AndroidEvent2.COLUMN_SCHEDULE_TAG to scheduleTag
+        )
+        if (fileName.isPresent)
+            values.put(Events._SYNC_ID, fileName.get())
         androidEvent.update(values)
-
-        if (fileName != null)
-            this.fileName = fileName
-        this.eTag = eTag
-        this.scheduleTag = scheduleTag
     }
 
     override fun updateFlags(flags: Int) {
-        val values = contentValuesOf(AndroidEvent.COLUMN_FLAGS to flags)
-        androidEvent.update(values)
+        androidEvent.update(contentValuesOf(
+            AndroidEvent2.COLUMN_FLAGS to flags
+        ))
+    }
 
-        androidEvent.flags = flags
+    override fun deleteLocal() {
+        recurringCalendar.deleteEventAndExceptions(id)
     }
 
     override fun resetDeleted() {
-        val values = contentValuesOf(Events.DELETED to 0)
-        androidEvent.update(values)
+        androidEvent.update(contentValuesOf(
+            Events.DELETED to 0
+        ))
     }
 
 }

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalGroup.kt

@@ -25,6 +25,7 @@ import at.bitfire.vcard4android.AndroidGroupFactory
 import at.bitfire.vcard4android.CachedGroupMembership
 import at.bitfire.vcard4android.Contact
 import java.util.LinkedList
+import java.util.Optional
 import java.util.UUID
 import java.util.logging.Logger
 import kotlin.jvm.optionals.getOrNull
@@ -111,7 +112,7 @@ class LocalGroup: AndroidGroup, LocalAddress {
 
     override var scheduleTag: String?
         get() = null
-        set(value) = throw NotImplementedError()
+        set(_) = throw NotImplementedError()
 
     override var flags: Int = 0
 
@@ -159,20 +160,20 @@ class LocalGroup: AndroidGroup, LocalAddress {
         return "$uid.vcf"
     }
 
-    override fun clearDirty(fileName: String?, eTag: String?, scheduleTag: String?) {
+    override fun clearDirty(fileName: Optional<String>, eTag: String?, scheduleTag: String?) {
         if (scheduleTag != null)
             throw IllegalArgumentException("Contact groups must not have a Schedule-Tag")
         val id = requireNotNull(id)
 
         val values = ContentValues(3)
-        if (fileName != null)
-            values.put(COLUMN_FILENAME, fileName)
+        if (fileName.isPresent)
+            values.put(COLUMN_FILENAME, fileName.get())
         values.putNull(COLUMN_ETAG)     // don't save changed ETag but null, so that the group is downloaded again, so that pendingMembers is updated
         values.put(Groups.DIRTY, 0)
         update(values)
 
-        if (fileName != null)
-            this.fileName = fileName
+        if (fileName.isPresent)
+            this.fileName = fileName.get()
         this.eTag = null
 
         // update cached group memberships
@@ -211,9 +212,13 @@ class LocalGroup: AndroidGroup, LocalAddress {
         batch.commit()
     }
 
-    override fun resetDeleted() {
-        val values = contentValuesOf(Groups.DELETED to 0)
-        addressBook.provider!!.update(groupSyncUri(), values, null, null)
+    override fun update(data: Contact, fileName: String?, eTag: String?, scheduleTag: String?, flags: Int) {
+        this.fileName = fileName
+        this.eTag = eTag
+        this.scheduleTag = scheduleTag
+
+        // processes this.{fileName, eTag, flags} and resets DIRTY flag
+        update(data)
     }
 
     override fun updateFlags(flags: Int) {
@@ -223,6 +228,15 @@ class LocalGroup: AndroidGroup, LocalAddress {
         this.flags = flags
     }
 
+    override fun deleteLocal() {
+        delete()
+    }
+
+    override fun resetDeleted() {
+        val values = contentValuesOf(Groups.DELETED to 0)
+        addressBook.provider!!.update(groupSyncUri(), values, null, null)
+    }
+
 
     // helpers
 

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalJtxCollectionStore.kt

@@ -37,8 +37,14 @@ class LocalJtxCollectionStore @Inject constructor(
     override val authority: String
         get() = JtxContract.AUTHORITY
 
-    override fun acquireContentProvider() =
-        context.contentResolver.acquireContentProviderClient(JtxContract.AUTHORITY)
+    override fun acquireContentProvider(throwOnMissingPermissions: Boolean) = try {
+        context.contentResolver.acquireContentProviderClient(authority)
+    } catch (e: SecurityException) {
+        if (throwOnMissingPermissions)
+            throw e
+        else
+            /* return */ null
+    }
 
     override fun create(provider: ContentProviderClient, fromCollection: Collection): LocalJtxCollection? {
         val service = serviceDao.get(fromCollection.serviceId) ?: throw IllegalArgumentException("Couldn't fetch DB service from collection")

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalJtxICalObject.kt

@@ -9,6 +9,8 @@ import at.bitfire.ical4android.JtxCollection
 import at.bitfire.ical4android.JtxICalObject
 import at.bitfire.ical4android.JtxICalObjectFactory
 import at.techbee.jtx.JtxContract
+import java.util.Optional
+import kotlin.jvm.optionals.getOrNull
 
 class LocalJtxICalObject(
     collection: JtxCollection<*>,
@@ -48,6 +50,24 @@ class LocalJtxICalObject(
 
     }
 
+    override fun update(data: JtxICalObject, fileName: String?, eTag: String?, scheduleTag: String?, flags: Int) {
+        this.fileName = fileName
+        this.eTag = eTag
+        this.scheduleTag = scheduleTag
+        this.flags = flags
+
+        // processes this.{fileName, eTag, scheduleTag, flags} and resets DIRTY flag
+        update(data)
+    }
+
+    override fun clearDirty(fileName: Optional<String>, eTag: String?, scheduleTag: String?) {
+        clearDirty(fileName.getOrNull(), eTag, scheduleTag)
+    }
+
+    override fun deleteLocal() {
+        delete()
+    }
+
     override fun resetDeleted() {
         throw NotImplementedError()
     }

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalResource.kt

@@ -4,8 +4,12 @@
 
 package at.bitfire.davdroid.resource
 
-import android.net.Uri
+import at.bitfire.davdroid.resource.LocalResource.Companion.FLAG_REMOTELY_PRESENT
+import java.util.Optional
 
+/**
+ * Defines operations that are used by SyncManager for all sync data types.
+ */
 interface LocalResource<in TData: Any> {
 
     companion object {
@@ -32,10 +36,10 @@ interface LocalResource<in TData: Any> {
     val fileName: String?
 
     /** remote ETag for the resource */
-    var eTag: String?
+    val eTag: String?
 
     /** remote Schedule-Tag for the resource */
-    var scheduleTag: String?
+    val scheduleTag: String?
 
     /** bitfield of flags; currently either [FLAG_REMOTELY_PRESENT] or 0 */
     val flags: Int
@@ -48,47 +52,41 @@ interface LocalResource<in TData: Any> {
      *   saved to the content provider. The sync manager is responsible for saving the file name that
      *   was actually used.
      *
-     * @return new file name of the resource (like "<uid>.vcf")
+     * @return suggestion for new file name of the resource (like "<uid>.vcf")
      */
     fun prepareForUpload(): String
 
     /**
-     * Unsets the /dirty/ field of the resource. Typically used after successfully uploading a
-     * locally modified resource.
+     * Unsets the _dirty_ field of the resource and updates other sync-related fields in the content provider.
+     * Does not affect `this` object itself (which is immutable).
      *
-     * @param fileName If this argument is not *null*, [LocalResource.fileName] will be set to its value.
-     * @param eTag ETag of the uploaded resource as returned by the server (null if the server didn't return one)
-     * @param scheduleTag CalDAV Schedule-Tag of the uploaded resource as returned by the server (null if not applicable or if the server didn't return one)
+     * @param fileName      If this optional argument is present, [LocalResource.fileName] will be set to its value.
+     * @param eTag          ETag of the uploaded resource as returned by the server (null if the server didn't return one)
+     * @param scheduleTag   CalDAV only: `Schedule-Tag` of the uploaded resource as returned by the server
+     *                      (null if not applicable or if the server didn't return one)
      */
-    fun clearDirty(fileName: String?, eTag: String?, scheduleTag: String? = null)
+    fun clearDirty(fileName: Optional<String>, eTag: String?, scheduleTag: String? = null)
 
     /**
-     * Sets (local) flags of the resource. At the moment, the only allowed values are
-     * 0 and [FLAG_REMOTELY_PRESENT].
+     * Sets (local) flags of the resource in the content provider.
+     * Does not affect `this` object itself (which is immutable).
+     *
+     * At the moment, the only allowed values are 0 and [FLAG_REMOTELY_PRESENT].
      */
     fun updateFlags(flags: Int)
 
-
-    /**
-     * Adds the data object to the content provider and ensures that the dirty flag is clear.
-     *
-     * @return content URI of the created row (e.g. event URI)
-     */
-    fun add(): Uri
-
     /**
      * Updates the data object in the content provider and ensures that the dirty flag is clear.
+     * Does not affect `this` or the [data] object (which are both immutable).
      *
      * @return content URI of the updated row (e.g. event URI)
      */
-    fun update(data: TData): Uri
+    fun update(data: TData, fileName: String?, eTag: String?, scheduleTag: String?, flags: Int)
 
     /**
      * Deletes the data object from the content provider.
-     *
-     * @return number of affected rows
      */
-    fun delete(): Int
+    fun deleteLocal()
 
     /**
      * Undoes deletion of the data object from the content provider.

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalTask.kt

@@ -12,6 +12,7 @@ import at.bitfire.ical4android.DmfsTaskList
 import at.bitfire.ical4android.Task
 import at.bitfire.synctools.storage.BatchOperation
 import org.dmfs.tasks.contract.TaskContract.Tasks
+import java.util.Optional
 import java.util.UUID
 
 class LocalTask: DmfsTask, LocalResource<Task> {
@@ -76,23 +77,33 @@ class LocalTask: DmfsTask, LocalResource<Task> {
         return "$uid.ics"
     }
 
-    override fun clearDirty(fileName: String?, eTag: String?, scheduleTag: String?) {
+    override fun clearDirty(fileName: Optional<String>, eTag: String?, scheduleTag: String?) {
         if (scheduleTag != null)
             logger.fine("Schedule-Tag for tasks not supported yet, won't save")
 
         val values = ContentValues(4)
-        if (fileName != null)
-            values.put(Tasks._SYNC_ID, fileName)
+        if (fileName.isPresent)
+            values.put(Tasks._SYNC_ID, fileName.get())
         values.put(COLUMN_ETAG, eTag)
         values.put(Tasks.SYNC_VERSION, task!!.sequence)
         values.put(Tasks._DIRTY, 0)
         taskList.provider.update(taskSyncURI(), values, null, null)
 
-        if (fileName != null)
-            this.fileName = fileName
+        if (fileName.isPresent)
+            this.fileName = fileName.get()
         this.eTag = eTag
     }
 
+    override fun update(data: Task, fileName: String?, eTag: String?, scheduleTag: String?, flags: Int) {
+        this.fileName = fileName
+        this.eTag = eTag
+        this.scheduleTag = scheduleTag
+        this.flags = flags
+
+        // processes this.{fileName, eTag, scheduleTag, flags} and resets DIRTY flag
+        update(data)
+    }
+
     override fun updateFlags(flags: Int) {
         if (id != null) {
             val values = contentValuesOf(COLUMN_FLAGS to flags)
@@ -102,6 +113,10 @@ class LocalTask: DmfsTask, LocalResource<Task> {
         this.flags = flags
     }
 
+    override fun deleteLocal() {
+        delete()
+    }
+
     override fun resetDeleted() {
         throw NotImplementedError()
     }
@@ -111,4 +126,4 @@ class LocalTask: DmfsTask, LocalResource<Task> {
         override fun fromProvider(taskList: DmfsTaskList<*>, values: ContentValues) =
                 LocalTask(taskList, values)
     }
-}
+}

app/src/main/kotlin/at/bitfire/davdroid/resource/LocalTaskListStore.kt

@@ -47,8 +47,14 @@ class LocalTaskListStore @AssistedInject constructor(
     override val authority: String
         get() = providerName.authority
 
-    override fun acquireContentProvider() =
+    override fun acquireContentProvider(throwOnMissingPermissions: Boolean) = try {
         context.contentResolver.acquireContentProviderClient(authority)
+    } catch (e: SecurityException) {
+        if (throwOnMissingPermissions)
+            throw e
+        else
+            /* return */ null
+    }
 
     override fun create(provider: ContentProviderClient, fromCollection: Collection): LocalTaskList? {
         val service = serviceDao.get(fromCollection.serviceId) ?: throw IllegalArgumentException("Couldn't fetch DB service from collection")

app/src/main/kotlin/at/bitfire/davdroid/servicedetection/CollectionListRefresher.kt

@@ -1,421 +0,0 @@
-/*
- * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
- */
-
-package at.bitfire.davdroid.servicedetection
-
-import at.bitfire.dav4jvm.DavResource
-import at.bitfire.dav4jvm.Property
-import at.bitfire.dav4jvm.Response
-import at.bitfire.dav4jvm.UrlUtils
-import at.bitfire.dav4jvm.exception.HttpException
-import at.bitfire.dav4jvm.property.caldav.CalendarColor
-import at.bitfire.dav4jvm.property.caldav.CalendarDescription
-import at.bitfire.dav4jvm.property.caldav.CalendarHomeSet
-import at.bitfire.dav4jvm.property.caldav.CalendarProxyReadFor
-import at.bitfire.dav4jvm.property.caldav.CalendarProxyWriteFor
-import at.bitfire.dav4jvm.property.caldav.CalendarTimezone
-import at.bitfire.dav4jvm.property.caldav.CalendarTimezoneId
-import at.bitfire.dav4jvm.property.caldav.Source
-import at.bitfire.dav4jvm.property.caldav.SupportedCalendarComponentSet
-import at.bitfire.dav4jvm.property.carddav.AddressbookDescription
-import at.bitfire.dav4jvm.property.carddav.AddressbookHomeSet
-import at.bitfire.dav4jvm.property.common.HrefListProperty
-import at.bitfire.dav4jvm.property.push.PushTransports
-import at.bitfire.dav4jvm.property.push.Topic
-import at.bitfire.dav4jvm.property.webdav.CurrentUserPrivilegeSet
-import at.bitfire.dav4jvm.property.webdav.DisplayName
-import at.bitfire.dav4jvm.property.webdav.GroupMembership
-import at.bitfire.dav4jvm.property.webdav.Owner
-import at.bitfire.dav4jvm.property.webdav.ResourceType
-import at.bitfire.davdroid.db.AppDatabase
-import at.bitfire.davdroid.db.Collection
-import at.bitfire.davdroid.db.HomeSet
-import at.bitfire.davdroid.db.Principal
-import at.bitfire.davdroid.db.Service
-import at.bitfire.davdroid.repository.DavCollectionRepository
-import at.bitfire.davdroid.repository.DavHomeSetRepository
-import at.bitfire.davdroid.settings.Settings
-import at.bitfire.davdroid.settings.SettingsManager
-import at.bitfire.davdroid.util.DavUtils.parent
-import dagger.assisted.Assisted
-import dagger.assisted.AssistedFactory
-import dagger.assisted.AssistedInject
-import okhttp3.HttpUrl
-import okhttp3.OkHttpClient
-import java.util.logging.Level
-import java.util.logging.Logger
-
-/**
- * Logic for refreshing the list of collections and home-sets and related information.
- */
-class CollectionListRefresher @AssistedInject constructor(
-    @Assisted private val service: Service,
-    @Assisted private val httpClient: OkHttpClient,
-    private val db: AppDatabase,
-    private val collectionRepository: DavCollectionRepository,
-    private val homeSetRepository: DavHomeSetRepository,
-    private val logger: Logger,
-    private val settings: SettingsManager
-) {
-
-    @AssistedFactory
-    interface Factory {
-        fun create(service: Service, httpClient: OkHttpClient): CollectionListRefresher
-    }
-
-    /**
-     * Principal properties to ask the server for.
-     */
-    private val principalProperties = arrayOf(
-        DisplayName.NAME,
-        ResourceType.NAME
-    )
-
-    /**
-     * Home-set class to use depending on the given service type.
-     */
-    private val homeSetClass: Class<out HrefListProperty> =
-        when (service.type) {
-            Service.TYPE_CARDDAV -> AddressbookHomeSet::class.java
-            Service.TYPE_CALDAV -> CalendarHomeSet::class.java
-            else -> throw IllegalArgumentException()
-        }
-
-    /**
-     * Home-set properties to ask for in a PROPFIND request to the principal URL,
-     * depending on the given service type.
-     */
-    private val homeSetProperties: Array<Property.Name> =
-        arrayOf(                        // generic WebDAV properties
-            DisplayName.NAME,
-            GroupMembership.NAME,
-            ResourceType.NAME
-        ) + when (service.type) {       // service-specific CalDAV/CardDAV properties
-                Service.TYPE_CARDDAV -> arrayOf(
-                    AddressbookHomeSet.NAME,
-                )
-                Service.TYPE_CALDAV -> arrayOf(
-                    CalendarHomeSet.NAME,
-                    CalendarProxyReadFor.NAME,
-                    CalendarProxyWriteFor.NAME
-                )
-                else -> throw IllegalArgumentException()
-            }
-
-    /**
-     * Collection properties to ask for in a PROPFIND request on a collection.
-     */
-    private val collectionProperties: Array<Property.Name> =
-        arrayOf(                        // generic WebDAV properties
-            CurrentUserPrivilegeSet.NAME,
-            DisplayName.NAME,
-            Owner.NAME,
-            ResourceType.NAME,
-            PushTransports.NAME,        // WebDAV-Push
-            Topic.NAME
-        ) + when (service.type) {       // service-specific CalDAV/CardDAV properties
-            Service.TYPE_CARDDAV -> arrayOf(
-                AddressbookDescription.NAME
-            )
-            Service.TYPE_CALDAV -> arrayOf(
-                CalendarColor.NAME,
-                CalendarDescription.NAME,
-                CalendarTimezone.NAME,
-                CalendarTimezoneId.NAME,
-                SupportedCalendarComponentSet.NAME,
-                Source.NAME
-            )
-            else -> throw IllegalArgumentException()
-        }
-
-
-
-    /**
-     * Starting at given principal URL, tries to recursively find and save all user relevant home sets.
-     *
-     * @param principalUrl              URL of principal to query (user-provided principal or current-user-principal)
-     * @param level                     Current recursion level (limited to 0, 1 or 2):
-     *   - 0: We assume found home sets belong to the current-user-principal
-     *   - 1 or 2: We assume found home sets don't directly belong to the current-user-principal
-     * @param alreadyQueriedPrincipals  The HttpUrls of principals which have been queried already, to avoid querying principals more than once.
-     * @param alreadySavedHomeSets      The HttpUrls of home sets which have been saved to database already, to avoid saving home sets
-     * more than once, which could overwrite the already set "personal" flag with `false`.
-     *
-     * @throws java.io.IOException                          on I/O errors
-     * @throws HttpException                                on HTTP errors
-     * @throws at.bitfire.dav4jvm.exception.DavException    on application-level or logical errors
-     */
-    internal fun discoverHomesets(
-        principalUrl: HttpUrl,
-        level: Int = 0,
-        alreadyQueriedPrincipals: MutableSet<HttpUrl> = mutableSetOf(),
-        alreadySavedHomeSets: MutableSet<HttpUrl> = mutableSetOf()
-    ) {
-        logger.fine("Discovering homesets of $principalUrl")
-        val relatedResources = mutableSetOf<HttpUrl>()
-
-        // Query the URL
-        val principal = DavResource(httpClient, principalUrl)
-        val personal = level == 0
-        try {
-            principal.propfind(0, *homeSetProperties) { davResponse, _ ->
-                alreadyQueriedPrincipals += davResponse.href
-
-                // If response holds home sets, save them
-                davResponse[homeSetClass]?.let { homeSets ->
-                    for (homeSetHref in homeSets.hrefs)
-                        principal.location.resolve(homeSetHref)?.let { homesetUrl ->
-                            val resolvedHomeSetUrl = UrlUtils.withTrailingSlash(homesetUrl)
-                            if (!alreadySavedHomeSets.contains(resolvedHomeSetUrl)) {
-                                homeSetRepository.insertOrUpdateByUrlBlocking(
-                                    // HomeSet is considered personal if this is the outer recursion call,
-                                    // This is because we assume the first call to query the current-user-principal
-                                    // Note: This is not be be confused with the DAV:owner attribute. Home sets can be owned by
-                                    // other principals while still being considered "personal" (belonging to the current-user-principal)
-                                    // and an owned home set need not always be personal either.
-                                    HomeSet(0, service.id, personal, resolvedHomeSetUrl)
-                                )
-                                alreadySavedHomeSets += resolvedHomeSetUrl
-                            }
-                        }
-                }
-
-                // Add related principals to be queried afterwards
-                if (personal) {
-                    val relatedResourcesTypes = listOf(
-                        // current resource is a read/write-proxy for other principals
-                        CalendarProxyReadFor::class.java,
-                        CalendarProxyWriteFor::class.java,
-                        // current resource is a member of a group (principal that can also have proxies)
-                        GroupMembership::class.java
-                    )
-                    for (type in relatedResourcesTypes)
-                        davResponse[type]?.let {
-                            for (href in it.hrefs)
-                                principal.location.resolve(href)?.let { url ->
-                                    relatedResources += url
-                                }
-                        }
-                }
-
-                // If current resource is a calendar-proxy-read/write, it's likely that its parent is a principal, too.
-                davResponse[ResourceType::class.java]?.let { resourceType ->
-                    val proxyProperties = arrayOf(
-                        ResourceType.CALENDAR_PROXY_READ,
-                        ResourceType.CALENDAR_PROXY_WRITE,
-                    )
-                    if (proxyProperties.any { resourceType.types.contains(it) })
-                        relatedResources += davResponse.href.parent()
-                }
-            }
-        } catch (e: HttpException) {
-            if (e.code/100 == 4)
-                logger.log(Level.INFO, "Ignoring Client Error 4xx while looking for ${service.type} home sets", e)
-            else
-                throw e
-        }
-
-        // query related resources
-        if (level <= 1)
-            for (resource in relatedResources)
-                if (alreadyQueriedPrincipals.contains(resource))
-                    logger.warning("$resource already queried, skipping")
-                else
-                    discoverHomesets(
-                        principalUrl = resource,
-                        level = level + 1,
-                        alreadyQueriedPrincipals = alreadyQueriedPrincipals,
-                        alreadySavedHomeSets = alreadySavedHomeSets
-                    )
-    }
-
-    /**
-     * Refreshes home-sets and their collections.
-     *
-     * Each stored home-set URL is queried (`PROPFIND`) and its collections are either saved, updated
-     * or marked as homeless - in case a collection was removed from its home-set.
-     *
-     * If a home-set URL in fact points to a collection directly, the collection will be saved with this URL,
-     * and a null value for it's home-set. Refreshing of collections without home-sets is then handled by [refreshHomelessCollections].
-     */
-    internal fun refreshHomesetsAndTheirCollections() {
-        val homesets = homeSetRepository.getByServiceBlocking(service.id).associateBy { it.url }.toMutableMap()
-        for((homeSetUrl, localHomeset) in homesets) {
-            logger.fine("Listing home set $homeSetUrl")
-
-            // To find removed collections in this homeset: create a queue from existing collections and remove every collection that
-            // is successfully rediscovered. If there are collections left, after processing is done, these are marked homeless.
-            val localHomesetCollections = db.collectionDao()
-                .getByServiceAndHomeset(service.id, localHomeset.id)
-                .associateBy { it.url }
-                .toMutableMap()
-
-            try {
-                DavResource(httpClient, homeSetUrl).propfind(1, *collectionProperties) { response, relation ->
-                    // Note: This callback may be called multiple times ([MultiResponseCallback])
-                    if (!response.isSuccess())
-                        return@propfind
-
-                    if (relation == Response.HrefRelation.SELF)
-                        // this response is about the home set itself
-                        homeSetRepository.insertOrUpdateByUrlBlocking(localHomeset.copy(
-                            displayName = response[DisplayName::class.java]?.displayName,
-                            privBind = response[CurrentUserPrivilegeSet::class.java]?.mayBind != false
-                        ))
-
-                    // in any case, check whether the response is about a usable collection
-                    var collection = Collection.fromDavResponse(response) ?: return@propfind
-                    collection = collection.copy(
-                        serviceId = service.id,
-                        homeSetId = localHomeset.id,
-                        sync = shouldPreselect(collection, homesets.values),
-                        ownerId = response[Owner::class.java]?.href  // save the principal id (collection owner)
-                            ?.let { response.href.resolve(it) }
-                            ?.let { principalUrl -> Principal.fromServiceAndUrl(service, principalUrl) }
-                            ?.let { principal -> db.principalDao().insertOrUpdate(service.id, principal) }
-                    )
-                    logger.log(Level.FINE, "Found collection", collection)
-
-                    // save or update collection if usable (ignore it otherwise)
-                    if (isUsableCollection(collection))
-                        collectionRepository.insertOrUpdateByUrlRememberSync(collection)
-
-                    // Remove this collection from queue - because it was found in the home set
-                    localHomesetCollections.remove(collection.url)
-                }
-            } catch (e: HttpException) {
-                // delete home set locally if it was not accessible (40x)
-                if (e.code in arrayOf(403, 404, 410))
-                    homeSetRepository.deleteBlocking(localHomeset)
-            }
-
-            // Mark leftover (not rediscovered) collections from queue as homeless (remove association)
-            for ((_, homelessCollection) in localHomesetCollections)
-                collectionRepository.insertOrUpdateByUrlRememberSync(
-                    homelessCollection.copy(homeSetId = null)
-                )
-
-        }
-    }
-
-    /**
-     * Refreshes collections which don't have a homeset.
-     *
-     * It queries each stored collection with a homeSetId of "null" and either updates or deletes (if inaccessible or unusable) them.
-     */
-    internal fun refreshHomelessCollections() {
-        val homelessCollections = db.collectionDao().getByServiceAndHomeset(service.id, null).associateBy { it.url }.toMutableMap()
-        for((url, localCollection) in homelessCollections) try {
-            DavResource(httpClient, url).propfind(0, *collectionProperties) { response, _ ->
-                if (!response.isSuccess()) {
-                    collectionRepository.delete(localCollection)
-                    return@propfind
-                }
-
-                // Save or update the collection, if usable, otherwise delete it
-                Collection.fromDavResponse(response)?.let { collection ->
-                    if (!isUsableCollection(collection))
-                        return@let
-                    collectionRepository.insertOrUpdateByUrlRememberSync(collection.copy(
-                        serviceId = localCollection.serviceId,          // use same service ID as previous entry
-                        ownerId = response[Owner::class.java]?.href     // save the principal id (collection owner)
-                            ?.let { response.href.resolve(it) }
-                            ?.let { principalUrl -> Principal.fromServiceAndUrl(service, principalUrl) }
-                            ?.let { principal -> db.principalDao().insertOrUpdate(service.id, principal) }
-                    ))
-                } ?: collectionRepository.delete(localCollection)
-            }
-        } catch (e: HttpException) {
-            // delete collection locally if it was not accessible (40x)
-            if (e.code in arrayOf(403, 404, 410))
-                collectionRepository.delete(localCollection)
-            else
-                throw e
-        }
-
-    }
-
-    /**
-     * Refreshes the principals (get their current display names).
-     * Also removes principals which do not own any collections anymore.
-     */
-    internal fun refreshPrincipals() {
-        // Refresh principals (collection owner urls)
-        val principals = db.principalDao().getByService(service.id)
-        for (oldPrincipal in principals) {
-            val principalUrl = oldPrincipal.url
-            logger.fine("Querying principal $principalUrl")
-            try {
-                DavResource(httpClient, principalUrl).propfind(0, *principalProperties) { response, _ ->
-                    if (!response.isSuccess())
-                        return@propfind
-                    Principal.fromDavResponse(service.id, response)?.let { principal ->
-                        logger.fine("Got principal: $principal")
-                        db.principalDao().insertOrUpdate(service.id, principal)
-                    }
-                }
-            } catch (e: HttpException) {
-                logger.info("Principal update failed with response code ${e.code}. principalUrl=$principalUrl")
-            }
-        }
-
-        // Delete principals which don't own any collections
-        db.principalDao().getAllWithoutCollections().forEach {principal ->
-            db.principalDao().delete(principal)
-        }
-    }
-
-    /**
-     * Finds out whether given collection is usable, by checking that either
-     *  - CalDAV/CardDAV: service and collection type match, or
-     *  - WebCal: subscription source URL is not empty
-     */
-    private fun isUsableCollection(collection: Collection) =
-        (service.type == Service.TYPE_CARDDAV && collection.type == Collection.TYPE_ADDRESSBOOK) ||
-                (service.type == Service.TYPE_CALDAV && arrayOf(Collection.TYPE_CALENDAR, Collection.TYPE_WEBCAL).contains(collection.type)) ||
-                (collection.type == Collection.TYPE_WEBCAL && collection.source != null)
-
-    /**
-     * Whether to preselect the given collection for synchronisation, according to the
-     * settings [Settings.PRESELECT_COLLECTIONS] (see there for allowed values) and
-     * [Settings.PRESELECT_COLLECTIONS_EXCLUDED].
-     *
-     * A collection is considered _personal_ if it is found in one of the current-user-principal's home-sets.
-     *
-     * Before a collection is pre-selected, we check whether its URL matches the regexp in
-     * [Settings.PRESELECT_COLLECTIONS_EXCLUDED], in which case *false* is returned.
-     *
-     * @param collection    the collection to check
-     * @param homeSets      list of personal home-sets
-     * @return *true* if the collection should be preselected for synchronization; *false* otherwise
-     */
-    internal fun shouldPreselect(collection: Collection, homeSets: Iterable<HomeSet>): Boolean {
-        val shouldPreselect = settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS)
-
-        val excluded by lazy {
-            val excludedRegex = settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED)
-            if (!excludedRegex.isNullOrEmpty())
-                Regex(excludedRegex).containsMatchIn(collection.url.toString())
-            else
-                false
-        }
-
-        return when (shouldPreselect) {
-            Settings.PRESELECT_COLLECTIONS_ALL ->
-                // preselect if collection url is not excluded
-                !excluded
-
-            Settings.PRESELECT_COLLECTIONS_PERSONAL ->
-                // preselect if is personal (in a personal home-set), but not excluded
-                homeSets
-                    .filter { homeset -> homeset.personal }
-                    .map { homeset -> homeset.id }
-                    .contains(collection.homeSetId)
-                    && !excluded
-
-            else -> // don't preselect
-                false
-        }
-    }
-}

app/src/main/kotlin/at/bitfire/davdroid/servicedetection/CollectionsWithoutHomeSetRefresher.kt

@@ -0,0 +1,73 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.servicedetection
+
+import at.bitfire.dav4jvm.DavResource
+import at.bitfire.dav4jvm.exception.HttpException
+import at.bitfire.dav4jvm.property.webdav.Owner
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.db.Collection
+import at.bitfire.davdroid.db.Principal
+import at.bitfire.davdroid.db.Service
+import at.bitfire.davdroid.repository.DavCollectionRepository
+import dagger.assisted.Assisted
+import dagger.assisted.AssistedFactory
+import dagger.assisted.AssistedInject
+import okhttp3.OkHttpClient
+
+/**
+ * Logic for refreshing the list of collections (and their related information)
+ * which do not belong to a home set.
+ */
+class CollectionsWithoutHomeSetRefresher @AssistedInject constructor(
+    @Assisted private val service: Service,
+    @Assisted private val httpClient: OkHttpClient,
+    private val db: AppDatabase,
+    private val collectionRepository: DavCollectionRepository,
+) {
+
+    @AssistedFactory
+    interface Factory {
+        fun create(service: Service, httpClient: OkHttpClient): CollectionsWithoutHomeSetRefresher
+    }
+
+    /**
+     * Refreshes collections which don't have a homeset.
+     *
+     * It queries each stored collection with a homeSetId of "null" and either updates or deletes (if inaccessible or unusable) them.
+     */
+    internal fun refreshCollectionsWithoutHomeSet() {
+        val withoutHomeSet = db.collectionDao().getByServiceAndHomeset(service.id, null).associateBy { it.url }.toMutableMap()
+        for ((url, localCollection) in withoutHomeSet) try {
+            val collectionProperties = ServiceDetectionUtils.collectionQueryProperties(service.type)
+            DavResource(httpClient, url).propfind(0, *collectionProperties) { response, _ ->
+                if (!response.isSuccess()) {
+                    collectionRepository.delete(localCollection)
+                    return@propfind
+                }
+
+                // Save or update the collection, if usable, otherwise delete it
+                Collection.fromDavResponse(response)?.let { collection ->
+                    if (!ServiceDetectionUtils.isUsableCollection(service, collection))
+                        return@let
+                    collectionRepository.insertOrUpdateByUrlRememberSync(collection.copy(
+                        serviceId = localCollection.serviceId,          // use same service ID as previous entry
+                        ownerId = response[Owner::class.java]?.href     // save the principal id (collection owner)
+                            ?.let { response.href.resolve(it) }
+                            ?.let { principalUrl -> Principal.fromServiceAndUrl(service, principalUrl) }
+                            ?.let { principal -> db.principalDao().insertOrUpdate(service.id, principal) }
+                    ))
+                } ?: collectionRepository.delete(localCollection)
+            }
+        } catch (e: HttpException) {
+            // delete collection locally if it was not accessible (40x)
+            if (e.code in arrayOf(403, 404, 410))
+                collectionRepository.delete(localCollection)
+            else
+                throw e
+        }
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/servicedetection/HomeSetRefresher.kt

@@ -0,0 +1,162 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.servicedetection
+
+import at.bitfire.dav4jvm.DavResource
+import at.bitfire.dav4jvm.Response
+import at.bitfire.dav4jvm.exception.HttpException
+import at.bitfire.dav4jvm.property.webdav.CurrentUserPrivilegeSet
+import at.bitfire.dav4jvm.property.webdav.DisplayName
+import at.bitfire.dav4jvm.property.webdav.Owner
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.db.Collection
+import at.bitfire.davdroid.db.HomeSet
+import at.bitfire.davdroid.db.Principal
+import at.bitfire.davdroid.db.Service
+import at.bitfire.davdroid.repository.DavCollectionRepository
+import at.bitfire.davdroid.repository.DavHomeSetRepository
+import at.bitfire.davdroid.settings.Settings
+import at.bitfire.davdroid.settings.SettingsManager
+import dagger.assisted.Assisted
+import dagger.assisted.AssistedFactory
+import dagger.assisted.AssistedInject
+import okhttp3.OkHttpClient
+import java.util.logging.Level
+import java.util.logging.Logger
+
+/**
+ * Used to update the list of synchronizable collections
+ */
+class HomeSetRefresher @AssistedInject constructor(
+    @Assisted private val service: Service,
+    @Assisted private val httpClient: OkHttpClient,
+    private val db: AppDatabase,
+    private val logger: Logger,
+    private val collectionRepository: DavCollectionRepository,
+    private val homeSetRepository: DavHomeSetRepository,
+    private val settings: SettingsManager
+) {
+
+    @AssistedFactory
+    interface Factory {
+        fun create(service: Service, httpClient: OkHttpClient): HomeSetRefresher
+    }
+
+    /**
+     * Refreshes home-sets and their collections.
+     *
+     * Each stored home-set URL is queried (`PROPFIND`) and its collections are either saved, updated
+     * or marked as "without home-set" - in case a collection was removed from its home-set.
+     *
+     * If a home-set URL in fact points to a collection directly, the collection will be saved with this URL,
+     * and a null value for it's home-set. Refreshing of collections without home-sets is then handled by [CollectionsWithoutHomeSetRefresher.refreshCollectionsWithoutHomeSet].
+     */
+    internal fun refreshHomesetsAndTheirCollections() {
+        val homesets = homeSetRepository.getByServiceBlocking(service.id).associateBy { it.url }.toMutableMap()
+        for ((homeSetUrl, localHomeset) in homesets) {
+            logger.fine("Listing home set $homeSetUrl")
+
+            // To find removed collections in this homeset: create a queue from existing collections and remove every collection that
+            // is successfully rediscovered. If there are collections left, after processing is done, these are marked as "without home-set".
+            val localHomesetCollections = db.collectionDao()
+                .getByServiceAndHomeset(service.id, localHomeset.id)
+                .associateBy { it.url }
+                .toMutableMap()
+
+            try {
+                val collectionProperties = ServiceDetectionUtils.collectionQueryProperties(service.type)
+                DavResource(httpClient, homeSetUrl).propfind(1, *collectionProperties) { response, relation ->
+                    // Note: This callback may be called multiple times ([MultiResponseCallback])
+                    if (!response.isSuccess())
+                        return@propfind
+
+                    if (relation == Response.HrefRelation.SELF)
+                    // this response is about the home set itself
+                        homeSetRepository.insertOrUpdateByUrlBlocking(
+                            localHomeset.copy(
+                                displayName = response[DisplayName::class.java]?.displayName,
+                                privBind = response[CurrentUserPrivilegeSet::class.java]?.mayBind != false
+                            )
+                        )
+
+                    // in any case, check whether the response is about a usable collection
+                    var collection = Collection.fromDavResponse(response) ?: return@propfind
+                    collection = collection.copy(
+                        serviceId = service.id,
+                        homeSetId = localHomeset.id,
+                        sync = shouldPreselect(collection, homesets.values),
+                        ownerId = response[Owner::class.java]?.href  // save the principal id (collection owner)
+                            ?.let { response.href.resolve(it) }
+                            ?.let { principalUrl -> Principal.fromServiceAndUrl(service, principalUrl) }
+                            ?.let { principal -> db.principalDao().insertOrUpdate(service.id, principal) }
+                    )
+                    logger.log(Level.FINE, "Found collection", collection)
+
+                    // save or update collection if usable (ignore it otherwise)
+                    if (ServiceDetectionUtils.isUsableCollection(service, collection))
+                        collectionRepository.insertOrUpdateByUrlRememberSync(collection)
+
+                    // Remove this collection from queue - because it was found in the home set
+                    localHomesetCollections.remove(collection.url)
+                }
+            } catch (e: HttpException) {
+                // delete home set locally if it was not accessible (40x)
+                if (e.code in arrayOf(403, 404, 410))
+                    homeSetRepository.deleteBlocking(localHomeset)
+            }
+
+            // Mark leftover (not rediscovered) collections from queue as "without home-set" (remove association)
+            for ((_, collection) in localHomesetCollections)
+                collectionRepository.insertOrUpdateByUrlRememberSync(
+                    collection.copy(homeSetId = null)
+                )
+
+        }
+    }
+
+    /**
+     * Whether to preselect the given collection for synchronisation, according to the
+     * settings [Settings.PRESELECT_COLLECTIONS] (see there for allowed values) and
+     * [Settings.PRESELECT_COLLECTIONS_EXCLUDED].
+     *
+     * A collection is considered _personal_ if it is found in one of the current-user-principal's home-sets.
+     *
+     * Before a collection is pre-selected, we check whether its URL matches the regexp in
+     * [Settings.PRESELECT_COLLECTIONS_EXCLUDED], in which case *false* is returned.
+     *
+     * @param collection    the collection to check
+     * @param homeSets      list of personal home-sets
+     * @return *true* if the collection should be preselected for synchronization; *false* otherwise
+     */
+    internal fun shouldPreselect(collection: Collection, homeSets: Iterable<HomeSet>): Boolean {
+        val shouldPreselect = settings.getIntOrNull(Settings.PRESELECT_COLLECTIONS)
+
+        val excluded by lazy {
+            val excludedRegex = settings.getString(Settings.PRESELECT_COLLECTIONS_EXCLUDED)
+            if (!excludedRegex.isNullOrEmpty())
+                Regex(excludedRegex).containsMatchIn(collection.url.toString())
+            else
+                false
+        }
+
+        return when (shouldPreselect) {
+            Settings.PRESELECT_COLLECTIONS_ALL ->
+                // preselect if collection url is not excluded
+                !excluded
+
+            Settings.PRESELECT_COLLECTIONS_PERSONAL ->
+                // preselect if is personal (in a personal home-set), but not excluded
+                homeSets
+                    .filter { homeset -> homeset.personal }
+                    .map { homeset -> homeset.id }
+                    .contains(collection.homeSetId)
+                        && !excluded
+
+            else -> // don't preselect
+                false
+        }
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/servicedetection/PrincipalsRefresher.kt

@@ -0,0 +1,73 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.servicedetection
+
+import at.bitfire.dav4jvm.DavResource
+import at.bitfire.dav4jvm.exception.HttpException
+import at.bitfire.dav4jvm.property.webdav.DisplayName
+import at.bitfire.dav4jvm.property.webdav.ResourceType
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.db.Principal
+import at.bitfire.davdroid.db.Service
+import dagger.assisted.Assisted
+import dagger.assisted.AssistedFactory
+import dagger.assisted.AssistedInject
+import okhttp3.OkHttpClient
+import java.util.logging.Logger
+
+/**
+ * Used to update the principals (their current display names) and delete those without collections.
+ */
+class PrincipalsRefresher @AssistedInject constructor(
+    @Assisted private val service: Service,
+    @Assisted private val httpClient: OkHttpClient,
+    private val db: AppDatabase,
+    private val logger: Logger
+) {
+
+    @AssistedFactory
+    interface Factory {
+        fun create(service: Service, httpClient: OkHttpClient): PrincipalsRefresher
+    }
+
+    /**
+     * Principal properties to ask the server for.
+     */
+    private val principalProperties = arrayOf(
+        DisplayName.NAME,
+        ResourceType.NAME
+    )
+
+    /**
+     * Refreshes the principals (get their current display names).
+     * Also removes principals which do not own any collections anymore.
+     */
+    fun refreshPrincipals() {
+        // Refresh principals (collection owner urls)
+        val principals = db.principalDao().getByService(service.id)
+        for (oldPrincipal in principals) {
+            val principalUrl = oldPrincipal.url
+            logger.fine("Querying principal $principalUrl")
+            try {
+                DavResource(httpClient, principalUrl).propfind(0, *principalProperties) { response, _ ->
+                    if (!response.isSuccess())
+                        return@propfind
+                    Principal.fromDavResponse(service.id, response)?.let { principal ->
+                        logger.fine("Got principal: $principal")
+                        db.principalDao().insertOrUpdate(service.id, principal)
+                    }
+                }
+            } catch (e: HttpException) {
+                logger.info("Principal update failed with response code ${e.code}. principalUrl=$principalUrl")
+            }
+        }
+
+        // Delete principals which don't own any collections
+        db.principalDao().getAllWithoutCollections().forEach { principal ->
+            db.principalDao().delete(principal)
+        }
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/servicedetection/RefreshCollectionsWorker.kt

@@ -62,11 +62,14 @@ import java.util.logging.Logger
 class RefreshCollectionsWorker @AssistedInject constructor(
     @Assisted appContext: Context,
     @Assisted workerParams: WorkerParameters,
-    private val collectionListRefresherFactory: CollectionListRefresher.Factory,
+    private val collectionsWithoutHomeSetRefresherFactory: CollectionsWithoutHomeSetRefresher.Factory,
+    private val homeSetRefresherFactory: HomeSetRefresher.Factory,
     private val httpClientBuilder: HttpClient.Builder,
     private val logger: Logger,
     private val notificationRegistry: NotificationRegistry,
+    private val principalsRefresherFactory: PrincipalsRefresher.Factory,
     private val pushRegistrationManager: PushRegistrationManager,
+    private val serviceRefresherFactory: ServiceRefresher.Factory,
     serviceRepository: DavServiceRepository
 ): CoroutineWorker(appContext, workerParams) {
 
@@ -156,22 +159,25 @@ class RefreshCollectionsWorker @AssistedInject constructor(
                 .use { httpClient ->
                     runInterruptible {
                         val httpClient = httpClient.okHttpClient
-                        val refresher = collectionListRefresherFactory.create(service, httpClient)
+                        val refresher = collectionsWithoutHomeSetRefresherFactory.create(service, httpClient)
 
                         // refresh home set list (from principal url)
                         service.principal?.let { principalUrl ->
                             logger.fine("Querying principal $principalUrl for home sets")
-                            refresher.discoverHomesets(principalUrl)
+                            val serviceRefresher = serviceRefresherFactory.create(service, httpClient)
+                            serviceRefresher.discoverHomesets(principalUrl)
                         }
 
                         // refresh home sets and their member collections
-                        refresher.refreshHomesetsAndTheirCollections()
+                        homeSetRefresherFactory.create(service, httpClient)
+                            .refreshHomesetsAndTheirCollections()
 
                         // also refresh collections without a home set
-                        refresher.refreshHomelessCollections()
+                        refresher.refreshCollectionsWithoutHomeSet()
 
                         // Lastly, refresh the principals (collection owners)
-                        refresher.refreshPrincipals()
+                        val principalsRefresher = principalsRefresherFactory.create(service, httpClient)
+                        principalsRefresher.refreshPrincipals()
                     }
                 }
 

app/src/main/kotlin/at/bitfire/davdroid/servicedetection/ServiceDetectionUtils.kt

@@ -0,0 +1,66 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.servicedetection
+
+import at.bitfire.dav4jvm.Property
+import at.bitfire.dav4jvm.property.caldav.CalendarColor
+import at.bitfire.dav4jvm.property.caldav.CalendarDescription
+import at.bitfire.dav4jvm.property.caldav.CalendarTimezone
+import at.bitfire.dav4jvm.property.caldav.CalendarTimezoneId
+import at.bitfire.dav4jvm.property.caldav.Source
+import at.bitfire.dav4jvm.property.caldav.SupportedCalendarComponentSet
+import at.bitfire.dav4jvm.property.carddav.AddressbookDescription
+import at.bitfire.dav4jvm.property.push.PushTransports
+import at.bitfire.dav4jvm.property.push.Topic
+import at.bitfire.dav4jvm.property.webdav.CurrentUserPrivilegeSet
+import at.bitfire.dav4jvm.property.webdav.DisplayName
+import at.bitfire.dav4jvm.property.webdav.Owner
+import at.bitfire.dav4jvm.property.webdav.ResourceType
+import at.bitfire.davdroid.db.Collection
+import at.bitfire.davdroid.db.Service
+import at.bitfire.davdroid.db.ServiceType
+
+object ServiceDetectionUtils {
+
+    /**
+     * WebDAV properties to ask for in a PROPFIND request on a collection.
+     */
+    fun collectionQueryProperties(@ServiceType serviceType: String): Array<Property.Name> =
+        arrayOf(                        // generic WebDAV properties
+            CurrentUserPrivilegeSet.NAME,
+            DisplayName.NAME,
+            Owner.NAME,
+            ResourceType.NAME,
+            PushTransports.NAME,        // WebDAV-Push
+            Topic.NAME
+        ) + when (serviceType) {       // service-specific CalDAV/CardDAV properties
+            Service.TYPE_CARDDAV -> arrayOf(
+                AddressbookDescription.NAME
+            )
+
+            Service.TYPE_CALDAV -> arrayOf(
+                CalendarColor.NAME,
+                CalendarDescription.NAME,
+                CalendarTimezone.NAME,
+                CalendarTimezoneId.NAME,
+                SupportedCalendarComponentSet.NAME,
+                Source.NAME
+            )
+
+            else -> throw IllegalArgumentException()
+        }
+
+    /**
+     * Finds out whether given collection is usable for synchronization, by checking that either
+     *
+     *  - CalDAV/CardDAV: service and collection type match, or
+     *  - WebCal: subscription source URL is not empty.
+     */
+    fun isUsableCollection(service: Service, collection: Collection) =
+        (service.type == Service.TYPE_CARDDAV && collection.type == Collection.TYPE_ADDRESSBOOK) ||
+                (service.type == Service.TYPE_CALDAV && arrayOf(Collection.TYPE_CALENDAR, Collection.TYPE_WEBCAL).contains(collection.type)) ||
+                (collection.type == Collection.TYPE_WEBCAL && collection.source != null)
+
+}

app/src/main/kotlin/at/bitfire/davdroid/servicedetection/ServiceRefresher.kt

@@ -0,0 +1,178 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.servicedetection
+
+import at.bitfire.dav4jvm.DavResource
+import at.bitfire.dav4jvm.Property
+import at.bitfire.dav4jvm.UrlUtils
+import at.bitfire.dav4jvm.exception.HttpException
+import at.bitfire.dav4jvm.property.caldav.CalendarHomeSet
+import at.bitfire.dav4jvm.property.caldav.CalendarProxyReadFor
+import at.bitfire.dav4jvm.property.caldav.CalendarProxyWriteFor
+import at.bitfire.dav4jvm.property.carddav.AddressbookHomeSet
+import at.bitfire.dav4jvm.property.common.HrefListProperty
+import at.bitfire.dav4jvm.property.webdav.DisplayName
+import at.bitfire.dav4jvm.property.webdav.GroupMembership
+import at.bitfire.dav4jvm.property.webdav.ResourceType
+import at.bitfire.davdroid.db.HomeSet
+import at.bitfire.davdroid.db.Service
+import at.bitfire.davdroid.repository.DavHomeSetRepository
+import at.bitfire.davdroid.util.DavUtils.parent
+import dagger.assisted.Assisted
+import dagger.assisted.AssistedFactory
+import dagger.assisted.AssistedInject
+import okhttp3.HttpUrl
+import okhttp3.OkHttpClient
+import java.util.logging.Level
+import java.util.logging.Logger
+
+/**
+ * ServiceRefresher is used to discover and save home sets of a given service.
+ */
+class ServiceRefresher @AssistedInject constructor(
+    @Assisted private val service: Service,
+    @Assisted private val httpClient: OkHttpClient,
+    private val logger: Logger,
+    private val homeSetRepository: DavHomeSetRepository
+) {
+
+    @AssistedFactory
+    interface Factory {
+        fun create(service: Service, httpClient: OkHttpClient): ServiceRefresher
+    }
+
+    /**
+     * Home-set class to use depending on the given service type.
+     */
+    private val homeSetClass: Class<out HrefListProperty> =
+        when (service.type) {
+            Service.TYPE_CARDDAV -> AddressbookHomeSet::class.java
+            Service.TYPE_CALDAV -> CalendarHomeSet::class.java
+            else -> throw IllegalArgumentException()
+        }
+
+    /**
+     * Home-set properties to ask for in a PROPFIND request to the principal URL,
+     * depending on the given service type.
+     */
+    private val homeSetProperties: Array<Property.Name> =
+        arrayOf(                        // generic WebDAV properties
+            DisplayName.NAME,
+            GroupMembership.NAME,
+            ResourceType.NAME
+        ) + when (service.type) {       // service-specific CalDAV/CardDAV properties
+            Service.TYPE_CARDDAV -> arrayOf(
+                AddressbookHomeSet.NAME,
+            )
+
+            Service.TYPE_CALDAV -> arrayOf(
+                CalendarHomeSet.NAME,
+                CalendarProxyReadFor.NAME,
+                CalendarProxyWriteFor.NAME
+            )
+
+            else -> throw IllegalArgumentException()
+        }
+
+    /**
+     * Starting at given principal URL, tries to recursively find and save all user relevant home sets.
+     *
+     * @param principalUrl              URL of principal to query (user-provided principal or current-user-principal)
+     * @param level                     Current recursion level (limited to 0, 1 or 2):
+     *   - 0: We assume found home sets belong to the current-user-principal
+     *   - 1 or 2: We assume found home sets don't directly belong to the current-user-principal
+     * @param alreadyQueriedPrincipals  The HttpUrls of principals which have been queried already, to avoid querying principals more than once.
+     * @param alreadySavedHomeSets      The HttpUrls of home sets which have been saved to database already, to avoid saving home sets
+     * more than once, which could overwrite the already set "personal" flag with `false`.
+     *
+     * @throws java.io.IOException                          on I/O errors
+     * @throws HttpException                                on HTTP errors
+     * @throws at.bitfire.dav4jvm.exception.DavException    on application-level or logical errors
+     */
+    internal fun discoverHomesets(
+        principalUrl: HttpUrl,
+        level: Int = 0,
+        alreadyQueriedPrincipals: MutableSet<HttpUrl> = mutableSetOf(),
+        alreadySavedHomeSets: MutableSet<HttpUrl> = mutableSetOf()
+    ) {
+        logger.fine("Discovering homesets of $principalUrl")
+        val relatedResources = mutableSetOf<HttpUrl>()
+
+        // Query the URL
+        val principal = DavResource(httpClient, principalUrl)
+        val personal = level == 0
+        try {
+            principal.propfind(0, *homeSetProperties) { davResponse, _ ->
+                alreadyQueriedPrincipals += davResponse.href
+
+                // If response holds home sets, save them
+                davResponse[homeSetClass]?.let { homeSets ->
+                    for (homeSetHref in homeSets.hrefs)
+                        principal.location.resolve(homeSetHref)?.let { homesetUrl ->
+                            val resolvedHomeSetUrl = UrlUtils.withTrailingSlash(homesetUrl)
+                            if (!alreadySavedHomeSets.contains(resolvedHomeSetUrl)) {
+                                homeSetRepository.insertOrUpdateByUrlBlocking(
+                                    // HomeSet is considered personal if this is the outer recursion call,
+                                    // This is because we assume the first call to query the current-user-principal
+                                    // Note: This is not be be confused with the DAV:owner attribute. Home sets can be owned by
+                                    // other principals while still being considered "personal" (belonging to the current-user-principal)
+                                    // and an owned home set need not always be personal either.
+                                    HomeSet(0, service.id, personal, resolvedHomeSetUrl)
+                                )
+                                alreadySavedHomeSets += resolvedHomeSetUrl
+                            }
+                        }
+                }
+
+                // Add related principals to be queried afterwards
+                if (personal) {
+                    val relatedResourcesTypes = listOf(
+                        // current resource is a read/write-proxy for other principals
+                        CalendarProxyReadFor::class.java,
+                        CalendarProxyWriteFor::class.java,
+                        // current resource is a member of a group (principal that can also have proxies)
+                        GroupMembership::class.java
+                    )
+                    for (type in relatedResourcesTypes)
+                        davResponse[type]?.let {
+                            for (href in it.hrefs)
+                                principal.location.resolve(href)?.let { url ->
+                                    relatedResources += url
+                                }
+                        }
+                }
+
+                // If current resource is a calendar-proxy-read/write, it's likely that its parent is a principal, too.
+                davResponse[ResourceType::class.java]?.let { resourceType ->
+                    val proxyProperties = arrayOf(
+                        ResourceType.CALENDAR_PROXY_READ,
+                        ResourceType.CALENDAR_PROXY_WRITE,
+                    )
+                    if (proxyProperties.any { resourceType.types.contains(it) })
+                        relatedResources += davResponse.href.parent()
+                }
+            }
+        } catch (e: HttpException) {
+            if (e.code / 100 == 4)
+                logger.log(Level.INFO, "Ignoring Client Error 4xx while looking for ${service.type} home sets", e)
+            else
+                throw e
+        }
+
+        // query related resources
+        if (level <= 1)
+            for (resource in relatedResources)
+                if (alreadyQueriedPrincipals.contains(resource))
+                    logger.warning("$resource already queried, skipping")
+                else
+                    discoverHomesets(
+                        principalUrl = resource,
+                        level = level + 1,
+                        alreadyQueriedPrincipals = alreadyQueriedPrincipals,
+                        alreadySavedHomeSets = alreadySavedHomeSets
+                    )
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/settings/AccountSettings.kt

@@ -354,7 +354,12 @@ class AccountSettings @AssistedInject constructor(
 
     companion object {
 
-        const val CURRENT_VERSION = 20
+        /**
+         * Current (usually the newest) account settings version. It's used to
+         * determine whether a migration ([AccountSettingsMigration])
+         * should be performed.
+         */
+        const val CURRENT_VERSION = 21
         const val KEY_SETTINGS_VERSION = "version"
 
         const val KEY_SYNC_INTERVAL_ADDRESSBOOKS = "sync_interval_addressbooks"

app/src/main/kotlin/at/bitfire/davdroid/settings/migration/AccountSettingsMigration.kt

@@ -10,7 +10,8 @@ import at.bitfire.davdroid.settings.AccountSettings
 interface AccountSettingsMigration {
 
     /**
-     * Migrate the account settings from the old version to the new version.
+     * Migrate the account settings from the old version to the new version which
+     * is set in [AccountSettings.CURRENT_VERSION].
      *
      * **The new (target) version number is registered in the Hilt module as [Int] key of the multi-binding of [AccountSettings].**
      *

app/src/main/kotlin/at/bitfire/davdroid/settings/migration/AccountSettingsMigration12.kt

@@ -12,8 +12,8 @@ import android.provider.CalendarContract
 import android.util.Base64
 import androidx.core.content.ContextCompat
 import androidx.core.content.contentValuesOf
-import at.bitfire.ical4android.AndroidEvent
 import at.bitfire.ical4android.UnknownProperty
+import at.bitfire.synctools.storage.calendar.AndroidEvent2
 import at.techbee.jtx.JtxContract.asSyncAdapter
 import dagger.Binds
 import dagger.Module
@@ -69,7 +69,7 @@ class AccountSettingsMigration12 @Inject constructor(
                                     val property = UnknownProperty.fromJsonString(rawValue)
                                     if (property is Url) {  // rewrite to MIMETYPE_URL
                                         val newValues = contentValuesOf(
-                                            CalendarContract.ExtendedProperties.NAME to AndroidEvent.EXTNAME_URL,
+                                            CalendarContract.ExtendedProperties.NAME to AndroidEvent2.EXTNAME_URL,
                                             CalendarContract.ExtendedProperties.VALUE to property.value
                                         )
                                         provider.update(uri, newValues, null, null)
@@ -77,7 +77,7 @@ class AccountSettingsMigration12 @Inject constructor(
                                 } catch (e: Exception) {
                                     logger.log(
                                         Level.WARNING,
-                                        "Couldn't rewrite URL from unknown property to ${AndroidEvent.EXTNAME_URL}",
+                                        "Couldn't rewrite URL from unknown property to ${AndroidEvent2.EXTNAME_URL}",
                                         e
                                     )
                                 }

app/src/main/kotlin/at/bitfire/davdroid/settings/migration/AccountSettingsMigration20.kt

@@ -65,12 +65,7 @@ class AccountSettingsMigration20 @Inject constructor(
 
     @OpenForTesting
     internal fun migrateAddressBooks(account: Account, cardDavServiceId: Long) {
-        try {
-            addressBookStore.acquireContentProvider()
-        } catch (_: SecurityException) {
-            // no contacts permission
-            null
-        }?.use { provider ->
+        addressBookStore.acquireContentProvider()?.use { provider ->
             for (addressBook in addressBookStore.getAll(account, provider)) {
                 val url = accountManager.getUserData(addressBook.addressBookAccount, ADDRESS_BOOK_USER_DATA_URL) ?: continue
                 val collection = collectionRepository.getByServiceAndUrl(cardDavServiceId, url) ?: continue
@@ -81,12 +76,7 @@ class AccountSettingsMigration20 @Inject constructor(
 
     @OpenForTesting
     internal fun migrateCalendars(account: Account, calDavServiceId: Long) {
-        try {
-            calendarStore.acquireContentProvider()
-        } catch (_: SecurityException) {
-            // no contacts permission
-            null
-        }?.use { client ->
+        calendarStore.acquireContentProvider()?.use { client ->
             val calendarProvider = AndroidCalendarProvider(account, client)
             // for each calendar, assign _SYNC_ID := ID if collection (identified by NAME field = URL)
             for (calendar in calendarProvider.findCalendars()) {
@@ -104,12 +94,7 @@ class AccountSettingsMigration20 @Inject constructor(
     @OpenForTesting
     internal fun migrateTaskLists(account: Account, calDavServiceId: Long) {
         val taskListStore = tasksAppManager.getDataStore() ?: /* no tasks app */ return
-        try {
-            taskListStore.acquireContentProvider()
-        } catch (_: SecurityException) {
-            // no tasks permission
-            null
-        }?.use { provider ->
+        taskListStore.acquireContentProvider()?.use { provider ->
             for (taskList in taskListStore.getAll(account, provider)) {
                 when (taskList) {
                     is LocalTaskList -> {       // tasks.org, OpenTasks

app/src/main/kotlin/at/bitfire/davdroid/settings/migration/AccountSettingsMigration21.kt

@@ -0,0 +1,76 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.settings.migration
+
+import android.accounts.Account
+import android.accounts.AccountManager
+import android.content.Context
+import android.os.Build
+import android.os.Bundle
+import android.provider.CalendarContract
+import android.provider.ContactsContract
+import at.bitfire.davdroid.R
+import at.bitfire.davdroid.sync.adapter.SyncFrameworkIntegration
+import dagger.Binds
+import dagger.Module
+import dagger.hilt.InstallIn
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.components.SingletonComponent
+import dagger.multibindings.IntKey
+import dagger.multibindings.IntoMap
+import java.util.logging.Logger
+import javax.inject.Inject
+
+/**
+ * On Android 14+ the pending sync state of the Sync Adapter Framework is not handled correctly.
+ * As a workaround we cancel incoming sync requests (clears pending flag) after enqueuing our own
+ * sync worker (work manager). With version 4.5.3 we started cancelling pending syncs for DAVx5
+ * accounts, but forgot to do that for address book accounts. With version 4.5.4 we also cancel
+ * those, but only when contact data of an address book has been edited.
+ *
+ * This migration cancels (once only) any possibly still wrongly pending address book and calendar
+ * (+tasks) account syncs.
+ */
+class AccountSettingsMigration21 @Inject constructor(
+    @ApplicationContext private val context: Context,
+    private val syncFrameworkIntegration: SyncFrameworkIntegration,
+    private val logger: Logger
+): AccountSettingsMigration {
+
+    private val accountManager = AccountManager.get(context)
+
+    private val calendarAccountType = context.getString(R.string.account_type)
+    private val addressBookAccountType = context.getString(R.string.account_type_address_book)
+
+    override fun migrate(account: Account) {
+        if (Build.VERSION.SDK_INT >= 34) {
+            // Cancel any (after an update) possibly forever pending calendar (+tasks) account syncs
+            cancelSyncs(calendarAccountType, CalendarContract.AUTHORITY)
+
+            // Cancel any (after an update) possibly forever pending address book account syncs
+            cancelSyncs(addressBookAccountType, ContactsContract.AUTHORITY)
+        }
+    }
+
+    /**
+     * Cancels any (possibly forever pending) syncs for the accounts of given account type for all
+     * authorities.
+     */
+    private fun cancelSyncs(accountType: String, authority: String) {
+        accountManager.getAccountsByType(accountType).forEach { account ->
+            logger.info("Android 14+: Canceling all (possibly forever pending) syncs for $account")
+            syncFrameworkIntegration.cancelSync(account, authority, Bundle())
+        }
+    }
+
+    @Module
+    @InstallIn(SingletonComponent::class)
+    abstract class AccountSettingsMigrationModule {
+        @Binds @IntoMap
+        @IntKey(21)
+        abstract fun provide(impl: AccountSettingsMigration21): AccountSettingsMigration
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/sync/AutomaticSyncManager.kt

@@ -11,6 +11,7 @@ import at.bitfire.davdroid.db.Service
 import at.bitfire.davdroid.repository.DavServiceRepository
 import at.bitfire.davdroid.resource.LocalAddressBookStore
 import at.bitfire.davdroid.settings.AccountSettings
+import at.bitfire.davdroid.sync.adapter.SyncFrameworkIntegration
 import at.bitfire.davdroid.sync.worker.SyncWorkerManager
 import kotlinx.coroutines.runBlocking
 import javax.inject.Inject

app/src/main/kotlin/at/bitfire/davdroid/sync/CalendarSyncManager.kt

@@ -28,7 +28,6 @@ import at.bitfire.davdroid.resource.LocalResource
 import at.bitfire.davdroid.resource.SyncState
 import at.bitfire.davdroid.settings.AccountSettings
 import at.bitfire.davdroid.util.DavUtils.lastSegment
-import at.bitfire.ical4android.AndroidEvent
 import at.bitfire.ical4android.Event
 import at.bitfire.ical4android.EventReader
 import at.bitfire.ical4android.EventWriter
@@ -50,6 +49,7 @@ import java.io.StringReader
 import java.io.StringWriter
 import java.time.Duration
 import java.time.ZonedDateTime
+import java.util.Optional
 import java.util.logging.Level
 
 /**
@@ -159,7 +159,7 @@ class CalendarSyncManager @AssistedInject constructor(
             for (event in localCollection.findDirty()) {
                 logger.warning("Resetting locally modified event to ETag=null (read-only calendar!)")
                 SyncException.wrapWithLocalResource(event) {
-                    event.clearDirty(null, null)
+                    event.clearDirty(Optional.empty(), null, null)
                 }
                 modified = true
             }
@@ -178,9 +178,16 @@ class CalendarSyncManager @AssistedInject constructor(
         return modified or superModified
     }
 
+    override fun onSuccessfulUpload(local: LocalEvent, newFileName: String, eTag: String?, scheduleTag: String?) {
+        super.onSuccessfulUpload(local, newFileName, eTag, scheduleTag)
+
+        // update local SEQUENCE to new value after successful upload
+        local.updateSequence(local.getCachedEvent().sequence)
+    }
+
     override fun generateUpload(resource: LocalEvent): RequestBody =
         SyncException.wrapWithLocalResource(resource) {
-            val event = requireNotNull(resource.androidEvent.event)
+            val event = resource.eventToUpload()
             logger.log(Level.FINE, "Preparing upload of event ${resource.fileName}", event)
 
             // write iCalendar to string and convert to request body
@@ -284,15 +291,22 @@ class CalendarSyncManager @AssistedInject constructor(
             SyncException.wrapWithLocalResource(local) {
                 if (local != null) {
                     logger.log(Level.INFO, "Updating $fileName in local calendar", event)
-                    local.eTag = eTag
-                    local.scheduleTag = scheduleTag
-                    local.update(event)
+                    local.update(
+                        data = event,
+                        fileName = fileName,
+                        eTag = eTag,
+                        scheduleTag = scheduleTag,
+                        flags = LocalResource.FLAG_REMOTELY_PRESENT
+                    )
                 } else {
                     logger.log(Level.INFO, "Adding $fileName to local calendar", event)
-                    val newLocal = LocalEvent(AndroidEvent(localCollection.androidCalendar, event, fileName, eTag, scheduleTag, LocalResource.FLAG_REMOTELY_PRESENT))
-                    SyncException.wrapWithLocalResource(newLocal) {
-                        newLocal.add()
-                    }
+                    localCollection.add(
+                        event = event,
+                        fileName = fileName,
+                        eTag = eTag,
+                        scheduleTag = scheduleTag,
+                        flags = LocalResource.FLAG_REMOTELY_PRESENT
+                    )
                 }
             }
         } else

app/src/main/kotlin/at/bitfire/davdroid/sync/ContactsSyncManager.kt

@@ -244,7 +244,7 @@ class ContactsSyncManager @AssistedInject constructor(
             for (group in localCollection.findDirtyGroups()) {
                 logger.warning("Resetting locally modified group to ETag=null (read-only address book!)")
                 SyncException.wrapWithLocalResource(group) {
-                    group.clearDirty(null, null)
+                    group.clearDirty(Optional.empty(), null)
                 }
                 modified = true
             }
@@ -252,7 +252,7 @@ class ContactsSyncManager @AssistedInject constructor(
             for (contact in localCollection.findDirtyContacts()) {
                 logger.warning("Resetting locally modified contact to ETag=null (read-only address book!)")
                 SyncException.wrapWithLocalResource(contact) {
-                    contact.clearDirty(null, null)
+                    contact.clearDirty(Optional.empty(), null)
                 }
                 modified = true
             }
@@ -391,56 +391,73 @@ class ContactsSyncManager @AssistedInject constructor(
         val newData = contacts.first()
         groupStrategy.verifyContactBeforeSaving(newData)
 
-        // update local contact, if it exists
-        val localOrNull = localCollection.findByName(fileName)
-        SyncException.wrapWithLocalResource(localOrNull) {
-            var local = localOrNull
-            if (local != null) {
-                logger.log(Level.INFO, "Updating $fileName in local address book", newData)
+        var updated: LocalAddress? = null
 
-                if (local is LocalGroup && newData.group) {
-                    // update group
-                    local.eTag = eTag
-                    local.flags = LocalResource.FLAG_REMOTELY_PRESENT
-                    local.update(newData)
+        val existing = localCollection.findByName(fileName)
+        if (existing == null) {
+            // create new contact/group
+            if (newData.group) {
+                logger.log(Level.INFO, "Creating local group", newData)
+                val newGroup = LocalGroup(localCollection, newData, fileName, eTag, LocalResource.FLAG_REMOTELY_PRESENT)
+                SyncException.wrapWithLocalResource(newGroup) {
+                    newGroup.add()
+                    updated = newGroup
+                }
 
-                } else if (local is LocalContact && !newData.group) {
-                    // update contact
-                    local.eTag = eTag
-                    local.flags = LocalResource.FLAG_REMOTELY_PRESENT
-                    local.update(newData)
+            } else {
+                logger.log(Level.INFO, "Creating local contact", newData)
+                val newContact = LocalContact(localCollection, newData, fileName, eTag, LocalResource.FLAG_REMOTELY_PRESENT)
+                SyncException.wrapWithLocalResource(newContact) {
+                    newContact.add()
+                    updated = newContact
+                }
+            }
+
+        } else {
+            // update existing local contact/group
+            logger.log(Level.INFO, "Updating $fileName in local address book", newData)
+
+            SyncException.wrapWithLocalResource(existing) {
+                if ((existing is LocalGroup && newData.group) || (existing is LocalContact && !newData.group)) {
+                    // update contact / group
+
+                    existing.update(
+                        data = newData,
+                        fileName = fileName,
+                        eTag = eTag,
+                        flags = LocalResource.FLAG_REMOTELY_PRESENT,
+                        scheduleTag = null
+                    )
+                    updated = existing
 
                 } else {
                     // group has become an individual contact or vice versa, delete and create with new type
-                    local.delete()
-                    local = null
-                }
-            }
+                    existing.deleteLocal()
 
-            if (local == null) {
-                if (newData.group) {
-                    logger.log(Level.INFO, "Creating local group", newData)
-                    val newGroup = LocalGroup(localCollection, newData, fileName, eTag, LocalResource.FLAG_REMOTELY_PRESENT)
-                    SyncException.wrapWithLocalResource(newGroup) {
-                        newGroup.add()
-                        local = newGroup
-                    }
-                } else {
-                    logger.log(Level.INFO, "Creating local contact", newData)
-                    val newContact = LocalContact(localCollection, newData, fileName, eTag, LocalResource.FLAG_REMOTELY_PRESENT)
-                    SyncException.wrapWithLocalResource(newContact) {
-                        newContact.add()
-                        local = newContact
+                    if (newData.group) {
+                        logger.log(Level.INFO, "Creating local group (was contact before)", newData)
+                        val newGroup = LocalGroup(localCollection, newData, fileName, eTag, LocalResource.FLAG_REMOTELY_PRESENT)
+                        SyncException.wrapWithLocalResource(newGroup) {
+                            newGroup.add()
+                            updated = newGroup
+                        }
+
+                    } else {
+                        logger.log(Level.INFO, "Creating local contact (was group before)", newData)
+                        val newContact = LocalContact(localCollection, newData, fileName, eTag, LocalResource.FLAG_REMOTELY_PRESENT)
+                        SyncException.wrapWithLocalResource(newContact) {
+                            newContact.add()
+                            updated = newContact
+                        }
                     }
                 }
             }
+        }
 
-            dirtyVerifier.getOrNull()?.let { verifier ->
-                // workaround for Android 7 which sets DIRTY flag when only meta-data is changed
-                (local as? LocalContact)?.let { localContact ->
-                    verifier.updateHashCode(localCollection, localContact)
-                }
-            }
+        // update hash code of updated contact, if applicable
+        (updated as? LocalContact)?.let { updatedContact ->
+            // workaround for Android 7 which sets DIRTY flag when only meta-data is changed
+            dirtyVerifier.getOrNull()?.updateHashCode(localCollection, updatedContact)
         }
     }
 

app/src/main/kotlin/at/bitfire/davdroid/sync/SyncAdapterServices.kt

@@ -1,221 +0,0 @@
-/*
- * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
- */
-
-package at.bitfire.davdroid.sync
-
-import android.accounts.Account
-import android.accounts.AccountManager
-import android.app.Service
-import android.content.AbstractThreadedSyncAdapter
-import android.content.ContentProviderClient
-import android.content.ContentResolver
-import android.content.Context
-import android.content.Intent
-import android.content.SyncResult
-import android.os.Bundle
-import android.os.IBinder
-import androidx.work.WorkInfo
-import androidx.work.WorkManager
-import at.bitfire.davdroid.BuildConfig
-import at.bitfire.davdroid.R
-import at.bitfire.davdroid.repository.DavCollectionRepository
-import at.bitfire.davdroid.repository.DavServiceRepository
-import at.bitfire.davdroid.resource.LocalAddressBook.Companion.USER_DATA_COLLECTION_ID
-import at.bitfire.davdroid.settings.AccountSettings
-import at.bitfire.davdroid.sync.account.InvalidAccountException
-import at.bitfire.davdroid.sync.worker.BaseSyncWorker
-import at.bitfire.davdroid.sync.worker.SyncWorkerManager
-import dagger.hilt.InstallIn
-import dagger.hilt.android.EntryPointAccessors
-import dagger.hilt.android.qualifiers.ApplicationContext
-import dagger.hilt.components.SingletonComponent
-import kotlinx.coroutines.CancellationException
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.cancel
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.runBlocking
-import kotlinx.coroutines.withTimeout
-import java.util.concurrent.atomic.AtomicBoolean
-import java.util.logging.Level
-import java.util.logging.Logger
-import javax.inject.Inject
-
-abstract class SyncAdapterService: Service() {
-
-    /**
-     * We don't use @AndroidEntryPoint / @Inject because it's unavoidable that instrumented tests sometimes accidentally / asynchronously
-     * create a [SyncAdapterService] instance before Hilt is initialized during the tests.
-     */
-    @dagger.hilt.EntryPoint
-    @InstallIn(SingletonComponent::class)
-    interface EntryPoint {
-        fun syncAdapter(): SyncAdapter
-    }
-
-    override fun onBind(intent: Intent?): IBinder {
-        if (BuildConfig.DEBUG && !syncActive.get()) {
-            // only for debug builds/testing: syncActive flag
-            val logger = Logger.getLogger(this@SyncAdapterService::class.java.name)
-            logger.log(Level.WARNING, "SyncAdapterService.onBind() was called but syncActive = false. Ignoring")
-
-            val fakeAdapter = object: AbstractThreadedSyncAdapter(this, false) {
-                override fun onPerformSync(account: Account, extras: Bundle, authority: String, provider: ContentProviderClient, syncResult: SyncResult) {
-                    val message = StringBuilder()
-                    message.append("FakeSyncAdapter onPerformSync(account=$account, extras=$extras, authority=$authority, syncResult=$syncResult)")
-                    for (key in extras.keySet())
-                        message.append("\n\textras[$key] = ${extras[key]}")
-                    logger.warning(message.toString())
-                }
-            }
-            return fakeAdapter.syncAdapterBinder
-        }
-
-        // create sync adapter via Hilt
-        val entryPoint = EntryPointAccessors.fromApplication<EntryPoint>(this)
-        val syncAdapter = entryPoint.syncAdapter()
-        return syncAdapter.syncAdapterBinder
-    }
-
-    companion object {
-        /**
-         * Flag to indicate whether the sync adapter should be active. When it is `false`, synchronization will not be run
-         * (only intended for tests).
-         */
-        val syncActive = AtomicBoolean(true)
-    }
-
-
-    /**
-     * Entry point for the Sync Adapter Framework.
-     *
-     * Handles incoming sync requests from the Sync Adapter Framework.
-     *
-     * Although we do not use the sync adapter for syncing anymore, we keep this sole
-     * adapter to provide exported services, which allow android system components and calendar,
-     * contacts or task apps to sync via DAVx5.
-     *
-     * All Sync Adapter Framework related interaction should happen inside [SyncFrameworkIntegration].
-     */
-    class SyncAdapter @Inject constructor(
-        private val accountSettingsFactory: AccountSettings.Factory,
-        private val collectionRepository: DavCollectionRepository,
-        private val serviceRepository: DavServiceRepository,
-        @ApplicationContext context: Context,
-        private val logger: Logger,
-        private val syncConditionsFactory: SyncConditions.Factory,
-        private val syncWorkerManager: SyncWorkerManager
-    ): AbstractThreadedSyncAdapter(
-        /* context = */ context,
-        /* autoInitialize = */ true     // Sets isSyncable=1 when isSyncable=-1 and SYNC_EXTRAS_INITIALIZE is set.
-                                        // Doesn't matter for us because we have android:isAlwaysSyncable="true" for all sync adapters.
-    ) {
-
-        /**
-         * Scope used to wait until the synchronization is finished. Will be cancelled when the sync framework
-         * requests cancellation.
-         */
-        private val waitScope = CoroutineScope(Dispatchers.Default)
-
-        override fun onPerformSync(accountOrAddressBookAccount: Account, extras: Bundle, authority: String, provider: ContentProviderClient, syncResult: SyncResult) {
-            // We have to pass this old SyncFramework extra for an Android 7 workaround
-            val upload = extras.containsKey(ContentResolver.SYNC_EXTRAS_UPLOAD)
-            logger.info("Sync request via sync framework for $accountOrAddressBookAccount $authority (upload=$upload)")
-
-            // If we should sync an address book account - find the account storing the settings
-            val account = if (accountOrAddressBookAccount.type == context.getString(R.string.account_type_address_book))
-                AccountManager.get(context)
-                    .getUserData(accountOrAddressBookAccount, USER_DATA_COLLECTION_ID)
-                    ?.toLongOrNull()
-                    ?.let { collectionId ->
-                    collectionRepository.get(collectionId)?.let { collection ->
-                        serviceRepository.getBlocking(collection.serviceId)?.let { service ->
-                            Account(service.accountName, context.getString(R.string.account_type))
-                        }
-                    }
-                }
-            else
-                accountOrAddressBookAccount
-
-            if (account == null) {
-                logger.warning("Address book account $accountOrAddressBookAccount doesn't have an associated collection")
-                return
-            }
-
-            // Check sync conditions
-            val accountSettings = try {
-                accountSettingsFactory.create(account)
-            } catch (e: InvalidAccountException) {
-                logger.log(Level.WARNING, "Account doesn't exist anymore", e)
-                return
-            }
-            val syncConditions = syncConditionsFactory.create(accountSettings)
-            // Should we run the sync at all?
-            if (!syncConditions.wifiConditionsMet()) {
-                logger.info("Sync conditions not met. Aborting sync framework initiated sync")
-                return
-            }
-
-            logger.fine("Starting OneTimeSyncWorker for $account $authority and waiting for it")
-            val workerName = syncWorkerManager.enqueueOneTime(account, dataType = SyncDataType.fromAuthority(authority), fromUpload = upload)
-
-
-            /* Because we are not allowed to observe worker state on a background thread, we can not
-            use it to block the sync adapter. Instead we use a Flow to get notified when the sync
-            has finished. */
-            val workManager = WorkManager.getInstance(context)
-
-            try {
-                val waitJob = waitScope.launch {
-                    // wait for finished worker state
-                    workManager.getWorkInfosForUniqueWorkFlow(workerName).collect { infoList ->
-                        for (info in infoList)
-                            if (info.state.isFinished) {
-                                if (info.state == WorkInfo.State.FAILED) {
-                                    if (info.outputData.getBoolean(BaseSyncWorker.OUTPUT_TOO_MANY_RETRIES, false))
-                                        syncResult.tooManyRetries = true
-                                    else
-                                        syncResult.databaseError = true
-                                }
-                                cancel("$workerName has finished")
-                            }
-                    }
-                }
-
-                runBlocking {
-                    withTimeout(10 * 60 * 1000) {   // block max. 10 minutes
-                        waitJob.join()              // wait until worker has finished
-                    }
-                }
-            } catch (_: CancellationException) {
-                // waiting for work was cancelled, either by timeout or because the worker has finished
-                logger.fine("Not waiting for OneTimeSyncWorker anymore.")
-            }
-
-            logger.log(Level.INFO, "Returning to sync framework.", syncResult)
-        }
-
-        override fun onSecurityException(account: Account, extras: Bundle, authority: String, syncResult: SyncResult) {
-            logger.log(Level.WARNING, "Security exception for $account/$authority")
-        }
-
-        override fun onSyncCanceled() {
-            logger.info("Sync adapter requested cancellation – won't cancel sync, but also won't block sync framework anymore")
-
-            // unblock sync framework
-            waitScope.cancel()
-        }
-
-        override fun onSyncCanceled(thread: Thread) = onSyncCanceled()
-
-    }
-
-}
-
-// exported sync adapter services; we need a separate class for each authority
-class CalendarsSyncAdapterService: SyncAdapterService()
-class ContactsSyncAdapterService: SyncAdapterService()
-class JtxSyncAdapterService: SyncAdapterService()
-class OpenTasksSyncAdapterService: SyncAdapterService()
-class TasksOrgSyncAdapterService: SyncAdapterService()

app/src/main/kotlin/at/bitfire/davdroid/sync/SyncDataType.kt

@@ -4,11 +4,13 @@
 
 package at.bitfire.davdroid.sync
 
+import android.content.Context
 import android.provider.CalendarContract
 import android.provider.ContactsContract
 import at.bitfire.ical4android.TaskProvider
 import dagger.hilt.EntryPoint
 import dagger.hilt.InstallIn
+import dagger.hilt.android.EntryPointAccessors
 import dagger.hilt.components.SingletonComponent
 
 enum class SyncDataType {
@@ -23,19 +25,38 @@ enum class SyncDataType {
         fun tasksAppManager(): TasksAppManager
     }
 
-
+    /**
+     * Returns authorities which exist for this sync data type. Used on [TASKS] the method
+     * may return an empty list if there are no tasks providers (installed tasks apps).
+     *
+     * @return list of authorities matching this data type
+     */
     fun possibleAuthorities(): List<String> =
         when (this) {
-            CONTACTS -> listOf(
-                ContactsContract.AUTHORITY
-            )
-            EVENTS -> listOf(
-                CalendarContract.AUTHORITY
-            )
-            TASKS ->
-                TaskProvider.ProviderName.entries.map { it.authority }
+            CONTACTS -> listOf(ContactsContract.AUTHORITY)
+            EVENTS -> listOf(CalendarContract.AUTHORITY)
+            TASKS -> TaskProvider.ProviderName.entries.map { it.authority }
         }
 
+    /**
+     * Returns the authority corresponding to this datatype.
+     * When more than one tasks provider exists (tasks apps installed) the authority for the active
+     * tasks provider (user selected tasks app) is returned.
+     *
+     * @param context android context used to determine the active/selected tasks provider
+     * @return the authority matching this data type or *null* for [TASKS] if no tasks app is installed
+     */
+    fun currentAuthority(context: Context): String? =
+        when (this) {
+            CONTACTS -> ContactsContract.AUTHORITY
+            EVENTS -> CalendarContract.AUTHORITY
+            TASKS -> EntryPointAccessors.fromApplication<SyncDataTypeEntryPoint>(context)
+                .tasksAppManager()
+                .currentProvider()
+                ?.authority
+        }
+
+
     companion object {
 
         fun fromAuthority(authority: String): SyncDataType {

app/src/main/kotlin/at/bitfire/davdroid/sync/SyncManager.kt

@@ -51,6 +51,7 @@ import java.io.IOException
 import java.net.HttpURLConnection
 import java.security.cert.CertificateException
 import java.util.LinkedList
+import java.util.Optional
 import java.util.concurrent.CancellationException
 import java.util.concurrent.LinkedBlockingQueue
 import java.util.logging.Level
@@ -347,7 +348,7 @@ abstract class SyncManager<ResourceType: LocalResource<*>, out CollectionType: L
                     }
                 } else
                     logger.info("Removing local record #${local.id} which has been deleted locally and was never uploaded")
-                local.delete()
+                local.deleteLocal()
             }
         }
         logger.info("Removed $numDeleted record(s) from server")
@@ -378,57 +379,83 @@ abstract class SyncManager<ResourceType: LocalResource<*>, out CollectionType: L
         return numUploaded > 0
     }
 
-    protected suspend fun uploadDirty(local: ResourceType) {
+    /**
+     * Uploads a dirty local resource.
+     *
+     * @param local         resource to upload
+     * @param forceAsNew    whether the ETag (and Schedule-Tag) of [local] are ignored and the resource
+     *                      is created as a new resource on the server
+     */
+    protected open suspend fun uploadDirty(local: ResourceType, forceAsNew: Boolean = false) {
         val existingFileName = local.fileName
-
-        var newFileName: String? = null
-        var eTag: String? = null
-        var scheduleTag: String? = null
-        val readTagsFromResponse: (okhttp3.Response) -> Unit = { response ->
-            eTag = GetETag.fromResponse(response)?.eTag
-            scheduleTag = ScheduleTag.fromResponse(response)?.scheduleTag
+        val fileName = if (existingFileName != null) {
+            // prepare upload (for UID etc), but ignore returned file name suggestion
+            local.prepareForUpload()
+            existingFileName
+        } else {
+            // prepare upload and use returned file name suggestion as new file name
+            local.prepareForUpload()
         }
 
+        val uploadUrl = collection.url.newBuilder().addPathSegment(fileName).build()
+        val remote = DavResource(httpClient.okHttpClient, uploadUrl)
+
         try {
-            if (existingFileName == null) {             // new resource
-                newFileName = local.prepareForUpload()
-
-                val uploadUrl = collection.url.newBuilder().addPathSegment(newFileName).build()
-                val remote = DavResource(httpClient.okHttpClient, uploadUrl)
-                SyncException.wrapWithRemoteResourceSuspending(uploadUrl) {
-                    logger.info("Uploading new record ${local.id} -> $newFileName")
+            SyncException.wrapWithRemoteResourceSuspending(uploadUrl) {
+                if (existingFileName == null || forceAsNew) {
+                    // create new resource on server
+                    logger.info("Uploading new resource ${local.id} -> $fileName")
                     val bodyToUpload = generateUpload(local)
+
+                    var newETag: String? = null
+                    var newScheduleTag: String? = null
                     runInterruptible {
                         remote.put(
                             bodyToUpload,
-                            ifNoneMatch = true,
-                            callback = readTagsFromResponse,
+                            ifNoneMatch = true,     // fails if there's already a resource with that name
+                            callback = { response ->
+                                newETag = GetETag.fromResponse(response)?.eTag
+                                newScheduleTag = ScheduleTag.fromResponse(response)?.scheduleTag
+                            },
                             headers = pushDontNotifyHeader
                         )
                     }
-                }
 
-            } else /* existingFileName != null */ {     // updated resource
-                local.prepareForUpload()
+                    logger.fine("Upload successful; new ETag=$newETag / Schedule-Tag=$newScheduleTag")
 
-                val uploadUrl = collection.url.newBuilder().addPathSegment(existingFileName).build()
-                val remote = DavResource(httpClient.okHttpClient, uploadUrl)
-                SyncException.wrapWithRemoteResourceSuspending(uploadUrl) {
-                    val lastScheduleTag = local.scheduleTag
-                    val lastETag = if (lastScheduleTag == null) local.eTag else null
-                    logger.info("Uploading modified record ${local.id} -> $existingFileName (ETag=$lastETag, Schedule-Tag=$lastScheduleTag)")
+                    // success (no exception thrown)
+                    onSuccessfulUpload(local, fileName, newETag, newScheduleTag)
+
+                } else {
+                    // update resource on server
+                    val ifScheduleTag = local.scheduleTag
+                    val ifETag = if (ifScheduleTag == null) local.eTag else null
+
+                    logger.info("Uploading modified resource ${local.id} -> $fileName (if ETag=$ifETag / Schedule-Tag=$ifScheduleTag)")
                     val bodyToUpload = generateUpload(local)
+
+                    var updatedETag: String? = null
+                    var updatedScheduleTag: String? = null
                     runInterruptible {
                         remote.put(
                             bodyToUpload,
-                            ifETag = lastETag,
-                            ifScheduleTag = lastScheduleTag,
-                            callback = readTagsFromResponse,
+                            ifETag = ifETag,
+                            ifScheduleTag = ifScheduleTag,
+                            callback = { response ->
+                                updatedETag = GetETag.fromResponse(response)?.eTag
+                                updatedScheduleTag = ScheduleTag.fromResponse(response)?.scheduleTag
+                            },
                             headers = pushDontNotifyHeader
                         )
                     }
+
+                    logger.fine("Upload successful; updated ETag=$updatedETag / Schedule-Tag=$updatedScheduleTag")
+
+                    // success (no exception thrown)
+                    onSuccessfulUpload(local, fileName, updatedETag, updatedScheduleTag)
                 }
             }
+
         } catch (e: SyncException) {
             when (val ex = e.cause) {
                 is ForbiddenException -> {
@@ -441,15 +468,14 @@ abstract class SyncManager<ResourceType: LocalResource<*>, out CollectionType: L
                 }
                 is NotFoundException, is GoneException -> {
                     // HTTP 404 Not Found (i.e. either original resource or the whole collection is not there anymore)
-                    if (local.scheduleTag != null || local.eTag != null) {      // this was an update of a previously existing resource
+                    if (!forceAsNew) {      // first try; if this fails with 404, too, the collection is gone
                         logger.info("Original version of locally modified resource is not there (anymore), trying as fresh upload")
-                        if (local.scheduleTag != null)  // contacts don't support scheduleTag, don't try to set it without check
-                            local.scheduleTag = null
-                        local.eTag = null
-                        uploadDirty(local)      // if this fails with 404, too, the collection is gone
+                        uploadDirty(local, forceAsNew = true)
                         return
-                    } else
-                        throw e                 // the collection is probably gone
+                    } else {
+                        // we tried with forceAsNew, collection probably gone
+                        throw e
+                    }
                 }
                 is ConflictException -> {
                     // HTTP 409 Conflict
@@ -464,13 +490,16 @@ abstract class SyncManager<ResourceType: LocalResource<*>, out CollectionType: L
                 else -> throw e
             }
         }
+    }
 
-        if (eTag != null)
-            logger.fine("Received new ETag=$eTag after uploading")
-        else
-            logger.fine("Didn't receive new ETag after uploading, setting to null")
-
-        local.clearDirty(newFileName, eTag, scheduleTag)
+    /**
+     * Called after a successful upload (either of a new or an updated resource) so that the local
+     * _dirty_ state can be reset.
+     *
+     * Note: [CalendarSyncManager] overrides this method to additionally store the updated SEQUENCE.
+     */
+    protected open fun onSuccessfulUpload(local: ResourceType, newFileName: String, eTag: String?, scheduleTag: String?) {
+        local.clearDirty(Optional.of(newFileName), eTag, scheduleTag)
     }
 
     /**
@@ -607,7 +636,7 @@ abstract class SyncManager<ResourceType: LocalResource<*>, out CollectionType: L
                         localCollection.findByName(name)?.let { local ->
                             SyncException.wrapWithLocalResource(local) {
                                 logger.info("$name has been deleted on server, deleting locally")
-                                local.delete()
+                                local.deleteLocal()
                             }
                         }
                     }

app/src/main/kotlin/at/bitfire/davdroid/sync/Syncer.kt

@@ -234,7 +234,7 @@ abstract class Syncer<StoreType: LocalDataStore<CollectionType>, CollectionType:
         logger.info("${dataStore.authority} sync of $account initiated (resync=$resync)")
 
         try {
-            dataStore.acquireContentProvider()
+            dataStore.acquireContentProvider(throwOnMissingPermissions = true)
         } catch (e: SecurityException) {
             logger.log(Level.WARNING, "Missing permissions for content provider authority ${dataStore.authority}", e)
             /* Don't show a notification here without possibility to permanently dismiss it!

app/src/main/kotlin/at/bitfire/davdroid/sync/adapter/SyncAdapter.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.sync.adapter
+
+import android.os.IBinder
+
+/**
+ * Interface for an Android sync adapter, as created by [SyncAdapterService].
+ *
+ * Sync adapters are bound services that communicate over IPC, so the only method is
+ * [getBinder], which returns the sync adapter binder.
+ */
+interface SyncAdapter {
+
+    fun getBinder(): IBinder
+
+}

app/src/main/kotlin/at/bitfire/davdroid/sync/adapter/SyncAdapterImpl.kt

@@ -0,0 +1,188 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.sync.adapter
+
+import android.accounts.Account
+import android.accounts.AccountManager
+import android.content.AbstractThreadedSyncAdapter
+import android.content.ContentProviderClient
+import android.content.ContentResolver
+import android.content.Context
+import android.content.SyncResult
+import android.os.Build
+import android.os.Bundle
+import android.os.IBinder
+import androidx.work.WorkInfo
+import androidx.work.WorkManager
+import at.bitfire.davdroid.R
+import at.bitfire.davdroid.repository.DavCollectionRepository
+import at.bitfire.davdroid.repository.DavServiceRepository
+import at.bitfire.davdroid.resource.LocalAddressBook
+import at.bitfire.davdroid.settings.AccountSettings
+import at.bitfire.davdroid.sync.SyncConditions
+import at.bitfire.davdroid.sync.SyncDataType
+import at.bitfire.davdroid.sync.account.InvalidAccountException
+import at.bitfire.davdroid.sync.worker.BaseSyncWorker
+import at.bitfire.davdroid.sync.worker.SyncWorkerManager
+import dagger.Binds
+import dagger.Module
+import dagger.hilt.InstallIn
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.components.SingletonComponent
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.withTimeout
+import java.util.logging.Level
+import java.util.logging.Logger
+import javax.inject.Inject
+
+/**
+ * Entry point for the Sync Adapter Framework.
+ *
+ * Handles incoming sync requests from the Sync Adapter Framework.
+ *
+ * Although we do not use the sync adapter for syncing anymore, we keep this sole
+ * adapter to provide exported services, which allow android system components and calendar,
+ * contacts or task apps to sync via DAVx5.
+ *
+ * All Sync Adapter Framework related interaction should happen inside [SyncFrameworkIntegration].
+ */
+class SyncAdapterImpl @Inject constructor(
+    private val accountSettingsFactory: AccountSettings.Factory,
+    private val collectionRepository: DavCollectionRepository,
+    private val serviceRepository: DavServiceRepository,
+    @ApplicationContext context: Context,
+    private val logger: Logger,
+    private val syncConditionsFactory: SyncConditions.Factory,
+    private val syncFrameworkIntegration: SyncFrameworkIntegration,
+    private val syncWorkerManager: SyncWorkerManager
+): AbstractThreadedSyncAdapter(
+    /* context = */ context,
+    /* autoInitialize = */ true     // Sets isSyncable=1 when isSyncable=-1 and SYNC_EXTRAS_INITIALIZE is set.
+                                    // Doesn't matter for us because we have android:isAlwaysSyncable="true" for all sync adapters.
+), SyncAdapter {
+
+    /**
+     * Scope used to wait until the synchronization is finished. Will be cancelled when the sync framework
+     * requests cancellation.
+     */
+    private val waitScope = CoroutineScope(Dispatchers.Default)
+
+    override fun onPerformSync(accountOrAddressBookAccount: Account, extras: Bundle, authority: String, provider: ContentProviderClient, syncResult: SyncResult) {
+        // We have to pass this old SyncFramework extra for an Android 7 workaround
+        val upload = extras.containsKey(ContentResolver.SYNC_EXTRAS_UPLOAD)
+        logger.info("Sync request via sync framework for $accountOrAddressBookAccount $authority (upload=$upload)")
+
+        // If we should sync an address book account - find the account storing the settings
+        val account = if (accountOrAddressBookAccount.type == context.getString(R.string.account_type_address_book))
+            AccountManager.get(context)
+                .getUserData(accountOrAddressBookAccount, LocalAddressBook.USER_DATA_COLLECTION_ID)
+                ?.toLongOrNull()
+                ?.let { collectionId ->
+                collectionRepository.get(collectionId)?.let { collection ->
+                    serviceRepository.getBlocking(collection.serviceId)?.let { service ->
+                        Account(service.accountName, context.getString(R.string.account_type))
+                    }
+                }
+            }
+        else
+            accountOrAddressBookAccount
+
+        if (account == null) {
+            logger.warning("Address book account $accountOrAddressBookAccount doesn't have an associated collection")
+            return
+        }
+
+        // Check sync conditions
+        val accountSettings = try {
+            accountSettingsFactory.create(account)
+        } catch (e: InvalidAccountException) {
+            logger.log(Level.WARNING, "Account doesn't exist anymore", e)
+            return
+        }
+        val syncConditions = syncConditionsFactory.create(accountSettings)
+        // Should we run the sync at all?
+        if (!syncConditions.wifiConditionsMet()) {
+            logger.info("Sync conditions not met. Aborting sync framework initiated sync")
+            return
+        }
+
+        logger.fine("Starting OneTimeSyncWorker for $account $authority and waiting for it")
+        val workerName = syncWorkerManager.enqueueOneTime(account, dataType = SyncDataType.Companion.fromAuthority(authority), fromUpload = upload)
+
+        // Android 14+ does not handle pending sync state correctly.
+        // As a defensive workaround, we can cancel specifically this still pending sync only
+        // See: https://github.com/bitfireAT/davx5-ose/issues/1458
+        if (Build.VERSION.SDK_INT >= 34) {
+            logger.fine("Android 14+ bug: Canceling forever pending sync adapter framework sync request for " +
+                    "account=$accountOrAddressBookAccount authority=$authority upload=$upload")
+            syncFrameworkIntegration.cancelSync(accountOrAddressBookAccount, authority, extras)
+        }
+
+        /* Because we are not allowed to observe worker state on a background thread, we can not
+        use it to block the sync adapter. Instead we use a Flow to get notified when the sync
+        has finished. */
+        val workManager = WorkManager.getInstance(context)
+
+        try {
+            val waitJob = waitScope.launch {
+                // wait for finished worker state
+                workManager.getWorkInfosForUniqueWorkFlow(workerName).collect { infoList ->
+                    for (info in infoList)
+                        if (info.state.isFinished) {
+                            if (info.state == WorkInfo.State.FAILED) {
+                                if (info.outputData.getBoolean(BaseSyncWorker.OUTPUT_TOO_MANY_RETRIES, false))
+                                    syncResult.tooManyRetries = true
+                                else
+                                    syncResult.databaseError = true
+                            }
+                            cancel("$workerName has finished")
+                        }
+                }
+            }
+
+            runBlocking {
+                withTimeout(10 * 60 * 1000) {   // block max. 10 minutes
+                    waitJob.join()              // wait until worker has finished
+                }
+            }
+        } catch (_: CancellationException) {
+            // waiting for work was cancelled, either by timeout or because the worker has finished
+            logger.fine("Not waiting for OneTimeSyncWorker anymore.")
+        }
+
+        logger.log(Level.INFO, "Returning to sync framework.", syncResult)
+    }
+
+    override fun onSecurityException(account: Account, extras: Bundle, authority: String, syncResult: SyncResult) {
+        logger.log(Level.WARNING, "Security exception for $account/$authority")
+    }
+
+    override fun onSyncCanceled() {
+        logger.info("Sync adapter requested cancellation – won't cancel sync, but also won't block sync framework anymore")
+
+        // unblock sync framework
+        waitScope.cancel()
+    }
+
+    override fun onSyncCanceled(thread: Thread) = onSyncCanceled()
+
+
+    // SyncAdapter implementation and Hilt module
+
+    override fun getBinder(): IBinder = syncAdapterBinder
+
+    @Module
+    @InstallIn(SingletonComponent::class)
+    abstract class RealSyncAdapterModule {
+        @Binds
+        abstract fun provide(impl: SyncAdapterImpl): SyncAdapter
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/sync/adapter/SyncAdapterServices.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.sync.adapter
+
+import android.app.Service
+import android.content.Intent
+import dagger.hilt.InstallIn
+import dagger.hilt.android.EarlyEntryPoint
+import dagger.hilt.android.EarlyEntryPoints
+import dagger.hilt.components.SingletonComponent
+
+abstract class SyncAdapterService: Service() {
+
+    /**
+     * We don't use @AndroidEntryPoint / @Inject because it's unavoidable that instrumented tests sometimes accidentally / asynchronously
+     * create a [SyncAdapterService] instance before Hilt is initialized by the HiltTestRunner.
+     */
+    @EarlyEntryPoint
+    @InstallIn(SingletonComponent::class)
+    interface SyncAdapterServicesEntryPoint {
+        fun syncAdapter(): SyncAdapter
+    }
+
+    // create syncAdapter on demand and cache it
+    val syncAdapter by lazy {
+        val entryPoint = EarlyEntryPoints.get(applicationContext, SyncAdapterServicesEntryPoint::class.java)
+        entryPoint.syncAdapter()
+    }
+
+    override fun onBind(intent: Intent?) = syncAdapter.getBinder()
+
+}
+
+// exported sync adapter services; we need a separate class for each authority
+class CalendarsSyncAdapterService: SyncAdapterService()
+class ContactsSyncAdapterService: SyncAdapterService()
+class JtxSyncAdapterService: SyncAdapterService()
+class OpenTasksSyncAdapterService: SyncAdapterService()
+class TasksOrgSyncAdapterService: SyncAdapterService()

app/src/main/kotlin/at/bitfire/davdroid/sync/adapter/SyncFrameworkIntegration.kt

@@ -2,19 +2,24 @@
  * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
  */
 
-package at.bitfire.davdroid.sync
+package at.bitfire.davdroid.sync.adapter
 
 import android.accounts.Account
 import android.content.ContentResolver
+import android.content.Context
+import android.content.SyncRequest
 import android.os.Build
-import android.provider.CalendarContract
+import android.os.Bundle
 import androidx.annotation.WorkerThread
 import at.bitfire.davdroid.resource.LocalAddressBookStore
+import at.bitfire.davdroid.sync.SyncDataType
 import dagger.Lazy
+import dagger.hilt.android.qualifiers.ApplicationContext
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.callbackFlow
+import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.flowOf
@@ -29,6 +34,7 @@ import javax.inject.Inject
  * Sync requests from the Sync Adapter Framework are handled by [SyncAdapterService].
  */
 class SyncFrameworkIntegration @Inject constructor(
+    @ApplicationContext private val context: Context,
     private val localAddressBookStore: Lazy<LocalAddressBookStore>,
     private val logger: Logger
 ) {
@@ -94,6 +100,27 @@ class SyncFrameworkIntegration @Inject constructor(
             setSyncOnContentChange(account, authority, false)
     }
 
+    /**
+     * Cancels the sync request in the Sync Adapter Framework by sync request. This
+     * is the defensive approach canceling only one specific sync request with matching
+     * sync extras.
+     *
+     * @param account The account for which the sync request should be canceled.
+     * @param authority The authority for which the sync request should be canceled.
+     * @param extras The original extras Bundle used to start the sync.
+     */
+    fun cancelSync(account: Account, authority: String, extras: Bundle) {
+        // Recreate the sync request which was used to start this sync
+        val syncRequest = SyncRequest.Builder()
+            .setSyncAdapter(account, authority)
+            .setExtras(extras)
+            .syncOnce()
+            .build()
+
+        // Cancel it
+        ContentResolver.cancelSync(syncRequest)
+    }
+
     /**
      * Enables/disables sync adapter automatic sync (content triggered sync) for the given
      * account and authority. Does *not* call [ContentResolver.setIsSyncable].
@@ -107,7 +134,7 @@ class SyncFrameworkIntegration @Inject constructor(
      *
      * @param account   account to enable/disable content change sync triggers for
      * @param enable    *true* enables automatic sync; *false* disables it
-     * @param authority sync authority (like [CalendarContract.AUTHORITY])
+     * @param authority sync authority (like [android.provider.CalendarContract.AUTHORITY])
      * @return whether the content triggered sync was enabled successfully
      */
     @WorkerThread
@@ -138,7 +165,7 @@ class SyncFrameworkIntegration @Inject constructor(
      *
      * @param account   account to enable/disable content change sync triggers for
      * @param enable    *true* enables automatic sync; *false* disables it
-     * @param authority sync authority (like [CalendarContract.AUTHORITY])
+     * @param authority sync authority (like [android.provider.CalendarContract.AUTHORITY])
      * @return whether the content triggered sync was enabled successfully
      */
     private fun setContentTrigger(account: Account, authority: String, enable: Boolean): Boolean =
@@ -153,55 +180,82 @@ class SyncFrameworkIntegration @Inject constructor(
     /**
      * Observe whether any of the given data types is currently pending for sync.
      *
+     * Note: On Android 14+ finished syncs stay by default pending. This is why we
+     * explicitly cancel the active sync in [SyncAdapterImpl] for Android 14+. Doing
+     * so allows us to have a reliable "pending" flag again, which is used in this method.
+     *
      * @param account   account to observe sync status for
      * @param dataTypes data types to observe sync status for
+     *
      * @return flow emitting true if any of the given data types has a sync pending, false otherwise
      */
     @OptIn(ExperimentalCoroutinesApi::class)
-    fun isSyncPending(account: Account, dataTypes: Iterable<SyncDataType>): Flow<Boolean> =
-        if (Build.VERSION.SDK_INT >= 34) {
-            // On Android 14+ pending sync checks always return true (bug), so we don't need to check.
-            // See: https://github.com/bitfireAT/davx5-ose/issues/1458
-            flowOf(false)
-        } else {
-            val authorities = dataTypes.flatMap { it.possibleAuthorities() }
-
-            // Use address book accounts if needed
-            val accountsFlow = if (dataTypes.contains(SyncDataType.CONTACTS))
-                localAddressBookStore.get().getAddressBookAccountsFlow(account)
-            else
-                flowOf(listOf(account))
-
-            // Observe sync pending state for the given accounts and authorities
-            accountsFlow.flatMapLatest { accounts ->
-                callbackFlow {
-                    // Observe sync pending state
-                    val listener = ContentResolver.addStatusChangeListener(
-                        ContentResolver.SYNC_OBSERVER_TYPE_PENDING
-                    ) {
-                        trySend(anyPendingSync(accounts, authorities))
-                    }
-
-                    // Emit initial value
-                    trySend(anyPendingSync(accounts, authorities))
-
-                    // Clean up listener on close
-                    awaitClose { ContentResolver.removeStatusChangeListener(listener) }
+    fun isSyncPending(account: Account, dataTypes: Iterable<SyncDataType>): Flow<Boolean> {
+        // Determine the pending state for each data type of the account as separate flows
+        val pendingStateFlows: List<Flow<Boolean>> = dataTypes.mapNotNull { dataType ->
+            // Map datatype to authority
+            dataType.currentAuthority(context)?.let { authority ->
+                // If checking contacts, we need to check all address book accounts instead of the single main account
+                val accountsFlow: Flow<List<Account>> = when (dataType) {
+                    SyncDataType.CONTACTS -> localAddressBookStore.get().getAddressBookAccountsFlow(account)
+                    else -> flowOf(listOf(account))
                 }
-            }.distinctUntilChanged()
+
+                // Return the pending state flow for accounts with this authority
+                anyPendingSyncFlow(accountsFlow, authority)
+            }
         }
 
+        // Combine the different per data type pending state flows into one
+        return combine(pendingStateFlows) { pendingStates ->
+            pendingStates.any { pending -> pending }
+        }.distinctUntilChanged()
+    }
+
     /**
-     * Check if any of the given accounts and authorities have a sync pending.
+     * Maps the given accounts flow to a simple boolean flow telling us whether any of the accounts
+     * has a pending sync for given authority.
+     *
+     * @param accountsFlow accounts to check sync status for
+     * @param authority authority to check sync status for
+     *
+     * @return returns flow which emits *true* if any of the accounts has a sync pending for
+     * the given authority and *false* otherwise
+     */
+    @OptIn(ExperimentalCoroutinesApi::class)
+    private fun anyPendingSyncFlow(
+        accountsFlow: Flow<List<Account>>,
+        authority: String
+    ): Flow<Boolean> = accountsFlow.flatMapLatest { accounts ->
+        // Observe sync pending state for the given accounts and data types
+        callbackFlow {
+            // Observe sync pending state
+            val listener = ContentResolver.addStatusChangeListener(
+                ContentResolver.SYNC_OBSERVER_TYPE_PENDING
+            ) {
+                trySend(anyPendingSync(accounts, authority))
+            }
+
+            // Emit initial value
+            trySend(anyPendingSync(accounts, authority))
+
+            // Clean up listener on close
+            awaitClose { ContentResolver.removeStatusChangeListener(listener) }
+        }
+    }
+
+    /**
+     * Check if any of the given accounts have a sync pending for given authority.
      *
      * @param accounts  accounts to check sync status for
-     * @param authorities authorities to check sync status for
-     * @return true if any of the given accounts and authorities has a sync pending, false otherwise
+     * @param authority authority to check sync status for
+     *
+     * @return *true* if any of the given accounts has a sync pending for given authority; *false* otherwise
      */
-    private fun anyPendingSync(accounts: List<Account>, authorities: List<String>): Boolean =
+    private fun anyPendingSync(accounts: List<Account>, authority: String): Boolean =
         accounts.any { account ->
-            authorities.any { authority ->
-                ContentResolver.isSyncPending(account, authority)
+            ContentResolver.isSyncPending(account, authority).also { pending ->
+                logger.finer("Sync pending($account, $authority) = $pending")
             }
         }
 

app/src/main/kotlin/at/bitfire/davdroid/sync/groups/CategoriesStrategy.kt

@@ -6,6 +6,7 @@ package at.bitfire.davdroid.sync.groups
 
 import at.bitfire.davdroid.resource.LocalAddressBook
 import at.bitfire.vcard4android.Contact
+import java.util.Optional
 import java.util.logging.Logger
 
 class CategoriesStrategy(val addressBook: LocalAddressBook): ContactGroupStrategy {
@@ -25,7 +26,7 @@ class CategoriesStrategy(val addressBook: LocalAddressBook): ContactGroupStrateg
         for (group in addressBook.findDirtyGroups()) {
             logger.fine("Marking members of modified group $group as dirty")
             group.markMembersDirty()
-            group.clearDirty(null, null)
+            group.clearDirty(Optional.empty(), null)
         }
     }
 

app/src/main/kotlin/at/bitfire/davdroid/ui/AccountsModel.kt

@@ -5,6 +5,8 @@
 package at.bitfire.davdroid.ui
 
 import android.accounts.Account
+import android.accounts.AccountManager
+import android.content.ContentResolver
 import android.content.Context
 import android.content.Intent
 import android.content.IntentFilter
@@ -13,6 +15,7 @@ import android.net.ConnectivityManager
 import android.net.Network
 import android.net.NetworkCapabilities
 import android.net.NetworkRequest
+import android.os.Build
 import android.os.PowerManager
 import android.provider.CalendarContract
 import android.provider.ContactsContract
@@ -22,13 +25,14 @@ import androidx.lifecycle.ViewModel
 import androidx.work.WorkInfo
 import androidx.work.WorkManager
 import androidx.work.WorkQuery
+import at.bitfire.davdroid.R
 import at.bitfire.davdroid.db.AppDatabase
 import at.bitfire.davdroid.repository.AccountRepository
 import at.bitfire.davdroid.servicedetection.RefreshCollectionsWorker
 import at.bitfire.davdroid.settings.Settings
 import at.bitfire.davdroid.settings.SettingsManager
 import at.bitfire.davdroid.sync.SyncDataType
-import at.bitfire.davdroid.sync.SyncFrameworkIntegration
+import at.bitfire.davdroid.sync.adapter.SyncFrameworkIntegration
 import at.bitfire.davdroid.sync.worker.BaseSyncWorker
 import at.bitfire.davdroid.sync.worker.OneTimeSyncWorker
 import at.bitfire.davdroid.sync.worker.SyncWorkerManager
@@ -296,4 +300,34 @@ class AccountsModel @AssistedInject constructor(
             false
         }
 
+    fun cancelSyncAdapterSyncs() {
+        if (Build.VERSION.SDK_INT >= 34) {
+            val calendarAccountType = context.getString(R.string.account_type)
+            val addressBookAccountType = context.getString(R.string.account_type_address_book)
+
+            // Cancel any (after an update) possibly forever pending calendar account syncs
+            cancelSyncs(calendarAccountType, SyncDataType.EVENTS.possibleAuthorities())
+
+            // Cancel any (after an update) possibly forever pending tasks account syncs
+            cancelSyncs(calendarAccountType, SyncDataType.TASKS.possibleAuthorities())
+
+            // Cancel any (after an update) possibly forever pending address book account syncs
+            cancelSyncs(addressBookAccountType, SyncDataType.CONTACTS.possibleAuthorities())
+        }
+    }
+
+    /**
+     * Cancels any (possibly forever pending) syncs for the accounts of given account type for all
+     * authorities.
+     */
+    private fun cancelSyncs(accountType: String, authorities: List<String>) {
+        val accountManager = AccountManager.get(context)
+        accountManager.getAccountsByType(accountType).forEach { account ->
+            logger.info("Android 14+: Canceling all (possibly forever pending) syncs for $account")
+            for (authority in authorities)
+                ContentResolver.cancelSync(account, authority)
+            }
+        }
+    }
+
 }

app/src/main/kotlin/at/bitfire/davdroid/ui/AccountsScreen.kt

@@ -23,6 +23,7 @@ import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.AccountCircle
 import androidx.compose.material.icons.filled.Add
 import androidx.compose.material.icons.filled.BatterySaver
+import androidx.compose.material.icons.filled.CancelScheduleSend
 import androidx.compose.material.icons.filled.DataSaverOn
 import androidx.compose.material.icons.filled.Menu
 import androidx.compose.material.icons.filled.NotificationsOff
@@ -111,6 +112,7 @@ fun AccountsScreen(
     }
 
     AccountsScreen(
+        cancelSyncAdapterSyncs = { model.cancelSyncAdapterSyncs() },
         accountsDrawerHandler = accountsDrawerHandler,
         accounts = accounts,
         showSyncAll = showSyncAll,
@@ -131,6 +133,7 @@ fun AccountsScreen(
 @OptIn(ExperimentalMaterial3Api::class, ExperimentalPermissionsApi::class)
 @Composable
 fun AccountsScreen(
+    cancelSyncAdapterSyncs: () -> Unit,
     accountsDrawerHandler: AccountsDrawerHandler,
     accounts: List<AccountsModel.AccountInfo>,
     showSyncAll: Boolean = true,
@@ -228,6 +231,17 @@ fun AccountsScreen(
                                     contentDescription = stringResource(R.string.accounts_sync_all)
                                 )
                             }
+                        FloatingActionButton(
+                            onClick = cancelSyncAdapterSyncs,
+                            containerColor = MaterialTheme.colorScheme.secondary,
+                            contentColor = MaterialTheme.colorScheme.onSecondary,
+                            modifier = Modifier.padding(top = 24.dp)
+                        ) {
+                            Icon(
+                                Icons.Default.CancelScheduleSend,
+                                contentDescription = stringResource(R.string.accounts_sync_all)
+                            )
+                        }
                     }
                 },
                 snackbarHost = { SnackbarHost(snackbarHostState) }
@@ -321,6 +335,7 @@ fun AccountsScreen(
 @Preview
 fun AccountsScreen_Preview_Empty() {
     AccountsScreen(
+        cancelSyncAdapterSyncs = {},
         accountsDrawerHandler = object: AccountsDrawerHandler() {
             @Composable
             override fun MenuEntries(snackbarHostState: SnackbarHostState) {
@@ -337,6 +352,7 @@ fun AccountsScreen_Preview_Empty() {
 @Preview
 fun AccountsScreen_Preview_OneAccount() {
     AccountsScreen(
+        cancelSyncAdapterSyncs = {},
         accountsDrawerHandler = object: AccountsDrawerHandler() {
             @Composable
             override fun MenuEntries(snackbarHostState: SnackbarHostState) {

app/src/main/kotlin/at/bitfire/davdroid/ui/DebugInfoGenerator.kt

@@ -41,8 +41,8 @@ import at.bitfire.davdroid.resource.LocalAddressBook
 import at.bitfire.davdroid.settings.AccountSettings
 import at.bitfire.davdroid.settings.SettingsManager
 import at.bitfire.davdroid.sync.SyncDataType
-import at.bitfire.davdroid.sync.SyncFrameworkIntegration
 import at.bitfire.davdroid.sync.account.InvalidAccountException
+import at.bitfire.davdroid.sync.adapter.SyncFrameworkIntegration
 import at.bitfire.davdroid.sync.worker.BaseSyncWorker
 import at.bitfire.ical4android.TaskProvider
 import at.techbee.jtx.JtxContract

app/src/main/kotlin/at/bitfire/davdroid/ui/NotificationRegistry.kt

@@ -47,7 +47,6 @@ class NotificationRegistry @Inject constructor(
         const val NOTIFY_DATABASE_CORRUPTED = 4
         const val NOTIFY_SYNC_ERROR = 10
         const val NOTIFY_INVALID_RESOURCE = 11
-        const val NOTIFY_WEBDAV_ACCESS = 12
         const val NOTIFY_SYNC_EXPEDITED = 14
         const val NOTIFY_TASKS_PROVIDER_TOO_OLD = 20
         const val NOTIFY_PERMISSIONS = 21

app/src/main/kotlin/at/bitfire/davdroid/ui/account/AccountProgressUseCase.kt

@@ -10,7 +10,7 @@ import androidx.work.WorkInfo
 import at.bitfire.davdroid.db.Service
 import at.bitfire.davdroid.servicedetection.RefreshCollectionsWorker
 import at.bitfire.davdroid.sync.SyncDataType
-import at.bitfire.davdroid.sync.SyncFrameworkIntegration
+import at.bitfire.davdroid.sync.adapter.SyncFrameworkIntegration
 import at.bitfire.davdroid.sync.worker.OneTimeSyncWorker
 import at.bitfire.davdroid.sync.worker.SyncWorkerManager
 import dagger.hilt.android.qualifiers.ApplicationContext

app/src/main/kotlin/at/bitfire/davdroid/ui/account/AccountScreen.kt

@@ -7,18 +7,29 @@ import android.Manifest
 import android.accounts.Account
 import android.content.Intent
 import android.widget.Toast
+import androidx.compose.animation.AnimatedContent
+import androidx.compose.animation.AnimatedVisibilityScope
+import androidx.compose.animation.ExperimentalSharedTransitionApi
+import androidx.compose.animation.SharedTransitionLayout
+import androidx.compose.animation.SharedTransitionScope
 import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.lazy.LazyListState
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.pager.HorizontalPager
 import androidx.compose.foundation.pager.rememberPagerState
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material.icons.filled.CalendarToday
 import androidx.compose.material.icons.filled.CreateNewFolder
 import androidx.compose.material.icons.filled.Delete
 import androidx.compose.material.icons.filled.DriveFileRenameOutline
+import androidx.compose.material.icons.filled.Group
+import androidx.compose.material.icons.filled.Link
 import androidx.compose.material.icons.filled.MoreVert
+import androidx.compose.material.icons.filled.Person
 import androidx.compose.material.icons.filled.Settings
 import androidx.compose.material.icons.filled.Sync
 import androidx.compose.material.icons.filled.SyncProblem
@@ -56,6 +67,7 @@ import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.alpha
+import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalInspectionMode
 import androidx.compose.ui.res.stringResource
@@ -78,6 +90,7 @@ import at.bitfire.davdroid.ui.account.CollectionsList
 import at.bitfire.davdroid.ui.account.RenameAccountDialog
 import at.bitfire.davdroid.ui.composable.ActionCard
 import at.bitfire.davdroid.ui.composable.ProgressBar
+import at.bitfire.davdroid.ui.icon.CalendarImport
 import at.bitfire.ical4android.TaskProvider
 import com.google.accompanist.permissions.ExperimentalPermissionsApi
 import com.google.accompanist.permissions.rememberMultiplePermissionsState
@@ -161,7 +174,7 @@ fun AccountScreen(
     )
 }
 
-@OptIn(ExperimentalFoundationApi::class, ExperimentalMaterial3Api::class)
+@OptIn(ExperimentalFoundationApi::class, ExperimentalMaterial3Api::class, ExperimentalSharedTransitionApi::class)
 @Composable
 fun AccountScreen(
     accountName: String,
@@ -238,6 +251,10 @@ fun AccountScreen(
                     (if (idxWebcal != null) 1 else 0)
         val pagerState = rememberPagerState(pageCount = { nrPages })
 
+        val calDavScrollState = rememberLazyListState()
+        val cardDavScrollState = rememberLazyListState()
+        val webcalScrollState = rememberLazyListState()
+
         Scaffold(
             topBar = {
                 TopAppBar(
@@ -310,52 +327,61 @@ fun AccountScreen(
                 modifier = Modifier.padding(padding)
             ) {
                 if (nrPages > 0) {
-                    TabRow(selectedTabIndex = pagerState.currentPage) {
-                        if (idxCalDav != null) {
-                            Tab(
-                                selected = pagerState.currentPage == idxCalDav,
-                                onClick = {
-                                    scope.launch {
-                                        pagerState.scrollToPage(idxCalDav)
-                                    }
-                                }
-                            ) {
-                                Text(
-                                    stringResource(R.string.account_caldav),
-                                    modifier = Modifier.padding(8.dp)
-                                )
-                            }
-                        }
+                    SharedTransitionLayout {
+                        val idxCurrentPage = pagerState.currentPage
 
-                        if (idxCardDav != null) {
-                            Tab(
-                                selected = pagerState.currentPage == idxCardDav,
-                                onClick = {
-                                    scope.launch {
-                                        pagerState.scrollToPage(idxCardDav)
-                                    }
-                                }
-                            ) {
-                                Text(
-                                    stringResource(R.string.account_carddav),
-                                    modifier = Modifier.padding(8.dp)
-                                )
-                            }
+                        // The icon shall be shown when the scroll state is at the top (= we can't scroll backward)
+                        val currentPageScrollState = when (idxCurrentPage) {
+                            idxCalDav -> calDavScrollState
+                            idxCardDav -> cardDavScrollState
+                            idxWebcal -> webcalScrollState
+                            else -> null
                         }
-
-                        if (idxWebcal != null) {
-                            Tab(
-                                selected = pagerState.currentPage == idxWebcal,
-                                onClick = {
-                                    scope.launch {
-                                        pagerState.scrollToPage(idxWebcal)
+                        AnimatedContent(
+                            targetState = currentPageScrollState?.canScrollBackward != true
+                        ) { showIcon ->
+                            TabRow(selectedTabIndex = idxCurrentPage) {
+                                if (idxCalDav != null)
+                                    AccountScreen_Tab(
+                                        selected = idxCurrentPage == idxCalDav,
+                                        showIcon = showIcon,
+                                        icon = Icons.Default.CalendarToday,
+                                        text = stringResource(R.string.account_caldav),
+                                        animatedVisibilityScope = this@AnimatedContent,
+                                        sharedTransitionScope = this@SharedTransitionLayout,
+                                    ) {
+                                        scope.launch {
+                                            pagerState.scrollToPage(idxCalDav)
+                                        }
+                                    }
+
+                                if (idxCardDav != null)
+                                    AccountScreen_Tab(
+                                        selected = idxCurrentPage == idxCardDav,
+                                        showIcon = showIcon,
+                                        icon = Icons.Default.Group,
+                                        text = stringResource(R.string.account_carddav),
+                                        animatedVisibilityScope = this@AnimatedContent,
+                                        sharedTransitionScope = this@SharedTransitionLayout,
+                                    ) {
+                                        scope.launch {
+                                            pagerState.scrollToPage(idxCardDav)
+                                        }
+                                    }
+
+                                if (idxWebcal != null)
+                                    AccountScreen_Tab(
+                                        selected = idxCurrentPage == idxWebcal,
+                                        showIcon = showIcon,
+                                        icon = Icons.Default.Link,
+                                        text = stringResource(R.string.account_webcal),
+                                        animatedVisibilityScope = this@AnimatedContent,
+                                        sharedTransitionScope = this@SharedTransitionLayout,
+                                    ) {
+                                        scope.launch {
+                                            pagerState.scrollToPage(idxWebcal)
+                                        }
                                     }
-                                }
-                            ) {
-                                Text(
-                                    stringResource(R.string.account_webcal),
-                                    modifier = Modifier.padding(8.dp)
-                                )
                             }
                         }
                     }
@@ -378,7 +404,8 @@ fun AccountScreen(
                                         progress = cardDavProgress,
                                         collections = addressBooks,
                                         onUpdateCollectionSync = onUpdateCollectionSync,
-                                        onCollectionDetails = onCollectionDetails
+                                        onCollectionDetails = onCollectionDetails,
+                                        state = cardDavScrollState
                                     )
 
                                 idxCalDav -> {
@@ -390,7 +417,8 @@ fun AccountScreen(
                                         progress = calDavProgress,
                                         collections = calendars,
                                         onUpdateCollectionSync = onUpdateCollectionSync,
-                                        onCollectionDetails = onCollectionDetails
+                                        onCollectionDetails = onCollectionDetails,
+                                        state = calDavScrollState
                                     )
                                 }
 
@@ -425,7 +453,8 @@ fun AccountScreen(
                                             requiredPermissions = listOf(Manifest.permission.WRITE_CALENDAR),
                                             progress = calDavProgress,
                                             collections = subscriptions,
-                                            onSubscribe = onSubscribe
+                                            onSubscribe = onSubscribe,
+                                            state = webcalScrollState
                                         )
                                     }
                                 }
@@ -438,6 +467,55 @@ fun AccountScreen(
     }
 }
 
+@Composable
+@OptIn(ExperimentalSharedTransitionApi::class)
+fun AccountScreen_Tab(
+    selected: Boolean,
+    showIcon: Boolean,
+    icon: ImageVector,
+    text: String,
+    sharedTransitionScope: SharedTransitionScope,
+    animatedVisibilityScope: AnimatedVisibilityScope,
+    onClick: () -> Unit,
+) {
+    with(sharedTransitionScope) {
+        if (showIcon) {
+            Tab(
+                selected = selected,
+                onClick = onClick,
+                icon = { Icon(imageVector = icon, contentDescription = text) },
+                text = {
+                    Text(
+                        text,
+                        modifier = Modifier
+                            .sharedBounds(
+                                rememberSharedContentState(key = text),
+                                animatedVisibilityScope = animatedVisibilityScope,
+                            )
+                            .padding(8.dp)
+                    )
+                }
+            )
+        } else {
+            Tab(
+                selected = selected,
+                onClick = onClick,
+                content = {
+                    Text(
+                        text,
+                        modifier = Modifier
+                            .sharedBounds(
+                                rememberSharedContentState(key = text),
+                                animatedVisibilityScope = animatedVisibilityScope,
+                            )
+                            .padding(8.dp)
+                    )
+                }
+            )
+        }
+    }
+}
+
 @Composable
 fun AccountScreen_Actions(
     accountName: String,
@@ -601,7 +679,8 @@ fun AccountScreen_ServiceTab(
     collections: LazyPagingItems<Collection>?,
     onUpdateCollectionSync: (collectionId: Long, sync: Boolean) -> Unit = { _, _ -> },
     onSubscribe: (Collection) -> Unit = {},
-    onCollectionDetails: ((Collection) -> Unit)? = null
+    onCollectionDetails: ((Collection) -> Unit)? = null,
+    state: LazyListState = rememberLazyListState()
 ) {
     val context = LocalContext.current
 
@@ -646,7 +725,8 @@ fun AccountScreen_ServiceTab(
                     onChangeSync = onUpdateCollectionSync,
                     onSubscribe = onSubscribe,
                     onCollectionDetails = onCollectionDetails,
-                    modifier = Modifier.weight(1f)
+                    modifier = Modifier.weight(1f),
+                    state = state
                 )
         }
     }

app/src/main/kotlin/at/bitfire/davdroid/ui/account/CollectionsList.kt

@@ -22,6 +22,8 @@ import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.LazyListState
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.EventNote
@@ -61,12 +63,14 @@ fun CollectionsList(
     onChangeSync: (collectionId: Long, sync: Boolean) -> Unit,
     modifier: Modifier = Modifier,
     onSubscribe: (collection: Collection) -> Unit = {},
-    onCollectionDetails: ((collection: Collection) -> Unit)? = null
+    onCollectionDetails: ((collection: Collection) -> Unit)? = null,
+    state: LazyListState = rememberLazyListState()
 ) {
     LazyColumn(
         contentPadding = PaddingValues(8.dp),
         verticalArrangement = Arrangement.spacedBy(12.dp, Alignment.Top),
-        modifier = modifier
+        modifier = modifier,
+        state = state
     ) {
         items(
             count = collections.itemCount,

app/src/main/kotlin/at/bitfire/davdroid/ui/account/CreateAddressBookScreen.kt

@@ -150,7 +150,6 @@ fun CreateAddressBookScreen(
                         value = description,
                         onValueChange = onSetDescription,
                         label = { Text(stringResource(R.string.create_collection_description_optional)) },
-                        supportingText = { Text(stringResource(R.string.create_collection_optional)) },
                         singleLine = true,
                         enabled = !isCreating,
                         keyboardOptions = KeyboardOptions(

app/src/main/kotlin/at/bitfire/davdroid/ui/account/CreateCalendarScreen.kt

@@ -228,7 +228,6 @@ fun CreateCalendarScreen(
                         value = description,
                         onValueChange = onSetDescription,
                         label = { Text(stringResource(R.string.create_collection_description_optional)) },
-                        supportingText = { Text(stringResource(R.string.create_collection_optional)) },
                         singleLine = true,
                         keyboardOptions = KeyboardOptions(
                             imeAction = ImeAction.Done
@@ -251,7 +250,6 @@ fun CreateCalendarScreen(
                             label = { Text(stringResource(R.string.create_calendar_time_zone_optional)) },
                             value = timeZone ?: stringResource(R.string.create_calendar_time_zone_none),
                             onValueChange = { /* read-only */ },
-                            supportingText = { Text(stringResource(R.string.create_collection_optional)) },
                             trailingIcon = { ExposedDropdownMenuDefaults.TrailingIcon(expanded = expanded) },
                             readOnly = true,
                             modifier = Modifier

app/src/main/kotlin/at/bitfire/davdroid/ui/icon/CalendarImport.kt

@@ -0,0 +1,67 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.ui.icon
+
+import androidx.compose.material.icons.Icons
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.SolidColor
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.graphics.vector.path
+import androidx.compose.ui.unit.dp
+
+val Icons.Filled.CalendarImport: ImageVector
+    get() {
+        if (_CalendarImport != null) {
+            return _CalendarImport!!
+        }
+        _CalendarImport = ImageVector.Builder(
+            name = "Filled.CalendarImport",
+            defaultWidth = 24.dp,
+            defaultHeight = 24.dp,
+            viewportWidth = 24f,
+            viewportHeight = 24f
+        ).apply {
+            path(fill = SolidColor(Color.Black)) {
+                moveTo(12f, 12f)
+                lineTo(8f, 16f)
+                horizontalLineTo(11f)
+                verticalLineTo(22f)
+                horizontalLineTo(13f)
+                verticalLineTo(16f)
+                horizontalLineTo(16f)
+                moveTo(19f, 3f)
+                horizontalLineTo(18f)
+                verticalLineTo(1f)
+                horizontalLineTo(16f)
+                verticalLineTo(3f)
+                horizontalLineTo(8f)
+                verticalLineTo(1f)
+                horizontalLineTo(6f)
+                verticalLineTo(3f)
+                horizontalLineTo(5f)
+                curveTo(3.9f, 3f, 3f, 3.9f, 3f, 5f)
+                verticalLineTo(19f)
+                curveTo(3f, 20.11f, 3.9f, 21f, 5f, 21f)
+                horizontalLineTo(9f)
+                verticalLineTo(19f)
+                horizontalLineTo(5f)
+                verticalLineTo(8f)
+                horizontalLineTo(19f)
+                verticalLineTo(19f)
+                horizontalLineTo(15f)
+                verticalLineTo(21f)
+                horizontalLineTo(19f)
+                curveTo(20.11f, 21f, 21f, 20.11f, 21f, 19f)
+                verticalLineTo(5f)
+                curveTo(21f, 3.9f, 20.11f, 3f, 19f, 3f)
+                close()
+            }
+        }.build()
+
+        return _CalendarImport!!
+    }
+
+@Suppress("ObjectPropertyName")
+private var _CalendarImport: ImageVector? = null

app/src/main/kotlin/at/bitfire/davdroid/ui/setup/AdvancedLogin.kt

@@ -179,12 +179,6 @@ fun AdvancedLoginScreen(
                 chosenAlias = certAlias,
                 onAliasChosen = onSetCertAlias
             )
-
-            Text(
-                stringResource(R.string.optional_label),
-                style = MaterialTheme.typography.bodyMedium,
-                modifier = Modifier.padding(top = 16.dp)
-            )
         }
     }
 

app/src/main/kotlin/at/bitfire/davdroid/ui/setup/NextcloudLogin.kt

@@ -89,7 +89,6 @@ object NextcloudLogin : LoginType {
                     // Custom Tabs are available
                     @Suppress("DEPRECATION")
                     val browser = CustomTabsIntent.Builder()
-                        .setToolbarColor(context.resources.getColor(R.color.primaryColor))
                         .build()
                     browser.intent.data = loginUri
                     browser.intent.putExtra(

app/src/main/kotlin/at/bitfire/davdroid/ui/webdav/AddWebdavMountScreen.kt

@@ -5,18 +5,17 @@
 package at.bitfire.davdroid.ui.webdav
 
 import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.text.KeyboardActions
 import androidx.compose.foundation.text.KeyboardOptions
-import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.ArrowBack
 import androidx.compose.material.icons.automirrored.filled.Help
+import androidx.compose.material.icons.filled.AccountCircle
 import androidx.compose.material.icons.filled.Cloud
-import androidx.compose.material3.Button
+import androidx.compose.material.icons.filled.Password
+import androidx.compose.material.icons.filled.Sell
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
@@ -42,8 +41,8 @@ import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
 import at.bitfire.davdroid.R
 import at.bitfire.davdroid.ui.AppTheme
+import at.bitfire.davdroid.ui.composable.Assistant
 import at.bitfire.davdroid.ui.composable.PasswordTextField
-import at.bitfire.davdroid.ui.composable.ProgressBar
 import at.bitfire.davdroid.ui.composable.SelectClientCertificateCard
 
 @Composable
@@ -136,21 +135,27 @@ fun AddWebDavMountScreen(
         },
         snackbarHost = { SnackbarHost(snackbarHostState) }
     ) { paddingValues ->
-        Column(
-            modifier = Modifier
-                .fillMaxSize()
-                .padding(paddingValues)
-                .verticalScroll(rememberScrollState())
+        Assistant(
+            nextLabel = stringResource(R.string.webdav_add_mount_add),
+            nextEnabled = canContinue && !isLoading,
+            isLoading = isLoading,
+            onNext = onAddMount
         ) {
-            if (isLoading)
-                ProgressBar(modifier = Modifier.fillMaxWidth())
-
             Column(
                 modifier = Modifier
-                    .fillMaxWidth()
+                    .padding(paddingValues)
                     .padding(8.dp)
             ) {
                 val focusRequester = remember { FocusRequester() }
+
+                Text(
+                    text = stringResource(R.string.webdav_add_mount_mountpoint_displayname),
+                    style = MaterialTheme.typography.headlineSmall,
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .padding(bottom = 8.dp)
+                )
+
                 OutlinedTextField(
                     label = { Text(stringResource(R.string.webdav_add_mount_url)) },
                     leadingIcon = { Icon(Icons.Default.Cloud, contentDescription = null) },
@@ -177,6 +182,9 @@ fun AddWebDavMountScreen(
                     value = displayName,
                     onValueChange = onSetDisplayName,
                     singleLine = true,
+                    leadingIcon = {
+                        Icon(Icons.Default.Sell, null)
+                    },
                     readOnly = isLoading,
                     keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
                     modifier = Modifier
@@ -192,10 +200,13 @@ fun AddWebDavMountScreen(
                         .padding(bottom = 8.dp)
                 )
                 OutlinedTextField(
-                    label = { Text(stringResource(R.string.login_user_name)) },
+                    label = { Text(stringResource(R.string.login_user_name_optional)) },
                     value = username,
                     onValueChange = onSetUsername,
                     singleLine = true,
+                    leadingIcon = {
+                        Icon(Icons.Default.AccountCircle, null)
+                    },
                     readOnly = isLoading,
                     keyboardOptions = KeyboardOptions(
                         imeAction = ImeAction.Next,
@@ -208,8 +219,11 @@ fun AddWebDavMountScreen(
                 PasswordTextField(
                     password = password,
                     onPasswordChange = onSetPassword,
-                    labelText = stringResource(R.string.login_password),
+                    labelText = stringResource(R.string.login_password_optional),
                     readOnly = isLoading,
+                    leadingIcon = {
+                        Icon(Icons.Default.Password, null)
+                    },
                     keyboardOptions = KeyboardOptions(
                         imeAction = ImeAction.Done
                     ),
@@ -229,15 +243,6 @@ fun AddWebDavMountScreen(
                         .fillMaxWidth()
                         .padding(bottom = 8.dp)
                 )
-
-                Button(
-                    enabled = canContinue && !isLoading,
-                    onClick = { onAddMount() }
-                ) {
-                    Text(
-                        text = stringResource(R.string.webdav_add_mount_add)
-                    )
-                }
             }
         }
     }

app/src/main/kotlin/at/bitfire/davdroid/webdav/DavDocumentsProvider.kt

@@ -4,817 +4,103 @@
 
 package at.bitfire.davdroid.webdav
 
-import android.app.AuthenticationRequiredException
-import android.app.PendingIntent
-import android.content.Context
-import android.content.Intent
-import android.content.res.AssetFileDescriptor
-import android.database.Cursor
-import android.database.MatrixCursor
-import android.graphics.Bitmap
-import android.graphics.BitmapFactory
 import android.graphics.Point
-import android.media.ThumbnailUtils
-import android.net.ConnectivityManager
-import android.os.Build
 import android.os.CancellationSignal
-import android.os.ParcelFileDescriptor
-import android.os.storage.StorageManager
-import android.provider.DocumentsContract.Document
-import android.provider.DocumentsContract.Root
-import android.provider.DocumentsContract.buildChildDocumentsUri
-import android.provider.DocumentsContract.buildRootsUri
 import android.provider.DocumentsProvider
-import android.webkit.MimeTypeMap
-import androidx.core.app.TaskStackBuilder
-import androidx.core.content.getSystemService
-import at.bitfire.dav4jvm.DavCollection
-import at.bitfire.dav4jvm.DavResource
-import at.bitfire.dav4jvm.Response
-import at.bitfire.dav4jvm.exception.HttpException
-import at.bitfire.dav4jvm.property.webdav.CurrentUserPrivilegeSet
-import at.bitfire.dav4jvm.property.webdav.DisplayName
-import at.bitfire.dav4jvm.property.webdav.GetContentLength
-import at.bitfire.dav4jvm.property.webdav.GetContentType
-import at.bitfire.dav4jvm.property.webdav.GetETag
-import at.bitfire.dav4jvm.property.webdav.GetLastModified
-import at.bitfire.dav4jvm.property.webdav.QuotaAvailableBytes
-import at.bitfire.dav4jvm.property.webdav.QuotaUsedBytes
-import at.bitfire.dav4jvm.property.webdav.ResourceType
-import at.bitfire.davdroid.R
-import at.bitfire.davdroid.db.AppDatabase
-import at.bitfire.davdroid.db.WebDavDocument
-import at.bitfire.davdroid.db.WebDavDocumentDao
-import at.bitfire.davdroid.di.IoDispatcher
-import at.bitfire.davdroid.network.HttpClient
-import at.bitfire.davdroid.network.MemoryCookieStore
-import at.bitfire.davdroid.ui.webdav.WebdavMountsActivity
-import at.bitfire.davdroid.webdav.cache.ThumbnailCache
-import dagger.assisted.Assisted
-import dagger.assisted.AssistedFactory
-import dagger.assisted.AssistedInject
+import at.bitfire.davdroid.webdav.operation.CopyDocumentOperation
+import at.bitfire.davdroid.webdav.operation.CreateDocumentOperation
+import at.bitfire.davdroid.webdav.operation.DeleteDocumentOperation
+import at.bitfire.davdroid.webdav.operation.IsChildDocumentOperation
+import at.bitfire.davdroid.webdav.operation.MoveDocumentOperation
+import at.bitfire.davdroid.webdav.operation.OpenDocumentOperation
+import at.bitfire.davdroid.webdav.operation.OpenDocumentThumbnailOperation
+import at.bitfire.davdroid.webdav.operation.QueryChildDocumentsOperation
+import at.bitfire.davdroid.webdav.operation.QueryDocumentOperation
+import at.bitfire.davdroid.webdav.operation.QueryRootsOperation
+import at.bitfire.davdroid.webdav.operation.RenameDocumentOperation
 import dagger.hilt.EntryPoint
-import dagger.hilt.EntryPoints
 import dagger.hilt.InstallIn
 import dagger.hilt.android.EntryPointAccessors
-import dagger.hilt.android.qualifiers.ApplicationContext
 import dagger.hilt.components.SingletonComponent
-import kotlinx.coroutines.CoroutineDispatcher
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.SupervisorJob
-import kotlinx.coroutines.async
-import kotlinx.coroutines.cancel
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.runBlocking
-import kotlinx.coroutines.runInterruptible
-import kotlinx.coroutines.withTimeout
-import okhttp3.CookieJar
-import okhttp3.HttpUrl
-import okhttp3.MediaType.Companion.toMediaTypeOrNull
-import okhttp3.RequestBody.Companion.toRequestBody
-import okhttp3.logging.HttpLoggingInterceptor
-import java.io.ByteArrayOutputStream
-import java.io.FileNotFoundException
-import java.net.HttpURLConnection
-import java.util.concurrent.ConcurrentHashMap
-import java.util.logging.Level
-import java.util.logging.Logger
-import javax.inject.Provider
 
 /**
  * Provides functionality on WebDav documents.
  *
- * Actual implementation should go into [DavDocumentsActor].
+ * Hilt constructor injection can't be used for content providers because SingletonComponent
+ * may not ready yet when the content provider is created. So we use an explicit EntryPoint.
+ *
+ * Note: A DocumentsProvider is a ContentProvider and thus has no well-defined lifecycle. It
+ * is created by Android when it's first accessed and then stays in memory until the process
+ * is killed.
  */
-class DavDocumentsProvider(
-    private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
-): DocumentsProvider() {
+class DavDocumentsProvider: DocumentsProvider() {
 
     @EntryPoint
     @InstallIn(SingletonComponent::class)
     interface DavDocumentsProviderEntryPoint {
-        fun appDatabase(): AppDatabase
-        fun davDocumentsActorFactory(): DavDocumentsActor.Factory
-        fun documentSortByMapper(): DocumentSortByMapper
-        fun logger(): Logger
-        fun randomAccessCallbackWrapperFactory(): RandomAccessCallbackWrapper.Factory
-        fun streamingFileDescriptorFactory(): StreamingFileDescriptor.Factory
-        fun webdavComponentBuilder(): WebdavComponentBuilder
+        fun copyDocumentOperation(): CopyDocumentOperation
+        fun createDocumentOperation(): CreateDocumentOperation
+        fun deleteDocumentOperation(): DeleteDocumentOperation
+        fun isChildDocumentOperation(): IsChildDocumentOperation
+        fun moveDocumentOperation(): MoveDocumentOperation
+        fun openDocumentOperation(): OpenDocumentOperation
+        fun openDocumentThumbnailOperation(): OpenDocumentThumbnailOperation
+        fun queryChildDocumentsOperation(): QueryChildDocumentsOperation
+        fun queryDocumentOperation(): QueryDocumentOperation
+        fun queryRootsOperation(): QueryRootsOperation
+        fun renameDocumentOperation(): RenameDocumentOperation
     }
 
-    @EntryPoint
-    @InstallIn(WebdavComponent::class)
-    interface DavDocumentsProviderWebdavEntryPoint {
-        fun credentialsStore(): CredentialsStore
-        fun thumbnailCache(): ThumbnailCache
+    private val entryPoint: DavDocumentsProviderEntryPoint by lazy {
+        EntryPointAccessors.fromApplication<DavDocumentsProviderEntryPoint>(context!!)
     }
 
-    companion object {
-        val DAV_FILE_FIELDS = arrayOf(
-            ResourceType.NAME,
-            CurrentUserPrivilegeSet.NAME,
-            DisplayName.NAME,
-            GetETag.NAME,
-            GetContentType.NAME,
-            GetContentLength.NAME,
-            GetLastModified.NAME,
-            QuotaAvailableBytes.NAME,
-            QuotaUsedBytes.NAME,
-        )
-
-        const val MAX_NAME_ATTEMPTS = 5
-        const val THUMBNAIL_TIMEOUT_MS = 15000L
-
-        fun notifyMountsChanged(context: Context) {
-            context.contentResolver.notifyChange(buildRootsUri(context.getString(R.string.webdav_authority)), null)
-        }
-
-    }
-
-    val documentProviderScope = CoroutineScope(SupervisorJob())
-
-    private val ourContext by lazy { context!! }        // requireContext() requires API level 30
-    private val authority by lazy { ourContext.getString(R.string.webdav_authority) }
-    private val globalEntryPoint by lazy { EntryPointAccessors.fromApplication<DavDocumentsProviderEntryPoint>(ourContext) }
-    private val webdavEntryPoint by lazy {
-        EntryPoints.get(
-            globalEntryPoint.webdavComponentBuilder().build(),
-            DavDocumentsProviderWebdavEntryPoint::class.java
-        )
-    }
-
-    private val logger by lazy { globalEntryPoint.logger() }
-
-    private val db by lazy { globalEntryPoint.appDatabase() }
-    private val mountDao by lazy { db.webDavMountDao() }
-    private val documentDao by lazy { db.webDavDocumentDao() }
-
-    private val thumbnailCache by lazy { webdavEntryPoint.thumbnailCache() }
-
-    private val connectivityManager by lazy { ourContext.getSystemService<ConnectivityManager>()!! }
-    private val storageManager by lazy { ourContext.getSystemService<StorageManager>()!! }
-
-    /** List of currently active [queryChildDocuments] runners.
-     *
-     *  Key: document ID (directory) for which children are listed.
-     *  Value: whether the runner is still running (*true*) or has already finished (*false*).
-     */
-    private val runningQueryChildren = ConcurrentHashMap<Long, Boolean>()
-
-    private val credentialsStore by lazy { webdavEntryPoint.credentialsStore() }
-    private val cookieStore by lazy { mutableMapOf<Long, CookieJar>() }
-    private val actor by lazy { globalEntryPoint.davDocumentsActorFactory().create(cookieStore, credentialsStore) }
 
     override fun onCreate() = true
 
-    override fun shutdown() {
-        documentProviderScope.cancel()
-    }
+    /* Note: shutdown() is NOT called automatically by Android; a content provider lives until
+    the process is killed. */
 
 
     /*** query ***/
 
-    override fun queryRoots(projection: Array<out String>?): Cursor {
-        logger.fine("WebDAV queryRoots")
-        val roots = MatrixCursor(projection ?: arrayOf(
-            Root.COLUMN_ROOT_ID,
-            Root.COLUMN_ICON,
-            Root.COLUMN_TITLE,
-            Root.COLUMN_FLAGS,
-            Root.COLUMN_DOCUMENT_ID,
-            Root.COLUMN_SUMMARY
-        ))
+    override fun queryRoots(projection: Array<out String>?) =
+        entryPoint.queryRootsOperation().invoke(projection)
 
-        runBlocking {
-            for (mount in mountDao.getAll()) {
-                val rootDocument = documentDao.getOrCreateRoot(mount)
-                logger.info("Root ID: $rootDocument")
+    override fun queryDocument(documentId: String, projection: Array<out String>?) =
+        entryPoint.queryDocumentOperation().invoke(documentId, projection)
 
-                roots.newRow().apply {
-                    add(Root.COLUMN_ROOT_ID, mount.id)
-                    add(Root.COLUMN_ICON, R.mipmap.ic_launcher)
-                    add(Root.COLUMN_TITLE, ourContext.getString(R.string.webdav_provider_root_title))
-                    add(Root.COLUMN_DOCUMENT_ID, rootDocument.id.toString())
-                    add(Root.COLUMN_SUMMARY, mount.name)
-                    add(Root.COLUMN_FLAGS, Root.FLAG_SUPPORTS_CREATE or Root.FLAG_SUPPORTS_IS_CHILD)
+    override fun queryChildDocuments(parentDocumentId: String, projection: Array<out String>?, sortOrder: String?) =
+        entryPoint.queryChildDocumentsOperation().invoke(parentDocumentId, projection, sortOrder)
 
-                    val quotaAvailable = rootDocument.quotaAvailable
-                    if (quotaAvailable != null)
-                        add(Root.COLUMN_AVAILABLE_BYTES, quotaAvailable)
-
-                    val quotaUsed = rootDocument.quotaUsed
-                    if (quotaAvailable != null && quotaUsed != null)
-                        add(Root.COLUMN_CAPACITY_BYTES, quotaAvailable + quotaUsed)
-                }
-            }
-        }
-
-        return roots
-    }
-
-    override fun queryDocument(documentId: String, projection: Array<out String>?): Cursor {
-        logger.fine("WebDAV queryDocument $documentId ${projection?.joinToString("+")}")
-
-        val doc = documentDao.get(documentId.toLong()) ?: throw FileNotFoundException()
-        val parent = doc.parentId?.let { parentId ->
-            documentDao.get(parentId)
-        }
-
-        return DocumentsCursor(projection ?: arrayOf(
-            Document.COLUMN_DOCUMENT_ID,
-            Document.COLUMN_DISPLAY_NAME,
-            Document.COLUMN_MIME_TYPE,
-            Document.COLUMN_FLAGS,
-            Document.COLUMN_SIZE,
-            Document.COLUMN_LAST_MODIFIED,
-            Document.COLUMN_ICON,
-            Document.COLUMN_SUMMARY
-        )).apply {
-            val bundle = doc.toBundle(parent)
-            logger.fine("queryDocument($documentId) = $bundle")
-
-            // override display names of root documents
-            if (parent == null) {
-                val mount = runBlocking { mountDao.getById(doc.mountId) }
-                bundle.putString(Document.COLUMN_DISPLAY_NAME, mount.name)
-            }
-
-            addRow(bundle)
-        }
-    }
-
-    /**
-     * Gets old or new children of given parent.
-     *
-     * Dispatches a worker querying the server for new children of given parent, and instantly
-     * returns old children (or nothing, on initial call).
-     * Once the worker finishes its query, it notifies the [android.content.ContentResolver] about
-     * change, which calls this method again. The worker being done
-     */
-    @Synchronized
-    override fun queryChildDocuments(parentDocumentId: String, projection: Array<out String>?, sortOrder: String?): Cursor {
-        logger.fine("WebDAV queryChildDocuments $parentDocumentId $projection $sortOrder")
-        val parentId = parentDocumentId.toLong()
-        val parent = documentDao.get(parentId) ?: throw FileNotFoundException()
-
-        val columns = projection ?: arrayOf(
-            Document.COLUMN_DOCUMENT_ID,
-            Document.COLUMN_DISPLAY_NAME,
-            Document.COLUMN_MIME_TYPE,
-            Document.COLUMN_FLAGS,
-            Document.COLUMN_SIZE,
-            Document.COLUMN_LAST_MODIFIED
-        )
-
-        // Register watcher
-        val result = DocumentsCursor(columns)
-        val notificationUri = buildChildDocumentsUri(authority, parentDocumentId)
-        result.setNotificationUri(ourContext.contentResolver, notificationUri)
-
-        // Dispatch worker querying for the children and keep track of it
-        val running = runningQueryChildren.getOrPut(parentId) {
-            documentProviderScope.launch {
-                actor.queryChildren(parent)
-                // Once the query is done, set query as finished (not running)
-                runningQueryChildren[parentId] = false
-                // .. and notify - effectively calling this method again
-                ourContext.contentResolver.notifyChange(notificationUri, null)
-            }
-            true
-        }
-
-        if (running)        // worker still running
-            result.loading = true
-        else                // remove worker from list if done
-            runningQueryChildren.remove(parentId)
-
-        // Prepare SORT BY clause
-        val mapper = globalEntryPoint.documentSortByMapper()
-        val sqlSortBy = if (sortOrder != null)
-            mapper.mapContentProviderToSql(sortOrder)
-        else
-            WebDavDocumentDao.DEFAULT_ORDER
-
-        // Regardless of whether the worker is done, return the children we already have
-        val children = documentDao.getChildren(parentId, sqlSortBy)
-        for (child in children) {
-            val bundle = child.toBundle(parent)
-            result.addRow(bundle)
-        }
-
-        return result
-    }
-
-    override fun isChildDocument(parentDocumentId: String, documentId: String): Boolean {
-        logger.fine("WebDAV isChildDocument $parentDocumentId $documentId")
-        val parent = documentDao.get(parentDocumentId.toLong()) ?: throw FileNotFoundException()
-
-        var iter: WebDavDocument? = documentDao.get(documentId.toLong()) ?: throw FileNotFoundException()
-        while (iter != null) {
-            val currentParentId = iter.parentId
-            if (currentParentId == parent.id)
-                return true
-
-            iter = if (currentParentId != null)
-                documentDao.get(currentParentId)
-            else
-                null
-        }
-        return false
-    }
+    override fun isChildDocument(parentDocumentId: String, documentId: String) =
+        entryPoint.isChildDocumentOperation().invoke(parentDocumentId, documentId)
 
 
     /*** copy/create/delete/move/rename ***/
 
-    override fun copyDocument(sourceDocumentId: String, targetParentDocumentId: String): String = runBlocking {
-        logger.fine("WebDAV copyDocument $sourceDocumentId $targetParentDocumentId")
-        val srcDoc = documentDao.get(sourceDocumentId.toLong()) ?: throw FileNotFoundException()
-        val dstFolder = documentDao.get(targetParentDocumentId.toLong()) ?: throw FileNotFoundException()
-        val name = srcDoc.name
+    override fun copyDocument(sourceDocumentId: String, targetParentDocumentId: String) =
+        entryPoint.copyDocumentOperation().invoke(sourceDocumentId, targetParentDocumentId)
 
-        if (srcDoc.mountId != dstFolder.mountId)
-            throw UnsupportedOperationException("Can't COPY between WebDAV servers")
+    override fun createDocument(parentDocumentId: String, mimeType: String, displayName: String): String? =
+        entryPoint.createDocumentOperation().invoke(parentDocumentId, mimeType, displayName)
 
-        actor.httpClient(srcDoc.mountId).use { client ->
-            val dav = DavResource(client.okHttpClient, srcDoc.toHttpUrl(db))
-            val dstUrl = dstFolder.toHttpUrl(db).newBuilder()
-                .addPathSegment(name)
-                .build()
+    override fun deleteDocument(documentId: String) =
+        entryPoint.deleteDocumentOperation().invoke(documentId)
 
-            try {
-                runInterruptible(ioDispatcher) {
-                    dav.copy(dstUrl, false) {
-                        // successfully copied
-                    }
-                }
-            } catch (e: HttpException) {
-                e.throwForDocumentProvider()
-            }
+    override fun moveDocument(sourceDocumentId: String, sourceParentDocumentId: String, targetParentDocumentId: String) =
+        entryPoint.moveDocumentOperation().invoke(sourceDocumentId, sourceParentDocumentId, targetParentDocumentId)
 
-            val dstDocId = documentDao.insertOrReplace(
-                WebDavDocument(
-                    mountId = dstFolder.mountId,
-                    parentId = dstFolder.id,
-                    name = name,
-                    isDirectory = srcDoc.isDirectory,
-                    displayName = srcDoc.displayName,
-                    mimeType = srcDoc.mimeType,
-                    size = srcDoc.size
-                )
-            ).toString()
-
-            actor.notifyFolderChanged(targetParentDocumentId)
-
-            /* return */ dstDocId
-        }
-    }
-
-    override fun createDocument(parentDocumentId: String, mimeType: String, displayName: String): String? = runBlocking {
-        logger.fine("WebDAV createDocument $parentDocumentId $mimeType $displayName")
-        val parent = documentDao.get(parentDocumentId.toLong()) ?: throw FileNotFoundException()
-        val createDirectory = mimeType == Document.MIME_TYPE_DIR
-
-        var docId: Long? = null
-        actor.httpClient(parent.mountId).use { client ->
-            for (attempt in 0..MAX_NAME_ATTEMPTS) {
-                val newName = displayNameToMemberName(displayName, attempt)
-                val parentUrl = parent.toHttpUrl(db)
-                val newLocation = parentUrl.newBuilder()
-                    .addPathSegment(newName)
-                    .build()
-                val doc = DavResource(client.okHttpClient, newLocation)
-                try {
-                    runInterruptible(ioDispatcher) {
-                        if (createDirectory)
-                            doc.mkCol(null) {
-                                // directory successfully created
-                            }
-                        else
-                            doc.put("".toRequestBody(null), ifNoneMatch = true) {
-                                // document successfully created
-                            }
-                    }
-
-                    docId = documentDao.insertOrReplace(
-                        WebDavDocument(
-                            mountId = parent.mountId,
-                            parentId = parent.id,
-                            name = newName,
-                            mimeType = mimeType.toMediaTypeOrNull(),
-                            isDirectory = createDirectory
-                        )
-                    )
-
-                    actor.notifyFolderChanged(parentDocumentId)
-
-                    return@runBlocking docId.toString()
-                } catch (e: HttpException) {
-                    e.throwForDocumentProvider(ignorePreconditionFailed = true)
-                }
-            }
-        }
-
-        null
-    }
-
-    override fun deleteDocument(documentId: String) = runBlocking {
-        logger.fine("WebDAV removeDocument $documentId")
-        val doc = documentDao.get(documentId.toLong()) ?: throw FileNotFoundException()
-
-        actor.httpClient(doc.mountId).use { client ->
-            val dav = DavResource(client.okHttpClient, doc.toHttpUrl(db))
-            try {
-                runInterruptible(ioDispatcher) {
-                    dav.delete {
-                        // successfully deleted
-                    }
-                }
-                logger.fine("Successfully removed")
-                documentDao.delete(doc)
-
-                actor.notifyFolderChanged(doc.parentId)
-            } catch (e: HttpException) {
-                e.throwForDocumentProvider()
-            }
-        }
-    }
-
-    override fun moveDocument(sourceDocumentId: String, sourceParentDocumentId: String, targetParentDocumentId: String): String = runBlocking {
-        logger.fine("WebDAV moveDocument $sourceDocumentId $sourceParentDocumentId $targetParentDocumentId")
-        val doc = documentDao.get(sourceDocumentId.toLong()) ?: throw FileNotFoundException()
-        val dstParent = documentDao.get(targetParentDocumentId.toLong()) ?: throw FileNotFoundException()
-
-        if (doc.mountId != dstParent.mountId)
-            throw UnsupportedOperationException("Can't MOVE between WebDAV servers")
-
-        val newLocation = dstParent.toHttpUrl(db).newBuilder()
-            .addPathSegment(doc.name)
-            .build()
-
-        actor.httpClient(doc.mountId).use { client ->
-            val dav = DavResource(client.okHttpClient, doc.toHttpUrl(db))
-            try {
-                runInterruptible(ioDispatcher) {
-                    dav.move(newLocation, false) {
-                        // successfully moved
-                    }
-                }
-
-                documentDao.update(doc.copy(parentId = dstParent.id))
-
-                actor.notifyFolderChanged(sourceParentDocumentId)
-                actor.notifyFolderChanged(targetParentDocumentId)
-            } catch (e: HttpException) {
-                e.throwForDocumentProvider()
-            }
-        }
-
-        doc.id.toString()
-    }
-
-    override fun renameDocument(documentId: String, displayName: String): String? = runBlocking {
-        logger.fine("WebDAV renameDocument $documentId $displayName")
-        val doc = documentDao.get(documentId.toLong()) ?: throw FileNotFoundException()
-
-        actor.httpClient(doc.mountId).use { client ->
-            for (attempt in 0..MAX_NAME_ATTEMPTS) {
-                val newName = displayNameToMemberName(displayName, attempt)
-                val oldUrl = doc.toHttpUrl(db)
-                val newLocation = oldUrl.newBuilder()
-                    .removePathSegment(oldUrl.pathSegments.lastIndex)
-                    .addPathSegment(newName)
-                    .build()
-                try {
-                    val dav = DavResource(client.okHttpClient, oldUrl)
-                    runInterruptible(ioDispatcher) {
-                        dav.move(newLocation, false) {
-                            // successfully renamed
-                        }
-                    }
-                    documentDao.update(doc.copy(name = newName))
-
-                    actor.notifyFolderChanged(doc.parentId)
-
-                    return@runBlocking doc.id.toString()
-                } catch (e: HttpException) {
-                    e.throwForDocumentProvider(true)
-                }
-            }
-        }
-
-        null
-    }
-
-    private fun displayNameToMemberName(displayName: String, appendNumber: Int = 0): String {
-        val safeName = displayName.filterNot { it.isISOControl() }
-
-        if (appendNumber != 0) {
-            val extension: String? = MimeTypeMap.getFileExtensionFromUrl(displayName)
-            if (extension != null) {
-                val baseName = safeName.removeSuffix(".$extension")
-                return "${baseName}_$appendNumber.$extension"
-            } else
-                return "${safeName}_$appendNumber"
-        } else
-            return safeName
-    }
+    override fun renameDocument(documentId: String, displayName: String): String? =
+        entryPoint.renameDocumentOperation().invoke(documentId, displayName)
 
 
     /*** read/write ***/
 
-    private suspend fun headRequest(client: HttpClient, url: HttpUrl): HeadResponse = runInterruptible(ioDispatcher) {
-        HeadResponse.fromUrl(client, url)
-    }
+    override fun openDocument(documentId: String, mode: String, signal: CancellationSignal?) =
+        entryPoint.openDocumentOperation().invoke(documentId, mode, signal)
 
-    override fun openDocument(documentId: String, mode: String, signal: CancellationSignal?): ParcelFileDescriptor = runBlocking {
-        logger.fine("WebDAV openDocument $documentId $mode $signal")
-
-        val doc = documentDao.get(documentId.toLong()) ?: throw FileNotFoundException()
-        val url = doc.toHttpUrl(db)
-        val client = actor.httpClient(doc.mountId, logBody = false)
-
-        val modeFlags = ParcelFileDescriptor.parseMode(mode)
-        val readAccess = when (mode) {
-            "r" -> true
-            "w", "wt" -> false
-            else -> throw UnsupportedOperationException("Mode $mode not supported by WebDAV")
-        }
-
-        val accessScope = CoroutineScope(SupervisorJob())
-        signal?.setOnCancelListener {
-            logger.fine("Cancelling WebDAV access to $url")
-            accessScope.cancel()
-        }
-
-        val fileInfo = accessScope.async {
-            headRequest(client, url)
-        }.await()
-        logger.fine("Received file info: $fileInfo")
-
-        // RandomAccessCallback.Wrapper / StreamingFileDescriptor are responsible for closing httpClient
-        return@runBlocking if (
-            Build.VERSION.SDK_INT >= 26 &&      // openProxyFileDescriptor exists since Android 8.0
-            readAccess &&                       // WebDAV doesn't support random write access natively
-            fileInfo.size != null &&            // file descriptor must return a useful value on getFileSize()
-            (fileInfo.eTag != null || fileInfo.lastModified != null) &&     // we need a method to determine whether the document has changed during access
-            fileInfo.supportsPartial == true    // WebDAV server must support random access
-        ) {
-            logger.fine("Creating RandomAccessCallback for $url")
-            val factory = globalEntryPoint.randomAccessCallbackWrapperFactory()
-            val accessor = factory.create(client, url, doc.mimeType, fileInfo, accessScope)
-            storageManager.openProxyFileDescriptor(modeFlags, accessor, accessor.workerHandler)
-        } else {
-            logger.fine("Creating StreamingFileDescriptor for $url")
-            val factory = globalEntryPoint.streamingFileDescriptorFactory()
-            val fd = factory.create(client, url, doc.mimeType, accessScope) { transferred ->
-                // called when transfer is finished
-
-                val now = System.currentTimeMillis()
-                if (!readAccess /* write access */) {
-                    // write access, update file size
-                    documentDao.update(doc.copy(size = transferred, lastModified = now))
-                }
-
-                actor.notifyFolderChanged(doc.parentId)
-            }
-
-            if (readAccess)
-                fd.download()
-            else
-                fd.upload()
-        }
-    }
-
-    override fun openDocumentThumbnail(documentId: String, sizeHint: Point, signal: CancellationSignal?): AssetFileDescriptor? {
-        logger.info("openDocumentThumbnail documentId=$documentId sizeHint=$sizeHint signal=$signal")
-
-        if (connectivityManager.isActiveNetworkMetered)
-            // don't download the large images just to create a thumbnail on metered networks
-            return null
-
-        if (signal == null) {
-            logger.warning("openDocumentThumbnail without cancellationSignal causes too much problems, please fix calling app")
-            return null
-        }
-        val accessScope = CoroutineScope(SupervisorJob())
-        signal.setOnCancelListener {
-            logger.fine("Cancelling thumbnail generation for $documentId")
-            accessScope.cancel()
-        }
-
-        val doc = documentDao.get(documentId.toLong()) ?: throw FileNotFoundException()
-
-        val docCacheKey = doc.cacheKey()
-        if (docCacheKey == null) {
-            logger.warning("openDocumentThumbnail won't generate thumbnails when document state (ETag/Last-Modified) is unknown")
-            return null
-        }
-
-        val thumbFile = thumbnailCache.get(docCacheKey, sizeHint) {
-            // create thumbnail
-            val job = accessScope.async {
-                withTimeout(THUMBNAIL_TIMEOUT_MS) {
-                    actor.httpClient(doc.mountId, logBody = false).use { client ->
-                        val url = doc.toHttpUrl(db)
-                        val dav = DavResource(client.okHttpClient, url)
-                        var result: ByteArray? = null
-                        runInterruptible(ioDispatcher) {
-                            dav.get("image/*", null) { response ->
-                                response.body.byteStream().use { data ->
-                                    BitmapFactory.decodeStream(data)?.let { bitmap ->
-                                        val thumb = ThumbnailUtils.extractThumbnail(bitmap, sizeHint.x, sizeHint.y)
-                                        val baos = ByteArrayOutputStream()
-                                        thumb.compress(Bitmap.CompressFormat.JPEG, 95, baos)
-                                        result = baos.toByteArray()
-                                    }
-                                }
-                            }
-                        }
-                        result
-                    }
-                }
-            }
-
-            try {
-                runBlocking {
-                    job.await()
-                }
-            } catch (e: Exception) {
-                logger.log(Level.WARNING, "Couldn't generate thumbnail", e)
-                null
-            }
-        }
-
-        if (thumbFile != null)
-            return AssetFileDescriptor(
-                ParcelFileDescriptor.open(thumbFile, ParcelFileDescriptor.MODE_READ_ONLY),
-                0, thumbFile.length()
-            )
-
-        return null
-    }
-
-
-    /**
-     * Acts on behalf of [DavDocumentsProvider].
-     *
-     * Encapsulates functionality to make it easily testable without generating lots of
-     * DocumentProviders during the tests.
-     *
-     * By containing the actual implementation logic of [DavDocumentsProvider], it adds a layer of separation
-     * to make the methods of [DavDocumentsProvider] more easily testable.
-     * [DavDocumentsProvider]s methods should do nothing more, but to call [DavDocumentsActor]s methods.
-     */
-    class DavDocumentsActor @AssistedInject constructor(
-        @Assisted private val cookieStores: MutableMap<Long, CookieJar>,
-        @Assisted private val credentialsStore: CredentialsStore,
-        @ApplicationContext private val context: Context,
-        private val db: AppDatabase,
-        private val httpClientBuilder: Provider<HttpClient.Builder>,
-        @IoDispatcher private val ioDispatcher: CoroutineDispatcher,
-        private val logger: Logger
-    ) {
-
-        @AssistedFactory
-        interface Factory {
-            fun create(cookieStore: MutableMap<Long, CookieJar>, credentialsStore: CredentialsStore): DavDocumentsActor
-        }
-
-        private val authority = context.getString(R.string.webdav_authority)
-        private val documentDao = db.webDavDocumentDao()
-
-        /**
-         * Finds children of given parent [WebDavDocument]. After querying, it
-         * updates existing children, adds new ones or removes deleted ones.
-         *
-         * There must never be more than one running instance per [parent]!
-         *
-         * @param parent    folder to search for children
-         */
-        internal suspend fun queryChildren(parent: WebDavDocument) {
-            val oldChildren = documentDao.getChildren(parent.id).associateBy { it.name }.toMutableMap() // "name" of file/folder must be unique
-            val newChildrenList = hashMapOf<String, WebDavDocument>()
-
-            val parentUrl = parent.toHttpUrl(db)
-            httpClient(parent.mountId).use { client ->
-                val folder = DavCollection(client.okHttpClient, parentUrl)
-
-                try {
-                    runInterruptible(ioDispatcher) {
-                        folder.propfind(1, *DAV_FILE_FIELDS) { response, relation ->
-                            logger.fine("$relation $response")
-
-                            val resource: WebDavDocument =
-                                when (relation) {
-                                    Response.HrefRelation.SELF ->       // it's about the parent
-                                        parent
-
-                                    Response.HrefRelation.MEMBER ->     // it's about a member
-                                        WebDavDocument(mountId = parent.mountId, parentId = parent.id, name = response.hrefName())
-
-                                    else -> {
-                                        // we didn't request this; log a warning and ignore it
-                                        logger.warning("Ignoring unexpected $response $relation in $parentUrl")
-                                        return@propfind
-                                    }
-                                }
-
-                            val updatedResource = resource.copy(
-                                isDirectory = response[ResourceType::class.java]?.types?.contains(ResourceType.COLLECTION)
-                                    ?: resource.isDirectory,
-                                displayName = response[DisplayName::class.java]?.displayName,
-                                mimeType = response[GetContentType::class.java]?.type,
-                                eTag = response[GetETag::class.java]?.takeIf { !it.weak }?.let { resource.eTag },
-                                lastModified = response[GetLastModified::class.java]?.lastModified?.toEpochMilli(),
-                                size = response[GetContentLength::class.java]?.contentLength,
-                                mayBind = response[CurrentUserPrivilegeSet::class.java]?.mayBind,
-                                mayUnbind = response[CurrentUserPrivilegeSet::class.java]?.mayUnbind,
-                                mayWriteContent = response[CurrentUserPrivilegeSet::class.java]?.mayWriteContent,
-                                quotaAvailable = response[QuotaAvailableBytes::class.java]?.quotaAvailableBytes,
-                                quotaUsed = response[QuotaUsedBytes::class.java]?.quotaUsedBytes,
-                            )
-
-                            if (resource == parent)
-                                documentDao.update(updatedResource)
-                            else {
-                                documentDao.insertOrUpdate(updatedResource)
-                                newChildrenList[resource.name] = updatedResource
-                            }
-
-                            // remove resource from known child nodes, because not found on server
-                            oldChildren.remove(resource.name)
-                        }
-                    }
-                } catch (e: Exception) {
-                    logger.log(Level.WARNING, "Couldn't query children", e)
-                }
-            }
-
-            // Delete child nodes which were not rediscovered (deleted serverside)
-            for ((_, oldChild) in oldChildren)
-                documentDao.delete(oldChild)
-        }
-
-
-        // helpers
-
-        /**
-         * Creates a HTTP client that can be used to access resources in the given mount.
-         *
-         * @param mountId    ID of the mount to access
-         * @param logBody    whether to log the body of HTTP requests (disable for potentially large files)
-         */
-        internal fun httpClient(mountId: Long, logBody: Boolean = true): HttpClient {
-            val builder = httpClientBuilder.get()
-                .loggerInterceptorLevel(if (logBody) HttpLoggingInterceptor.Level.BODY else HttpLoggingInterceptor.Level.HEADERS)
-                .setCookieStore(
-                    cookieStores.getOrPut(mountId) { MemoryCookieStore() }
-                )
-
-            credentialsStore.getCredentials(mountId)?.let { credentials ->
-                builder.authenticate(host = null, getCredentials = { credentials })
-            }
-
-            return builder.build()
-        }
-
-        internal fun notifyFolderChanged(parentDocumentId: Long?) {
-            if (parentDocumentId != null)
-                context.contentResolver.notifyChange(buildChildDocumentsUri(authority, parentDocumentId.toString()), null)
-        }
-
-        internal fun notifyFolderChanged(parentDocumentId: String) {
-            context.contentResolver.notifyChange(buildChildDocumentsUri(authority, parentDocumentId), null)
-        }
-
-
-    }
-
-
-    private fun HttpException.throwForDocumentProvider(ignorePreconditionFailed: Boolean = false) {
-        when (code) {
-            HttpURLConnection.HTTP_UNAUTHORIZED -> {
-                if (Build.VERSION.SDK_INT >= 26) {
-                    // TODO edit mount
-                    val intent = Intent(ourContext, WebdavMountsActivity::class.java)
-                    throw AuthenticationRequiredException(
-                        this,
-                        TaskStackBuilder.create(ourContext)
-                            .addNextIntentWithParentStack(intent)
-                            .getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE)
-                    )
-                }
-            }
-            HttpURLConnection.HTTP_NOT_FOUND ->
-                throw FileNotFoundException()
-            HttpURLConnection.HTTP_PRECON_FAILED ->
-                if (ignorePreconditionFailed)
-                    return
-        }
-
-        // re-throw
-        throw this
-    }
+    override fun openDocumentThumbnail(documentId: String, sizeHint: Point, signal: CancellationSignal?) =
+        entryPoint.openDocumentThumbnailOperation().invoke(documentId, sizeHint, signal)
 
 }

app/src/main/kotlin/at/bitfire/davdroid/webdav/DavHttpClientBuilder.kt

@@ -0,0 +1,49 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav
+
+import at.bitfire.davdroid.network.HttpClient
+import at.bitfire.davdroid.network.MemoryCookieStore
+import okhttp3.CookieJar
+import okhttp3.logging.HttpLoggingInterceptor
+import javax.inject.Inject
+import javax.inject.Provider
+
+class DavHttpClientBuilder @Inject constructor(
+    private val credentialsStore: CredentialsStore,
+    private val httpClientBuilder: Provider<HttpClient.Builder>,
+) {
+
+    /**
+     * Creates an HTTP client that can be used to access resources in the given mount.
+     *
+     * @param mountId    ID of the mount to access
+     * @param logBody    whether to log the body of HTTP requests (disable for potentially large files)
+     */
+    fun build(mountId: Long, logBody: Boolean = true): HttpClient {
+        val cookieStore = cookieStores.getOrPut(mountId) {
+            MemoryCookieStore()
+        }
+        val builder = httpClientBuilder.get()
+            .loggerInterceptorLevel(if (logBody) HttpLoggingInterceptor.Level.BODY else HttpLoggingInterceptor.Level.HEADERS)
+            .setCookieStore(cookieStore)
+
+        credentialsStore.getCredentials(mountId)?.let { credentials ->
+            builder.authenticate(host = null, getCredentials = { credentials })
+        }
+
+        return builder.build()
+    }
+
+
+    companion object {
+
+        /** in-memory cookie stores (one per mount ID) that are available until the content
+         * provider (= process) is terminated */
+        private val cookieStores = mutableMapOf<Long, CookieJar>()
+
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/webdav/DocumentProviderUtils.kt

@@ -0,0 +1,91 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav
+
+import android.app.AuthenticationRequiredException
+import android.app.PendingIntent
+import android.content.Context
+import android.content.Intent
+import android.os.Build
+import android.provider.DocumentsContract.buildChildDocumentsUri
+import android.provider.DocumentsContract.buildRootsUri
+import android.webkit.MimeTypeMap
+import androidx.core.app.TaskStackBuilder
+import at.bitfire.dav4jvm.exception.HttpException
+import at.bitfire.davdroid.R
+import at.bitfire.davdroid.ui.webdav.WebdavMountsActivity
+import java.io.FileNotFoundException
+import java.net.HttpURLConnection
+
+object DocumentProviderUtils  {
+
+    const val MAX_DISPLAYNAME_TO_MEMBERNAME_ATTEMPTS = 5
+
+    internal fun displayNameToMemberName(displayName: String, appendNumber: Int = 0): String {
+        val safeName = displayName.filterNot { it.isISOControl() }
+
+        if (appendNumber != 0) {
+            val extension: String? = MimeTypeMap.getFileExtensionFromUrl(displayName)
+            if (extension != null) {
+                val baseName = safeName.removeSuffix(".$extension")
+                return "${baseName}_$appendNumber.$extension"
+            } else
+                return "${safeName}_$appendNumber"
+        } else
+            return safeName
+    }
+
+    internal fun notifyFolderChanged(context: Context, parentDocumentId: Long?) {
+        if (parentDocumentId != null)
+            context.contentResolver.notifyChange(
+                buildChildDocumentsUri(
+                    context.getString(R.string.webdav_authority),
+                    parentDocumentId.toString()
+                ),
+                null
+            )
+    }
+
+    internal fun notifyFolderChanged(context: Context, parentDocumentId: String) {
+        context.contentResolver.notifyChange(
+            buildChildDocumentsUri(
+                context.getString(R.string.webdav_authority),
+                parentDocumentId
+            ),
+            null
+        )
+    }
+
+    internal fun notifyMountsChanged(context: Context) {
+        context.contentResolver.notifyChange(
+            buildRootsUri(context.getString(R.string.webdav_authority)),
+            null)
+    }
+
+}
+
+internal fun HttpException.throwForDocumentProvider(context: Context, ignorePreconditionFailed: Boolean = false) {
+    when (code) {
+        HttpURLConnection.HTTP_UNAUTHORIZED -> {
+            if (Build.VERSION.SDK_INT >= 26) {
+                val intent = Intent(context, WebdavMountsActivity::class.java)
+                throw AuthenticationRequiredException(
+                    this,
+                    TaskStackBuilder.create(context)
+                        .addNextIntentWithParentStack(intent)
+                        .getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE)
+                )
+            }
+        }
+        HttpURLConnection.HTTP_NOT_FOUND ->
+            throw FileNotFoundException()
+        HttpURLConnection.HTTP_PRECON_FAILED ->
+            if (ignorePreconditionFailed)
+                return
+    }
+
+    // re-throw
+    throw this
+}

app/src/main/kotlin/at/bitfire/davdroid/webdav/RandomAccessCallback.kt

@@ -5,20 +5,20 @@
 package at.bitfire.davdroid.webdav
 
 import android.content.Context
+import android.os.Handler
+import android.os.HandlerThread
+import android.os.ParcelFileDescriptor
 import android.os.ProxyFileDescriptorCallback
+import android.os.storage.StorageManager
 import android.system.ErrnoException
 import android.system.OsConstants
-import android.text.format.Formatter
 import androidx.annotation.RequiresApi
-import androidx.core.app.NotificationCompat
-import androidx.core.app.NotificationManagerCompat
+import androidx.core.content.getSystemService
 import at.bitfire.dav4jvm.DavResource
 import at.bitfire.dav4jvm.HttpUtils
 import at.bitfire.dav4jvm.exception.DavException
 import at.bitfire.dav4jvm.exception.HttpException
-import at.bitfire.davdroid.R
 import at.bitfire.davdroid.network.HttpClient
-import at.bitfire.davdroid.ui.NotificationRegistry
 import at.bitfire.davdroid.util.DavUtils
 import com.google.common.cache.CacheBuilder
 import com.google.common.cache.CacheLoader
@@ -40,17 +40,17 @@ import okhttp3.MediaType
 import java.io.InterruptedIOException
 import java.net.HttpURLConnection
 import java.util.logging.Logger
+import javax.annotation.WillClose
 
 @RequiresApi(26)
 class RandomAccessCallback @AssistedInject constructor(
-    @Assisted val httpClient: HttpClient,
-    @Assisted val url: HttpUrl,
-    @Assisted val mimeType: MediaType?,
+    @Assisted @WillClose private val httpClient: HttpClient,
+    @Assisted private val url: HttpUrl,
+    @Assisted private val mimeType: MediaType?,
     @Assisted headResponse: HeadResponse,
     @Assisted private val externalScope: CoroutineScope,
-    @ApplicationContext val context: Context,
-    private val logger: Logger,
-    private val notificationRegistry: NotificationRegistry
+    @ApplicationContext private val context: Context,
+    private val logger: Logger
 ): ProxyFileDescriptorCallback() {
 
     companion object {
@@ -77,26 +77,34 @@ class RandomAccessCallback @AssistedInject constructor(
     private val fileSize = headResponse.size ?: throw IllegalArgumentException("Can only be used with given file size")
     private val documentState = headResponse.toDocumentState() ?: throw IllegalArgumentException("Can only be used with ETag/Last-Modified")
 
-    private val notificationManager = NotificationManagerCompat.from(context)
-    private val notification = NotificationCompat.Builder(context, notificationRegistry.CHANNEL_STATUS)
-        .setPriority(NotificationCompat.PRIORITY_LOW)
-        .setCategory(NotificationCompat.CATEGORY_STATUS)
-        .setContentTitle(context.getString(R.string.webdav_notification_access))
-        .setContentText(dav.fileName())
-        .setSubText(Formatter.formatFileSize(context, fileSize))
-        .setSmallIcon(R.drawable.ic_storage_notify)
-        .setOngoing(true)
-    private val notificationTag = url.toString()
-
     private val pageLoader = PageLoader(externalScope)
     private val pageCache: LoadingCache<PageIdentifier, ByteArray> = CacheBuilder.newBuilder()
         .maximumSize(10)    // don't cache more than 10 entries (MAX_PAGE_SIZE each)
-        .softValues()       // use SoftReference for the page contents so they will be garbage collected if memory is needed
+        .softValues()       // use SoftReference for the page contents so they will be garbage-collected if memory is needed
         .build(pageLoader)  // fetch actual content using pageLoader
 
+    /** This thread will be used for I/O operations like [onRead]. Using the main looper would cause ANRs. */
+    private val ioThread = HandlerThread("WebDAV I/O").apply {
+        start()
+    }
+
     private val pagingReader = PagingReader(fileSize, MAX_PAGE_SIZE, pageCache)
 
 
+    // file descriptor
+
+    /**
+     * Returns a random-access file descriptor that can be used in a DocumentsProvider.
+     */
+    fun fileDescriptor(): ParcelFileDescriptor {
+        val storageManager = context.getSystemService<StorageManager>()!!
+        val ioHandler = Handler(ioThread.looper)
+        return storageManager.openProxyFileDescriptor(ParcelFileDescriptor.MODE_READ_ONLY, this, ioHandler)
+    }
+
+
+    // implementation
+
     override fun onFsync() { /* not used */ }
 
     override fun onGetSize(): Long = runBlockingFd("onGetFileSize") {
@@ -117,7 +125,10 @@ class RandomAccessCallback @AssistedInject constructor(
 
     override fun onRelease() {
         logger.fine("onRelease")
-        notificationManager.cancel(notificationTag, NotificationRegistry.NOTIFY_WEBDAV_ACCESS)
+
+        // free resources
+        ioThread.quitSafely()
+        httpClient.close()
     }
 
 
@@ -185,16 +196,6 @@ class RandomAccessCallback @AssistedInject constructor(
             val size = key.size
             logger.fine("Loading page $url $offset/$size")
 
-            // update notification
-            notificationRegistry.notifyIfPossible(NotificationRegistry.NOTIFY_WEBDAV_ACCESS, tag = notificationTag) {
-                val progress =
-                    if (fileSize == 0L)     // avoid division by zero
-                        100
-                    else
-                        (offset * 100 / fileSize).toInt()
-                notification.setProgress(100, progress, false).build()
-            }
-
             val ifMatch: Headers =
                 documentState.eTag?.let { eTag ->
                     Headers.headersOf("If-Match", "\"$eTag\"")

app/src/main/kotlin/at/bitfire/davdroid/webdav/RandomAccessCallbackWrapper.kt

@@ -4,183 +4,85 @@
 
 package at.bitfire.davdroid.webdav
 
-import android.os.Build
-import android.os.Handler
-import android.os.HandlerThread
 import android.os.ProxyFileDescriptorCallback
+import android.system.ErrnoException
+import android.system.OsConstants
 import androidx.annotation.RequiresApi
 import at.bitfire.davdroid.network.HttpClient
-import at.bitfire.davdroid.webdav.RandomAccessCallbackWrapper.Companion.TIMEOUT_INTERVAL
 import dagger.assisted.Assisted
 import dagger.assisted.AssistedFactory
 import dagger.assisted.AssistedInject
 import kotlinx.coroutines.CoroutineScope
 import okhttp3.HttpUrl
 import okhttp3.MediaType
-import ru.nsk.kstatemachine.event.Event
-import ru.nsk.kstatemachine.state.State
-import ru.nsk.kstatemachine.state.finalState
-import ru.nsk.kstatemachine.state.initialState
-import ru.nsk.kstatemachine.state.onEntry
-import ru.nsk.kstatemachine.state.onExit
-import ru.nsk.kstatemachine.state.onFinished
-import ru.nsk.kstatemachine.state.state
-import ru.nsk.kstatemachine.state.transitionOn
-import ru.nsk.kstatemachine.statemachine.StateMachine
-import ru.nsk.kstatemachine.statemachine.createStdLibStateMachine
-import ru.nsk.kstatemachine.statemachine.processEventBlocking
-import java.util.Timer
-import java.util.TimerTask
-import java.util.logging.Logger
-import kotlin.concurrent.schedule
 
 /**
- * (2021/12/02) Currently Android's `StorageManager.openProxyFileDescriptor` has a memory leak:
+ * Use this wrapper to ensure that all memory is released as soon as [onRelease] is called.
+ *
+ * - (2021/12/02) Currently Android's `StorageManager.openProxyFileDescriptor` has a memory leak:
  * the given callback is registered in `com.android.internal.os.AppFuseMount` (which adds it to
  * a [Map]), but is not unregistered anymore. So it stays in the memory until the whole mount
- * is unloaded. See https://issuetracker.google.com/issues/208788568
+ * is unloaded. See https://issuetracker.google.com/issues/208788568.
+ * - (2024/08/24) [Fixed in Android.](https://android.googlesource.com/platform/frameworks/base/+/e7dbf78143ba083af7a8ecadd839a9dbf6f01655%5E%21/#F0)
  *
- * Use this wrapper to
+ * **All fields of objects of this class must be set to `null` when [onRelease] is called!**
+ * Otherwise they will leak memory.
  *
- * - ensure that all memory is released as soon as [onRelease] is called,
- * - provide timeout functionality: [RandomAccessCallback] will be closed when not
- *
- * used for more than [TIMEOUT_INTERVAL] ms and re-created when necessary.
- *
- * @param httpClient    HTTP client – [RandomAccessCallbackWrapper] is responsible to close it
+ * @param httpClient    HTTP client ([RandomAccessCallbackWrapper] is responsible to close it)
  */
-@RequiresApi(Build.VERSION_CODES.O)
+@RequiresApi(26)
 class RandomAccessCallbackWrapper @AssistedInject constructor(
-    @Assisted private val httpClient: HttpClient,
-    @Assisted private val url: HttpUrl,
-    @Assisted private val mimeType: MediaType?,
-    @Assisted private val headResponse: HeadResponse,
-    @Assisted private val externalScope: CoroutineScope,
-    private val logger: Logger,
-    private val callbackFactory: RandomAccessCallback.Factory
+    @Assisted httpClient: HttpClient,
+    @Assisted url: HttpUrl,
+    @Assisted mimeType: MediaType?,
+    @Assisted headResponse: HeadResponse,
+    @Assisted externalScope: CoroutineScope,
+    callbackFactory: RandomAccessCallback.Factory
 ): ProxyFileDescriptorCallback() {
 
-    companion object {
-        const val TIMEOUT_INTERVAL = 15000L
-    }
-
     @AssistedFactory
     interface Factory {
         fun create(httpClient: HttpClient, url: HttpUrl, mimeType: MediaType?, headResponse: HeadResponse, externalScope: CoroutineScope): RandomAccessCallbackWrapper
     }
 
-    sealed class Events {
-        object Transfer : Event
-        object NowIdle : Event
-        object GoStandby : Event
-        object Close : Event
-    }
-    /* We don't use a sealed class for states here because the states would then be singletons, while we can have
-    multiple instances of the state machine (which require multiple instances of the states, too). */
-    private val machine = createStdLibStateMachine {
-        lateinit var activeIdleState: State
-        lateinit var activeTransferringState: State
-        lateinit var standbyState: State
-        lateinit var closedState: State
 
-        initialState("active") {
-            onEntry {
-                _callback = callbackFactory.create(httpClient, url, mimeType, headResponse, externalScope)
-            }
-            onExit {
-                _callback?.onRelease()
-                _callback = null
-            }
+    // callback reference
 
-            transitionOn<Events.GoStandby> { targetState = { standbyState } }
-            transitionOn<Events.Close> { targetState = { closedState } }
+    /**
+     * This field is initialized with a strong reference to the callback. It is cleared when
+     * [onRelease] is called so that the garbage collector can remove the actual [RandomAccessCallback].
+     */
+    private var callbackRef: RandomAccessCallback? =
+        callbackFactory.create(httpClient, url, mimeType, headResponse, externalScope)
 
-            // active has two nested states: transferring (I/O running) and idle (starts timeout timer)
-            activeIdleState = initialState("idle") {
-                val timer: Timer = Timer(true)
-                var timeout: TimerTask? = null
-
-                onEntry {
-                    timeout = timer.schedule(TIMEOUT_INTERVAL) {
-                        machine.processEventBlocking(Events.GoStandby)
-                    }
-                }
-                onExit {
-                    timeout?.cancel()
-                    timeout = null
-                }
-                onFinished {
-                    timer.cancel()
-                }
-
-                transitionOn<Events.Transfer> { targetState = { activeTransferringState } }
-            }
-
-            activeTransferringState = state("transferring") {
-                transitionOn<Events.NowIdle> { targetState = { activeIdleState } }
-            }
-        }
-
-        standbyState = state("standby") {
-            transitionOn<Events.Transfer> { targetState = { activeTransferringState } }
-            transitionOn<Events.NowIdle> { targetState = { activeIdleState } }
-            transitionOn<Events.Close> { targetState = { closedState } }
-        }
-
-        closedState = finalState("closed")
-        onFinished {
-            shutdown()
-        }
-
-        logger = StateMachine.Logger { message ->
-            this@RandomAccessCallbackWrapper.logger.finer(message())
-        }
-    }
-
-    private val workerThread = HandlerThread(javaClass.simpleName).apply { start() }
-    val workerHandler: Handler = Handler(workerThread.looper)
-
-    private var _callback: RandomAccessCallback? = null
-
-    fun<T> requireCallback(block: (callback: RandomAccessCallback) -> T): T {
-        machine.processEventBlocking(Events.Transfer)
-        try {
-            return block(_callback ?: throw IllegalStateException())
-        } finally {
-            machine.processEventBlocking(Events.NowIdle)
-        }
-    }
+    private fun requireCallback(functionName: String): RandomAccessCallback =
+        callbackRef ?: throw ErrnoException(functionName, OsConstants.EBADF)
 
 
-    /// states ///
+    // non-interface delegates
 
-    @Synchronized
-    private fun shutdown() {
-        httpClient.close()
-        workerThread.quit()
-    }
+    fun fileDescriptor() =
+        requireCallback("fileDescriptor").fileDescriptor()
 
 
-    /// delegating implementation of ProxyFileDescriptorCallback ///
+    // delegating implementation of ProxyFileDescriptorCallback
 
-    @Synchronized
     override fun onFsync() { /* not used */ }
 
-    @Synchronized
     override fun onGetSize() =
-        requireCallback { it.onGetSize() }
+        requireCallback("onGetSize").onGetSize()
 
-    @Synchronized
     override fun onRead(offset: Long, size: Int, data: ByteArray) =
-        requireCallback { it.onRead(offset, size, data) }
+        requireCallback("onRead").onRead(offset, size, data)
 
-    @Synchronized
     override fun onWrite(offset: Long, size: Int, data: ByteArray) =
-        requireCallback { it.onWrite(offset, size, data) }
+        requireCallback("onWrite").onWrite(offset, size, data)
 
-    @Synchronized
     override fun onRelease() {
-        machine.processEventBlocking(Events.Close)
+        requireCallback("onRelease").onRelease()
+
+        // remove reference to allow garbage collection
+        callbackRef = null
     }
 
 }

app/src/main/kotlin/at/bitfire/davdroid/webdav/StreamingFileDescriptor.kt

@@ -4,23 +4,15 @@
 
 package at.bitfire.davdroid.webdav
 
-import android.content.Context
 import android.os.ParcelFileDescriptor
-import android.text.format.Formatter
-import androidx.annotation.WorkerThread
-import androidx.core.app.NotificationCompat
-import androidx.core.app.NotificationManagerCompat
 import at.bitfire.dav4jvm.DavResource
 import at.bitfire.dav4jvm.exception.HttpException
-import at.bitfire.davdroid.R
 import at.bitfire.davdroid.di.IoDispatcher
 import at.bitfire.davdroid.network.HttpClient
-import at.bitfire.davdroid.ui.NotificationRegistry
 import at.bitfire.davdroid.util.DavUtils
 import dagger.assisted.Assisted
 import dagger.assisted.AssistedFactory
 import dagger.assisted.AssistedInject
-import dagger.hilt.android.qualifiers.ApplicationContext
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.launch
@@ -32,27 +24,21 @@ import okio.BufferedSink
 import java.io.IOException
 import java.util.logging.Level
 import java.util.logging.Logger
+import javax.annotation.WillClose
 
 /**
- * @param client    HTTP client– [StreamingFileDescriptor] is responsible to close it
+ * @param client    HTTP client ([StreamingFileDescriptor] is responsible to close it)
  */
 class StreamingFileDescriptor @AssistedInject constructor(
-    @Assisted private val client: HttpClient,
+    @Assisted @WillClose private val client: HttpClient,
     @Assisted private val url: HttpUrl,
     @Assisted private val mimeType: MediaType?,
     @Assisted private val externalScope: CoroutineScope,
     @Assisted private val finishedCallback: OnSuccessCallback,
-    @ApplicationContext private val context: Context,
     @IoDispatcher private val ioDispatcher: CoroutineDispatcher,
-    private val logger: Logger,
-    private val notificationRegistry: NotificationRegistry
+    private val logger: Logger
 ) {
 
-    companion object {
-        /** 1 MB transfer buffer */
-        private const val BUFFER_SIZE = 1024*1024
-    }
-
     @AssistedFactory
     interface Factory {
         fun create(client: HttpClient, url: HttpUrl, mimeType: MediaType?, externalScope: CoroutineScope, finishedCallback: OnSuccessCallback): StreamingFileDescriptor
@@ -61,28 +47,21 @@ class StreamingFileDescriptor @AssistedInject constructor(
     val dav = DavResource(client.okHttpClient, url)
     var transferred: Long = 0
 
-    private val notificationManager = NotificationManagerCompat.from(context)
-    private val notification = NotificationCompat.Builder(context, notificationRegistry.CHANNEL_STATUS)
-        .setPriority(NotificationCompat.PRIORITY_LOW)
-        .setCategory(NotificationCompat.CATEGORY_STATUS)
-        .setContentText(dav.fileName())
-        .setSmallIcon(R.drawable.ic_storage_notify)
-        .setOngoing(true)
-    val notificationTag = url.toString()
-
-
     fun download() = doStreaming(false)
     fun upload() = doStreaming(true)
 
     private fun doStreaming(upload: Boolean): ParcelFileDescriptor {
         val (readFd, writeFd) = ParcelFileDescriptor.createReliablePipe()
 
-        externalScope.launch(ioDispatcher) {
+        var success = false
+        externalScope.launch {
             try {
                 if (upload)
                     uploadNow(readFd)
                 else
                     downloadNow(writeFd)
+
+                success = true
             } catch (e: HttpException) {
                 logger.log(Level.WARNING, "HTTP error when opening remote file", e)
                 writeFd.closeWithError("${e.code} ${e.message}")
@@ -90,17 +69,15 @@ class StreamingFileDescriptor @AssistedInject constructor(
                 logger.log(Level.INFO, "Couldn't serve file (not necessarily an error)", e)
                 writeFd.closeWithError(e.message)
             } finally {
+                // close pipe
+                try {
+                    readFd.close()
+                    writeFd.close()
+                } catch (_: IOException) {}
+
                 client.close()
+                finishedCallback.onFinished(transferred, success)
             }
-
-            try {
-                readFd.close()
-                writeFd.close()
-            } catch (_: IOException) {}
-
-            notificationManager.cancel(notificationTag, NotificationRegistry.NOTIFY_WEBDAV_ACCESS)
-
-            finishedCallback.onSuccess(transferred)
         }
 
         return if (upload)
@@ -109,49 +86,20 @@ class StreamingFileDescriptor @AssistedInject constructor(
             readFd
     }
 
-    @WorkerThread
-    private suspend fun downloadNow(writeFd: ParcelFileDescriptor) = runInterruptible {
+    /**
+     * Downloads a WebDAV resource.
+     *
+     * @param writeFd   destination file descriptor (could for instance represent a local file)
+     */
+    private suspend fun downloadNow(writeFd: ParcelFileDescriptor) = runInterruptible(ioDispatcher) {
         dav.get(DavUtils.acceptAnything(preferred = mimeType), null) { response ->
             response.body.use { body ->
                 if (response.isSuccessful) {
-                    val length = body.contentLength()
-
-                    notification.setContentTitle(context.getString(R.string.webdav_notification_download))
-                    if (length == -1L)
-                        // unknown file size, show notification now (no updates on progress)
-                        notificationRegistry.notifyIfPossible(NotificationRegistry.NOTIFY_WEBDAV_ACCESS, notificationTag) {
-                            notification
-                                .setProgress(100, 0, true)
-                                .build()
-                        }
-                    else
-                        // known file size
-                        notification.setSubText(Formatter.formatFileSize(context, length))
-
-                    ParcelFileDescriptor.AutoCloseOutputStream(writeFd).use { output ->
-                        val buffer = ByteArray(BUFFER_SIZE)
+                    ParcelFileDescriptor.AutoCloseOutputStream(writeFd).use { destination ->
                         body.byteStream().use { source ->
-                            // read first chunk
-                            var bytes = source.read(buffer)
-                            while (bytes != -1) {
-                                // update notification (if file size is known)
-                                if (length > 0)
-                                    notificationRegistry.notifyIfPossible(NotificationRegistry.NOTIFY_WEBDAV_ACCESS, notificationTag) {
-                                        val progress = (transferred*100/length).toInt()
-                                        notification
-                                            .setProgress(100, progress, false)
-                                            .build()
-                                    }
-
-                                // write chunk
-                                output.write(buffer, 0, bytes)
-                                transferred += bytes
-
-                                // read next chunk
-                                bytes = source.read(buffer)
-                            }
-                            logger.finer("Downloaded $transferred byte(s) from $url")
+                            transferred += source.copyTo(destination)
                         }
+                        logger.finer("Downloaded $transferred byte(s) from $url")
                     }
 
                 } else
@@ -160,31 +108,18 @@ class StreamingFileDescriptor @AssistedInject constructor(
         }
     }
 
-    @WorkerThread
-    private suspend fun uploadNow(readFd: ParcelFileDescriptor) = runInterruptible {
+    /**
+     * Uploads a WebDAV resource.
+     *
+     * @param readFd    source file descriptor (could for instance represent a local file)
+     */
+    private suspend fun uploadNow(readFd: ParcelFileDescriptor) = runInterruptible(ioDispatcher) {
         val body = object: RequestBody() {
             override fun contentType(): MediaType? = mimeType
             override fun isOneShot() = true
             override fun writeTo(sink: BufferedSink) {
-                notificationRegistry.notifyIfPossible(NotificationRegistry.NOTIFY_WEBDAV_ACCESS, notificationTag) {
-                    notification
-                        .setContentTitle(context.getString(R.string.webdav_notification_upload))
-                        .build()
-                }
-
                 ParcelFileDescriptor.AutoCloseInputStream(readFd).use { input ->
-                    val buffer = ByteArray(BUFFER_SIZE)
-
-                    // read first chunk
-                    var size = input.read(buffer)
-                    while (size != -1) {
-                        // write chunk
-                        sink.write(buffer, 0, size)
-                        transferred += size
-
-                        // read next chunk
-                        size = input.read(buffer)
-                    }
+                    transferred += input.copyTo(sink.outputStream())
                     logger.finer("Uploaded $transferred byte(s) to $url")
                 }
             }
@@ -196,7 +131,7 @@ class StreamingFileDescriptor @AssistedInject constructor(
 
 
     fun interface OnSuccessCallback {
-        fun onSuccess(transferred: Long)
+        fun onFinished(transferred: Long, success: Boolean)
     }
 
 }

app/src/main/kotlin/at/bitfire/davdroid/webdav/WebDavMountRepository.kt

@@ -50,12 +50,13 @@ class WebDavMountRepository @Inject constructor(
         displayName: String,
         credentials: Credentials?
     ): Boolean {
-        if (!hasWebDav(url, credentials))
+        val webdavUrl = hasWebDav(url, credentials)
+        if (webdavUrl == null)
             return false
 
         // create in database
         val mount = WebDavMount(
-            url = url,
+            url = webdavUrl,
             name = displayName
         )
         val id = db.webDavMountDao().insert(mount)
@@ -65,7 +66,7 @@ class WebDavMountRepository @Inject constructor(
         credentialsStore.setCredentials(id, credentials)
 
         // notify content URI listeners
-        DavDocumentsProvider.notifyMountsChanged(context)
+        DocumentProviderUtils.notifyMountsChanged(context)
 
         return true
     }
@@ -78,7 +79,7 @@ class WebDavMountRepository @Inject constructor(
         CredentialsStore(context).setCredentials(mount.id, null)
 
         // notify content URI listeners
-        DavDocumentsProvider.notifyMountsChanged(context)
+        DocumentProviderUtils.notifyMountsChanged(context)
     }
 
     fun getAllFlow() = mountDao.getAllFlow()
@@ -110,11 +111,19 @@ class WebDavMountRepository @Inject constructor(
 
     // helpers
 
+    /**
+     * Checks whether WebDAV is supported at given URL with given credentials
+     * and returns the resulting if following a few redirects.
+     *
+     * @param url The URL to check
+     * @param credentials The credentials to use for the request
+     * @return The URL at which WebDAV support was found
+     */
     @VisibleForTesting
     internal suspend fun hasWebDav(
         url: HttpUrl,
         credentials: Credentials?
-    ): Boolean = withContext(ioDispatcher) {
+    ): HttpUrl? = withContext(ioDispatcher) {
         val validVersions = arrayOf("1", "2", "3")
 
         val builder = httpClientBuilder.get()
@@ -125,18 +134,18 @@ class WebDavMountRepository @Inject constructor(
                 getCredentials = { credentials }
             )
 
-        var supported = false
+        var webdavUrl: HttpUrl? = null
         builder.build().use { httpClient ->
             val dav = DavResource(httpClient.okHttpClient, url)
             runInterruptible {
-                dav.options { davCapabilities, _ ->
+                dav.options(followRedirects = true) { davCapabilities, response ->
                     if (davCapabilities.any { it in validVersions })
-                        supported = true
+                        webdavUrl = dav.location
                 }
             }
         }
 
-        supported
+        webdavUrl
     }
 
 }

app/src/main/kotlin/at/bitfire/davdroid/webdav/WebdavScope.kt

@@ -1,22 +0,0 @@
-/*
- * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
- */
-
-package at.bitfire.davdroid.webdav
-
-import dagger.hilt.DefineComponent
-import dagger.hilt.components.SingletonComponent
-import javax.inject.Scope
-
-@Scope
-@Retention(AnnotationRetention.BINARY)
-annotation class WebdavScoped
-
-@WebdavScoped
-@DefineComponent(parent = SingletonComponent::class)
-interface WebdavComponent
-
-@DefineComponent.Builder
-interface WebdavComponentBuilder {
-    fun build(): WebdavComponent
-}

app/src/main/kotlin/at/bitfire/davdroid/webdav/cache/ThumbnailCache.kt

@@ -11,7 +11,6 @@ import android.os.storage.StorageManager
 import android.text.format.Formatter
 import androidx.core.content.getSystemService
 import at.bitfire.davdroid.db.WebDavDocument
-import at.bitfire.davdroid.webdav.WebdavScoped
 import com.google.common.hash.Hashing
 import dagger.hilt.android.qualifiers.ApplicationContext
 import java.io.File
@@ -21,7 +20,6 @@ import javax.inject.Inject
 /**
  * Simple disk cache for image thumbnails.
  */
-@WebdavScoped
 class ThumbnailCache @Inject constructor(
     @ApplicationContext context: Context,
     logger: Logger

app/src/main/kotlin/at/bitfire/davdroid/webdav/operation/CopyDocumentOperation.kt

@@ -0,0 +1,77 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav.operation
+
+import android.content.Context
+import at.bitfire.dav4jvm.DavResource
+import at.bitfire.dav4jvm.exception.HttpException
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.db.WebDavDocument
+import at.bitfire.davdroid.di.IoDispatcher
+import at.bitfire.davdroid.webdav.DavHttpClientBuilder
+import at.bitfire.davdroid.webdav.DocumentProviderUtils
+import at.bitfire.davdroid.webdav.throwForDocumentProvider
+import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.runInterruptible
+import java.io.FileNotFoundException
+import java.util.logging.Logger
+import javax.inject.Inject
+
+class CopyDocumentOperation @Inject constructor(
+    @ApplicationContext private val context: Context,
+    private val db: AppDatabase,
+    private val httpClientBuilder: DavHttpClientBuilder,
+    @IoDispatcher private val ioDispatcher: CoroutineDispatcher,
+    private val logger: Logger
+) {
+
+    private val documentDao = db.webDavDocumentDao()
+
+    operator fun invoke(sourceDocumentId: String, targetParentDocumentId: String): String = runBlocking {
+        logger.fine("WebDAV copyDocument $sourceDocumentId $targetParentDocumentId")
+        val srcDoc = documentDao.get(sourceDocumentId.toLong()) ?: throw FileNotFoundException()
+        val dstFolder = documentDao.get(targetParentDocumentId.toLong()) ?: throw FileNotFoundException()
+        val name = srcDoc.name
+
+        if (srcDoc.mountId != dstFolder.mountId)
+            throw UnsupportedOperationException("Can't COPY between WebDAV servers")
+
+        httpClientBuilder.build(srcDoc.mountId).use { client ->
+            val dav = DavResource(client.okHttpClient, srcDoc.toHttpUrl(db))
+            val dstUrl = dstFolder.toHttpUrl(db).newBuilder()
+                .addPathSegment(name)
+                .build()
+
+            try {
+                runInterruptible(ioDispatcher) {
+                    dav.copy(dstUrl, false) {
+                        // successfully copied
+                    }
+                }
+            } catch (e: HttpException) {
+                e.throwForDocumentProvider(context)
+            }
+
+            val dstDocId = documentDao.insertOrReplace(
+                WebDavDocument(
+                    mountId = dstFolder.mountId,
+                    parentId = dstFolder.id,
+                    name = name,
+                    isDirectory = srcDoc.isDirectory,
+                    displayName = srcDoc.displayName,
+                    mimeType = srcDoc.mimeType,
+                    size = srcDoc.size
+                )
+            ).toString()
+
+            DocumentProviderUtils.notifyFolderChanged(context, targetParentDocumentId)
+
+            /* return */ dstDocId
+        }
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/webdav/operation/CreateDocumentOperation.kt

@@ -0,0 +1,89 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav.operation
+
+import android.content.Context
+import android.provider.DocumentsContract.Document
+import at.bitfire.dav4jvm.DavResource
+import at.bitfire.dav4jvm.exception.HttpException
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.db.WebDavDocument
+import at.bitfire.davdroid.di.IoDispatcher
+import at.bitfire.davdroid.webdav.DavHttpClientBuilder
+import at.bitfire.davdroid.webdav.DocumentProviderUtils
+import at.bitfire.davdroid.webdav.DocumentProviderUtils.displayNameToMemberName
+import at.bitfire.davdroid.webdav.throwForDocumentProvider
+import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.runInterruptible
+import okhttp3.MediaType.Companion.toMediaTypeOrNull
+import okhttp3.RequestBody
+import java.io.FileNotFoundException
+import java.util.logging.Logger
+import javax.inject.Inject
+
+class CreateDocumentOperation @Inject constructor(
+    @ApplicationContext private val context: Context,
+    private val db: AppDatabase,
+    private val httpClientBuilder: DavHttpClientBuilder,
+    @IoDispatcher private val ioDispatcher: CoroutineDispatcher,
+    private val logger: Logger
+) {
+
+    private val documentDao = db.webDavDocumentDao()
+
+    operator fun invoke(parentDocumentId: String, mimeType: String, displayName: String): String? = runBlocking {
+        logger.fine("WebDAV createDocument $parentDocumentId $mimeType $displayName")
+        val parent = documentDao.get(parentDocumentId.toLong()) ?: throw FileNotFoundException()
+        val createDirectory = mimeType == Document.MIME_TYPE_DIR
+
+        var docId: Long?
+        httpClientBuilder.build(parent.mountId).use { client ->
+            for (attempt in 0..DocumentProviderUtils.MAX_DISPLAYNAME_TO_MEMBERNAME_ATTEMPTS) {
+                val newName = displayNameToMemberName(displayName, attempt)
+                val parentUrl = parent.toHttpUrl(db)
+                val newLocation = parentUrl.newBuilder()
+                    .addPathSegment(newName)
+                    .build()
+                val doc = DavResource(client.okHttpClient, newLocation)
+                try {
+                    runInterruptible(ioDispatcher) {
+                        if (createDirectory)
+                            doc.mkCol(null) {
+                                // directory successfully created
+                            }
+                        else
+                            doc.put(RequestBody.EMPTY, ifNoneMatch = true) {
+                                // document successfully created
+                            }
+                    }
+
+                    docId = documentDao.insertOrReplace(
+                        WebDavDocument(
+                            mountId = parent.mountId,
+                            parentId = parent.id,
+                            name = newName,
+                            isDirectory = createDirectory,
+                            mimeType = mimeType.toMediaTypeOrNull(),
+                            eTag = null,
+                            lastModified = null,
+                            size = if (createDirectory) null else 0
+                        )
+                    )
+
+                    DocumentProviderUtils.notifyFolderChanged(context, parentDocumentId)
+
+                    return@runBlocking docId.toString()
+                } catch (e: HttpException) {
+                    e.throwForDocumentProvider(context, ignorePreconditionFailed = true)
+                }
+            }
+        }
+
+        null
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/webdav/operation/DeleteDocumentOperation.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav.operation
+
+import android.content.Context
+import at.bitfire.dav4jvm.DavResource
+import at.bitfire.dav4jvm.exception.HttpException
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.di.IoDispatcher
+import at.bitfire.davdroid.webdav.DavHttpClientBuilder
+import at.bitfire.davdroid.webdav.DocumentProviderUtils
+import at.bitfire.davdroid.webdav.throwForDocumentProvider
+import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.runInterruptible
+import java.io.FileNotFoundException
+import java.util.logging.Logger
+import javax.inject.Inject
+
+class DeleteDocumentOperation @Inject constructor(
+    @ApplicationContext private val context: Context,
+    private val db: AppDatabase,
+    private val httpClientBuilder: DavHttpClientBuilder,
+    @IoDispatcher private val ioDispatcher: CoroutineDispatcher,
+    private val logger: Logger
+) {
+
+    private val documentDao = db.webDavDocumentDao()
+
+    operator fun invoke(documentId: String) = runBlocking {
+        logger.fine("WebDAV removeDocument $documentId")
+        val doc = documentDao.get(documentId.toLong()) ?: throw FileNotFoundException()
+
+        httpClientBuilder.build(doc.mountId).use { client ->
+            val dav = DavResource(client.okHttpClient, doc.toHttpUrl(db))
+            try {
+                runInterruptible(ioDispatcher) {
+                    dav.delete {
+                        // successfully deleted
+                    }
+                }
+                logger.fine("Successfully removed")
+                documentDao.delete(doc)
+
+                DocumentProviderUtils.notifyFolderChanged(context, doc.parentId)
+            } catch (e: HttpException) {
+                e.throwForDocumentProvider(context)
+            }
+        }
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/webdav/operation/IsChildDocumentOperation.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav.operation
+
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.db.WebDavDocument
+import java.io.FileNotFoundException
+import java.util.logging.Logger
+import javax.inject.Inject
+
+class IsChildDocumentOperation @Inject constructor(
+    db: AppDatabase,
+    private val logger: Logger
+) {
+
+    private val documentDao = db.webDavDocumentDao()
+
+    operator fun invoke(parentDocumentId: String, documentId: String): Boolean {
+        logger.fine("WebDAV isChildDocument $parentDocumentId $documentId")
+        val parent = documentDao.get(parentDocumentId.toLong()) ?: throw FileNotFoundException()
+
+        var iter: WebDavDocument? = documentDao.get(documentId.toLong()) ?: throw FileNotFoundException()
+        while (iter != null) {
+            val currentParentId = iter.parentId
+            if (currentParentId == parent.id)
+                return true
+
+            iter = if (currentParentId != null)
+                documentDao.get(currentParentId)
+            else
+                null
+        }
+        return false
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/webdav/operation/MoveDocumentOperation.kt

@@ -0,0 +1,66 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav.operation
+
+import android.content.Context
+import at.bitfire.dav4jvm.DavResource
+import at.bitfire.dav4jvm.exception.HttpException
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.di.IoDispatcher
+import at.bitfire.davdroid.webdav.DavHttpClientBuilder
+import at.bitfire.davdroid.webdav.DocumentProviderUtils
+import at.bitfire.davdroid.webdav.throwForDocumentProvider
+import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.runInterruptible
+import java.io.FileNotFoundException
+import java.util.logging.Logger
+import javax.inject.Inject
+
+class MoveDocumentOperation @Inject constructor(
+    @ApplicationContext private val context: Context,
+    private val db: AppDatabase,
+    private val httpClientBuilder: DavHttpClientBuilder,
+    @IoDispatcher private val ioDispatcher: CoroutineDispatcher,
+    private val logger: Logger
+) {
+
+    private val documentDao = db.webDavDocumentDao()
+
+    operator fun invoke(sourceDocumentId: String, sourceParentDocumentId: String, targetParentDocumentId: String): String = runBlocking {
+        logger.fine("WebDAV moveDocument $sourceDocumentId $sourceParentDocumentId $targetParentDocumentId")
+        val doc = documentDao.get(sourceDocumentId.toLong()) ?: throw FileNotFoundException()
+        val dstParent = documentDao.get(targetParentDocumentId.toLong()) ?: throw FileNotFoundException()
+
+        if (doc.mountId != dstParent.mountId)
+            throw UnsupportedOperationException("Can't MOVE between WebDAV servers")
+
+        val newLocation = dstParent.toHttpUrl(db).newBuilder()
+            .addPathSegment(doc.name)
+            .build()
+
+        httpClientBuilder.build(doc.mountId).use { client ->
+            val dav = DavResource(client.okHttpClient, doc.toHttpUrl(db))
+            try {
+                runInterruptible(ioDispatcher) {
+                    dav.move(newLocation, false) {
+                        // successfully moved
+                    }
+                }
+
+                documentDao.update(doc.copy(parentId = dstParent.id))
+
+                DocumentProviderUtils.notifyFolderChanged(context, sourceParentDocumentId)
+                DocumentProviderUtils.notifyFolderChanged(context, targetParentDocumentId)
+            } catch (e: HttpException) {
+                e.throwForDocumentProvider(context)
+            }
+        }
+
+        doc.id.toString()
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/webdav/operation/OpenDocumentOperation.kt

@@ -0,0 +1,115 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav.operation
+
+import android.content.Context
+import android.os.Build
+import android.os.CancellationSignal
+import android.os.ParcelFileDescriptor
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.di.IoDispatcher
+import at.bitfire.davdroid.network.HttpClient
+import at.bitfire.davdroid.webdav.DavHttpClientBuilder
+import at.bitfire.davdroid.webdav.DocumentProviderUtils
+import at.bitfire.davdroid.webdav.HeadResponse
+import at.bitfire.davdroid.webdav.RandomAccessCallbackWrapper
+import at.bitfire.davdroid.webdav.StreamingFileDescriptor
+import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.async
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.runInterruptible
+import okhttp3.HttpUrl
+import java.io.FileNotFoundException
+import java.util.logging.Logger
+import javax.inject.Inject
+
+class OpenDocumentOperation @Inject constructor(
+    @ApplicationContext private val context: Context,
+    private val db: AppDatabase,
+    private val httpClientBuilder: DavHttpClientBuilder,
+    @IoDispatcher private val ioDispatcher: CoroutineDispatcher,
+    private val logger: Logger,
+    private val randomAccessCallbackWrapperFactory: RandomAccessCallbackWrapper.Factory,
+    private val streamingFileDescriptorFactory: StreamingFileDescriptor.Factory
+) {
+
+    private val documentDao = db.webDavDocumentDao()
+
+    operator fun invoke(documentId: String, mode: String, signal: CancellationSignal?): ParcelFileDescriptor = runBlocking {
+        logger.fine("WebDAV openDocument $documentId $mode $signal")
+
+        val doc = documentDao.get(documentId.toLong()) ?: throw FileNotFoundException()
+        val url = doc.toHttpUrl(db)
+        val client = httpClientBuilder.build(doc.mountId, logBody = false)
+
+        val readOnlyMode = when (mode) {
+            "r" -> true
+            "w", "wt" -> false
+            else -> throw UnsupportedOperationException("Mode $mode not supported by WebDAV")
+        }
+
+        val accessScope = CoroutineScope(SupervisorJob())
+        signal?.setOnCancelListener {
+            logger.fine("Cancelling WebDAV access to $url")
+            accessScope.cancel()
+        }
+
+        val fileInfo = accessScope.async {
+            headRequest(client, url)
+        }.await()
+        logger.fine("Received file info: $fileInfo")
+
+        // RandomAccessCallback.Wrapper / StreamingFileDescriptor are responsible for closing httpClient
+        return@runBlocking if (
+            androidSupportsRandomAccess &&
+            readOnlyMode &&                     // WebDAV doesn't support random write access (natively)
+            fileInfo.size != null &&            // file descriptor must return a useful value on getFileSize()
+            (fileInfo.eTag != null || fileInfo.lastModified != null) &&     // we need a method to determine when the document changes during access
+            fileInfo.supportsPartial == true    // WebDAV server must advertise random access
+        ) {
+            logger.fine("Creating RandomAccessCallback for $url")
+            val accessor = randomAccessCallbackWrapperFactory.create(client, url, doc.mimeType, fileInfo, accessScope)
+            accessor.fileDescriptor()
+
+        } else {
+            logger.fine("Creating StreamingFileDescriptor for $url")
+            val fd = streamingFileDescriptorFactory.create(client, url, doc.mimeType, accessScope) { transferred, success ->
+                // called when transfer is finished
+                if (!success)
+                    return@create
+
+                val now = System.currentTimeMillis()
+                if (!readOnlyMode /* write access */) {
+                    // write access, update file size
+                    documentDao.update(doc.copy(size = transferred, lastModified = now))
+                }
+
+                DocumentProviderUtils.notifyFolderChanged(context, doc.parentId)
+            }
+
+            if (readOnlyMode)
+                fd.download()
+            else
+                fd.upload()
+        }
+    }
+
+    private suspend fun headRequest(client: HttpClient, url: HttpUrl): HeadResponse = runInterruptible(ioDispatcher) {
+        HeadResponse.fromUrl(client, url)
+    }
+
+
+    companion object {
+
+        /** openProxyFileDescriptor (required for random access) exists since Android 8.0 */
+        val androidSupportsRandomAccess = Build.VERSION.SDK_INT >= 26
+
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/webdav/operation/OpenDocumentThumbnailOperation.kt

@@ -0,0 +1,126 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav.operation
+
+import android.content.Context
+import android.content.res.AssetFileDescriptor
+import android.graphics.Bitmap
+import android.graphics.BitmapFactory
+import android.graphics.Point
+import android.media.ThumbnailUtils
+import android.net.ConnectivityManager
+import android.os.CancellationSignal
+import android.os.ParcelFileDescriptor
+import androidx.core.content.getSystemService
+import at.bitfire.dav4jvm.DavResource
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.di.IoDispatcher
+import at.bitfire.davdroid.webdav.DavHttpClientBuilder
+import at.bitfire.davdroid.webdav.cache.ThumbnailCache
+import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.async
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.runInterruptible
+import kotlinx.coroutines.withTimeout
+import java.io.ByteArrayOutputStream
+import java.io.FileNotFoundException
+import java.util.logging.Level
+import java.util.logging.Logger
+import javax.inject.Inject
+import kotlin.use
+
+class OpenDocumentThumbnailOperation @Inject constructor(
+    @ApplicationContext private val context: Context,
+    private val db: AppDatabase,
+    private val httpClientBuilder: DavHttpClientBuilder,
+    @IoDispatcher private val ioDispatcher: CoroutineDispatcher,
+    private val logger: Logger,
+    private val thumbnailCache: ThumbnailCache
+) {
+
+    private val documentDao = db.webDavDocumentDao()
+
+    operator fun invoke(documentId: String, sizeHint: Point, signal: CancellationSignal?): AssetFileDescriptor? {
+        logger.info("openDocumentThumbnail documentId=$documentId sizeHint=$sizeHint signal=$signal")
+
+        // don't download the large images just to create a thumbnail on metered networks
+        val connectivityManager = context.getSystemService<ConnectivityManager>()!!
+        if (connectivityManager.isActiveNetworkMetered)
+            return null
+
+        if (signal == null) {
+            logger.warning("openDocumentThumbnail without cancellationSignal causes too much problems, please fix calling app")
+            return null
+        }
+        val accessScope = CoroutineScope(SupervisorJob())
+        signal.setOnCancelListener {
+            logger.fine("Cancelling thumbnail generation for $documentId")
+            accessScope.cancel()
+        }
+
+        val doc = documentDao.get(documentId.toLong()) ?: throw FileNotFoundException()
+
+        val docCacheKey = doc.cacheKey()
+        if (docCacheKey == null) {
+            logger.warning("openDocumentThumbnail won't generate thumbnails when document state (ETag/Last-Modified) is unknown")
+            return null
+        }
+
+        val thumbFile = thumbnailCache.get(docCacheKey, sizeHint) {
+            // create thumbnail
+            val job = accessScope.async {
+                withTimeout(THUMBNAIL_TIMEOUT_MS) {
+                    httpClientBuilder.build(doc.mountId, logBody = false).use { client ->
+                        val url = doc.toHttpUrl(db)
+                        val dav = DavResource(client.okHttpClient, url)
+                        var result: ByteArray? = null
+                        runInterruptible(ioDispatcher) {
+                            dav.get("image/*", null) { response ->
+                                response.body.byteStream().use { data ->
+                                    BitmapFactory.decodeStream(data)?.let { bitmap ->
+                                        val thumb = ThumbnailUtils.extractThumbnail(bitmap, sizeHint.x, sizeHint.y)
+                                        val baos = ByteArrayOutputStream()
+                                        thumb.compress(Bitmap.CompressFormat.JPEG, 95, baos)
+                                        result = baos.toByteArray()
+                                    }
+                                }
+                            }
+                        }
+                        result
+                    }
+                }
+            }
+
+            try {
+                runBlocking {
+                    job.await()
+                }
+            } catch (e: Exception) {
+                logger.log(Level.WARNING, "Couldn't generate thumbnail", e)
+                null
+            }
+        }
+
+        if (thumbFile != null)
+            return AssetFileDescriptor(
+                ParcelFileDescriptor.open(thumbFile, ParcelFileDescriptor.MODE_READ_ONLY),
+                0, thumbFile.length()
+            )
+
+        return null
+    }
+
+
+    companion object {
+
+        const val THUMBNAIL_TIMEOUT_MS = 15000L
+
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/webdav/operation/QueryChildDocumentsOperation.kt

@@ -0,0 +1,214 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav.operation
+
+import android.content.Context
+import android.provider.DocumentsContract.Document
+import android.provider.DocumentsContract.buildChildDocumentsUri
+import at.bitfire.dav4jvm.DavCollection
+import at.bitfire.dav4jvm.Response
+import at.bitfire.dav4jvm.property.webdav.CurrentUserPrivilegeSet
+import at.bitfire.dav4jvm.property.webdav.DisplayName
+import at.bitfire.dav4jvm.property.webdav.GetContentLength
+import at.bitfire.dav4jvm.property.webdav.GetContentType
+import at.bitfire.dav4jvm.property.webdav.GetETag
+import at.bitfire.dav4jvm.property.webdav.GetLastModified
+import at.bitfire.dav4jvm.property.webdav.QuotaAvailableBytes
+import at.bitfire.dav4jvm.property.webdav.QuotaUsedBytes
+import at.bitfire.dav4jvm.property.webdav.ResourceType
+import at.bitfire.davdroid.R
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.db.WebDavDocument
+import at.bitfire.davdroid.db.WebDavDocumentDao
+import at.bitfire.davdroid.di.IoDispatcher
+import at.bitfire.davdroid.webdav.DavHttpClientBuilder
+import at.bitfire.davdroid.webdav.DocumentSortByMapper
+import at.bitfire.davdroid.webdav.DocumentsCursor
+import dagger.Lazy
+import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.runInterruptible
+import java.io.FileNotFoundException
+import java.util.concurrent.ConcurrentHashMap
+import java.util.logging.Level
+import java.util.logging.Logger
+import javax.inject.Inject
+
+class QueryChildDocumentsOperation @Inject constructor(
+    @ApplicationContext private val context: Context,
+    private val db: AppDatabase,
+    private val documentSortByMapper: Lazy<DocumentSortByMapper>,
+    private val httpClientBuilder: DavHttpClientBuilder,
+    @IoDispatcher private val ioDispatcher: CoroutineDispatcher,
+    private val logger: Logger
+) {
+
+    private val authority = context.getString(R.string.webdav_authority)
+    private val documentDao = db.webDavDocumentDao()
+
+    private val backgroundScope = CoroutineScope(SupervisorJob())
+
+    operator fun invoke(parentDocumentId: String, projection: Array<out String>?, sortOrder: String?) =
+        synchronized(QueryChildDocumentsOperation::class.java) {
+            queryChildDocuments(parentDocumentId, projection, sortOrder)
+        }
+
+    private fun queryChildDocuments(
+        parentDocumentId: String,
+        projection: Array<out String>?,
+        sortOrder: String?
+    ): DocumentsCursor {
+        logger.fine("WebDAV queryChildDocuments $parentDocumentId $projection $sortOrder")
+        val parentId = parentDocumentId.toLong()
+        val parent = documentDao.get(parentId) ?: throw FileNotFoundException()
+
+        val columns = projection ?: arrayOf(
+            Document.COLUMN_DOCUMENT_ID,
+            Document.COLUMN_DISPLAY_NAME,
+            Document.COLUMN_MIME_TYPE,
+            Document.COLUMN_FLAGS,
+            Document.COLUMN_SIZE,
+            Document.COLUMN_LAST_MODIFIED
+        )
+
+        // Register watcher
+        val result = DocumentsCursor(columns)
+        val notificationUri = buildChildDocumentsUri(authority, parentDocumentId)
+        result.setNotificationUri(context.contentResolver, notificationUri)
+
+        // Dispatch worker querying for the children and keep track of it
+        val running = runningQueryChildren.getOrPut(parentId) {
+            backgroundScope.launch {
+                queryChildren(parent)
+                // Once the query is done, set query as finished (not running)
+                runningQueryChildren[parentId] = false
+                // .. and notify - effectively calling this method again
+                context.contentResolver.notifyChange(notificationUri, null)
+            }
+            true
+        }
+
+        if (running)        // worker still running
+            result.loading = true
+        else                // remove worker from list if done
+            runningQueryChildren.remove(parentId)
+
+        // Prepare SORT BY clause
+        val mapper = documentSortByMapper.get()
+        val sqlSortBy = if (sortOrder != null)
+            mapper.mapContentProviderToSql(sortOrder)
+        else
+            WebDavDocumentDao.DEFAULT_ORDER
+
+        // Regardless of whether the worker is done, return the children we already have
+        val children = documentDao.getChildren(parentId, sqlSortBy)
+        for (child in children) {
+            val bundle = child.toBundle(parent)
+            result.addRow(bundle)
+        }
+
+        return result
+    }
+
+    /**
+     * Finds children of given parent [WebDavDocument]. After querying, it
+     * updates existing children, adds new ones or removes deleted ones.
+     *
+     * There must never be more than one running instance per [parent]!
+     *
+     * @param parent    folder to search for children
+     */
+    internal suspend fun queryChildren(parent: WebDavDocument) {
+        val oldChildren = documentDao.getChildren(parent.id).associateBy { it.name }.toMutableMap() // "name" of file/folder must be unique
+        val newChildrenList = hashMapOf<String, WebDavDocument>()
+
+        val parentUrl = parent.toHttpUrl(db)
+        httpClientBuilder.build(parent.mountId).use { client ->
+            val folder = DavCollection(client.okHttpClient, parentUrl)
+
+            try {
+                runInterruptible(ioDispatcher) {
+                    folder.propfind(1, *DAV_FILE_FIELDS) { response, relation ->
+                        logger.fine("$relation $response")
+
+                        val resource: WebDavDocument =
+                            when (relation) {
+                                Response.HrefRelation.SELF ->       // it's about the parent
+                                    parent
+
+                                Response.HrefRelation.MEMBER ->     // it's about a member
+                                    WebDavDocument(mountId = parent.mountId, parentId = parent.id, name = response.hrefName())
+
+                                else -> {
+                                    // we didn't request this; log a warning and ignore it
+                                    logger.warning("Ignoring unexpected $response $relation in $parentUrl")
+                                    return@propfind
+                                }
+                            }
+
+                        val updatedResource = resource.copy(
+                            isDirectory = response[ResourceType::class.java]?.types?.contains(ResourceType.COLLECTION)
+                                ?: resource.isDirectory,
+                            displayName = response[DisplayName::class.java]?.displayName,
+                            mimeType = response[GetContentType::class.java]?.type,
+                            eTag = response[GetETag::class.java]?.takeIf { !it.weak }?.eTag,
+                            lastModified = response[GetLastModified::class.java]?.lastModified?.toEpochMilli(),
+                            size = response[GetContentLength::class.java]?.contentLength,
+                            mayBind = response[CurrentUserPrivilegeSet::class.java]?.mayBind,
+                            mayUnbind = response[CurrentUserPrivilegeSet::class.java]?.mayUnbind,
+                            mayWriteContent = response[CurrentUserPrivilegeSet::class.java]?.mayWriteContent,
+                            quotaAvailable = response[QuotaAvailableBytes::class.java]?.quotaAvailableBytes,
+                            quotaUsed = response[QuotaUsedBytes::class.java]?.quotaUsedBytes,
+                        )
+
+                        if (resource == parent)
+                            documentDao.update(updatedResource)
+                        else {
+                            documentDao.insertOrUpdate(updatedResource)
+                            newChildrenList[resource.name] = updatedResource
+                        }
+
+                        // remove resource from known child nodes, because not found on server
+                        oldChildren.remove(resource.name)
+                    }
+                }
+            } catch (e: Exception) {
+                logger.log(Level.WARNING, "Couldn't query children", e)
+            }
+        }
+
+        // Delete child nodes which were not rediscovered (deleted serverside)
+        for ((_, oldChild) in oldChildren)
+            documentDao.delete(oldChild)
+    }
+
+
+    companion object {
+
+        val DAV_FILE_FIELDS = arrayOf(
+            ResourceType.NAME,
+            CurrentUserPrivilegeSet.NAME,
+            DisplayName.NAME,
+            GetETag.NAME,
+            GetContentType.NAME,
+            GetContentLength.NAME,
+            GetLastModified.NAME,
+            QuotaAvailableBytes.NAME,
+            QuotaUsedBytes.NAME,
+        )
+
+        /** List of currently active [queryChildDocuments] runners.
+         *
+         *  Key: document ID (directory) for which children are listed.
+         *  Value: whether the runner is still running (*true*) or has already finished (*false*).
+         */
+        private val runningQueryChildren = ConcurrentHashMap<Long, Boolean>()
+
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/webdav/operation/QueryDocumentOperation.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav.operation
+
+import android.database.Cursor
+import android.provider.DocumentsContract.Document
+import at.bitfire.davdroid.db.AppDatabase
+import at.bitfire.davdroid.webdav.DocumentsCursor
+import kotlinx.coroutines.runBlocking
+import java.io.FileNotFoundException
+import java.util.logging.Logger
+import javax.inject.Inject
+
+class QueryDocumentOperation @Inject constructor(
+    db: AppDatabase,
+    private val logger: Logger
+) {
+
+    private val documentDao = db.webDavDocumentDao()
+    private val mountDao = db.webDavMountDao()
+
+    operator fun invoke(documentId: String, projection: Array<out String>?): Cursor {
+        logger.fine("WebDAV queryDocument $documentId ${projection?.joinToString("+")}")
+
+        val doc = documentDao.get(documentId.toLong()) ?: throw FileNotFoundException()
+        val parent = doc.parentId?.let { parentId ->
+            documentDao.get(parentId)
+        }
+
+        return DocumentsCursor(projection ?: arrayOf(
+            Document.COLUMN_DOCUMENT_ID,
+            Document.COLUMN_DISPLAY_NAME,
+            Document.COLUMN_MIME_TYPE,
+            Document.COLUMN_FLAGS,
+            Document.COLUMN_SIZE,
+            Document.COLUMN_LAST_MODIFIED,
+            Document.COLUMN_ICON,
+            Document.COLUMN_SUMMARY
+        )).apply {
+            val bundle = doc.toBundle(parent)
+            logger.fine("queryDocument($documentId) = $bundle")
+
+            // override display names of root documents
+            if (parent == null) {
+                val mount = runBlocking { mountDao.getById(doc.mountId) }
+                bundle.putString(Document.COLUMN_DISPLAY_NAME, mount.name)
+            }
+
+            addRow(bundle)
+        }
+    }
+
+}

app/src/main/kotlin/at/bitfire/davdroid/webdav/operation/QueryRootsOperation.kt

@@ -0,0 +1,65 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ */
+
+package at.bitfire.davdroid.webdav.operation
+
+import android.content.Context
+import android.database.Cursor
+import android.database.MatrixCursor
+import android.provider.DocumentsContract.Root
+import at.bitfire.davdroid.R
+import at.bitfire.davdroid.db.AppDatabase
+import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.coroutines.runBlocking
+import java.util.logging.Logger
+import javax.inject.Inject
+
+class QueryRootsOperation @Inject constructor(
+    @ApplicationContext private val context: Context,
+    db: AppDatabase,
+    private val logger: Logger
+) {
+
+    private val documentDao = db.webDavDocumentDao()
+    private val mountDao = db.webDavMountDao()
+
+    operator fun invoke(projection: Array<out String>?): Cursor {
+        logger.fine("WebDAV queryRoots")
+        val roots = MatrixCursor(projection ?: arrayOf(
+            Root.COLUMN_ROOT_ID,
+            Root.COLUMN_ICON,
+            Root.COLUMN_TITLE,
+            Root.COLUMN_FLAGS,
+            Root.COLUMN_DOCUMENT_ID,
+            Root.COLUMN_SUMMARY
+        ))
+
+        runBlocking {
+            for (mount in mountDao.getAll()) {
+                val rootDocument = documentDao.getOrCreateRoot(mount)
+                logger.info("Root ID: $rootDocument")
+
+                roots.newRow().apply {
+                    add(Root.COLUMN_ROOT_ID, mount.id)
+                    add(Root.COLUMN_ICON, R.mipmap.ic_launcher)
+                    add(Root.COLUMN_TITLE, context.getString(R.string.webdav_provider_root_title))
+                    add(Root.COLUMN_DOCUMENT_ID, rootDocument.id.toString())
+                    add(Root.COLUMN_SUMMARY, mount.name)
+                    add(Root.COLUMN_FLAGS, Root.FLAG_SUPPORTS_CREATE or Root.FLAG_SUPPORTS_IS_CHILD)
+
+                    val quotaAvailable = rootDocument.quotaAvailable
+                    if (quotaAvailable != null)
+                        add(Root.COLUMN_AVAILABLE_BYTES, quotaAvailable)
+
+                    val quotaUsed = rootDocument.quotaUsed
+                    if (quotaAvailable != null && quotaUsed != null)
+                        add(Root.COLUMN_CAPACITY_BYTES, quotaAvailable + quotaUsed)
+                }
+            }
+        }
+
+        return roots
+    }
+
+}