Don't claim we have bluetooth access until the user grants location

permissions.  This fixes an ugly behavior when for when the user does
a from scratch install and first runs the app (and the dialog comes up
to grant access).

Previously we were starting our BLE scan for devices before that dialog
has been approved by the user, which Android doesn't return an error for
it instead just silently refuses to show devices.  If the user switched
away from the app and came back, we'd restart our scan and they could see
their device.

This fixes things so that the user doesn't have to switch away from our
app once before the devices appear.

app/src/main/java/com/geeksville/mesh/MainActivity.kt

@@ -167,10 +167,47 @@ class MainActivity : AppCompatActivity(), Logging,
         }
     }
 
+
     private val btStateReceiver = BluetoothStateReceiver { enabled ->
+        updateBluetoothEnabled()
+    }
+
+
+    /**
+     * Don't tell our app we have bluetooth until we have bluetooth _and_ location access
+     */
+    private fun updateBluetoothEnabled() {
+        var enabled = false // assume failure
+
+        val requiredPerms = listOf(
+            Manifest.permission.ACCESS_FINE_LOCATION,
+            Manifest.permission.BLUETOOTH,
+            Manifest.permission.BLUETOOTH_ADMIN
+        )
+
+
+        if (getMissingPermissions(requiredPerms).isEmpty()) {
+            /// ask the adapter if we have access
+            bluetoothAdapter?.apply {
+                enabled = isEnabled
+            }
+        } else
+            errormsg("Still missing needed bluetooth permissions")
+
+        debug("Detected our bluetooth access=$enabled")
         model.bluetoothEnabled.value = enabled
     }
 
+    /**
+     * return a list of the permissions we don't have
+     */
+    private fun getMissingPermissions(perms: List<String>) = perms.filter {
+        ContextCompat.checkSelfPermission(
+            this,
+            it
+        ) != PackageManager.PERMISSION_GRANTED
+    }
+
     private fun requestPermission() {
         debug("Checking permissions")
 
@@ -194,12 +231,7 @@ class MainActivity : AppCompatActivity(), Logging,
             perms.add(Manifest.permission.REQUEST_COMPANION_USE_DATA_IN_BACKGROUND)
         }
 
-        val missingPerms = perms.filter {
-            ContextCompat.checkSelfPermission(
-                this,
-                it
-            ) != PackageManager.PERMISSION_GRANTED
-        }
+        val missingPerms = getMissingPermissions(perms)
         if (missingPerms.isNotEmpty()) {
             missingPerms.forEach {
                 // Permission is not granted
@@ -255,6 +287,7 @@ class MainActivity : AppCompatActivity(), Logging,
                 Toast.LENGTH_LONG
             ).show()
         }
+        updateBluetoothEnabled()
     }
 
 
@@ -313,9 +346,7 @@ class MainActivity : AppCompatActivity(), Logging,
         model.ownerName.value = prefs.getString("owner", "")!!
 
         /// Set initial bluetooth state
-        bluetoothAdapter?.apply {
-            model.bluetoothEnabled.value = isEnabled
-        }
+        updateBluetoothEnabled()
 
         /// We now want to be informed of bluetooth state
         registerReceiver(btStateReceiver, btStateReceiver.intent)

app/src/main/java/com/geeksville/mesh/ui/SettingsFragment.kt

@@ -518,7 +518,7 @@ class SettingsFragment : ScreenFragment("Settings"), Logging {
 
     override fun onResume() {
         super.onResume()
-        if (!hasCompanionDeviceApi)
+        if (!hasCompanionDeviceApi && model.bluetoothEnabled.value!!)
             scanModel.startScan()
     }
 }