feat: collect bondedDevices flow in BTScanModel

app/src/main/java/com/geeksville/mesh/model/BTScanModel.kt

@@ -93,6 +93,10 @@ class BTScanModel @Inject constructor(
     private val context: Context get() = application.applicationContext
 
     init {
+        bluetoothRepository.state.value.bondedDevices.onEach {
+            setupScan() // TODO clean up device list updates
+        }.launchIn(viewModelScope)
+
         debug("BTScanModel created")
     }
 

app/src/main/java/com/geeksville/mesh/repository/bluetooth/BluetoothRepository.kt

@@ -13,7 +13,6 @@ import com.geeksville.mesh.android.hasBluetoothPermission
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.*
 import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
 import javax.inject.Inject
 import javax.inject.Singleton
 
@@ -95,19 +94,13 @@ class BluetoothRepository @Inject constructor(
      * Creates a cold Flow used to obtain the set of bonded devices.
      */
     @SuppressLint("MissingPermission") // Already checked prior to calling
-    private suspend fun createBondedDevicesFlow(adapter: BluetoothAdapter): Flow<Set<BluetoothDevice>>? {
-        return if (adapter.isEnabled) {
-            flow<Set<BluetoothDevice>> {
-                withContext(dispatchers.default) {
-                    while (true) {
-                        emit(adapter.bondedDevices)
-                        delay(REFRESH_DELAY_MS)
-                    }
-                }
-            }.flowOn(dispatchers.default)
-        } else {
-            null
-        }
+    private suspend fun createBondedDevicesFlow(adapter: BluetoothAdapter): Flow<Set<BluetoothDevice>> {
+        return flow<Set<BluetoothDevice>> {
+            while (true) {
+                emit(adapter.bondedDevices ?: emptySet())
+                delay(REFRESH_DELAY_MS)
+            }
+        }.flowOn(dispatchers.default).distinctUntilChanged()
     }
 
     companion object {

app/src/main/java/com/geeksville/mesh/repository/bluetooth/BluetoothState.kt

@@ -2,6 +2,7 @@ package com.geeksville.mesh.repository.bluetooth
 
 import android.bluetooth.BluetoothDevice
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flowOf
 
 /**
  * A snapshot in time of the state of the bluetooth subsystem.
@@ -12,5 +13,5 @@ data class BluetoothState(
     /** If we have adequate permissions and bluetooth is enabled */
     val enabled: Boolean = false,
     /** If enabled, a cold flow of the currently bonded devices */
-    val bondedDevices: Flow<Set<BluetoothDevice>>? = null
+    val bondedDevices: Flow<Set<BluetoothDevice>> = flowOf(emptySet())
 )

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

@@ -290,10 +290,6 @@ class SettingsFragment : ScreenFragment("Settings"), Logging {
         regionAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
         spinner.adapter = regionAdapter
 
-        bluetoothViewModel.enabled.observe(viewLifecycleOwner) { enabled ->
-            if (enabled) scanModel.setupScan()
-        }
-
         model.ownerName.observe(viewLifecycleOwner) { name ->
             binding.usernameEditText.isEnabled = !name.isNullOrEmpty()
             binding.usernameEditText.setText(name)