fix: background audio handling

android/app/src/main/kotlin/com/rtirl/chat/MainActivity.kt

@@ -4,10 +4,15 @@ import android.app.NotificationChannel
 import android.app.NotificationManager
 import android.content.Context
 import android.content.Intent
+import android.media.AudioAttributes
+import android.media.AudioFocusRequest
 import android.media.AudioManager
+import android.media.AudioManager.OnAudioFocusChangeListener
 import android.net.Uri
 import android.os.Build
 import android.os.Bundle
+import android.os.Handler
+import android.os.Looper
 import android.provider.Settings
 import android.speech.tts.TextToSpeech
 import android.speech.tts.UtteranceProgressListener
@@ -24,9 +29,14 @@ import io.flutter.plugin.common.MethodChannel.Result
 import java.util.Locale
 import java.util.UUID
 
-class MainActivity : FlutterActivity() {
+class MainActivity : FlutterActivity(), AudioManager.OnAudioFocusChangeListener {
 
     private var sharedData: String = ""
+    private lateinit var audioManager: AudioManager
+    private lateinit var focusRequest: AudioFocusRequest
+    private val handler = Handler(Looper.getMainLooper())
+    private var playbackDelayed = false
+    private var wasDucking = false 
 
     companion object {
         var methodChannel: MethodChannel? = null
@@ -36,6 +46,16 @@ class MainActivity : FlutterActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         handleIntent()
+        audioManager = getSystemService(Context.AUDIO_SERVICE) as AudioManager
+        focusRequest = AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK).run {
+            setAudioAttributes(AudioAttributes.Builder()
+                .setUsage(AudioAttributes.USAGE_ASSISTANCE_ACCESSIBILITY)
+                .setContentType(AudioAttributes.CONTENT_TYPE_SPEECH)
+                .build())
+            setAcceptsDelayedFocusGain(true)
+            setOnAudioFocusChangeListener(this@MainActivity, handler)
+            build()
+        }
     }
 
     private fun startNotificationService() {
@@ -48,17 +68,38 @@ class MainActivity : FlutterActivity() {
         }
     }
 
+    override fun onAudioFocusChange(focusChange: Int) {
+        when (focusChange) {
+            AudioManager.AUDIOFOCUS_GAIN -> {
+                if (wasDucking) {
+                    methodChannel?.invokeMethod("audioVolume", 1.0)
+                    wasDucking = false 
+                }
+
+                if (playbackDelayed) {
+                    playbackDelayed = false
+                } else {
+                    methodChannel?.invokeMethod("audioVolume", 1.0) 
+                }
+            }
+            AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK -> {
+                methodChannel?.invokeMethod("audioVolume", 0.3) 
+                wasDucking = true
+            }
+            AudioManager.AUDIOFOCUS_LOSS, 
+            AudioManager.AUDIOFOCUS_LOSS_TRANSIENT -> { 
+                if (!wasDucking) {
+                    // handle other cases if necessary
+                }
+            }
+        }
+    }
+
     override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
         val ttsPlugin = TextToSpeechPlugin(this)
-        val ttsChannel = MethodChannel(
-            flutterEngine.dartExecutor.binaryMessenger,
-            "ttsPlugin"
-        )
-
-        val notificationChannel = MethodChannel(
-            flutterEngine.dartExecutor.binaryMessenger,
-            "tts_notifications"
-        )
+        val ttsChannel = MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "ttsPlugin")
+        val notificationChannel = MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "tts_notifications")
+        val volumeChannel = MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "volume_channel")
 
         methodChannel = notificationChannel
 
@@ -81,18 +122,36 @@ class MainActivity : FlutterActivity() {
             }
         }
 
+        volumeChannel.setMethodCallHandler { call, result ->
+            when (call.method) {
+                "tts_on" -> {
+                    val res = audioManager.requestAudioFocus(focusRequest)
+                    when (res) {
+                        AudioManager.AUDIOFOCUS_REQUEST_GRANTED -> {
+                            methodChannel?.invokeMethod("audioFocus", "gained")
+                            Log.d("Permission granted", "response granted")
+                        }
+                        AudioManager.AUDIOFOCUS_REQUEST_DELAYED -> {
+                            playbackDelayed = true
+                            methodChannel?.invokeMethod("audioFocus", "delayed")
+                        }
+                        else -> methodChannel?.invokeMethod("audioFocus", "failed")
+                    }
+                }
+                "tts_off" -> {
+                    audioManager.abandonAudioFocusRequest(focusRequest)
+                    methodChannel?.invokeMethod("audioFocus", "lost")
+                }
+                else -> result.notImplemented()
+            }
+        }
+
         ttsChannel.setMethodCallHandler(ttsPlugin)
-        MethodChannel(
-            flutterEngine.dartExecutor.binaryMessenger,
-            "com.rtirl.chat/audio"
-        ).setMethodCallHandler { call, result ->
+        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "com.rtirl.chat/audio").setMethodCallHandler { call, result ->
             when (call.method) {
                 "set" -> {
                     val intent = Intent(this, AudioService::class.java)
-                    intent.putStringArrayListExtra(
-                        "urls",
-                        ArrayList(call.argument<List<String>>("urls") ?: listOf())
-                    )
+                    intent.putStringArrayListExtra("urls", ArrayList(call.argument<List<String>>("urls") ?: listOf()))
                     intent.action = AudioService.ACTION_START_SERVICE
                     startService(intent)
                     result.success(true)
@@ -104,35 +163,19 @@ class MainActivity : FlutterActivity() {
                     result.success(true)
                 }
                 "hasPermission" -> {
-                    result.success(
-                        Build.VERSION.SDK_INT < Build.VERSION_CODES.M ||
-                                Settings.canDrawOverlays(this)
-                    )
+                    result.success(Build.VERSION.SDK_INT < Build.VERSION_CODES.M || Settings.canDrawOverlays(this))
                 }
                 "requestPermission" -> {
-                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M &&
-                        !Settings.canDrawOverlays(this)
-                    ) {
-                        startActivityForResult(
-                            Intent(
-                                Settings.ACTION_MANAGE_OVERLAY_PERMISSION,
-                                Uri.parse("package:$packageName")
-                            ), 8675309
-                        )
+                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && !Settings.canDrawOverlays(this)) {
+                        startActivityForResult(Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse("package:$packageName")), 8675309)
                     }
-                    result.success(
-                        Build.VERSION.SDK_INT < Build.VERSION_CODES.M ||
-                                Settings.canDrawOverlays(this)
-                    )
+                    result.success(Build.VERSION.SDK_INT < Build.VERSION_CODES.M || Settings.canDrawOverlays(this))
                 }
                 else -> result.notImplemented()
             }
         }
 
-        MethodChannel(
-            flutterEngine.dartExecutor.binaryMessenger,
-            "com.rtirl.chat/share"
-        ).setMethodCallHandler { call, result ->
+        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "com.rtirl.chat/share").setMethodCallHandler { call, result ->
             if (call.method == "getSharedData") {
                 result.success(sharedData)
                 sharedData = ""
@@ -143,7 +186,6 @@ class MainActivity : FlutterActivity() {
     }
 
     private fun handleIntent() {
-        // Handle the received text share intent
         if (intent?.action == Intent.ACTION_SEND && intent.type == "text/plain") {
             intent.getStringExtra(Intent.EXTRA_TEXT)?.let { intentData ->
                 sharedData = intentData
@@ -152,7 +194,6 @@ class MainActivity : FlutterActivity() {
     }
 }
 
-
 class TextToSpeechPlugin(private val context: Context) : MethodCallHandler, TextToSpeech.OnInitListener {
     private var tts: TextToSpeech? = null
     private val audioManager: AudioManager = context.getSystemService(Context.AUDIO_SERVICE) as AudioManager
@@ -228,11 +269,7 @@ class TextToSpeechPlugin(private val context: Context) : MethodCallHandler, Text
         tts?.setOnUtteranceProgressListener(object : UtteranceProgressListener() {
             override fun onStart(utteranceId: String) {
                 if (volume != null && Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
-                    audioManager.setStreamVolume(
-                        AudioManager.STREAM_MUSIC,
-                        (audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC) * volume).toInt(),
-                        0
-                    )
+                    audioManager.setStreamVolume(AudioManager.STREAM_MUSIC, (audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC) * volume).toInt(), 0)
                 }
             }
 

lib/models/tts.dart

@@ -16,6 +16,7 @@ import 'package:rtchat/models/messages/twitch/user.dart';
 import 'package:rtchat/models/tts/language.dart';
 import 'package:rtchat/models/tts/bytes_audio_source.dart';
 import 'package:rtchat/models/user.dart';
+import 'package:rtchat/volume_plugin.dart';
 import 'package:flutter_tts/flutter_tts.dart';
 import 'package:flutter_gen/gen_l10n/app_localizations.dart';
 
@@ -173,6 +174,10 @@ class TtsModel extends ChangeNotifier {
     if (value) {
       _lastMessageTime = DateTime.now();
     }
+    if (value) {
+      VolumePlugin.reduceVolumeOnTtsStart();
+    }
+
     say(
         localizations,
         SystemMessageModel(
@@ -384,6 +389,9 @@ class TtsModel extends ChangeNotifier {
         await audioPlayer.setAudioSource(BytesAudioSource(bytes));
         await audioPlayer.play();
         await Future.delayed(audioPlayer.duration ?? const Duration());
+        if (_pending.isEmpty) {
+          VolumePlugin.increaseVolumeOnTtsStop();
+        }
       }
     }
 
@@ -395,10 +403,14 @@ class TtsModel extends ChangeNotifier {
 
   void unsay(String messageId) {
     _pending.remove(messageId);
+    if (_pending.isEmpty) {
+      VolumePlugin.increaseVolumeOnTtsStop();
+    }
   }
 
   void stop() {
     _pending.clear();
+    VolumePlugin.increaseVolumeOnTtsStop();
   }
 
   void updateFromJson(Map<String, dynamic> json) {

lib/screens/home.dart

@@ -27,6 +27,7 @@ import 'package:rtchat/models/tts.dart';
 import 'package:rtchat/models/user.dart';
 import 'package:rtchat/notifications_plugin.dart';
 import 'package:rtchat/tts_plugin.dart';
+import 'package:rtchat/volume_plugin.dart';
 import 'package:wakelock_plus/wakelock_plus.dart';
 
 class ResizableWidget extends StatefulWidget {
@@ -298,6 +299,7 @@ class _HomeScreenState extends State<HomeScreen> with TickerProviderStateMixin {
                                       "Text to speech disabled");
                                   await TextToSpeechPlugin.disableTTS();
                                   NotificationsPlugin.cancelNotification();
+                                  VolumePlugin.reduceVolumeOnTtsStart();
                                 } else {
                                   // Start listening to the stream before toggling newTtsEnabled
                                   channelStreamController.stream
@@ -312,6 +314,7 @@ class _HomeScreenState extends State<HomeScreen> with TickerProviderStateMixin {
                                     "${userModel.activeChannel?.provider}:${userModel.activeChannel?.channelId}",
                                   );
                                   NotificationsPlugin.showNotification();
+                                  VolumePlugin.increaseVolumeOnTtsStop();
                                   NotificationsPlugin.listenToTts(ttsModel);
                                 }
                               }

lib/tts_plugin.dart

@@ -5,6 +5,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:rtchat/main.dart';
 import 'package:rtchat/notifications_plugin.dart';
+import 'package:rtchat/volume_plugin.dart';
 
 class TextToSpeechPlugin {
   static const MethodChannel channel = MethodChannel('ttsPlugin');
@@ -93,6 +94,7 @@ class TTSQueue {
     }
 
     if (queue.isNotEmpty) {
+      VolumePlugin.reduceVolumeOnTtsStart();
       final previous = queue.last;
       queue.addLast(element);
       await previous.completer.future;
@@ -101,10 +103,18 @@ class TTSQueue {
       }
       await TextToSpeechPlugin.speak(text, speed: speed ?? 1.5, volume: volume);
       completer.complete();
+
+      if (isEmpty) {
+        VolumePlugin.increaseVolumeOnTtsStop();
+      }
     } else {
       queue.addLast(element);
       await TextToSpeechPlugin.speak(text, speed: speed ?? 1.5, volume: volume);
       completer.complete();
+
+      if (isEmpty) {
+        VolumePlugin.increaseVolumeOnTtsStop();
+      }
     }
     queue.remove(element);
   }

lib/volume_plugin.dart

@@ -0,0 +1,13 @@
+import 'package:flutter/services.dart';
+
+class VolumePlugin {
+  static const MethodChannel channel = MethodChannel('volume_channel');
+
+  static Future<void> reduceVolumeOnTtsStart() async {
+    await channel.invokeMethod('tts_on');
+  }
+
+  static Future<void> increaseVolumeOnTtsStop() async {
+    await channel.invokeMethod('tts_off');
+  }
+}

test/models/tts_test.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:rtchat/tts_plugin.dart';
+import 'package:rtchat/volume_plugin.dart';
 
 void main() {
   final ttsQueue = TTSQueue();
@@ -16,11 +17,24 @@ void main() {
             (MethodCall method) async {
       return null;
     });
+
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
+        .setMockMethodCallHandler(VolumePlugin.channel,
+            (MethodCall method) async {
+      if (method.method == 'tts_on' || method.method == 'tts_off') {
+        return null; // Mock response for volume channel methods
+      }
+      throw MissingPluginException(
+          'No implementation found for method ${method.method} on channel ${VolumePlugin.channel.name}');
+    });
   });
 
   tearDown(() {
     TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
         .setMockMethodCallHandler(TextToSpeechPlugin.channel, null);
+
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
+        .setMockMethodCallHandler(VolumePlugin.channel, null);
   });
 
   test('Speak adds elements to the queue', () async {