mobile: Update dependencies and adapt to changes

common/lib/src/playback.dart

@@ -122,10 +122,12 @@ abstract class MusicusPlayback {
   ///
   /// Requires [playlist] to be up to date.
   void updateCurrentTrack(int index) {
-    currentIndex.add(index);
+    if (index != null) {
+      currentIndex.add(index);
 
-    if (playlist.value != null && index >= 0 && index < playlist.value.length) {
+      if (playlist.value != null && index >= 0 && index < playlist.value.length) {
-      currentTrack.add(playlist.value[index]);
+        currentTrack.add(playlist.value[index]);
+      }
     }
   }
 }

database/lib/src/database.drift

@@ -198,3 +198,8 @@ SELECT *
 FROM tracks
 WHERE recording = :id
 ORDER BY "index";
+
+tracksById:
+SELECT *
+FROM tracks
+WHERE id = :id;

mobile/android/app/build.gradle

@@ -26,23 +26,27 @@ apply plugin: 'kotlin-android'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
-    compileSdkVersion 29
+    compileSdkVersion flutter.compileSdkVersion
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
 
     sourceSets {
         main.java.srcDirs += 'src/main/kotlin'
     }
 
-    lintOptions {
-        disable 'InvalidPackage'
-    }
-
     defaultConfig {
         applicationId "de.johrpan.musicus"
-        minSdkVersion 21
+        minSdkVersion flutter.minSdkVersion
-        targetSdkVersion 29
+        targetSdkVersion flutter.targetSdkVersion
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName
-        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
     buildTypes {
@@ -50,8 +54,6 @@ android {
             // TODO: Add your own signing config for the release build.
             // Signing with the debug keys for now, so `flutter run --release` works.
             signingConfig signingConfigs.debug
-            // See https://github.com/ryanheise/audio_service/blob/master/README.md#android-setup
-            shrinkResources false
         }
     }
 }
@@ -62,7 +64,4 @@ flutter {
 
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
-    testImplementation 'junit:junit:4.12'
-    androidTestImplementation 'androidx.test:runner:1.1.1'
-    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
 }

mobile/android/app/src/main/AndroidManifest.xml

@@ -1,18 +1,24 @@
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+<manifest
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
     package="de.johrpan.musicus">
 
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.WAKE_LOCK" />
 
+    <!-- TODO: Actually manage obtaining this permission -->
+    <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />
+
     <application
-        android:name="io.flutter.app.FlutterApplication"
+        android:name="${applicationName}"
         android:label="Musicus"
         android:icon="@mipmap/ic_launcher"
         android:roundIcon="@mipmap/ic_launcher_round">
 
         <activity
             android:name=".MainActivity"
+            android:exported="true"
             android:launchMode="singleTop"
             android:theme="@style/LaunchTheme"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
@@ -25,13 +31,21 @@
             </intent-filter>
         </activity>
 
-        <service android:name="com.ryanheise.audioservice.AudioService">
+        <service
+            android:name="com.ryanheise.audioservice.AudioService"
+            android:exported="true"
+            tools:ignore="Instantiatable">
+
             <intent-filter>
-               <action android:name="android.media.browse.MediaBrowserService" />
+                <action android:name="android.media.browse.MediaBrowserService" />
             </intent-filter>
         </service>
 
-        <receiver android:name="androidx.media.session.MediaButtonReceiver" >
+        <receiver
+            android:name="com.ryanheise.audioservice.MediaButtonReceiver"
+            android:exported="true"
+            tools:ignore="Instantiatable">
+        
             <intent-filter>
                <action android:name="android.intent.action.MEDIA_BUTTON" />
             </intent-filter>

mobile/android/app/src/main/kotlin/de/johrpan/musicus/MainActivity.kt

@@ -1,240 +1,12 @@
 package de.johrpan.musicus
 
-import android.app.Activity
+import android.content.Context
-import android.content.Intent
+import com.ryanheise.audioservice.AudioServicePlugin
-import android.net.Uri
-import android.provider.DocumentsContract
-import androidx.annotation.NonNull
 import io.flutter.embedding.android.FlutterActivity
 import io.flutter.embedding.engine.FlutterEngine
-import io.flutter.plugin.common.MethodChannel
-import io.flutter.plugins.GeneratedPluginRegistrant
-
-class Document(private val id: String, private val name: String, private val parentId: String?, private val isDirectory: Boolean) {
-    fun toMap(): Map<String, Any?> {
-        return mapOf(
-                "id" to id,
-                "name" to name,
-                "parentId" to parentId,
-                "isDirectory" to isDirectory
-        )
-    }
-}
 
 class MainActivity : FlutterActivity() {
-    private val CHANNEL = "de.johrpan.musicus/platform"
+    override fun provideFlutterEngine(context: Context): FlutterEngine {
-    private val AODT_REQUEST = 0
+        return AudioServicePlugin.getFlutterEngine(context);
-
-    private var aodtResult: MethodChannel.Result? = null
-
-    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
-        GeneratedPluginRegistrant.registerWith(flutterEngine)
-
-        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL).setMethodCallHandler { call, result ->
-            if (call.method == "openTree") {
-                aodtResult = result
-                // We will get the result within onActivityResult
-                openTree()
-            } else if (call.method == "getChildren") {
-                val treeUri = Uri.parse(call.argument<String>("treeUri"))
-                val parentId = call.argument<String>("parentId")
-                val children = getChildren(treeUri, parentId)
-                result.success(children.map { it.toMap() })
-            } else if (call.method == "readFile") {
-                val treeUri = Uri.parse(call.argument<String>("treeUri"))
-                val id = call.argument<String>("id")!!
-                result.success(readFile(treeUri, id))
-            } else if (call.method == "getUriByName") {
-                val treeUri = Uri.parse(call.argument<String>("treeUri"))
-                val parentId = call.argument<String>("parentId")!!
-                val fileName = call.argument<String>("fileName")!!
-                result.success(getUriByName(treeUri, parentId, fileName).toString())
-            } else if (call.method == "readFileByName") {
-                val treeUri = Uri.parse(call.argument<String>("treeUri"))
-                val parentId = call.argument<String>("parentId")!!
-                val fileName = call.argument<String>("fileName")!!
-                result.success(readFileByName(treeUri, parentId, fileName))
-            } else if (call.method == "writeFileByName") {
-                val treeUri = Uri.parse(call.argument<String>("treeUri"))
-                val parentId = call.argument<String>("parentId")!!
-                val fileName = call.argument<String>("fileName")!!
-                val content = call.argument<String>("content")!!
-                writeFileByName(treeUri, parentId, fileName, content)
-                result.success(null)
-            } else {
-                result.notImplemented()
-            }
-        }
-    }
-
-    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
-        super.onActivityResult(requestCode, resultCode, data)
-
-        if (requestCode == AODT_REQUEST) {
-            if (resultCode == Activity.RESULT_OK && data?.data != null) {
-                // Drop all old URIs
-                contentResolver.persistedUriPermissions.forEach {
-                    contentResolver.releasePersistableUriPermission(it.uri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
-                }
-
-                // We already checked for null
-                val uri = data.data!!
-                contentResolver.takePersistableUriPermission(uri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
-
-                aodtResult?.success(uri.toString())
-            } else {
-                aodtResult?.success(null)
-            }
-        }
-    }
-
-    /**
-     * Open a document tree using the storage access framework
-     *
-     * The result is handled within [onActivityResult]
-     */
-    private fun openTree() {
-        val intent = Intent(Intent.ACTION_OPEN_DOCUMENT_TREE)
-        intent.addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
-        intent.addFlags(Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION)
-
-        startActivityForResult(intent, AODT_REQUEST)
-    }
-
-    /**
-     * List children of a directory
-     *
-     * @param treeUri The treeUri from the ACTION_OPEN_DOCUMENT_TREE request
-     * @param parentId Document ID of the parent directory or null for the top level directory
-     * @return List of directories and files within the directory
-     */
-    private fun getChildren(treeUri: Uri, parentId: String?): List<Document> {
-        val realParentId = parentId ?: DocumentsContract.getTreeDocumentId(treeUri)
-        val children = ArrayList<Document>()
-        val childrenUri = DocumentsContract.buildChildDocumentsUriUsingTree(treeUri, realParentId)
-
-        val cursor = contentResolver.query(
-                childrenUri,
-                arrayOf(DocumentsContract.Document.COLUMN_DOCUMENT_ID,
-                        DocumentsContract.Document.COLUMN_DISPLAY_NAME,
-                        DocumentsContract.Document.COLUMN_MIME_TYPE),
-                null, null, null)
-
-        if (cursor != null) {
-            while (cursor.moveToNext()) {
-                val id = cursor.getString(0)
-                val name = cursor.getString(1)
-                val isDirectory = cursor.getString(2) == DocumentsContract.Document.MIME_TYPE_DIR
-
-                // Use parentId here to let the consumer know that we are at the top level.
-                children.add(Document(id, name, parentId, isDirectory))
-            }
-
-            cursor.close()
-        }
-
-        return children
-    }
-
-    /**
-     * Look for a file by name
-     *
-     * @param treeUri The treeUri from the ACTION_OPEN_DOCUMENT_TREE request
-     * @param parentId The directory in which the file is searched for
-     * @param fileName Name of the file
-     * @return The URI of the file or null
-     */
-    private fun getUriByName(treeUri: Uri, parentId: String, fileName: String): Uri? {
-        var uri: Uri? = null
-
-        val childrenUri = DocumentsContract.buildChildDocumentsUriUsingTree(treeUri, parentId)
-        val projection = arrayOf(DocumentsContract.Document.COLUMN_DOCUMENT_ID, DocumentsContract.Document.COLUMN_DISPLAY_NAME)
-        
-        // The file system provider doesn't support a select clause.
-        val cursor = contentResolver.query(childrenUri, projection, null, null, null)
-
-        if (cursor != null) {
-            while (cursor.moveToNext()) {
-                val id = cursor.getString(0)
-                val name = cursor.getString(1)
-
-                if (name == fileName) {
-                    uri = DocumentsContract.buildDocumentUriUsingTree(treeUri, id)
-                    break
-                }
-            }
-
-            cursor.close()
-        }
-
-        return uri
-    }
-
-    /**
-     * Read content of a file
-     *
-     * @param treeUri The URI from ACTION_OPEN_DOCUMENT_TREE
-     * @param id The document ID of the file
-     * @return File content or null
-     */
-    private fun readFile(treeUri: Uri, id: String): String? {
-        val uri = DocumentsContract.buildDocumentUriUsingTree(treeUri, id)
-
-        // TODO: Handle errors.
-        val input = contentResolver.openInputStream(uri)!!
-        val result = input.reader().readText()
-        input.close()
-
-        return result
-    }
-
-    /**
-     * Read content of a file by name
-     *
-     * @param treeUri The URI from ACTION_OPEN_DOCUMENT_TREE
-     * @param parentId Document ID of the parent directory
-     * @param fileName Name of the file
-     * @return File content or null
-     */
-    private fun readFileByName(treeUri: Uri, parentId: String, fileName: String): String? {
-        var uri = getUriByName(treeUri, parentId, fileName)
-
-        return if (uri != null) {
-            // TODO: Handle errors.
-            val input = contentResolver.openInputStream(uri)!!
-            val result = input.reader().readText()
-            input.close()
-
-            return result
-        } else {
-            null
-        }
-    }
-
-    /**
-     * Write to file by name
-     * 
-     * The file will always have the MIME type application/json.
-     *
-     * @param treeUri The URI from ACTION_OPEN_DOCUMENT_TREE
-     * @param parentId Document ID of the parent directory
-     * @param fileName Name of the file
-     * @param content Content to write
-     * @return File content or null
-     */
-    private fun writeFileByName(treeUri: Uri, parentId: String, fileName: String, content: String) {
-        var uri = getUriByName(treeUri, parentId, fileName);
-
-        if (uri == null) {
-            val parentUri = DocumentsContract.buildDocumentUriUsingTree(treeUri, parentId)
-            uri = DocumentsContract.createDocument(contentResolver, parentUri, "application/json", fileName)
-        }
-
-        // TODO: Handle errors.
-        val output = contentResolver.openOutputStream(uri!!)!!;
-        val writer = output.writer()
-        writer.write(content)
-        writer.close()
-        output.close()
     }
 }

mobile/android/app/src/main/res/raw/keep.xml

@@ -0,0 +1,3 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources xmlns:tools="http://schemas.android.com/tools"
+  tools:keep="@drawable/*" />

mobile/android/build.gradle

@@ -1,12 +1,12 @@
 buildscript {
-    ext.kotlin_version = '1.3.50'
+    ext.kotlin_version = '1.6.10'
     repositories {
         google()
-        jcenter()
+        mavenCentral()
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.5.0'
+        classpath 'com.android.tools.build:gradle:7.1.3'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
@@ -14,7 +14,7 @@ buildscript {
 allprojects {
     repositories {
         google()
-        jcenter()
+        mavenCentral()
     }
 }
 

mobile/android/gradle.properties

@@ -1,4 +1,3 @@
 org.gradle.jvmargs=-Xmx1536M
-android.enableR8=true
 android.useAndroidX=true
 android.enableJetifier=true

mobile/android/settings.gradle

@@ -1,15 +1,11 @@
 include ':app'
 
-def flutterProjectRoot = rootProject.projectDir.parentFile.toPath()
+def localPropertiesFile = new File(rootProject.projectDir, "local.properties")
+def properties = new Properties()
 
-def plugins = new Properties()
+assert localPropertiesFile.exists()
-def pluginsFile = new File(flutterProjectRoot.toFile(), '.flutter-plugins')
+localPropertiesFile.withReader("UTF-8") { reader -> properties.load(reader) }
-if (pluginsFile.exists()) {
-    pluginsFile.withReader('UTF-8') { reader -> plugins.load(reader) }
-}
 
-plugins.each { name, path ->
+def flutterSdkPath = properties.getProperty("flutter.sdk")
-    def pluginDirectory = flutterProjectRoot.resolve(path).resolve('android').toFile()
+assert flutterSdkPath != null, "flutter.sdk not set in local.properties"
-    include ":$name"
+apply from: "$flutterSdkPath/packages/flutter_tools/gradle/app_plugin_loader.gradle"
-    project(":$name").projectDir = pluginDirectory
-}

mobile/lib/main.dart

@@ -1,11 +1,9 @@
-import 'package:audio_service/audio_service.dart';
 import 'package:flutter/widgets.dart';
 import 'package:musicus_common/musicus_common.dart';
 import 'package:path/path.dart' as p;
 import 'package:path_provider/path_provider.dart' as pp;
 
 import 'settings.dart';
-import 'platform.dart';
 import 'playback.dart';
 
 Future<void> main() async {
@@ -14,12 +12,11 @@ Future<void> main() async {
   final dir = await pp.getApplicationDocumentsDirectory();
   final dbPath = p.join(dir.path, 'db.sqlite');
 
-  runApp(AudioServiceWidget(
+  runApp(
-    child: MusicusApp(
+    MusicusApp(
       dbPath: dbPath,
       settingsStorage: SettingsStorage(),
-      platform: MusicusAndroidPlatform(),
+      playback: MusicusMobilePlayback(),
-      playback: Playback(),
     ),
-  ));
+  );
 }

mobile/lib/platform.dart

@@ -1,76 +0,0 @@
-import 'package:flutter/services.dart';
-import 'package:musicus_common/musicus_common.dart';
-
-class MusicusAndroidPlatform extends MusicusPlatform {
-  static const _platform = MethodChannel('de.johrpan.musicus/platform');
-
-  @override
-  Future<String> chooseBasePath() async {
-    return await _platform.invokeMethod<String>('openTree');
-  }
-
-  @override
-  Future<List<Document>> getChildren(String parentId) async {
-    final List<Map<dynamic, dynamic>> childrenJson =
-        await _platform.invokeListMethod(
-      'getChildren',
-      {
-        'treeUri': basePath,
-        'parentId': parentId,
-      },
-    );
-
-    return childrenJson
-        .map((childJson) => Document.fromJson(childJson))
-        .toList();
-  }
-
-  @override
-  Future<String> getIdentifier(String parentId, String fileName) async {
-    return await _platform.invokeMethod(
-      'getUriByName',
-      {
-        'treeUri': basePath,
-        'parentId': parentId,
-        'fileName': fileName,
-      },
-    );
-  }
-
-  @override
-  Future<String> readDocument(String id) async {
-    return await _platform.invokeMethod(
-      'readFile',
-      {
-        'treeUri': basePath,
-        'id': id,
-      },
-    );
-  }
-
-  @override
-  Future<String> readDocumentByName(String parentId, String fileName) async {
-    return await _platform.invokeMethod(
-      'readFileByName',
-      {
-        'treeUri': basePath,
-        'parentId': parentId,
-        'fileName': fileName,
-      },
-    );
-  }
-
-  @override
-  Future<void> writeDocumentByName(
-      String parentId, String fileName, String contents) async {
-    await _platform.invokeMethod(
-      'writeFileByName',
-      {
-        'treeUri': basePath,
-        'parentId': parentId,
-        'fileName': fileName,
-        'content': contents,
-      },
-    );
-  }
-}

mobile/lib/playback.dart

@@ -1,535 +1,317 @@
 import 'dart:async';
-import 'dart:convert';
-import 'dart:isolate';
-import 'dart:ui';
 
 import 'package:audio_service/audio_service.dart';
-import 'package:moor/isolate.dart';
-import 'package:musicus_client/musicus_client.dart';
 import 'package:musicus_common/musicus_common.dart';
 import 'package:musicus_player/musicus_player.dart';
+import 'package:path/path.dart' as p;
 
-const _portName = 'playbackService';
+class MusicusMobilePlayback extends MusicusPlayback {
+  AudioHandler audioHandler;
+  MusicusLibrary library;
 
-/// Entrypoint for the playback service.
+  @override
-void _playbackServiceEntrypoint() {
+  Future<void> setup(MusicusLibrary musicusLibrary) async {
-  AudioServiceBackground.run(() => _PlaybackService());
+    library = musicusLibrary;
-}
 
-class Playback extends MusicusPlayback {
+    audioHandler = await AudioService.init(
-  StreamSubscription _playbackServiceStateSubscription;
+      builder: () => MusicusAudioHandler(musicusLibrary),
-
+      config: AudioServiceConfig(
-  /// Start playback service.
+        androidNotificationChannelId: 'de.johrpan.musicus.channel.audio',
-  Future<void> _start() async {
-    if (!AudioService.running) {
-      await AudioService.start(
-        backgroundTaskEntrypoint: _playbackServiceEntrypoint,
         androidNotificationChannelName: 'Musicus playback',
         androidNotificationChannelDescription:
             'Keeps Musicus playing in the background',
         androidNotificationIcon: 'drawable/ic_notification',
-      );
+      ),
+    );
 
-      active.add(true);
+    listen();
-    }
   }
 
-  @override
+  Future<void> listen() async {
-  Future<void> setup() async {
+    audioHandler.customEvent.listen((event) {
-    if (_playbackServiceStateSubscription != null) {
+      if (event != null && event is PlaylistEvent) {
-      _playbackServiceStateSubscription.cancel();
+        playlist.add(event.playlist);
-    }
-
-    // We will receive updated state information from the playback service,
-    // which runs in its own isolate, through this port.
-    final receivePort = ReceivePort();
-    receivePort.asBroadcastStream(
-      onListen: (subscription) {
-        _playbackServiceStateSubscription = subscription;
-      },
-    ).listen((msg) {
-      // If state is null, the background audio service has stopped.
-      if (msg == null) {
-        dispose();
-      } else {
-        if (!active.value) {
-          active.add(true);
-        }
-
-        if (msg is _StatusMessage) {
-          playing.add(msg.playing);
-        } else if (msg is _PositionMessage) {
-          updatePosition(msg.positionMs);
-        } else if (msg is _TrackMessage) {
-          updateCurrentTrack(msg.currentTrack);
-          updateDuration(msg.positionMs, msg.durationMs);
-        } else if (msg is _PlaylistMessage) {
-          playlist.add(msg.playlist);
-          updateCurrentTrack(msg.currentTrack);
-          updateDuration(msg.positionMs, msg.durationMs);
-        }
       }
     });
 
-    IsolateNameServer.removePortNameMapping(_portName);
+    audioHandler.playbackState.listen((event) {
-    IsolateNameServer.registerPortWithName(receivePort.sendPort, _portName);
+      if (event != null) {
+        playing.add(event.playing);
+        updatePosition(event.position);
+        updateCurrentTrack(event.queueIndex);
+      }
+    });
 
-    if (AudioService.running) {
+    audioHandler.mediaItem.listen((event) {
-      active.add(true);
+      if (event != null) {
+        updateDuration(event.duration);
+      }
+    });
 
-      // Instruct the background service to send its current state. This will
+    await audioHandler.customAction('sendState');
-      // by handled in the listeners, that were already set in the constructor.
-      AudioService.customAction('sendState');
-    }
   }
 
   @override
-  Future<void> addTracks(List<InternalTrack> tracks) async {
+  Future<void> addTracks(List<String> tracks) async {
-    if (!AudioService.running) {
+    await audioHandler.customAction('addTracks', {'tracks': tracks});
-      await _start();
+    active.add(true);
-    }
-
-    await AudioService.customAction('addTracks', jsonEncode(tracks));
-  }
-
-  @override
-  Future<void> removeTrack(int index) async {
-    if (AudioService.running) {
-      await AudioService.customAction('removeTrack', index);
-    }
   }
 
   @override
   Future<void> playPause() async {
-    if (active.value) {
+    if (playing.value) {
-      if (playing.value) {
+      await audioHandler.pause();
-        await AudioService.pause();
+    } else {
-      } else {
+      await audioHandler.play();
-        await AudioService.play();
-      }
     }
   }
 
+  @override
+  Future<void> removeTrack(int index) async {
+    await audioHandler.customAction('removeTrack', {'index': index});
+  }
+
   @override
   Future<void> seekTo(double pos) async {
-    if (active.value && pos >= 0.0 && pos <= 1.0) {
+    if (pos >= 0.0 && pos <= 1.0) {
-      final durationMs = duration.value.inMilliseconds;
+      final durationMs = audioHandler.mediaItem.value.duration.inMilliseconds;
-      await AudioService.seekTo((pos * durationMs).floor());
+      await audioHandler
-    }
+          .seek(Duration(milliseconds: (pos * durationMs).floor()));
-  }
-
-  @override
-  Future<void> skipToPrevious() async {
-    if (AudioService.running) {
-      await AudioService.skipToPrevious();
-    }
-  }
-
-  @override
-  Future<void> skipToNext() async {
-    if (AudioService.running) {
-      await AudioService.skipToNext();
     }
   }
 
   @override
   Future<void> skipTo(int index) async {
-    if (AudioService.running) {
+    await audioHandler.skipToQueueItem(index);
-      await AudioService.customAction('skipTo', index);
+  }
+
+  @override
+  Future<void> skipToNext() async {
+    await audioHandler.skipToNext();
+  }
+
+  @override
+  Future<void> skipToPrevious() async {
+    await audioHandler.skipToPrevious();
+  }
+}
+
+class MusicusAudioHandler extends BaseAudioHandler {
+  final MusicusLibrary library;
+
+  MusicusPlayer player;
+
+  List<String> playlist = [];
+  int currentTrack = -1;
+  int durationMs = 1000;
+  bool playing = false;
+
+  MusicusAudioHandler(this.library) {
+    player = MusicusPlayer(onComplete: () async {
+      if (currentTrack < playlist.length - 1) {
+        await skipToNext();
+      } else {
+        playing = false;
+        await sendState();
+      }
+    });
+  }
+
+  @override
+  Future<void> play() async {
+    await player.play();
+    playing = true;
+    await sendState();
+    keepSendingPosition();
+  }
+
+  Future<void> pause() async {
+    await player.pause();
+    playing = false;
+    await sendState();
+  }
+
+  Future<void> stop() async {
+    playlist.clear();
+    await player.stop();
+
+    super.stop();
+  }
+
+  Future<void> seek(Duration position) async {
+    await player.seekTo(position.inMilliseconds);
+    await sendState();
+  }
+
+  @override
+  Future<void> skipToPrevious() async {
+    if (currentTrack > 0 && currentTrack < playlist.length) {
+      await skipToQueueItem(currentTrack - 1);
     }
   }
 
   @override
-  void dispose() {
+  Future<void> skipToNext() async {
-    super.dispose();
+    if (currentTrack >= 0 && currentTrack < playlist.length - 1) {
-    _playbackServiceStateSubscription.cancel();
+      await skipToQueueItem(currentTrack + 1);
+    }
   }
-}
 
-/// A message from the playback service to the UI.
+  @override
-abstract class _Message {}
+  Future<void> skipToQueueItem(int index) async {
+    if (index >= 0 && index < playlist.length) {
+      currentTrack = index;
+      final track = await library.db.tracksById(playlist[index]).getSingle();
+      durationMs = await player.setUri(p.join(library.basePath, track.path));
 
-/// Playback status update.
+      await sendState();
-class _StatusMessage extends _Message {
+      await sendMediaItem();
-  /// Whether the player is playing (or paused).
+    }
-  final bool playing;
+  }
 
-  /// Playback position in milliseconds.
+  @override
-  final int positionMs;
+  Future<void> customAction(String name, [Map<String, dynamic> extras]) async {
+    if (name == 'sendState') {
+      await sendPlaylist();
+      await sendMediaItem();
+      await sendState();
+    } else if (name == 'addTracks') {
+      await addTracks(extras['tracks']);
+    } else if (name == 'removeTrack') {
+      await removeTrack(extras['index']);
+    }
+  }
 
-  _StatusMessage({
+  Future<void> addTracks(List<String> tracks) async {
-    this.playing,
+    if (tracks != null && tracks.isNotEmpty) {
-    this.positionMs,
+      final wasEmpty = playlist.isEmpty;
-  });
-}
 
-/// The playback position has changed.
+      playlist.addAll(tracks);
-///
+      await sendPlaylist();
-/// This could be due to seeking or because time progressed.
-class _PositionMessage extends _Message {
-  /// Playback position in milliseconds.
-  final int positionMs;
 
-  _PositionMessage({
+      if (wasEmpty) {
-    this.positionMs,
+        await skipToQueueItem(0);
-  });
+        await play();
-}
-
-/// The current track has changed.
-///
-/// This also notifies about the playback position, as the old position could be
-/// behind the new duration.
-class _TrackMessage extends _Message {
-  /// Index of the new track within the playlist.
-  final int currentTrack;
-
-  /// Duration of the new track in milliseconds.
-  final int durationMs;
-
-  /// Playback position in milliseconds.
-  final int positionMs;
-
-  _TrackMessage({
-    this.currentTrack,
-    this.durationMs,
-    this.positionMs,
-  });
-}
-
-/// The playlist was changed.
-///
-/// This also notifies about the current track, as the old index could be out of
-/// range in the new playlist.
-class _PlaylistMessage extends _Message {
-  /// The new playlist.
-  final List<InternalTrack> playlist;
-
-  /// The current track.
-  final int currentTrack;
-
-  /// Duration of the current track in milliseconds.
-  final int durationMs;
-
-  /// Playback position in milliseconds.
-  final int positionMs;
-
-  _PlaylistMessage({
-    this.playlist,
-    this.currentTrack,
-    this.durationMs,
-    this.positionMs,
-  });
-}
-
-class _PlaybackService extends BackgroundAudioTask {
-  /// The interval between playback position updates in milliseconds.
-  static const positionUpdateInterval = 250;
-
-  static const playControl = MediaControl(
-    androidIcon: 'drawable/ic_play',
-    label: 'Play',
-    action: MediaAction.play,
-  );
-
-  static const pauseControl = MediaControl(
-    androidIcon: 'drawable/ic_pause',
-    label: 'Pause',
-    action: MediaAction.pause,
-  );
-
-  static const stopControl = MediaControl(
-    androidIcon: 'drawable/ic_stop',
-    label: 'Stop',
-    action: MediaAction.stop,
-  );
-
-  final _completer = Completer();
-  final _loading = Completer();
-  final List<InternalTrack> _playlist = [];
-
-  MusicusClientDatabase db;
-  MusicusPlayer _player;
-  int _currentTrack = 0;
-  bool _playing = false;
-  int _durationMs = 1000;
-
-  _PlaybackService() {
-    _player = MusicusPlayer(onComplete: () async {
-      if (_currentTrack < _playlist.length - 1) {
-        await _setCurrentTrack(_currentTrack + 1);
-        _sendTrack();
       } else {
-        _playing = false;
+        await sendState();
-        _sendStatus();
-        _setState();
       }
-    });
+    }
-
-    _load();
   }
 
-  /// Initialize database.
+  Future<void> removeTrack(int index) async {
-  Future<void> _load() async {
+    if (index >= 0 && index < playlist.length) {
-    final moorPort = IsolateNameServer.lookupPortByName('moor');
+      playlist.removeAt(index);
-    final moorIsolate = MoorIsolate.fromConnectPort(moorPort);
+
-    db = MusicusClientDatabase.connect(connection: await moorIsolate.connect());
+      if (playlist.isNotEmpty) {
-    _loading.complete();
+        if (currentTrack == index) {
+          await skipToQueueItem(index);
+        } else if (currentTrack > index) {
+          currentTrack--;
+        }
+      }
+
+      await sendPlaylist();
+      await sendState();
+    }
   }
 
-  /// Update the audio service status for the system.
+  Future<void> sendPlaylist() async {
-  Future<void> _setState() async {
+    customEvent.add(PlaylistEvent(playlist));
-    final positionMs = await _player.getPosition() ?? 0;
+  }
-    final updateTime = DateTime.now().millisecondsSinceEpoch;
 
-    AudioServiceBackground.setState(
+  Future<void> sendState() async {
-      controls:
+    List<MediaControl> controls = [];
-          _playing ? [pauseControl, stopControl] : [playControl, stopControl],
+    Set<MediaAction> actions = {};
-      basicState:
-          _playing ? BasicPlaybackState.playing : BasicPlaybackState.paused,
-      position: positionMs,
-      updateTime: updateTime,
-    );
 
-    if (_playlist.isNotEmpty) {
+    if (playlist.isNotEmpty) {
-      await _loading.future;
+      if (currentTrack < 0 || currentTrack >= playlist.length) {
+        currentTrack = 0;
+      }
 
-      final track = _playlist[_currentTrack];
+      if (currentTrack > 0) {
-      final recordingInfo = await db.getRecording(track.track.recordingId);
+        controls.add(MediaControl.skipToPrevious);
-      final workInfo = await db.getWork(recordingInfo.recording.work);
+      }
 
-      final title = workInfo.composers
+      if (playing) {
-          .map((p) => '${p.firstName} ${p.lastName}')
+        controls.add(MediaControl.pause);
-          .join(', ');
+      } else {
+        controls.add(MediaControl.play);
+      }
 
-      final subtitleBuffer = StringBuffer(workInfo.work.title);
+      if (currentTrack < playlist.length - 1) {
+        controls.add(MediaControl.skipToNext);
+      }
 
-      final partIds = track.track.partIds;
+      actions.add(MediaAction.seek);
-      if (partIds.isNotEmpty) {
+    } else {
-        subtitleBuffer.write(': ');
+      currentTrack = -1;
+    }
 
-        final section = workInfo.sections.lastWhere(
+    playbackState.add(PlaybackState(
-          (s) => s.beforePartIndex <= partIds[0],
+      processingState: AudioProcessingState.ready,
-          orElse: () => null,
+      playing: playing,
-        );
+      controls: controls,
+      systemActions: actions,
+      updatePosition: Duration(milliseconds: await player.getPosition()),
+      queueIndex: currentTrack,
+    ));
+  }
 
-        if (section != null) {
+  Future<void> sendMediaItem() async {
-          subtitleBuffer.write(section.title);
+    if (currentTrack >= 0 && currentTrack < playlist.length) {
+      final track =
+          await library.db.tracksById(playlist[currentTrack]).getSingle();
+
+      final recording =
+          await library.db.recordingById(track.recording).getSingle();
+
+      final workInfo = await library.db.getWork(recording.work);
+
+      final partIds = track.workParts
+          .split(',')
+          .where((p) => p.isNotEmpty)
+          .map((p) => int.parse(p))
+          .toList();
+
+      String title;
+      String subtitle;
+
+      if (workInfo != null) {
+        title = '${workInfo.composer.firstName} ${workInfo.composer.lastName}';
+
+        final subtitleBuffer = StringBuffer(workInfo.work.title);
+
+        if (partIds.isNotEmpty) {
           subtitleBuffer.write(': ');
+          subtitleBuffer
+              .write(partIds.map((i) => workInfo.parts[i].title).join(', '));
         }
 
-        subtitleBuffer
+        subtitle = subtitleBuffer.toString();
-            .write(partIds.map((i) => workInfo.parts[i].part.title).join(', '));
+      } else {
+        title = '...';
+        subtitle = '...';
       }
 
-      final subtitle = subtitleBuffer.toString();
+      mediaItem.add(MediaItem(
-
+        id: track.id,
-      AudioServiceBackground.setMediaItem(MediaItem(
+        title: subtitle,
-        id: track.identifier,
+        album: title,
-        album: subtitle,
+        duration: Duration(milliseconds: durationMs),
-        title: title,
-        displayTitle: title,
-        displaySubtitle: subtitle,
       ));
     }
   }
 
-  /// Send a message to the UI.
-  void _sendMsg(_Message msg) {
-    final sendPort = IsolateNameServer.lookupPortByName(_portName);
-    sendPort?.send(msg);
-  }
-
-  /// Notify the UI about the current playback status.
-  Future<void> _sendStatus() async {
-    _sendMsg(_StatusMessage(
-      playing: _playing,
-      positionMs: await _player.getPosition(),
-    ));
-  }
-
-  /// Notify the UI about the current playback position.
-  Future<void> _sendPosition() async {
-    _sendMsg(_PositionMessage(
-      positionMs: await _player.getPosition(),
-    ));
-  }
-
-  /// Notify the UI about the current track.
-  Future<void> _sendTrack() async {
-    _sendMsg(_TrackMessage(
-      currentTrack: _currentTrack,
-      durationMs: _durationMs,
-      positionMs: await _player.getPosition(),
-    ));
-  }
-
-  /// Notify the UI about the current playlist.
-  Future<void> _sendPlaylist() async {
-    _sendMsg(_PlaylistMessage(
-      playlist: _playlist,
-      currentTrack: _currentTrack,
-      durationMs: _durationMs,
-      positionMs: await _player.getPosition(),
-    ));
-  }
-
   /// Notify the UI of the new playback position periodically.
-  Future<void> _updatePosition() async {
+  Future<void> keepSendingPosition() async {
-    while (_playing) {
+    while (playing) {
-      _sendPosition();
+      sendState();
-      await Future.delayed(
+      await Future.delayed(const Duration(seconds: 1));
-          const Duration(milliseconds: positionUpdateInterval));
     }
   }
-
+}
-  /// Set the current track, update the player and notify the system.
+
-  Future<void> _setCurrentTrack(int index) async {
+class PlaylistEvent {
-    _currentTrack = index;
+  final List<String> playlist;
-    _durationMs = await _player.setUri(_playlist[_currentTrack].identifier);
+  PlaylistEvent(this.playlist);
-    _setState();
-  }
-
-  /// Add [tracks] to the playlist.
-  Future<void> _addTracks(List<InternalTrack> tracks) async {
-    final play = _playlist.isEmpty;
-
-    _playlist.addAll(tracks);
-    if (play) {
-      await _setCurrentTrack(0);
-    }
-
-    _sendPlaylist();
-  }
-
-  /// Remove the track at [index] from the playlist.
-  ///
-  /// If it was the current track, the next track will be played.
-  Future<void> _removeTrack(int index) async {
-    if (index >= 0 && index < _playlist.length) {
-      _playlist.removeAt(index);
-
-      if (_playlist.isEmpty) {
-        onStop();
-      } else {
-        if (_currentTrack == index) {
-          await _setCurrentTrack(index);
-        } else if (_currentTrack > index) {
-          _currentTrack--;
-        }
-
-        _sendPlaylist();
-      }
-    }
-  }
-
-  /// Jump to the beginning of the track with the index [index].
-  Future<void> _skipTo(int index) async {
-    if (index >= 0 && index < _playlist.length) {
-      await _setCurrentTrack(index);
-      _sendTrack();
-    }
-  }
-
-  @override
-  Future<void> onStart() async {
-    _setState();
-    await _completer.future;
-  }
-
-  @override
-  Future<void> onCustomAction(String name, dynamic arguments) async {
-    super.onCustomAction(name, arguments);
-
-    // addTracks expects a List<Map<String, dynamic>> as its argument.
-    // skipTo and removeTrack expect an integer as their argument.
-    if (name == 'addTracks') {
-      final tracksJson = jsonDecode(arguments);
-      final List<InternalTrack> tracks = List.castFrom(
-          tracksJson.map((j) => InternalTrack.fromJson(j)).toList());
-
-      _addTracks(tracks);
-    } else if (name == 'removeTrack') {
-      final index = arguments as int;
-      _removeTrack(index);
-    } else if (name == 'skipTo') {
-      final index = arguments as int;
-      _skipTo(index);
-    } else if (name == 'sendState') {
-      _sendPlaylist();
-      _sendStatus();
-    }
-  }
-
-  @override
-  void onPlay() {
-    super.onPlay();
-
-    _player.play();
-    _playing = true;
-
-    _sendStatus();
-    _updatePosition();
-    _setState();
-  }
-
-  @override
-  void onPause() {
-    super.onPause();
-
-    _player.pause();
-    _playing = false;
-
-    _sendStatus();
-    _setState();
-  }
-
-  @override
-  Future<void> onSeekTo(int position) async {
-    super.onSeekTo(position);
-
-    await _player.seekTo(position);
-
-    _sendPosition();
-    _setState();
-  }
-
-  @override
-  Future<void> onSkipToNext() async {
-    super.onSkipToNext();
-
-    if (_playlist.length > 1 && _currentTrack < _playlist.length - 1) {
-      await _setCurrentTrack(_currentTrack + 1);
-      _sendTrack();
-    }
-  }
-
-  @override
-  Future<void> onSkipToPrevious() async {
-    super.onSkipToPrevious();
-
-    // If more than five seconds of the current track have been played, go back
-    // to its beginning, else, switch to the previous track.
-    if (await _player.getPosition() > 5000) {
-      await _setCurrentTrack(_currentTrack);
-      _sendTrack();
-    } else if (_playlist.length > 1 && _currentTrack > 0) {
-      await _setCurrentTrack(_currentTrack - 1);
-      _sendTrack();
-    }
-  }
-
-  @override
-  void onStop() {
-    _player.stop();
-
-    AudioServiceBackground.setState(
-      controls: [],
-      basicState: BasicPlaybackState.stopped,
-    );
-
-    _sendMsg(null);
-
-    // This will end onStart.
-    _completer.complete();
-  }
 }

mobile/pubspec.yaml

@@ -1,24 +1,28 @@
 name: musicus
 version: 0.1.0
 description: The classical music player and organizer.
-author: Elias Projahn <johrpan@gmail.com>
 homepage: https://musicus.org
 repository: https://github.com/johrpan/musicus
+publish_to: none
 
 environment:
   sdk: ">=2.3.0 <3.0.0"
 
 dependencies:
-  audio_service:
+  audio_service: ^0.18.4
+  drift: ^1.0.0
   flutter:
     sdk: flutter
   musicus_common:
     path: ../common
+  musicus_database:
+    path: ../database
   musicus_player:
     path: ../player
   path:
   path_provider:
   shared_preferences:
+  sqlite3_flutter_libs: ^0.5.0
 
 flutter:
   uses-material-design: true

player/android/build.gradle

@@ -2,14 +2,14 @@ group 'de.johrpan.musicus_player'
 version '1.0-SNAPSHOT'
 
 buildscript {
-    ext.kotlin_version = '1.3.50'
+    ext.kotlin_version = '1.6.10'
     repositories {
         google()
-        jcenter()
+        mavenCentral()
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.5.0'
+        classpath 'com.android.tools.build:gradle:4.1.0'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
@@ -17,7 +17,7 @@ buildscript {
 rootProject.allprojects {
     repositories {
         google()
-        jcenter()
+        mavenCentral()
     }
 }
 
@@ -25,17 +25,24 @@ apply plugin: 'com.android.library'
 apply plugin: 'kotlin-android'
 
 android {
-    compileSdkVersion 28
+    compileSdkVersion 31
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
 
     sourceSets {
         main.java.srcDirs += 'src/main/kotlin'
     }
+
     defaultConfig {
         minSdkVersion 16
     }
-    lintOptions {
-        disable 'InvalidPackage'
-    }
 }
 
 dependencies {

player/android/gradle.properties

@@ -1,4 +0,0 @@
-org.gradle.jvmargs=-Xmx1536M
-android.enableR8=true
-android.useAndroidX=true
-android.enableJetifier=true