Refactored the bridge to use load the JVM in a separate Isolate that receives messages in a queue executing them, this way it doesn't block the UI thread

lib/aniyomi_bridge.dart

@@ -1,11 +1,15 @@
+import 'dart:async';
 import 'dart:io';
+import 'dart:isolate';
+import 'dart:math';
 import 'package:flutter/services.dart';
 import 'package:jni/jni.dart';
+import 'package:k3vinb5_aniyomi_bridge/jni_isolate.dart';
+import 'package:k3vinb5_aniyomi_bridge/jni_isolate_message.dart';
 import 'package:k3vinb5_aniyomi_bridge/models/extension.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:path/path.dart' as path;
 import 'package:k3vinb5_aniyomi_bridge/jmodels/jvideo.dart';
-import 'package:k3vinb5_aniyomi_bridge/jmodels/janiyomibridge.dart';
 import 'package:k3vinb5_aniyomi_bridge/jmodels/jsanime.dart';
 import 'package:k3vinb5_aniyomi_bridge/jmodels/jsepisode.dart';
 import 'package:k3vinb5_aniyomi_bridge/jmodels/jsmanga.dart';
@@ -13,168 +17,205 @@ import 'package:k3vinb5_aniyomi_bridge/jmodels/jschapter.dart';
 import 'package:k3vinb5_aniyomi_bridge/jmodels/jpage.dart';
 
 class AniyomiBridge {
-  static const String _aniyomiBridgeDir = "aniyomibridge";
+  // static consts
   static const String _aniyomiBridgeAnimeExtensionsDir = "animeExtensions";
   static const String _aniyomiBridgeMangaExtensionsDir = "mangaExtensions";
+  static const String _aniyomiBridgeDir = "aniyomibridge";
   static const String _aniyomiBridgeJarName = "aniyomibridge-core.jar";
   static const String _packageAssetsDir =
       "packages/k3vinb5_aniyomi_bridge/assets";
-  static late final JAniyomiBridge _jAniyomiBridge;
-  static late final String _supportDirectoryPath;
-  bool _isReady = false;
+
+  // static variables
+  static bool _isReady = false;
+  static late final JniIsolate _jniIsolate;
+  static late final ReceivePort _jniReceiverPort;
+  static late final SendPort _jniSenderPort;
+
+  // instance variables
+  late final String _supportDirectoryPath;
+  final Random _random = Random();
+  final Map<int, Completer> _pendingRequests = {};
+
 
   AniyomiBridge() {
     _initJvm();
   }
 
   Future<void> _initJvm() async {
+    if (_isReady) {
+      return;
+    }
     Directory supportDirectory = await getApplicationSupportDirectory();
     _supportDirectoryPath = supportDirectory.path;
     await _loadJarIfNeeded(supportDirectory);
-    Jni.spawnIfNotExists(
-      dylibDir: _getDylibDir(supportDirectory),
-      classPath: _getClassPath(supportDirectory),
+    Jni.setDylibDir(dylibDir: _getDylibDir(supportDirectory));
+
+    _jniIsolate = JniIsolate();
+    final readyPort = ReceivePort();
+    _jniReceiverPort = ReceivePort();
+    (bool, SendPort) response = await _jniIsolate.initJniIsolate(
+      readyPort,
+      _jniReceiverPort,
+      supportDirectory,
+      _getDylibDir(supportDirectory),
+      _getClassPath(supportDirectory),
     );
-    JAniyomiBridge.init();
-    _jAniyomiBridge = JAniyomiBridge();
-    _isReady = true;
+    _isReady = response.$1;
+    _jniSenderPort = response.$2;
+    _jniReceiverPort.listen((message) {
+      if (message is JniIsolateError) {
+        final id = message.id;
+        final completer = _pendingRequests.remove(id);
+        if (completer == null) return;
+        completer.completeError(message.error);
+      } else if (message is JniIsolateResponse) {
+        final id = message.id;
+        final completer = _pendingRequests.remove(id);
+        if (completer == null) return;
+        if (message.results == null) {
+          completer.complete();
+          return;
+        }
+        completer.complete(message.results);
+      }
+    });
   }
 
   bool isReady() {
     return _isReady;
   }
 
-  List<JSAnime> getAnimeSearchResults(String query, int page, String source) {
-    JList<JObject?>? searchResults = _jAniyomiBridge.getAnimeSearchResults(
-      JString.fromString(query),
-      page,
-      JString.fromString(source),
-    );
-    if (searchResults == null) {
-      return [];
-    }
-    return searchResults
-        .cast<JObject?>()
-        .where(_jObjIsNotNull)
-        .map((jObj) => jObj!.as<JSAnime>(JSAnime.type))
-        .toList();
-  }
-
-  List<JSManga> getMangaSearchResults(String query, int page, String source) {
-    JList<JObject?>? searchResults = _jAniyomiBridge.getMangaSearchResults(
-      JString.fromString(query),
-      page,
-      JString.fromString(source),
-    );
-    if (searchResults == null) {
-      return [];
-    }
-    return searchResults
-        .cast<JObject?>()
-        .where(_jObjIsNotNull)
-        .map((jObj) => jObj!.as<JSManga>(JSManga.type))
-        .toList();
-  }
-
-  List<JSEpisode> getEpisodeList(JSAnime sAnime, String source) {
-    JList<JObject?>? episodeList = _jAniyomiBridge.getEpisodeList(
-      sAnime,
-      JString.fromString(source),
-    );
-    if (episodeList == null) {
-      return [];
-    }
-    return episodeList
-        .cast<JObject?>()
-        .where(_jObjIsNotNull)
-        .map((jObj) => jObj!.as<JSEpisode>(JSEpisode.type))
-        .toList();
-  }
-
-  List<JSChapter> getChapterList(JSManga sManga, String source) {
-    JList<JObject?>? episodeList = _jAniyomiBridge.getEpisodeList(
-      sManga,
-      JString.fromString(source),
-    );
-    if (episodeList == null) {
-      return [];
-    }
-    return episodeList
-        .cast<JObject?>()
-        .where(_jObjIsNotNull)
-        .map((jObj) => jObj!.as<JSChapter>(JSChapter.type))
-        .toList();
-  }
-
-  List<JVideo> getVideoList(JSEpisode sEpisode, String source) {
-    JList<JObject?>? videoList = _jAniyomiBridge.getVideoList(
-      sEpisode,
-      JString.fromString(source),
-    );
-    if (videoList == null) {
-      return [];
-    }
-    return videoList
-        .cast<JObject?>()
-        .where(_jObjIsNotNull)
-        .map((jObj) => jObj!.as<JVideo>(JVideo.type))
-        .toList();
-  }
-
-  List<JPage> getPageList(JSChapter sChapter, String source) {
-    JList<JObject?>? videoList = _jAniyomiBridge.getVideoList(
-      sChapter,
-      JString.fromString(source),
-    );
-    if (videoList == null) {
-      return [];
-    }
-    return videoList
-        .cast<JObject?>()
-        .where(_jObjIsNotNull)
-        .map((jObj) => jObj!.as<JPage>(JPage.type))
-        .toList();
-  }
-
-  void loadAnimeExtension(String extensionUrl) {
-    _jAniyomiBridge.loadAnimeExtension(
-      JString.fromString(extensionUrl),
-      JString.fromString(
-        path.join(_supportDirectoryPath, _aniyomiBridgeAnimeExtensionsDir),
+  Future<List<JSAnime>> getAnimeSearchResults(String query, int page, String source) async {
+    return _sendJniIsolateMessage<List<JSAnime>>(
+      JniIsolateMessage(
+        id: _random.nextInt(1 << 32),
+        type: JniIsolateMessageType.getAnimeSearchResults,
+        args: {
+         'query': query,
+          'page': page,
+          'source': source,
+        },
       ),
     );
   }
 
-  void unloadAnimeExtension(String extensionName, String extensionVersion) {
-    _jAniyomiBridge.unloadAnimeExtension(
-      JString.fromString(extensionName),
-      JString.fromString(extensionVersion),
-      JString.fromString(
-        path.join(_supportDirectoryPath, _aniyomiBridgeAnimeExtensionsDir),
-      )
-    );
-  }
-
-  void loadMangaExtension(String extensionUrl) {
-    _jAniyomiBridge.loadMangaExtension(
-      JString.fromString(extensionUrl),
-      JString.fromString(
-        path.join(_supportDirectoryPath, _aniyomiBridgeMangaExtensionsDir),
+  Future<List<JSManga>> getMangaSearchResults(String query, int page, String source) async {
+    return _sendJniIsolateMessage<List<JSManga>>(
+      JniIsolateMessage(
+        id: _random.nextInt(1 << 32),
+        type: JniIsolateMessageType.getMangaSearchResults,
+        args: {
+          'query': query,
+          'page': page,
+          'source': source,
+        },
       ),
     );
   }
 
-  void unloadMangaExtension(String extensionName, String extensionVersion) {
-    _jAniyomiBridge.unloadMangaExtension(
-      JString.fromString(extensionName),
-      JString.fromString(extensionVersion),
-      JString.fromString(
-        path.join(_supportDirectoryPath, _aniyomiBridgeMangaExtensionsDir),
-      )
+  Future<List<JSEpisode>> getEpisodeList(JSAnime sAnime, String source) async {
+    return _sendJniIsolateMessage<List<JSEpisode>>(
+      JniIsolateMessage(
+        id: _random.nextInt(1 << 32),
+        type: JniIsolateMessageType.getEpisodeList,
+        args: {
+         'sAnime': sAnime,
+          'source': source,
+        },
+      ),
     );
   }
 
-  Future<Set<Extension>> getInstalledAnimeExtensions() async{
+  Future<List<JSChapter>> getChapterList(JSManga sManga, String source) async {
+    return _sendJniIsolateMessage<List<JSChapter>>(
+      JniIsolateMessage(
+        id: _random.nextInt(1 << 32),
+        type: JniIsolateMessageType.getChapterList,
+        args: {
+         'sManga': sManga,
+          'source': source,
+        },
+      ),
+    );
+  }
+
+  Future<List<JVideo>> getVideoList(JSEpisode sEpisode, String source) async {
+    return _sendJniIsolateMessage<List<JVideo>>(
+      JniIsolateMessage(
+        id: _random.nextInt(1 << 32),
+        type: JniIsolateMessageType.getVideoList,
+        args: {
+         'sEpisode': sEpisode,
+          'source': source,
+        },
+      ),
+    );
+  }
+
+  Future<List<JPage>> getPageList(JSChapter sChapter, String source) async {
+    return _sendJniIsolateMessage<List<JPage>>(
+      JniIsolateMessage(
+        id: _random.nextInt(1 << 32),
+        type: JniIsolateMessageType.getPageList,
+        args: {
+         'sChapter': sChapter,
+          'source': source,
+        },
+      ),
+    );
+  }
+
+  Future<void> loadAnimeExtension(String extensionUrl) async {
+    return _sendJniIsolateMessage<void>(
+      JniIsolateMessage(
+        id: _random.nextInt(1 << 32),
+        type: JniIsolateMessageType.loadAnimeExtension,
+        args: {
+         'extensionUrl': extensionUrl,
+        },
+      ),
+    );
+  }
+
+  Future<void> unloadAnimeExtension(String extensionName, String extensionVersion) async {
+    return _sendJniIsolateMessage<void>(
+      JniIsolateMessage(
+        id: _random.nextInt(1 << 32),
+        type: JniIsolateMessageType.unloadAnimeExtension,
+        args: {
+          'extensionName': extensionName,
+          'extensionVersion': extensionVersion,
+        },
+      ),
+    );
+  }
+
+  Future<void> loadMangaExtension(String extensionUrl) async {
+    return _sendJniIsolateMessage<void>(
+      JniIsolateMessage(
+        id: _random.nextInt(1 << 32),
+        type: JniIsolateMessageType.loadMangaExtension,
+        args: {
+         'extensionUrl': extensionUrl,
+        },
+      ),
+    );
+  }
+
+  Future<void> unloadMangaExtension(String extensionName, String extensionVersion) async {
+    return _sendJniIsolateMessage<void>(
+      JniIsolateMessage(
+        id: _random.nextInt(1 << 32),
+        type: JniIsolateMessageType.unloadMangaExtension,
+        args: {
+          'extensionName': extensionName,
+          'extensionVersion': extensionVersion,
+        },
+      ),
+    );
+  }
+
+  Future<Set<Extension>> getInstalledAnimeExtensions() async {
     Directory animeExtDir = Directory(
       path.join(_supportDirectoryPath, _aniyomiBridgeAnimeExtensionsDir),
     );
@@ -193,7 +234,7 @@ class AniyomiBridge {
     return extensions;
   }
 
-  Future<Set<Extension>> getInstalledMangaExtensions() async{
+  Future<Set<Extension>> getInstalledMangaExtensions() async {
     Directory mangaExtDir = Directory(
       path.join(_supportDirectoryPath, _aniyomiBridgeMangaExtensionsDir),
     );
@@ -212,33 +253,37 @@ class AniyomiBridge {
     return extensions;
   }
 
-  List<String>? getLoadedAnimeExtensions() {
-    JList<JString?>? loadedExtensions = _jAniyomiBridge
-        .getAnimeLoadedExtensions();
-    if (loadedExtensions == null) {
-      return null;
-    }
-    return loadedExtensions
-        .cast<JString>()
-        .map((jStr) => jStr.toDartString())
-        .toList();
-  }
+  // List<String>? getLoadedAnimeExtensions() {
+  //   JList<JString?>? loadedExtensions = _jAniyomiBridge
+  //       .getAnimeLoadedExtensions();
+  //   if (loadedExtensions == null) {
+  //     return null;
+  //   }
+  //   return loadedExtensions
+  //       .cast<JString>()
+  //       .map((jStr) => jStr.toDartString())
+  //       .toList();
+  // }
+  //
+  // List<String>? getLoadedMangaExtensions() {
+  //   JList<JString?>? loadedExtensions = _jAniyomiBridge
+  //       .getMangaLoadedExtensions();
+  //   if (loadedExtensions == null) {
+  //     return null;
+  //   }
+  //   return loadedExtensions
+  //       .cast<JString>()
+  //       .map((jStr) => jStr.toDartString())
+  //       .toList();
+  // }
 
-  List<String>? getLoadedMangaExtensions() {
-    JList<JString?>? loadedExtensions = _jAniyomiBridge
-        .getMangaLoadedExtensions();
-    if (loadedExtensions == null) {
-      return null;
-    }
-    return loadedExtensions
-        .cast<JString>()
-        .map((jStr) => jStr.toDartString())
-        .toList();
+  Future<T> _sendJniIsolateMessage<T>(JniIsolateMessage message) {
+    final completer = Completer<T>();
+    _pendingRequests[message.id] = completer;
+    _jniSenderPort.send(message);
+    return completer.future;
   }
 
-  bool Function(JObject? jObj) get _jObjIsNotNull =>
-      (jObj) => jObj != null;
-
   String _getDylibDir(Directory supportDirectory) {
     String executablePath = File(Platform.resolvedExecutable).parent.path;
     if (Platform.isLinux) {

lib/jni_isolate.dart

@@ -0,0 +1,325 @@
+import 'dart:io';
+import 'dart:isolate';
+
+import 'package:jni/jni.dart';
+import 'package:k3vinb5_aniyomi_bridge/jni_isolate_message.dart';
+import 'package:path/path.dart' as path;
+
+import 'jmodels/janiyomibridge.dart';
+import 'jmodels/jpage.dart';
+import 'jmodels/jsanime.dart';
+import 'jmodels/jschapter.dart';
+import 'jmodels/jsepisode.dart';
+import 'jmodels/jsmanga.dart';
+import 'jmodels/jvideo.dart';
+
+class JniIsolate {
+  // Static consts
+  static const String _aniyomiBridgeAnimeExtensionsDir = "animeExtensions";
+  static const String _aniyomiBridgeMangaExtensionsDir = "mangaExtensions";
+  // Static variables
+  static late Isolate _jvmIsolate;
+  static late SendPort _jvmIsolateSendPort;
+  // Instance variables
+  late final Directory _supportDirectory;
+  late final String _supportDirectoryPath;
+
+  Future<(bool, SendPort)> initJniIsolate(
+    ReceivePort readyPort,
+    ReceivePort mainIsolateReceiverPort,
+    Directory supportDirectory,
+    String dyLibDir,
+    List<String> classPath,
+  ) async {
+    _supportDirectory = supportDirectory;
+    _supportDirectoryPath = supportDirectory.path;
+    _jvmIsolate = await Isolate.spawn(
+        _jniWorkerEntryPoint, {
+      'readyPort': readyPort.sendPort,
+      'mainIsolateSendPort': mainIsolateReceiverPort.sendPort,
+      'dylibDir': dyLibDir,
+      'classPath': classPath,
+    }, debugName: 'Aniyomi-JNI-Isolate');
+    final message = await readyPort.first;
+    readyPort.close();
+    if (message is SendPort) {
+      _jvmIsolateSendPort = message;
+    } else if (message is Map && message['error'] != null) {
+      throw Exception('Failed to initialize JVM: ${message['error']}');
+    } else {
+      throw Exception('Unexpected message from JVM isolate: $message');
+    }
+    return (true, _jvmIsolateSendPort);
+  }
+
+  void _jniWorkerEntryPoint(Map<String, dynamic> parameters) {
+    final SendPort readyPort = parameters['readyPort'];
+    final SendPort mainIsolateSendPort = parameters['mainIsolateSendPort'];
+    final String dylibDir = parameters['dylibDir'];
+    final List<String> classPath = parameters['classPath'];
+
+    final jniIsolateReceiverPort = ReceivePort();
+    readyPort.send(jniIsolateReceiverPort.sendPort);
+
+    try {
+      Jni.spawnIfNotExists(dylibDir: dylibDir, classPath: classPath);
+      JAniyomiBridge.init();
+      JAniyomiBridge jAniyomiBridge = JAniyomiBridge();
+      jniIsolateReceiverPort.listen((message) {
+        if (message is! JniIsolateMessage) {
+          mainIsolateSendPort.send(
+            JniIsolateError(
+              id: 0,
+              error: 'Invalid message type received',
+              stackTrace: '',
+            ),
+          );
+          return;
+        }
+        try {
+          switch ((message).type) {
+            case JniIsolateMessageType.getAnimeSearchResults:
+              List<JSAnime> results = _getAnimeSearchResults(
+                jAniyomiBridge,
+                message.args['query'] as String,
+                message.args['page'] as int,
+                message.args['source'] as String,
+              );
+              mainIsolateSendPort.send(
+                JniIsolateResponse(id: message.id, results: results),
+              );
+            case JniIsolateMessageType.getMangaSearchResults:
+              List<JSManga> results = _getMangaSearchResults(
+                jAniyomiBridge,
+                message.args['query'] as String,
+                message.args['page'] as int,
+                message.args['source'] as String,
+              );
+              mainIsolateSendPort.send(
+                JniIsolateResponse(id: message.id, results: results),
+              );
+            case JniIsolateMessageType.getEpisodeList:
+              List<JSEpisode> results = _getEpisodeList(
+                jAniyomiBridge,
+                message.args['sAnime'] as JSAnime,
+                message.args['source'] as String,
+              );
+              mainIsolateSendPort.send(
+                JniIsolateResponse(id: message.id, results: results),
+              );
+            case JniIsolateMessageType.getChapterList:
+              List<JSChapter> results = _getChapterList(
+                jAniyomiBridge,
+                message.args['sManga'] as JSManga,
+                message.args['source'] as String,
+              );
+              mainIsolateSendPort.send(
+                JniIsolateResponse(id: message.id, results: results),
+              );
+            case JniIsolateMessageType.getVideoList:
+              List<JVideo> results = _getVideoList(
+                jAniyomiBridge,
+                message.args['sEpisode'] as JSEpisode,
+                message.args['source'] as String,
+              );
+              mainIsolateSendPort.send(
+                JniIsolateResponse(id: message.id, results: results),
+              );
+            case JniIsolateMessageType.getPageList:
+              List<JPage> results = _getPageList(
+                jAniyomiBridge,
+                message.args['sChapter'] as JSChapter,
+                message.args['source'] as String,
+              );
+              mainIsolateSendPort.send(
+                JniIsolateResponse(id: message.id, results: results),
+              );
+            case JniIsolateMessageType.loadAnimeExtension:
+              _loadAnimeExtension(
+                jAniyomiBridge,
+                message.args['extensionUrl'] as String,
+              );
+              mainIsolateSendPort.send(
+                JniIsolateResponse(id: message.id),
+              );
+            case JniIsolateMessageType.loadMangaExtension:
+              _loadMangaExtension(
+                jAniyomiBridge,
+                message.args['extensionUrl'] as String,
+              );
+              mainIsolateSendPort.send(
+                JniIsolateResponse(id: message.id),
+              );
+            case JniIsolateMessageType.unloadAnimeExtension:
+              _unloadAnimeExtension(
+                jAniyomiBridge,
+                message.args['extensionName'] as String,
+                message.args['extensionVersion'] as String,
+              );
+              mainIsolateSendPort.send(
+                JniIsolateResponse(id: message.id),
+              );
+            case JniIsolateMessageType.unloadMangaExtension:
+              _unloadMangaExtension(
+                jAniyomiBridge,
+                message.args['extensionName'] as String,
+                message.args['extensionVersion'] as String,
+              );
+              mainIsolateSendPort.send(
+                JniIsolateResponse(id: message.id),
+              );
+          }
+        } catch (e, stackTrace) {
+          mainIsolateSendPort.send(
+            JniIsolateError(
+              id: message.id,
+              error: e.toString(),
+              stackTrace: stackTrace.toString(),
+            ),
+          );
+        }
+      });
+    } catch (e, stackTrace) {
+      mainIsolateSendPort.send(
+        JniIsolateError(
+          id: 0,
+          error: e.toString(),
+          stackTrace: stackTrace.toString(),
+        ),
+      );
+    }
+  }
+
+  List<JSAnime> _getAnimeSearchResults(JAniyomiBridge jAniyomiBridge, String query, int page, String source) {
+    JList<JObject?>? searchResults = jAniyomiBridge.getAnimeSearchResults(
+      JString.fromString(query),
+      page,
+      JString.fromString(source),
+    );
+    if (searchResults == null) {
+      return [];
+    }
+    return searchResults
+        .cast<JObject?>()
+        .where(_jObjIsNotNull)
+        .map((jObj) => jObj!.as<JSAnime>(JSAnime.type))
+        .toList();
+  }
+
+  List<JSManga> _getMangaSearchResults(JAniyomiBridge jAniyomiBridge, String query, int page, String source) {
+    JList<JObject?>? searchResults = jAniyomiBridge.getMangaSearchResults(
+      JString.fromString(query),
+      page,
+      JString.fromString(source),
+    );
+    if (searchResults == null) {
+      return [];
+    }
+    return searchResults
+        .cast<JObject?>()
+        .where(_jObjIsNotNull)
+        .map((jObj) => jObj!.as<JSManga>(JSManga.type))
+        .toList();
+  }
+
+  List<JSEpisode> _getEpisodeList(JAniyomiBridge jAniyomiBridge, JSAnime sAnime, String source) {
+    JList<JObject?>? episodeList = jAniyomiBridge.getEpisodeList(
+      sAnime,
+      JString.fromString(source),
+    );
+    if (episodeList == null) {
+      return [];
+    }
+    return episodeList
+        .cast<JObject?>()
+        .where(_jObjIsNotNull)
+        .map((jObj) => jObj!.as<JSEpisode>(JSEpisode.type))
+        .toList();
+  }
+
+  List<JSChapter> _getChapterList(JAniyomiBridge jAniyomiBridge, JSManga sManga, String source) {
+    JList<JObject?>? episodeList = jAniyomiBridge.getEpisodeList(
+      sManga,
+      JString.fromString(source),
+    );
+    if (episodeList == null) {
+      return [];
+    }
+    return episodeList
+        .cast<JObject?>()
+        .where(_jObjIsNotNull)
+        .map((jObj) => jObj!.as<JSChapter>(JSChapter.type))
+        .toList();
+  }
+
+  List<JVideo> _getVideoList(JAniyomiBridge jAniyomiBridge, JSEpisode sEpisode, String source) {
+    JList<JObject?>? videoList = jAniyomiBridge.getVideoList(
+      sEpisode,
+      JString.fromString(source),
+    );
+    if (videoList == null) {
+      return [];
+    }
+    return videoList
+        .cast<JObject?>()
+        .where(_jObjIsNotNull)
+        .map((jObj) => jObj!.as<JVideo>(JVideo.type))
+        .toList();
+  }
+
+  List<JPage> _getPageList(JAniyomiBridge jAniyomiBridge, JSChapter sChapter, String source) {
+    JList<JObject?>? videoList = jAniyomiBridge.getVideoList(
+      sChapter,
+      JString.fromString(source),
+    );
+    if (videoList == null) {
+      return [];
+    }
+    return videoList
+        .cast<JObject?>()
+        .where(_jObjIsNotNull)
+        .map((jObj) => jObj!.as<JPage>(JPage.type))
+        .toList();
+  }
+
+  void _loadAnimeExtension(JAniyomiBridge jAniyomiBridge, String extensionUrl) {
+    jAniyomiBridge.loadAnimeExtension(
+      JString.fromString(extensionUrl),
+      JString.fromString(
+        path.join(_supportDirectoryPath, _aniyomiBridgeAnimeExtensionsDir),
+      ),
+    );
+  }
+
+  void _unloadAnimeExtension(JAniyomiBridge jAniyomiBridge, String extensionName, String extensionVersion) {
+    jAniyomiBridge.unloadAnimeExtension(
+      JString.fromString(extensionName),
+      JString.fromString(extensionVersion),
+      JString.fromString(
+        path.join(_supportDirectoryPath, _aniyomiBridgeAnimeExtensionsDir),
+      ),
+    );
+  }
+
+  void _loadMangaExtension(JAniyomiBridge jAniyomiBridge, String extensionUrl) {
+    jAniyomiBridge.loadMangaExtension(
+      JString.fromString(extensionUrl),
+      JString.fromString(
+        path.join(_supportDirectoryPath, _aniyomiBridgeMangaExtensionsDir),
+      ),
+    );
+  }
+
+  void _unloadMangaExtension(JAniyomiBridge jAniyomiBridge, String extensionName, String extensionVersion) {
+    jAniyomiBridge.unloadMangaExtension(
+      JString.fromString(extensionName),
+      JString.fromString(extensionVersion),
+      JString.fromString(
+        path.join(_supportDirectoryPath, _aniyomiBridgeMangaExtensionsDir),
+      ),
+    );
+  }
+
+  bool Function(JObject? jObj) get _jObjIsNotNull =>
+      (jObj) => jObj != null;
+}

lib/jni_isolate_message.dart

@@ -0,0 +1,35 @@
+class JniIsolateMessage {
+  final int id;
+  final JniIsolateMessageType type;
+  final Map<String, dynamic> args;
+
+  JniIsolateMessage({required this.id, required this.type, required this.args});
+}
+
+class JniIsolateResponse {
+  final int id;
+  final dynamic results;
+
+  JniIsolateResponse({required this.id, this.results});
+}
+
+class JniIsolateError {
+  final int id;
+  final String error;
+  final String stackTrace;
+
+  JniIsolateError({required this.id, required this.error, required this.stackTrace});
+}
+
+enum JniIsolateMessageType {
+  getAnimeSearchResults,
+  getMangaSearchResults,
+  getEpisodeList,
+  getChapterList,
+  getVideoList,
+  getPageList,
+  loadAnimeExtension,
+  loadMangaExtension,
+  unloadAnimeExtension,
+  unloadMangaExtension,
+}