feat: Update app layout with MainAppHeader and enhance user settings interface

lib/features/reader/providers/tts_provider.dart

@@ -0,0 +1,133 @@
+import 'dart:async';
+
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_tts/flutter_tts.dart';
+
+enum TtsStatus { idle, playing, paused, stopped }
+
+class TtsState {
+  final TtsStatus status;
+  final int currentSentenceIndex;
+  final List<String> sentences;
+  final double speechRate;
+  final double volume;
+  final double pitch;
+  final String? currentLanguage;
+
+  const TtsState({
+    this.status = TtsStatus.idle,
+    this.currentSentenceIndex = 0,
+    this.sentences = const [],
+    this.speechRate = 0.5,
+    this.volume = 1.0,
+    this.pitch = 1.0,
+    this.currentLanguage,
+  });
+
+  TtsState copyWith({
+    TtsStatus? status,
+    int? currentSentenceIndex,
+    List<String>? sentences,
+    double? speechRate,
+    double? volume,
+    double? pitch,
+    String? currentLanguage,
+  }) {
+    return TtsState(
+      status: status ?? this.status,
+      currentSentenceIndex: currentSentenceIndex ?? this.currentSentenceIndex,
+      sentences: sentences ?? this.sentences,
+      speechRate: speechRate ?? this.speechRate,
+      volume: volume ?? this.volume,
+      pitch: pitch ?? this.pitch,
+      currentLanguage: currentLanguage ?? this.currentLanguage,
+    );
+  }
+}
+
+class TtsNotifier extends Notifier<TtsState> {
+  late FlutterTts _tts;
+
+  @override
+  TtsState build() {
+    _tts = FlutterTts();
+    _initTts();
+    ref.onDispose(() async {
+      await _tts.stop();
+    });
+    return const TtsState();
+  }
+
+  Future<void> _initTts() async {
+    await _tts.setLanguage('vi-VN');
+    await _tts.setSpeechRate(state.speechRate);
+    await _tts.setVolume(state.volume);
+    await _tts.setPitch(state.pitch);
+    // Do NOT use awaitSpeakCompletion(true) — it blocks the Dart↔native channel
+    // between sentences, causing Android TTS service to disconnect.
+    await _tts.awaitSpeakCompletion(false);
+
+    _tts.setCompletionHandler(_onSentenceComplete);
+
+    _tts.setCancelHandler(() {
+      if (state.status == TtsStatus.playing) {
+        state = state.copyWith(status: TtsStatus.stopped);
+      }
+    });
+
+    _tts.setErrorHandler((msg) {
+      state = state.copyWith(status: TtsStatus.stopped);
+    });
+  }
+
+  void _onSentenceComplete() {
+    if (state.status != TtsStatus.playing) return;
+    final nextIndex = state.currentSentenceIndex + 1;
+    if (nextIndex < state.sentences.length) {
+      state = state.copyWith(currentSentenceIndex: nextIndex);
+      _speakCurrent();
+    } else {
+      state = state.copyWith(
+          status: TtsStatus.stopped, currentSentenceIndex: 0);
+    }
+  }
+
+  Future<void> _speakCurrent() async {
+    if (state.sentences.isEmpty) return;
+    if (state.status != TtsStatus.playing) return;
+    final sentence = state.sentences[state.currentSentenceIndex];
+    await _tts.speak(sentence);
+  }
+
+  Future<void> play(List<String> sentences) async {
+    await _tts.stop();
+    state = state.copyWith(
+      sentences: sentences,
+      currentSentenceIndex: 0,
+      status: TtsStatus.playing,
+    );
+    await _speakCurrent();
+  }
+
+  Future<void> pause() async {
+    state = state.copyWith(status: TtsStatus.paused);
+    await _tts.pause();
+  }
+
+  Future<void> resume() async {
+    state = state.copyWith(status: TtsStatus.playing);
+    await _speakCurrent();
+  }
+
+  Future<void> stop() async {
+    state = state.copyWith(status: TtsStatus.stopped, currentSentenceIndex: 0);
+    await _tts.stop();
+  }
+
+  Future<void> setSpeechRate(double rate) async {
+    await _tts.setSpeechRate(rate);
+    state = state.copyWith(speechRate: rate);
+  }
+}
+
+final ttsProvider = NotifierProvider<TtsNotifier, TtsState>(TtsNotifier.new);