English/kouyu_english/lib/core/voice_service.dart

import 'dart:io';

import 'package:audioplayers/audioplayers.dart';
import 'package:flutter_tts/flutter_tts.dart';
import 'package:path_provider/path_provider.dart';
import 'package:record/record.dart';
import 'package:speech_to_text/speech_to_text.dart';

/// Device speech facilities are optional. Callers must keep a text fallback
/// because availability depends on device language packs and permissions.
class VoiceService {
  VoiceService._();
  static final instance = VoiceService._();

  final FlutterTts _tts = FlutterTts();
  final SpeechToText _stt = SpeechToText();
  final AudioRecorder _recorder = AudioRecorder();
  final AudioPlayer _player = AudioPlayer();
  bool _speechReady = false;
  bool _ttsInitialized = false;

  void Function(String status)? _statusListener;
  void Function(String error)? _errorListener;

  Future<void> _initTts() async {
    if (_ttsInitialized) return;
    try {
      if (Platform.isIOS) {
        await _tts.setIosAudioCategory(
          IosTextToSpeechAudioCategory.playback,
          [
            IosTextToSpeechAudioCategoryOptions.allowBluetooth,
            IosTextToSpeechAudioCategoryOptions.allowBluetoothA2DP,
            IosTextToSpeechAudioCategoryOptions.mixWithOthers,
          ],
        );
      }
      await _tts.setVolume(1.0);
      await _tts.setPitch(1.0);
      _ttsInitialized = true;
    } catch (_) {}
  }

  Future<void> speak(String text, {bool slow = false}) async {
    try {
      await _initTts();
      await _tts.stop();
      try {
        final isAvailable = await _tts.isLanguageAvailable('en-US');
        if (isAvailable == true) {
          await _tts.setLanguage('en-US');
        } else {
          await _tts.setLanguage('en');
        }
      } catch (_) {
        try {
          await _tts.setLanguage('en-US');
        } catch (_) {}
      }
      await _tts.setSpeechRate(slow ? 0.35 : 0.48);
      await _tts.speak(text);
    } catch (_) {}
  }

  Future<void> stopSpeaking() async {
    try {
      await _tts.stop();
    } catch (_) {}
  }

  Future<bool> hasRecordPermission() => _recorder.hasPermission();

  Future<bool> startRecording() async {
    if (!await _recorder.hasPermission()) return false;
    final directory = await getApplicationDocumentsDirectory();
    final recordings = Directory('${directory.path}/recordings');
    if (!await recordings.exists()) await recordings.create(recursive: true);
    final timestamp = DateTime.now().microsecondsSinceEpoch;
    await _recorder.start(
      const RecordConfig(
        encoder: AudioEncoder.wav,
        sampleRate: 16000,
        numChannels: 1,
        noiseSuppress: true,
        echoCancel: true,
        autoGain: true,
      ),
      path: '${recordings.path}/practice_$timestamp.wav',
    );
    return true;
  }

  Future<String?> stopRecording() => _recorder.stop();

  Future<void> playRecording(String path) async {
    await _player.stop();
    await _player.play(DeviceFileSource(path));
  }

  Future<void> stopRecordingPlayback() => _player.stop();

  Future<void> deleteRecording(String? path) async {
    if (path == null || path.isEmpty) return;
    final file = File(path);
    if (await file.exists()) await file.delete();
  }

  Future<int> deleteAllRecordings() async {
    final directory = await getApplicationDocumentsDirectory();
    final recordings = Directory('${directory.path}/recordings');
    if (!await recordings.exists()) return 0;
    final files = await recordings
        .list()
        .where((item) => item is File)
        .toList();
    for (final file in files.cast<File>()) {
      await file.delete();
    }
    return files.length;
  }

  Future<List<String>> listRecordingPaths() async {
    final directory = await getApplicationDocumentsDirectory();
    final recordings = Directory('${directory.path}/recordings');
    if (!await recordings.exists()) return const [];
    final files = await recordings
        .list()
        .where((item) => item is File && (item.path.endsWith('.wav') || item.path.endsWith('.m4a')))
        .cast<File>()
        .toList();
    files.sort((left, right) => right.path.compareTo(left.path));
    return files.map((file) => file.path).toList();
  }

  Future<void> disposeRecording() async {
    await _recorder.dispose();
    await _player.dispose();
  }

  Future<bool> initializeSpeech({
    void Function(String status)? onStatus,
    void Function(String error)? onError,
  }) async {
    _statusListener = onStatus;
    _errorListener = onError;
    try {
      _speechReady = await _stt.initialize(
        onError: (val) {
          _errorListener?.call(val.errorMsg);
        },
        onStatus: (val) {
          _statusListener?.call(val);
        },
        debugLogging: false,
      );
      return _speechReady;
    } catch (_) {
      _speechReady = false;
      return false;
    }
  }

  Future<bool> startListening(
    void Function(String text, bool finalResult) onResult, {
    void Function(String status)? onStatus,
    void Function(String error)? onError,
  }) async {
    _statusListener = onStatus;
    _errorListener = onError;
    try {
      if (!_speechReady || !_stt.isAvailable) {
        final ready = await initializeSpeech(onStatus: onStatus, onError: onError);
        if (!ready) return false;
      }

      String? targetLocaleId = 'en_US';
      try {
        final locales = await _stt.locales();
        if (locales.isNotEmpty) {
          final enLocale = locales.firstWhere(
            (l) => l.localeId.toLowerCase().startsWith('en'),
            orElse: () => locales.first,
          );
          targetLocaleId = enLocale.localeId;
        }
      } catch (_) {}

      await _stt.listen(
        onResult: (result) =>
            onResult(result.recognizedWords, result.finalResult),
        listenOptions: SpeechListenOptions(
          localeId: targetLocaleId,
          listenFor: const Duration(seconds: 30),
          pauseFor: const Duration(seconds: 4),
          partialResults: true,
          cancelOnError: false,
        ),
      );
      return _stt.isListening;
    } catch (e) {
      if (onError != null) onError(e.toString());
      return false;
    }
  }

  Future<void> stopListening() => _stt.stop();
  bool get isListening => _stt.isListening;
}