import 'dart:async';
import 'package:flutter/foundation.dart';
import 'package:get/get.dart';
import 'package:speech_to_text/speech_to_text.dart' as stt;
import 'package:speech_to_text/speech_recognition_result.dart';
import 'package:speech_to_text/speech_recognition_error.dart';
import '../../../core/utils/logger.dart';
import '../asr_service.dart';

/// ASR状态枚举
enum AsrState {
  /// 未初始化
  notInitialized,

  /// 已初始化但未开始监听
  initialized,

  /// 正在监听
  listening,

  /// 正在处理识别结果
  processing,

  /// 识别完成
  done,

  /// 发生错误
  error,
}

/// Flutter ASR服务，负责本地语音转文本功能
/// 使用speech_to_text插件实现语音识别功能
class FlutterAsrService extends GetxService implements AsrService {
  static final FlutterAsrService to = Get.put(FlutterAsrService());

  // speech_to_text 实例
  final stt.SpeechToText _speech = stt.SpeechToText();

  // 可用的语音识别语言
  final List<String> _supportedLanguages = [];
  @override
  List<String> get supportedLanguages => _supportedLanguages;

  // 当前选择的语言
  final RxString _currentLocale = ''.obs;
  String get currentLocale => _currentLocale.value;

  // 是否可用
  final RxBool _isAvailable = false.obs;
  bool get isAvailable => _isAvailable.value;

  // 是否正在监听
  bool _isListening = false;

  // 当前ASR状态
  final Rx<AsrState> _asrState = AsrState.notInitialized.obs;
  AsrState get asrState => _asrState.value;

  // 连续识别模式的结果流控制器
  StreamController<RecognitionEvent>? _continuousRecognitionController;

  FlutterAsrService() {
    _initSpeech();
  }

  /// 初始化语音识别
  Future<void> _initSpeech() async {
    try {
      _asrState.value = AsrState.notInitialized;

      // 初始化语音识别，使用较短的最终超时时间，提高响应速度
      _isAvailable.value = await _speech.initialize(
        onStatus: _onSpeechStatus,
        onError: _onSpeechError,
        debugLogging: false,
        finalTimeout: const Duration(milliseconds: 800), // 更短的最终超时时间，加速结果返回
      );

      if (_isAvailable.value) {
        // 获取支持的语言列表
        final systemLocales = await _speech.locales();

        // 清空并重新填充支持的语言列表
        _supportedLanguages.clear();
        for (var locale in systemLocales) {
          if (!_supportedLanguages.contains(locale.localeId)) {
            _supportedLanguages.add(locale.localeId);
          }
        }

        // 设置默认语言（优先使用系统语言或中文）
        var systemLocale = await _speech.systemLocale();
        if (systemLocale != null) {
          _currentLocale.value = systemLocale.localeId;
        } else if (_supportedLanguages.contains('zh-CN')) {
          _currentLocale.value = 'zh-CN';
        } else if (_supportedLanguages.isNotEmpty) {
          _currentLocale.value = _supportedLanguages.first;
        }

        _asrState.value = AsrState.initialized;
        Logger.info('语音识别初始化成功，支持 ${_supportedLanguages.length} 种语言');
      } else {
        _asrState.value = AsrState.error;
        Logger.error('语音识别不可用');
      }
    } catch (e) {
      _isAvailable.value = false;
      _asrState.value = AsrState.error;
      Logger.error('语音识别初始化失败: $e');
    }
  }

  /// 处理语音识别状态变化
  void _onSpeechStatus(String status) {
    Logger.info('语音识别状态: $status');

    switch (status) {
      case 'listening':
        _asrState.value = AsrState.listening;
        _isListening = true;
        break;
      case 'notListening':
        if (_asrState.value == AsrState.listening) {
          _asrState.value = AsrState.processing;
        }
        _isListening = false;
        break;
      case 'done':
        _asrState.value = AsrState.done;
        _isListening = false;

        // 在连续识别模式下，当一次识别完成后立即开始下一次识别
        if (_continuousRecognitionController != null &&
            !_continuousRecognitionController!.isClosed) {
          _restartContinuousRecognition();
        }
        break;
    }
  }

  /// 处理语音识别错误
  void _onSpeechError(SpeechRecognitionError error) {
    Logger.error('语音识别错误: ${error.errorMsg} (永久性错误: ${error.permanent})');
    _asrState.value = AsrState.error;

    // 向连续识别控制器发送错误事件（如果存在）
    _continuousRecognitionController
        ?.add(RecognitionEvent.error(error.errorMsg));

    // 在连续识别模式下，尝试从错误中恢复（非永久性错误）
    if (!error.permanent &&
        _continuousRecognitionController != null &&
        !_continuousRecognitionController!.isClosed) {
      _restartContinuousRecognition();
    }
  }

  /// 启动语音识别的统一方法
  Future<bool> _startListening({
    required Function(SpeechRecognitionResult) onResult,
    Duration listenFor = const Duration(seconds: 30),
    Duration pauseFor = const Duration(seconds: 3),
    bool autoPunctuation = true,
  }) async {
    try {
      // 如果当前正在监听，先停止
      if (_speech.isListening) {
        await _speech.stop();
        // 延长等待时间，确保资源完全释放
        await Future.delayed(const Duration(milliseconds: 800));
      }

      // 在启动前再次检查状态
      if (_speech.isListening) {
        Logger.warning('停止识别后，仍处于监听状态，可能有系统冲突');
        await _speech.stop();
        await Future.delayed(const Duration(milliseconds: 500));
      }

      // 启动语音识别前确保状态正确
      _asrState.value = AsrState.listening;

      // 启动语音识别
      final result = await _speech.listen(
            onResult: onResult,
            localeId: _currentLocale.value,
            listenFor: listenFor,
            pauseFor: pauseFor,
            listenOptions: stt.SpeechListenOptions(
              partialResults: true,
              autoPunctuation: autoPunctuation,
              // 使用独白模式，减少与系统交互冲突
              listenMode: stt.ListenMode.dictation,
            ),
          ) ??
          false;

      if (!result) {
        Logger.error('语音识别启动失败');
        _asrState.value = AsrState.error;
      }

      return result;
    } catch (e) {
      Logger.error('启动语音识别失败: $e');
      _asrState.value = AsrState.error;
      return false;
    }
  }

  /// 重新启动连续识别
  Future<void> _restartContinuousRecognition() async {
    try {
      // 确保控制器有效
      if (_continuousRecognitionController == null ||
          _continuousRecognitionController!.isClosed) {
        Logger.info('连续识别控制器已关闭，跳过重启');
        return;
      }

      // 检查系统状态，避免频繁重启
      if (_speech.isListening) {
        Logger.info('当前已在监听中，无需重启');
        return;
      }

      // 延长等待时间，避免与系统资源冲突
      await Future.delayed(const Duration(milliseconds: 1000));

      // 再次检查状态
      if (_continuousRecognitionController == null ||
          _continuousRecognitionController!.isClosed) {
        Logger.info('延迟期间控制器已关闭，跳过重启');
        return;
      }

      Logger.info('尝试重新启动连续识别');

      // 使用统一方法启动识别
      final success = await _startListening(
        onResult: _onSpeechResult,
        // 增加超时时间和暂停时间
        listenFor: const Duration(seconds: 30),
        pauseFor: const Duration(seconds: 4),
      );

      if (success) {
        Logger.info('连续识别重启成功');
      } else {
        Logger.error('连续识别重启失败');
        _continuousRecognitionController
            ?.add(RecognitionEvent.error('重启语音识别失败，可能存在系统资源冲突'));
      }
    } catch (e) {
      Logger.error('重启连续识别失败: $e');

      // 发送错误给控制器
      _continuousRecognitionController?.add(RecognitionEvent.error('重启失败: $e'));
    }
  }

  /// 处理语音识别结果
  void _onSpeechResult(SpeechRecognitionResult result) {
    // 如果是连续识别，发送到连续识别控制器
    if (_continuousRecognitionController != null) {
      if (result.finalResult) {
        Logger.info('收到最终识别结果: "${result.recognizedWords}"');
        _continuousRecognitionController!.add(RecognitionEvent.finalResult(
          text: result.recognizedWords,
          detectedLanguage: currentLocale,
        ));
      } else {
        _continuousRecognitionController!.add(RecognitionEvent(
          type: RecognitionEventType.intermediateResult,
          text: result.recognizedWords,
          detectedLanguage: currentLocale,
        ));
      }
    }
  }

  /// 设置当前语言
  void setLocale(String localeId) {
    if (_supportedLanguages.contains(localeId)) {
      _currentLocale.value = localeId;
      Logger.info('设置语音识别语言: $localeId');
    } else {
      Logger.error('不支持的语言: $localeId');
    }
  }

  @override
  Future<bool> initialize({
    List<String>? supportedLanguages,
  }) async {
    try {
      if (supportedLanguages != null && supportedLanguages.isNotEmpty) {
        _supportedLanguages.clear();
        _supportedLanguages.addAll(supportedLanguages);
      }

      // 初始化语音识别
      await _initSpeech();
      return _isAvailable.value;
    } catch (e) {
      Logger.error('语音识别初始化失败: $e');
      return false;
    }
  }

  @override
  Future<RecognitionEvent> recognizeOnce() async {
    try {
      if (!_isAvailable.value) {
        return RecognitionEvent.error('语音识别不可用');
      }

      if (_isListening) {
        await stopContinuousRecognition();
      }

      // 创建Completer来等待最终结果
      final completer = Completer<RecognitionEvent>();

      // 开始监听
      _asrState.value = AsrState.listening;

      // 定义结果处理函数
      void resultListener(SpeechRecognitionResult result) {
        if (result.finalResult) {
          // 只有在最终结果时才完成completer
          completer.complete(RecognitionEvent.finalResult(
            text: result.recognizedWords,
            detectedLanguage: currentLocale,
          ));
        }
      }

      // 使用统一方法启动识别，单次识别使用更短的时间参数
      final success = await _startListening(
        onResult: resultListener,
        listenFor: const Duration(seconds: 15),
        pauseFor: const Duration(seconds: 2),
      );

      if (!success) {
        return RecognitionEvent.error('启动语音识别失败');
      }

      // 设置较短的超时时间
      return await completer.future.timeout(
        const Duration(seconds: 20), // 略长于listenFor以确保获取到结果
        onTimeout: () {
          _speech.stop();
          return RecognitionEvent.error('语音识别超时');
        },
      );
    } catch (e) {
      Logger.error('一次性语音识别失败: $e');
      return RecognitionEvent.error('$e');
    }
  }

  @override
  Future<Stream<RecognitionEvent>> startContinuousRecognition() async {
    try {
      if (!_isAvailable.value) {
        final controller = StreamController<RecognitionEvent>.broadcast();
        controller.add(RecognitionEvent.error('语音识别不可用'));
        controller.close();
        return controller.stream;
      }

      // 如果已经在监听，先停止
      if (_isListening) {
        await stopContinuousRecognition();
      }

      // 创建新的流控制器
      _continuousRecognitionController =
          StreamController<RecognitionEvent>.broadcast();

      // 开始会话
      _continuousRecognitionController!
          .add(RecognitionEvent(type: RecognitionEventType.sessionStarted));

      // 开始连续监听
      _asrState.value = AsrState.listening;

      // 使用统一方法启动识别，连续识别使用较长的参数
      final success = await _startListening(
        onResult: _onSpeechResult,
      );

      if (!success) {
        // 添加错误事件，但保留流
        _continuousRecognitionController!
            .add(RecognitionEvent.error('启动连续语音识别失败'));

        // 返回已有的流控制器
        return _continuousRecognitionController!.stream;
      }

      _isListening = true;
      return _continuousRecognitionController!.stream;
    } catch (e) {
      Logger.error('启动连续语音识别失败: $e');

      // 如果已经创建了控制器，使用它
      if (_continuousRecognitionController != null) {
        _continuousRecognitionController!.add(RecognitionEvent.error('$e'));
        return _continuousRecognitionController!.stream;
      } else {
        // 否则创建新的控制器
        final controller = StreamController<RecognitionEvent>.broadcast();
        controller.add(RecognitionEvent.error('$e'));
        return controller.stream;
      }
    }
  }

  @override
  Future<bool> stopContinuousRecognition() async {
    try {
      // 无论是否正在监听，都尝试停止
      if (_speech.isListening) {
        await _speech.stop();
      }

      _isListening = false;

      // 发送会话结束事件
      _continuousRecognitionController
          ?.add(RecognitionEvent(type: RecognitionEventType.sessionStopped));

      // 关闭流控制器
      await _continuousRecognitionController?.close();
      _continuousRecognitionController = null;

      _asrState.value = AsrState.done;
      return true;
    } catch (e) {
      Logger.error('停止连续语音识别失败: $e');

      // 强制重置状态
      _isListening = false;
      _asrState.value = AsrState.error;

      return false;
    }
  }

  @override
  bool isContinuousRecognitionActive() {
    return _isListening;
  }

  @override
  Future<void> dispose() async {
    try {
      // 确保停止所有识别活动
      if (_speech.isListening) {
        await _speech.stop();
      }

      // 关闭控制器
      await _continuousRecognitionController?.close();
      _continuousRecognitionController = null;

      _isListening = false;
      _asrState.value = AsrState.notInitialized;
    } catch (e) {
      Logger.error('释放语音识别资源失败: $e');
    }
  }

  @override
  Future<void> pushAudioData(Uint8List data) async {}
}