import 'dart:async';
import 'dart:convert';

import 'package:flutter/services.dart';

/// ChatAPI服务异常
class ChatApiException implements Exception {
  final String message;

  ChatApiException(this.message);

  @override
  String toString() => 'ChatApiException: $message';
}

/// ChatAPI服务事件类型
enum ChatApiEventType {
  token,
  complete,
  error,
  functionCall,
}

/// ChatAPI服务事件
class ChatApiEvent {
  final ChatApiEventType type;
  final dynamic content;
  final Map<String, dynamic>? meta;

  ChatApiEvent({required this.type, this.content, this.meta});

  factory ChatApiEvent.fromMap(Map<String, dynamic> map) {
    final typeStr = map['type'] as String;
    final content = map['content'];
    final rawMeta = map['meta'] as String?;
    final meta = rawMeta != null ? jsonDecode(rawMeta) : null;
    return ChatApiEvent(
      type: _typeFromString(typeStr),
      content: content,
      meta: meta,
    );
  }

  static ChatApiEventType _typeFromString(String typeStr) {
    switch (typeStr) {
      case 'token':
        return ChatApiEventType.token;
      case 'complete':
        return ChatApiEventType.complete;
      case 'error':
        return ChatApiEventType.error;
      case 'functionCall':
        return ChatApiEventType.functionCall;
      default:
        throw ArgumentError('未知的事件类型: $typeStr');
    }
  }
}

/// ChatAPI服务插件
class ChatApiService {
  static const MethodChannel _channel =
      MethodChannel('com.yunqiinnovation.chat_api/methods');
  static const EventChannel _eventChannel =
      EventChannel('com.yunqiinnovation.chat_api/events');

  /// 事件流控制器
  StreamController<ChatApiEvent>? _eventStreamController;

  /// 事件流
  Stream<ChatApiEvent>? _eventStream;

  /// 获取事件流
  Stream<ChatApiEvent> get eventStream {
    if (_eventStream == null) {
      _eventStreamController = StreamController<ChatApiEvent>.broadcast();
      _eventStream = _eventStreamController!.stream;

      // 监听原生事件
      _eventChannel.receiveBroadcastStream().listen(
        (dynamic event) {
          if (event is Map<dynamic, dynamic>) {
            final eventMap = Map<String, dynamic>.from(event);
            final chatApiEvent = ChatApiEvent.fromMap(eventMap);
            _eventStreamController!.add(chatApiEvent);
          }
        },
        onError: (error) {
          _eventStreamController!.addError(ChatApiException('事件流错误: $error'));
        },
      );
    }

    return _eventStream!;
  }

  /// 初始化ChatAPI服务
  ///
  /// [apiKey] OpenAI API密钥
  /// [baseUrl] 可选，自定义API基础URL
  /// [model] 可选，自定义使用的模型
  /// [mcpServer] 可选，MCP服务器地址配置
  Future<bool> initialize({
    required String apiKey,
    String baseUrl = '',
    String model = '',
    String mcpServer = '',
  }) async {
    try {
      final result = await _channel.invokeMethod<bool>(
        'initialize',
        {
          'apiKey': apiKey,
          'baseUrl': baseUrl,
          'model': model,
          'mcpServer': mcpServer,
        },
      );

      return result ?? false;
    } catch (e) {
      throw ChatApiException('初始化失败: $e');
    }
  }

  /// 注册函数
  ///
  /// [name] 函数名称
  /// [description] 函数描述
  /// [parameters] 函数参数
  Future<bool> registerFunction({
    required String name,
    required String description,
    required Map<String, dynamic> parameters,
  }) async {
    try {
      final result = await _channel.invokeMethod<bool>(
        'registerFunction',
        {
          'name': name,
          'description': description,
          'parameters': parameters,
        },
      );

      return result ?? false;
    } catch (e) {
      throw ChatApiException('注册函数失败: $e');
    }
  }

  /// 创建用户消息
  ///
  /// [content] 消息内容
  Future<Map<String, dynamic>> createUserMessage(String content) async {
    try {
      final result = await _channel.invokeMethod<Map<dynamic, dynamic>>(
        'createUserMessage',
        {'content': content},
      );

      if (result == null) {
        throw ChatApiException('创建用户消息失败: 结果为空');
      }

      return Map<String, dynamic>.from(result);
    } catch (e) {
      throw ChatApiException('创建用户消息失败: $e');
    }
  }

  /// 创建助手消息
  ///
  /// [content] 消息内容
  Future<Map<String, dynamic>> createAssistantMessage(String content) async {
    try {
      final result = await _channel.invokeMethod<Map<dynamic, dynamic>>(
        'createAssistantMessage',
        {'content': content},
      );

      if (result == null) {
        throw ChatApiException('创建助手消息失败: 结果为空');
      }

      return Map<String, dynamic>.from(result);
    } catch (e) {
      throw ChatApiException('创建助手消息失败: $e');
    }
  }

  /// 发送消息（非流式输出）
  ///
  /// [messages] 消息列表
  Future<String> sendMessage({
    required List<Map<String, dynamic>> messages,
    String? systemPrompt, //提示词
    String? userProperties, //用户属性
  }) async {
    try {
      // 构建新的消息列表
      final List<Map<String, dynamic>> updatedMessages = [];
      // 如果有提示词，先添加 system role
      if (systemPrompt != null && systemPrompt.isNotEmpty) {
        updatedMessages.add({
          'role': 'system',
          'content': systemPrompt,
        });
      }

      // 如果有用户属性，可以作为 user 的一个"隐式指令"传进去
      if (userProperties != null && userProperties.isNotEmpty) {
        updatedMessages.add({
          'role': 'user',
          'content': '【用户属性】$userProperties',
        });
      }
      // 添加原始消息
      updatedMessages.addAll(messages);
      final result = await _channel.invokeMethod<String>(
        'sendMessage',
        {
          'messages': updatedMessages,
        },
      );

      if (result == null) {
        throw ChatApiException('发送消息失败: 结果为空');
      }

      return result;
    } catch (e) {
      throw ChatApiException('发送消息失败: $e');
    }
  }

  /// 发送消息（流式输出）
  ///
  /// [messages] 消息列表
  ///
  /// 返回一个布尔值，表示请求是否已开始
  Future<bool> sendMessageStream({
    required List<Map<String, dynamic>> messages,
    String? systemPrompt, //提示词
    String? userProperties, //用户属性
  }) async {
    try {
      // 构建新的消息列表
      final List<Map<String, dynamic>> updatedMessages = [];
      // 如果有提示词，先添加 system role
      if (systemPrompt != null && systemPrompt.isNotEmpty) {
        updatedMessages.add({
          'role': 'system',
          'content': systemPrompt,
        });
      }

      // 如果有用户属性，可以作为 user 的一个"隐式指令"传进去
      if (userProperties != null && userProperties.isNotEmpty) {
        updatedMessages.add({
          'role': 'user',
          'content': '【用户属性】$userProperties',
        });
      }
      // 添加原始消息
      updatedMessages.addAll(messages);
      final result = await _channel.invokeMethod<bool>(
        'sendMessageStream',
        {
          'messages': updatedMessages,
        },
      );

      return result ?? false;
    } catch (e) {
      throw ChatApiException('发送流式消息失败: $e');
    }
  }

  /// 发送函数调用结果
  ///
  /// [messages] 消息列表
  /// [functionCall] 函数调用信息
  /// [functionResult] 函数调用结果
  ///
  /// 返回一个布尔值，表示请求是否已开始
  Future<bool> sendFunctionCallResult({
    required List<Map<String, dynamic>> messages,
    required Map<String, dynamic> functionCall,
    required String functionResult,
  }) async {
    try {
      final result = await _channel.invokeMethod<bool>(
        'sendFunctionCallResult',
        {
          'messages': messages,
          'functionCall': functionCall,
          'functionResult': functionResult,
        },
      );

      return result ?? false;
    } catch (e) {
      throw ChatApiException('发送函数调用结果失败: $e');
    }
  }

  /// 取消当前流式请求
  Future<bool> cancelCurrentStream() async {
    try {
      final result = await _channel.invokeMethod<bool>('cancelCurrentStream');
      return result ?? false;
    } catch (e) {
      throw ChatApiException('取消请求失败: $e');
    }
  }

  /// 从JSON字符串解析函数调用
  Map<String, dynamic> parseFunctionCall(String functionCallJson) {
    try {
      return json.decode(functionCallJson) as Map<String, dynamic>;
    } catch (e) {
      throw ChatApiException('解析函数调用失败: $e');
    }
  }

  /// 初始化MCP客户端
  ///
  /// [serverUrl] MCP服务器WebSocket地址
  ///
  /// 返回一个布尔值，表示请求是否已开始初始化（实际初始化过程是异步的）
  Future<bool> initializeMcpClient(String serverUrl) async {
    try {
      final result = await _channel.invokeMethod<bool>(
        'initializeMcpClient',
        {'serverUrl': serverUrl},
      );

      return result ?? false;
    } catch (e) {
      throw ChatApiException('初始化MCP客户端失败: $e');
    }
  }

  /// 检查MCP客户端是否已初始化
  Future<bool> isMcpInitialized() async {
    try {
      final result = await _channel.invokeMethod<bool>('isMcpInitialized');
      return result ?? false;
    } catch (e) {
      throw ChatApiException('检查MCP客户端状态失败: $e');
    }
  }

  /// 关闭MCP客户端
  Future<bool> closeMcpClient() async {
    try {
      final result = await _channel.invokeMethod<bool>('closeMcpClient');
      return result ?? false;
    } catch (e) {
      throw ChatApiException('关闭MCP客户端失败: $e');
    }
  }

  /// 处理MCP工具调用
  ///
  /// [functionCall] 函数调用信息，必须包含name和arguments字段
  ///
  /// 返回工具调用结果
  Future<String> handleMcpToolCall(Map<String, dynamic> functionCall) async {
    try {
      final result = await _channel.invokeMethod<String>(
        'handleMcpToolCall',
        {'functionCall': jsonEncode(functionCall)},
      );

      return result ?? "处理MCP工具调用失败: 结果为空";
    } catch (e) {
      throw ChatApiException('处理MCP工具调用失败: $e');
    }
  }

  /// 处理函数调用（自动处理本地函数和MCP工具）
  ///
  /// 这是一个辅助方法，用于简化函数调用处理流程：
  /// 1. MCP工具会被自动处理，不会通过回调返回
  /// 2. 只有本地函数才需要手动处理
  /// 3. 提供统一的处理接口
  ///
  /// 参数:
  /// [functionCall] 函数调用信息
  /// [messages] 消息上下文
  /// [localFunctionHandler] 本地函数处理器，接收函数名和参数，返回处理结果
  ///
  /// 返回值:
  /// 布尔值表示是否成功处理（已将结果发送回OpenAI）
  Future<bool> handleFunctionCall({
    required Map<String, dynamic> functionCall,
    required List<Map<String, dynamic>> messages,
    required Future<String> Function(
            String name, Map<String, dynamic> arguments)
        localFunctionHandler,
  }) async {
    final name = functionCall['name'] as String;
    final argumentsJson = functionCall['arguments'] as String;

    // 解析参数
    Map<String, dynamic> arguments;
    try {
      arguments = json.decode(argumentsJson) as Map<String, dynamic>;
    } catch (e) {
      arguments = <String, dynamic>{};
    }

    try {
      // 调用本地函数处理器
      final result = await localFunctionHandler(name, arguments);

      // 发送结果回ChatAPI
      return sendFunctionCallResult(
        messages: messages,
        functionCall: functionCall,
        functionResult: result,
      );
    } catch (e) {
      throw ChatApiException('处理函数调用失败: $e');
    }
  }
}