/**
 * 用户在线状态管理器
 * 基于WebSocket心跳检测实现
 */

class PresenceManager {
  constructor() {
    this.ws = null;
    this.heartbeatTimer = null;
    this.reconnectTimer = null;
    this.heartbeatInterval = 30000; // 30秒心跳
    this.reconnectInterval = 5000; // 5秒重连
    this.isConnected = false;
    this.userId = null;
    this.statusCallbacks = new Map(); // 存储状态变化回调
    this.onlineStatusCache = new Map(); // 缓存在线状态
    this.messageCallbacks = []; // 存储消息回调（用于已读回执等）
    
    // WebSocket服务器地址（使用实际的聊天WebSocket服务）
    this.wsUrl = 'ws://localhost:8083/ws/chat';
    this.httpUrl = 'http://localhost:8083/api/online'; // HTTP API地址
  }
  
  /**
   * 连接WebSocket
   * @param {String} userId 当前用户ID
   */
  connect(userId) {
    if (this.isConnected || !userId) {
      return;
    }
    
    this.userId = userId;
    
    try {
      // uni-app的WebSocket API
      this.ws = uni.connectSocket({
        url: `${this.wsUrl}?userId=${userId}`,
        success: () => {
          console.log('🔌 WebSocket连接请求已发送');
        },
        fail: (err) => {
          console.error('❌ WebSocket连接失败:', err);
          this.scheduleReconnect();
        }
      });
      
      // 监听连接打开
      uni.onSocketOpen(() => {
        console.log('✅ WebSocket已连接');
        this.isConnected = true;
        this.startHeartbeat();
      });
      
      // 监听消息
      uni.onSocketMessage((res) => {
        this.handleMessage(res.data);
      });
      
      // 监听错误
      uni.onSocketError((err) => {
        console.error('❌ WebSocket错误:', err);
        this.isConnected = false;
        this.scheduleReconnect();
      });
      
      // 监听关闭
      uni.onSocketClose(() => {
        console.log('🔌 WebSocket已关闭');
        this.isConnected = false;
        this.stopHeartbeat();
        this.scheduleReconnect();
      });
      
    } catch (error) {
      console.error('❌ WebSocket连接异常:', error);
      this.scheduleReconnect();
    }
  }
  
  /**
   * 处理接收到的消息
   */
  handleMessage(data) {
    try {
      const message = typeof data === 'string' ? JSON.parse(data) : data;
      
      switch (message.type) {
        case 'PONG':
          // 心跳响应
          console.log('💓 收到心跳响应');
          break;
          
        case 'ONLINE':
          // 用户上线通知
          if (message.fromUserId) {
            this.onlineStatusCache.set(String(message.fromUserId), true);
            this.notifyStatusChange(String(message.fromUserId), 'online');
          }
          break;
          
        case 'OFFLINE':
          // 用户离线通知
          if (message.fromUserId) {
            this.onlineStatusCache.set(String(message.fromUserId), false);
            this.notifyStatusChange(String(message.fromUserId), 'offline');
          }
          break;
          
        case 'STATUS_UPDATE':
          // 用户状态更新
          if (message.userId) {
            const status = message.online ? 'online' : 'offline';
            this.onlineStatusCache.set(String(message.userId), message.online);
            this.notifyStatusChange(String(message.userId), status);
          }
          break;
          
        default:
          // 其他消息类型，调用注册的回调
          if (this.messageCallbacks && this.messageCallbacks.length > 0) {
            this.messageCallbacks.forEach(callback => {
              try {
                callback(message);
              } catch (err) {
                console.error('❌ 消息回调执行失败:', err);
              }
            });
          }
          break;
      }
    } catch (error) {
      console.error('❌ 消息解析失败:', error);
    }
  }
  
  /**
   * 通过HTTP API查询用户在线状态
   * @param {String} userId 目标用户ID
   * @return {Promise<Boolean>} 是否在线
   */
  async queryOnlineStatus(userId) {
    try {
      const [err, res] = await uni.request({
        url: `${this.httpUrl}/checkStatus`,
        method: 'GET',
        data: {
          userId: userId
        }
      });
      
      if (err) {
        console.error('❌ 查询在线状态失败:', err);
        return false;
      }
      
      if (res.data && res.data.code === 200) {
        const isOnline = res.data.data.online || false;
        this.onlineStatusCache.set(String(userId), isOnline);
        return isOnline;
      }
      
      return false;
    } catch (error) {
      console.error('❌ 查询在线状态异常:', error);
      return false;
    }
  }
  
  /**
   * 获取缓存的在线状态
   * @param {String} userId 目标用户ID
   * @return {Boolean|null} 在线状态，null表示未知
   */
  getCachedStatus(userId) {
    return this.onlineStatusCache.get(String(userId)) || null;
  }
  
  /**
   * 启动心跳
   */
  startHeartbeat() {
    this.stopHeartbeat();
    
    this.heartbeatTimer = setInterval(() => {
      if (this.isConnected) {
        this.sendMessage({
          type: 'PING',
          fromUserId: this.userId,
          timestamp: Date.now()
        });
      }
    }, this.heartbeatInterval);
  }
  
  /**
   * 停止心跳
   */
  stopHeartbeat() {
    if (this.heartbeatTimer) {
      clearInterval(this.heartbeatTimer);
      this.heartbeatTimer = null;
    }
  }
  
  /**
   * 发送消息
   */
  sendMessage(data) {
    if (!this.isConnected) {
      console.warn('⚠️ WebSocket未连接，无法发送消息');
      return;
    }
    
    try {
      uni.sendSocketMessage({
        data: JSON.stringify(data),
        fail: (err) => {
          console.error('❌ 发送消息失败:', err);
        }
      });
    } catch (error) {
      console.error('❌ 发送消息异常:', error);
    }
  }
  
  /**
   * 订阅用户状态
   * @param {String} targetUserId 目标用户ID
   */
  subscribeUser(targetUserId) {
    if (!this.isConnected || !targetUserId) {
      return;
    }
    
    this.sendMessage({
      type: 'SUBSCRIBE',
      fromUserId: this.userId,
      toUserId: targetUserId
    });
  }
  
  /**
   * 取消订阅用户状态
   * @param {String} targetUserId 目标用户ID
   */
  unsubscribeUser(targetUserId) {
    if (!this.isConnected || !targetUserId) {
      return;
    }
    
    this.sendMessage({
      type: 'UNSUBSCRIBE',
      fromUserId: this.userId,
      toUserId: targetUserId
    });
  }
  
  /**
   * 监听用户状态变化
   * @param {String} targetUserId 目标用户ID
   * @param {Function} callback 回调函数 (status) => {}
   */
  onStatusChange(targetUserId, callback) {
    if (!this.statusCallbacks.has(targetUserId)) {
      this.statusCallbacks.set(targetUserId, []);
    }
    this.statusCallbacks.get(targetUserId).push(callback);
    
    // 订阅该用户
    this.subscribeUser(targetUserId);
  }
  
  /**
   * 移除状态监听
   * @param {String} targetUserId 目标用户ID
   * @param {Function} callback 回调函数
   */
  offStatusChange(targetUserId, callback) {
    if (!this.statusCallbacks.has(targetUserId)) {
      return;
    }
    
    const callbacks = this.statusCallbacks.get(targetUserId);
    const index = callbacks.indexOf(callback);
    if (index > -1) {
      callbacks.splice(index, 1);
    }
    
    // 如果没有回调了，取消订阅
    if (callbacks.length === 0) {
      this.statusCallbacks.delete(targetUserId);
      this.unsubscribeUser(targetUserId);
    }
  }
  
  /**
   * 通知状态变化
   */
  notifyStatusChange(userId, status) {
    console.log(`👤 用户 ${userId} 状态变更: ${status}`);
    
    const callbacks = this.statusCallbacks.get(userId);
    if (callbacks && callbacks.length > 0) {
      callbacks.forEach(callback => {
        try {
          callback(status);
        } catch (error) {
          console.error('❌ 状态回调执行失败:', error);
        }
      });
    }
  }
  
  /**
   * 计划重连
   */
  scheduleReconnect() {
    if (this.reconnectTimer) {
      return;
    }
    
    console.log('🔄 将在5秒后重连...');
    this.reconnectTimer = setTimeout(() => {
      this.reconnectTimer = null;
      if (!this.isConnected && this.userId) {
        console.log('🔄 尝试重连...');
        this.connect(this.userId);
      }
    }, this.reconnectInterval);
  }
  
  /**
   * 断开连接
   */
  disconnect() {
    this.stopHeartbeat();
    
    if (this.reconnectTimer) {
      clearTimeout(this.reconnectTimer);
      this.reconnectTimer = null;
    }
    
    if (this.isConnected) {
      uni.closeSocket();
      this.isConnected = false;
    }
    
    this.statusCallbacks.clear();
    this.messageCallbacks = []; // 清空消息回调
    this.userId = null;
  }
  
  /**
   * 获取连接状态
   */
  getConnectionStatus() {
    return this.isConnected;
  }
}

// 导出单例
export default new PresenceManager();