import pako from 'pako';

import { AppState, AppStateStatus } from 'react-native';

import { api, WS_URL } from './api';
import { eventBus } from '@/core/events/EventBus';
import { MessageCategory, SystemMessageType, SystemMessageExtraData, MessageSegment } from '@/types/dto';
import { systemNotificationService } from '../notification/systemNotificationService';
import { showVerificationModal } from './verification';

export type WSMessageType =
  | 'chat'
  | 'message'
  | 'read'
  | 'typing'
  | 'recall'
  | 'notification'
  | 'announcement'
  | 'group_message'
  | 'group_typing'
  | 'group_notice'
  | 'group_mention'
  | 'group_read'
  | 'group_recall'
  | 'notice'
  | 'request'
  | 'meta'
  | 'private'
  | 'group'
  | 'follow'
  | 'like'
  | 'comment'
  | 'heartbeat'
  | 'pong'
  | 'message_sent'
  | 'message_recalled'
  | 'error'
  | 'call_incoming'
  | 'call_accepted'
  | 'call_rejected'
  | 'call_busy'
  | 'call_ready'
  | 'call_ended'
  | 'call_peer_muted'
  | 'call_invited'
  | 'call_answered_elsewhere'
  | 'call_participant_joined'
  | 'call_participant_left'
  | 'sync_required';

export interface WSCallIncomingMessage {
  type: 'call_incoming';
  call_id: string;
  conversation_id: string;
  caller_id: string;
  call_type: string;
  media_type?: string;
  created_at: number;
  lifetime?: number;
}

export interface WSCallAcceptedMessage {
  type: 'call_accepted';
  call_id: string;
  started_at: number;
}

export interface WSCallRejectedMessage {
  type: 'call_rejected';
  call_id: string;
  reason?: string;
}

export interface WSCallBusyMessage {
  type: 'call_busy';
  call_id: string;
}

export interface WSCallEndedMessage {
  type: 'call_ended';
  call_id: string;
  ended_by?: string;
  reason?: string;
  duration?: number;
  ended_at?: number;
}

export interface WSCallPeerMutedMessage {
  type: 'call_peer_muted';
  call_id: string;
  user_id: string;
  muted: boolean;
}

export interface WSCallInvitedMessage {
  type: 'call_invited';
  call_id: string;
  conversation_id: string;
  callee_id: string;
}

export interface WSCallAnsweredElsewhereMessage {
  type: 'call_answered_elsewhere';
  call_id: string;
  reason?: string;
}

export interface WSCallParticipantJoinedMessage {
  type: 'call_participant_joined';
  call_id: string;
  user_id: string;
}

export interface WSCallParticipantLeftMessage {
  type: 'call_participant_left';
  call_id: string;
  user_id: string;
  reason?: string;
}

export interface WSErrorMessage {
  type: 'error';
  code: string;
  message: string;
}

export interface WSChatMessage {
  type: 'chat';
  conversation_id: string;
  id: string;
  sender_id: string;
  seq: number;
  segments?: MessageSegment[];
  created_at: string;
}

export interface WSReadMessage {
  type: 'read';
  conversation_id: string;
  user_id: string;
  seq: number;
}

export interface WSTypingMessage {
  type: 'typing';
  conversation_id: string;
  user_id: string;
  is_typing: boolean;
}

export interface WSRecallMessage {
  type: 'recall';
  conversation_id: string;
  message_id: string;
}

export interface WSNotificationMessage {
  type: 'notification';
  id: string;
  sender_id?: string;
  receiver_id?: string;
  content: string;
  category?: MessageCategory;
  system_type?: SystemMessageType;
  extra_data?: SystemMessageExtraData;
  is_read?: boolean;
  created_at: string;
}

export interface WSAnnouncementMessage {
  type: 'announcement';
  id: string;
  sender_id?: string;
  receiver_id?: string;
  content: string;
  category?: MessageCategory;
  system_type?: SystemMessageType;
  extra_data?: SystemMessageExtraData;
  created_at: string;
}

export interface WSGroupMentionMessage {
  type: 'group_mention';
  group_id: string;
  conversation_id: string;
  message_id: string;
  from_user_id: string;
  content: string;
  mention_all: boolean;
  created_at: string;
}

export interface WSGroupChatMessage {
  type: 'group_message';
  conversation_id: string;
  group_id: string;
  id: string;
  sender_id: string;
  seq: number;
  segments?: MessageSegment[];
  created_at: string;
}

export interface WSGroupTypingMessage {
  type: 'group_typing';
  group_id: string;
  user_id: string;
  is_typing: boolean;
}

export type GroupNoticeType = 'member_join' | 'member_leave' | 'member_removed' | 'role_changed' | 'muted' | 'unmuted';

export interface WSGroupNoticeMessage {
  type: 'group_notice';
  notice_type: GroupNoticeType;
  group_id: string;
  data: {
    user_id?: string;
    operator_id?: string;
    role?: string;
    [key: string]: any;
  };
  timestamp: number;
  message_id?: string;
  seq?: number;
}

export interface WSGroupReadMessage {
  type: 'group_read';
  group_id: string;
  conversation_id: string;
  user_id: string;
  seq: number;
}

export interface WSGroupRecallMessage {
  type: 'group_recall';
  group_id: string;
  conversation_id: string;
  message_id: string;
}

export interface WSSyncRequiredMessage {
  type: 'sync_required';
}

export interface WSServerMessage {
  event_id?: number;
  type: string;
  ts?: number;
  payload?: any;
}

export type WSMessage =
  | WSChatMessage
  | WSReadMessage
  | WSTypingMessage
  | WSRecallMessage
  | WSNotificationMessage
  | WSAnnouncementMessage
  | WSGroupChatMessage
  | WSGroupTypingMessage
  | WSGroupNoticeMessage
  | WSGroupMentionMessage
  | WSGroupReadMessage
  | WSGroupRecallMessage
  | WSCallIncomingMessage
  | WSCallAcceptedMessage
  | WSCallRejectedMessage
  | WSCallBusyMessage
  | WSCallEndedMessage
  | WSCallPeerMutedMessage
  | WSCallInvitedMessage
  | WSCallAnsweredElsewhereMessage
  | WSCallParticipantJoinedMessage
  | WSCallParticipantLeftMessage
  | WSErrorMessage
  | WSSyncRequiredMessage;

type MessageHandler<T extends WSMessage = WSMessage> = (message: T) => void;
type ConnectionHandler = () => void;

// 发送队列中的消息
interface PendingMessage {
  id: string;
  type: string;
  payload: any;
  resolve: (value: any) => void;
  reject: (reason: any) => void;
  timestamp: number;
}

class WebSocketService {
  private ws: WebSocket | null = null;
  private isConnecting = false;
  private connected = false;
  private reconnectAttempts = 0;
  private maxReconnectAttempts = 20;
  private reconnectDelay = 3000;
  private reconnectTimer: ReturnType<typeof setTimeout> | null = null;
  private heartbeatTimer: ReturnType<typeof setTimeout> | null = null;
  private heartbeatInterval = 30000; // 30秒心跳
  private messageHandlers: Map<WSMessageType, MessageHandler[]> = new Map();
  private connectionHandlers: ConnectionHandler[] = [];
  private disconnectionHandlers: ConnectionHandler[] = [];
  private appStateSubscription: any = null;
  private lastAppState: AppStateStatus = 'active';
  private shouldRun = false;
  private lastEventId = '';
  private lastActivityAt = 0;

  // 发送队列
  private pendingMessages: PendingMessage[] = [];
  private messageIdCounter = 0;

  // 降级状态
  private isFallbackMode = false;
  private fallbackCheckTimer: ReturnType<typeof setTimeout> | null = null;

  // 通话中阻止后台断开（对方请求权限等场景会导致 AppState 切换，不应断开 WebSocket）
  preventDisconnectOnBackground = false;

  private getWSUrl(token: string | null): string {
    return `${WS_URL}?token=${encodeURIComponent(token || '')}&compress=1`;
  }

  async connect(): Promise<boolean> {
    this.shouldRun = true;
    if (this.isConnecting || this.isConnected()) {
      console.log('[WebSocket] Already connected or connecting');
      return true;
    }
    this.isConnecting = true;
    console.log('[WebSocket] Connecting...');

    try {
      const token = await api.getToken();
      if (!token) {
        console.log('[WebSocket] No token available, skipping connection');
        this.isConnecting = false;
        // 没有 token 时不要重连，等待用户登录后再连接
        return false;
      }

      const url = this.getWSUrl(token);
      console.log('[WebSocket] Connecting to:', url.replace(token, '***'));
      
      this.ws = new WebSocket(url);
      this.ws.binaryType = 'arraybuffer';

      this.ws.onopen = () => {
        console.log('[WebSocket] Connected successfully');
        this.isConnecting = false;
        this.connected = true;
        this.reconnectAttempts = 0;
        this.isFallbackMode = false;
        this.markActivity();
        this.startHeartbeat();
        this.connectionHandlers.forEach(h => h());

        // 发送队列中的消息
        this.flushPendingMessages();
      };

      this.ws.onmessage = (event) => {
        this.markActivity();
        this.handleIncoming(event.data);
      };

      this.ws.onerror = (error) => {
        console.error('[WebSocket] Error:', error);
      };

      this.ws.onclose = (event) => {
        console.log('[WebSocket] Closed:', event.code, event.reason);
        this.handleDisconnected();
      };

      return true;
    } catch (error) {
      console.error('[WebSocket] Connection error:', error);
      this.isConnecting = false;
      this.scheduleReconnect();
      return false;
    }
  }

  private handleIncoming(data: string | ArrayBuffer): void {
    let textData: string;
    if (typeof data === 'string') {
      textData = data;
    } else {
      // Binary frame — gzip decompress
      const decompressed = pako.inflate(new Uint8Array(data as ArrayBuffer));
      textData = new TextDecoder('utf-8').decode(decompressed);
    }
    // 后端 writePump 会将多条消息以 \n 分隔合并发送，需要逐条解析
    const lines = textData.split('\n');
    for (const line of lines) {
      const trimmed = line.trim();
      if (!trimmed) continue;
      try {
        const msg: WSServerMessage = JSON.parse(trimmed);
        this.processMessage(msg);
      } catch (error) {
        console.error('Failed to parse WebSocket message:', error);
      }
    }
  }

  private processMessage(msg: WSServerMessage): void {
      // 处理pong响应
      if (msg.type === 'pong') {
        return;
      }

      // 处理错误消息 - emit 到上层处理
      if (msg.type === 'error') {
        console.error('WebSocket error:', msg.payload);
        const errorCode: string = msg.payload?.code || 'unknown';
        const err: WSErrorMessage = {
          type: 'error',
          code: errorCode,
          message: msg.payload?.message || 'Unknown error',
        };
        if (errorCode === 'VERIFICATION_REQUIRED') {
          this.handleVerificationRequired();
        }
        this.emit('error', err);
        return;
      }

      // 处理消息发送成功响应
      if (msg.type === 'message_sent') {
        this.handleMessageSent(msg.payload);
        return;
      }

      // 处理消息撤回响应
      if (msg.type === 'message_recalled') {
        this.handleMessageRecalled(msg.payload);
        return;
      }

      // 保存事件ID用于断线重连
      if (msg.event_id) {
        this.lastEventId = String(msg.event_id);
      }

      // 分发事件
      this.dispatchServerMessage(msg);
  }

  private dispatchServerMessage(msg: WSServerMessage): void {
    const { type, payload } = msg;

    switch (type) {
      case 'chat_message':
        this.handleChatMessage(payload);
        break;
      case 'message_read':
        this.handleMessageRead(payload);
        break;
      case 'typing':
        this.handleTyping(payload);
        break;
      case 'message_recall':
        this.handleMessageRecall(payload);
        break;
      case 'group_notice':
        this.handleGroupNotice(payload);
        break;
      case 'system_notification':
        this.handleSystemNotification(payload);
        break;
      // Call signaling messages
      case 'call_incoming':
        this.handleCallIncoming(payload);
        break;
      case 'call_accepted':
        this.handleCallAccepted(payload);
        break;
      case 'call_rejected':
        this.handleCallRejected(payload);
        break;
      case 'call_busy':
        this.handleCallBusy(payload);
        break;
      case 'call_ended':
        this.handleCallEnded(payload);
        break;
      case 'call_peer_muted':
        this.handleCallPeerMuted(payload);
        break;
      case 'call_invited':
        this.handleCallInvited(payload);
        break;
      case 'call_answered_elsewhere':
        this.handleCallAnsweredElsewhere(payload);
        break;
      case 'sync_required':
        this.emit('sync_required', { type: 'sync_required' });
        break;
      default:
        console.log('Unknown message type:', type);
    }
  }

  private handleChatMessage(payload: any): void {
    const detailType = payload?.detail_type || 'private';
    const m = payload?.message || payload;
    
    if (detailType === 'group') {
      const gm: WSGroupChatMessage = {
        type: 'group_message',
        conversation_id: m.conversation_id,
        group_id: String(m.group_id ?? ''),
        id: m.id,
        sender_id: m.sender_id,
        seq: Number(m.seq || 0),
        segments: m.segments || [],
        created_at: m.created_at || new Date().toISOString(),
      };
      this.emit('group_message', gm);
    } else {
      const cm: WSChatMessage = {
        type: 'chat',
        conversation_id: m.conversation_id,
        id: m.id,
        sender_id: m.sender_id,
        seq: Number(m.seq || 0),
        segments: m.segments || [],
        created_at: m.created_at || new Date().toISOString(),
      };
      this.emit('chat', cm);
    }
  }

  private handleMessageRead(payload: any): void {
    const detailType = payload?.detail_type || 'private';
    
    if (detailType === 'group') {
      const m: WSGroupReadMessage = {
        type: 'group_read',
        group_id: String(payload.group_id ?? ''),
        conversation_id: payload.conversation_id,
        user_id: payload.user_id,
        seq: Number(payload.seq || 0),
      };
      this.emit('group_read', m);
    } else {
      const m: WSReadMessage = {
        type: 'read',
        conversation_id: payload.conversation_id,
        user_id: payload.user_id,
        seq: Number(payload.seq || 0),
      };
      this.emit('read', m);
    }
  }

  private handleTyping(payload: any): void {
    const detailType = payload?.detail_type || 'private';
    
    if (detailType === 'group') {
      const m: WSGroupTypingMessage = {
        type: 'group_typing',
        group_id: String(payload.group_id ?? ''),
        user_id: payload.user_id,
        is_typing: payload.is_typing !== false,
      };
      this.emit('group_typing', m);
    } else {
      const m: WSTypingMessage = {
        type: 'typing',
        conversation_id: payload.conversation_id,
        user_id: payload.user_id,
        is_typing: payload.is_typing !== false,
      };
      this.emit('typing', m);
    }
  }

  private handleMessageRecall(payload: any): void {
    const detailType = payload?.detail_type || 'private';
    
    if (detailType === 'group') {
      const m: WSGroupRecallMessage = {
        type: 'group_recall',
        group_id: String(payload.group_id ?? ''),
        conversation_id: payload.conversation_id,
        message_id: payload.message_id,
      };
      this.emit('group_recall', m);
    } else {
      const m: WSRecallMessage = {
        type: 'recall',
        conversation_id: payload.conversation_id,
        message_id: payload.message_id,
      };
      this.emit('recall', m);
    }
  }

  private handleGroupNotice(payload: any): void {
    const m: WSGroupNoticeMessage = {
      type: 'group_notice',
      notice_type: payload.notice_type,
      group_id: String(payload.group_id ?? ''),
      data: payload.data || {},
      timestamp: payload.timestamp || Date.now(),
      message_id: payload.message_id,
      seq: payload.seq,
    };
    this.emit('group_notice', m);
  }

  private handleSystemNotification(payload: any): void {
    const m: WSNotificationMessage = {
      type: 'notification',
      id: String(payload.id ?? ''),
      content: payload.content || '',
      sender_id: payload.sender_id,
      receiver_id: payload.receiver_id,
      category: payload.category,
      system_type: payload.system_type,
      extra_data: payload.extra_data || payload.extra || payload.data,
      is_read: !!payload.is_read,
      created_at: payload.created_at || new Date().toISOString(),
    };
    this.emit('notification', m);
    if (!m.is_read) {
      systemNotificationService.handleWSMessage(m as any).catch(() => {});
    }
  }

  // Call signaling handlers
  private handleCallIncoming(payload: any): void {
    console.log('[WSService] call_incoming payload:', JSON.stringify({
      call_type: payload.call_type,
      media_type: payload.media_type,
    }));
    const m: WSCallIncomingMessage = {
      type: 'call_incoming',
      call_id: payload.call_id,
      conversation_id: payload.conversation_id,
      caller_id: payload.caller_id,
      call_type: payload.media_type || payload.call_type,
      created_at: payload.created_at,
      lifetime: payload.lifetime,
    };
    this.emit('call_incoming', m);
  }

  private handleCallAccepted(payload: any): void {
    const m: WSCallAcceptedMessage = {
      type: 'call_accepted',
      call_id: payload.call_id,
      started_at: payload.started_at,
    };
    this.emit('call_accepted', m);
  }

  private handleCallRejected(payload: any): void {
    const m: WSCallRejectedMessage = {
      type: 'call_rejected',
      call_id: payload.call_id,
      reason: payload.reason,
    };
    this.emit('call_rejected', m);
  }

  private handleCallBusy(payload: any): void {
    const m: WSCallBusyMessage = {
      type: 'call_busy',
      call_id: payload.call_id,
    };
    this.emit('call_busy', m);
  }

  private handleCallEnded(payload: any): void {
    const m: WSCallEndedMessage = {
      type: 'call_ended',
      call_id: payload.call_id,
      ended_by: payload.ended_by,
      reason: payload.reason,
      duration: payload.duration,
      ended_at: payload.ended_at,
    };
    this.emit('call_ended', m);
  }

  private handleCallPeerMuted(payload: any): void {
    const m: WSCallPeerMutedMessage = {
      type: 'call_peer_muted',
      call_id: payload.call_id,
      user_id: payload.user_id,
      muted: payload.muted,
    };
    this.emit('call_peer_muted', m);
  }

  private handleCallInvited(payload: any): void {
    const m: WSCallInvitedMessage = {
      type: 'call_invited',
      call_id: payload.call_id,
      conversation_id: payload.conversation_id,
      callee_id: payload.callee_id,
    };
    this.emit('call_invited', m);
  }

  private handleCallAnsweredElsewhere(payload: any): void {
    const m: WSCallAnsweredElsewhereMessage = {
      type: 'call_answered_elsewhere',
      call_id: payload.call_id,
      reason: payload.reason,
    };
    this.emit('call_answered_elsewhere', m);
  }

  // Call signaling send methods
  sendCallInvite(conversationId: string, calleeId: string, callType: 'voice' | 'video' = 'voice'): void {
    this.sendFireAndForget('call_invite', {
      conversation_id: conversationId,
      callee_id: calleeId,
      call_type: callType,
    });
  }

  /**
   * 查询当前活跃的通话
   * 用于 WebSocket 重连后恢复通话状态
   */
  async getActiveCall(): Promise<any | null> {
    try {
      const { api } = await import('./api');
      const response = await api.get('/calls/active');
      return response.data || null;
    } catch (error) {
      console.log('[WSService] No active call found');
      return null;
    }
  }

  sendCallAnswer(callId: string): void {
    this.sendFireAndForget('call_answer', { call_id: callId });
  }

  sendCallReject(callId: string): void {
    this.sendFireAndForget('call_reject', { call_id: callId });
  }

  sendCallBusy(callId: string): void {
    this.sendFireAndForget('call_busy', { call_id: callId });
  }

  sendCallEnd(callId: string, reason?: string): void {
    this.sendFireAndForget('call_end', { call_id: callId, reason });
  }

  sendCallMute(callId: string, muted: boolean): void {
    this.sendFireAndForget('call_mute', { call_id: callId, muted });
  }

  sendCallReady(callId: string): void {
    this.sendFireAndForget('call_ready', { call_id: callId });
  }

  sendCallGroupInvite(groupId: string, conversationId: string, callType: string): void {
    this.sendFireAndForget('call_group_invite', {
      group_id: groupId,
      conversation_id: conversationId,
      call_type: callType,
    });
  }

  private handleMessageSent(payload: any): void {
    // 使用后端回带的 client_msg_id 精确匹配单条消息
    // 避免同会话连续发送时，第一条 ACK 误清掉第二条的 pending 记录
    const clientId = payload?.client_msg_id;
    let pendingMsg: PendingMessage | undefined;
    if (clientId) {
      pendingMsg = this.pendingMessages.find(p => p.id === clientId);
    }
    // 兜底：旧版后端不回带 client_msg_id 时，按 conversation_id + 类型匹配最旧一条
    if (!pendingMsg) {
      pendingMsg = this.pendingMessages.find(p =>
        p.type === 'chat' && p.payload.conversation_id === payload.conversation_id
      );
    }
    if (pendingMsg) {
      pendingMsg.resolve(payload);
      this.removePendingMessage(pendingMsg.id);
    }
  }

  private handleMessageRecalled(payload: any): void {
    const clientId = payload?.client_msg_id;
    let pendingMsg: PendingMessage | undefined;
    if (clientId) {
      pendingMsg = this.pendingMessages.find(p => p.id === clientId);
    }
    if (!pendingMsg) {
      pendingMsg = this.pendingMessages.find(p =>
        p.type === 'recall' && p.payload.message_id === payload.message_id
      );
    }
    if (pendingMsg) {
      pendingMsg.resolve(payload);
      this.removePendingMessage(pendingMsg.id);
    }
  }

  // 发送消息（支持降级到HTTP）
  async sendMessage(
    conversationId: string,
    detailType: 'private' | 'group',
    segments: MessageSegment[],
    replyToId?: string
  ): Promise<any> {
    const payload = {
      conversation_id: conversationId,
      detail_type: detailType,
      segments,
      reply_to_id: replyToId,
    };

    // 如果WebSocket连接正常，优先使用WebSocket发送
    if (this.isConnected() && !this.isFallbackMode) {
      return this.sendViaWebSocket('chat', payload);
    }

    // 降级到HTTP发送
    return this.sendViaHTTP(conversationId, detailType, segments, replyToId);
  }

  // 标记已读
  async markRead(conversationId: string, seq: number): Promise<void> {
    const payload = {
      conversation_id: conversationId,
      seq,
    };

    if (this.isConnected() && !this.isFallbackMode) {
      this.sendViaWebSocket('read', payload).catch(() => {});
    }
    // 已读不需要等待响应，失败也不影响
  }

  // 发送输入状态
  sendTyping(conversationId: string, isTyping: boolean): void {
    const payload = {
      conversation_id: conversationId,
      is_typing: isTyping,
    };

    if (this.isConnected() && !this.isFallbackMode) {
      this.sendViaWebSocket('typing', payload).catch(() => {});
    }
  }

  // 撤回消息
  async recallMessage(messageId: string): Promise<any> {
    const payload = { message_id: messageId };

    if (this.isConnected() && !this.isFallbackMode) {
      return this.sendViaWebSocket('recall', payload);
    }

    // 降级到HTTP
    const { api } = await import('./api');
    return api.post('/messages/delete_msg', { message_id: messageId });
  }

  // 通过WebSocket发送（fire-and-forget，不等待确认）
  private sendFireAndForget(type: string, payload: any): void {
    if (!this.ws || this.ws.readyState !== WebSocket.OPEN) {
      return;
    }
    const message = { type, payload };
    this.ws.send(JSON.stringify(message));
  }

  // 发送 ACK 确认（fire-and-forget）
  sendAck(messageId: string): void {
    this.sendFireAndForget('ack', { message_id: messageId });
  }

  // 通过WebSocket发送
  private sendViaWebSocket(type: string, payload: any): Promise<any> {
    return new Promise((resolve, reject) => {
      if (!this.ws || this.ws.readyState !== WebSocket.OPEN) {
        reject(new Error('WebSocket not connected'));
        return;
      }

      const messageId = `msg_${++this.messageIdCounter}_${Date.now()}`;
      // 携带 client_msg_id：用于服务器回 ACK / message_sent 时精确匹配单条消息
      const payloadWithId = { ...payload, client_msg_id: messageId };
      const message = {
        type,
        payload: payloadWithId,
      };

      // 添加到待处理队列
      const pendingMsg: PendingMessage = {
        id: messageId,
        type,
        payload: payloadWithId,
        resolve,
        reject,
        timestamp: Date.now(),
      };
      this.pendingMessages.push(pendingMsg);

      // 发送消息
      this.ws.send(JSON.stringify(message));

      // 设置超时
      setTimeout(() => {
        const index = this.pendingMessages.findIndex(p => p.id === messageId);
        if (index >= 0) {
          this.pendingMessages[index].reject(new Error('Message timeout'));
          this.removePendingMessage(messageId);
        }
      }, 10000);
    });
  }

  // 通过HTTP发送（降级方案）
  private async sendViaHTTP(
    conversationId: string,
    detailType: 'private' | 'group',
    segments: MessageSegment[],
    replyToId?: string
  ): Promise<any> {
    const { api } = await import('./api');
    const body: any = {
      detail_type: detailType,
      segments,
    };
    if (replyToId) {
      body.reply_to_id = replyToId;
    }
    return api.post(`/conversations/${conversationId}/messages`, body);
  }

  // 刷新待发送消息队列
  // 过期判定：
  //   - 单条 sendViaWebSocket 自带 10s 超时，正常情况下 pending 消息不会超过这么久
  //   - 重连后链路刚恢复时，距离"刚入队"的消息一律视为有效（避免把刚刚挂起的消息误清）
  //   - 兜底：超过 STALE_PENDING_MS（60s）一定视为过期丢弃
  private static readonly STALE_PENDING_MS = 60000;
  private flushPendingMessages(): void {
    if (this.pendingMessages.length === 0) return;

    const now = Date.now();
    const expiredMessages: PendingMessage[] = [];
    const validMessages: PendingMessage[] = [];

    // 分离过期和有效的消息
    for (const msg of this.pendingMessages) {
      const ageMs = now - msg.timestamp;
      const isStale = ageMs > WebSocketService.STALE_PENDING_MS;
      if (isStale) {
        expiredMessages.push(msg);
      } else {
        validMessages.push(msg);
      }
    }

    // 拒绝过期消息
    expiredMessages.forEach(msg => {
      msg.reject(new Error('Message expired'));
    });

    // 重新发送有效消息：直接复用原 client_msg_id，否则重连后服务端 ACK 无法回带到原 pending 记录
    // 注意：不能调 sendViaWebSocket（会重新生成 id 并入队），必须直接 ws.send
    this.pendingMessages = validMessages;
    for (let i = 0; i < validMessages.length; i++) {
      const msg = validMessages[i];
      if (!this.ws || this.ws.readyState !== WebSocket.OPEN) {
        // 链路断开，剩余消息留在队列等下次重连
        break;
      }
      try {
        this.ws.send(JSON.stringify({ type: msg.type, payload: msg.payload }));
      } catch {
        // ws.send 抛异常时 reject 并移出队列，避免无限残留
        msg.reject(new Error('WebSocket send failed on flush'));
        this.removePendingMessage(msg.id);
        continue;
      }
      // 重置 10s 超时
      setTimeout(() => {
        const index = this.pendingMessages.findIndex(p => p.id === msg.id);
        if (index >= 0) {
          this.pendingMessages[index].reject(new Error('Message timeout'));
          this.removePendingMessage(msg.id);
        }
      }, 10000);
    }
  }

  private removePendingMessage(id: string): void {
    const index = this.pendingMessages.findIndex(p => p.id === id);
    if (index >= 0) {
      this.pendingMessages.splice(index, 1);
    }
  }

  disconnect(): void {
    this.shouldRun = false;
    this.connected = false;
    this.isConnecting = false;
    this.isFallbackMode = false;
    this.reconnectAttempts = 0;  // 重置重连计数
    this.lastEventId = '';       // 重置事件ID
    this.lastActivityAt = 0;     // 重置活动时间
    
    if (this.ws) {
      this.ws.close();
      this.ws = null;
    }
    
    this.stopHeartbeat();
    this.stopReconnect();
    this.stopFallbackCheck();

    // 拒绝所有待处理消息
    this.pendingMessages.forEach(msg => {
      msg.reject(new Error('WebSocket disconnected'));
    });
    this.pendingMessages = [];
  }

  private scheduleReconnect(): void {
    if (this.reconnectAttempts >= this.maxReconnectAttempts) {
      // 超过最大重试次数，进入降级模式
      this.enterFallbackMode();
      return;
    }
    
    this.stopReconnect();
    console.log(`[WebSocket] Reconnecting in ${this.reconnectDelay}ms (attempt ${this.reconnectAttempts + 1}/${this.maxReconnectAttempts})`);
    this.reconnectTimer = setTimeout(() => {
      this.reconnectAttempts += 1;
      this.connect();
    }, this.reconnectDelay);
  }

  private stopReconnect() {
    if (this.reconnectTimer) {
      clearTimeout(this.reconnectTimer);
      this.reconnectTimer = null;
    }
  }

  isConnected(): boolean {
    return this.connected && this.ws?.readyState === WebSocket.OPEN;
  }

  isInFallbackMode(): boolean {
    return this.isFallbackMode;
  }

  // 进入降级模式
  private enterFallbackMode(): void {
    if (this.isFallbackMode) return;
    
    this.isFallbackMode = true;
    console.log('WebSocket entering fallback mode, using HTTP API');
    
    // 启动降级模式检查定时器，定期尝试重连WebSocket
    this.startFallbackCheck();
  }

  // 启动降级模式检查
  private startFallbackCheck(): void {
    this.stopFallbackCheck();
    this.fallbackCheckTimer = setInterval(() => {
      if (!this.isConnected()) {
        this.reconnectAttempts = 0;
        this.connect();
      }
    }, 30000); // 每30秒尝试重连
  }

  private stopFallbackCheck(): void {
    if (this.fallbackCheckTimer) {
      clearInterval(this.fallbackCheckTimer);
      this.fallbackCheckTimer = null;
    }
  }

  private emit<T extends WSMessageType>(type: T, message: Extract<WSMessage, { type: T }>) {
    const handlers = this.messageHandlers.get(type) || [];
    handlers.forEach(h => h(message as WSMessage));
  }

  on<T extends WSMessageType>(type: T, handler: MessageHandler<Extract<WSMessage, { type: T }>>): () => void {
    const list = this.messageHandlers.get(type) || [];
    list.push(handler as MessageHandler);
    this.messageHandlers.set(type, list);
    return () => {
      const current = this.messageHandlers.get(type) || [];
      const idx = current.indexOf(handler as MessageHandler);
      if (idx >= 0) current.splice(idx, 1);
    };
  }

  onConnect(handler: ConnectionHandler): () => void {
    this.connectionHandlers.push(handler);
    return () => {
      const i = this.connectionHandlers.indexOf(handler);
      if (i >= 0) this.connectionHandlers.splice(i, 1);
    };
  }

  onDisconnect(handler: ConnectionHandler): () => void {
    this.disconnectionHandlers.push(handler);
    return () => {
      const i = this.disconnectionHandlers.indexOf(handler);
      if (i >= 0) this.disconnectionHandlers.splice(i, 1);
    };
  }

  private setupAppStateListener(): void {
    if (this.appStateSubscription) return;
    this.lastAppState = AppState.currentState;
    this.appStateSubscription = AppState.addEventListener('change', (nextState: AppStateStatus) => {
      // 进入后台时断开 WebSocket，由 JPush 负责后台推送通知
      // 但如果正在通话中则不断开，避免对方请求权限等场景导致通话中断
      if (this.lastAppState === 'active' && nextState.match(/inactive|background/)) {
        if (this.preventDisconnectOnBackground) {
          console.log('[WebSocket] App entering background but call is active, skipping disconnect');
        } else {
          console.log('[WebSocket] App entering background, disconnecting');
          this.disconnect();
        }
      }
      // 回到前台时重连 WebSocket
      if (this.lastAppState.match(/inactive|background/) && nextState === 'active' && !this.isConnected()) {
        console.log('[WebSocket] App returning to foreground, reconnecting');
        this.reconnectAttempts = 0;
        this.connect();
      }
      this.lastAppState = nextState;
    });
  }

  async start(): Promise<boolean> {
    this.setupAppStateListener();
    return this.connect();
  }

  stop(): void {
    if (this.appStateSubscription) {
      this.appStateSubscription.remove();
      this.appStateSubscription = null;
    }
    this.disconnect();
  }

  private markActivity(): void {
    this.lastActivityAt = Date.now();
  }

  private handleVerificationRequired(): void {
    showVerificationModal();
  }

  private startHeartbeat(): void {
    this.stopHeartbeat();
    this.heartbeatTimer = setInterval(() => {
      if (this.ws?.readyState === WebSocket.OPEN) {
        this.ws.send(JSON.stringify({ type: 'ping' }));
      }
    }, this.heartbeatInterval);
  }

  private stopHeartbeat(): void {
    if (this.heartbeatTimer) {
      clearInterval(this.heartbeatTimer);
      this.heartbeatTimer = null;
    }
  }

  private handleDisconnected(): void {
    // 防止重复调用
    if (!this.connected && !this.ws && !this.isConnecting) {
      console.log('[WebSocket] Already disconnected, ignoring');
      return;
    }
    
    console.log('[WebSocket] Handling disconnect...');
    
    const wasActive = this.connected || this.ws != null || this.isConnecting;
    this.isConnecting = false;
    this.connected = false;
    
    if (this.ws) {
      this.ws.close();
      this.ws = null;
    }
    
    this.stopHeartbeat();
    
    if (wasActive) {
      this.disconnectionHandlers.forEach(h => h());
    }
    
    if (this.shouldRun) {
      this.scheduleReconnect();
    } else {
      console.log('[WebSocket] shouldRun is false, not reconnecting');
    }
  }
}

export const wsService = new WebSocketService();