import * as signalR from '@microsoft/signalr';
import { tokenManager } from '@/lib/api/client';
import { SIGNALR_CONFIG } from './config';

export type ConnectionState =
  | 'disconnected'
  | 'connecting'
  | 'connected'
  | 'reconnecting';

export class SignalRConnectionManager {
  private connection: signalR.HubConnection | null = null;
  private hubUrl: string;
  private reconnectAttempt = 0;
  private stateListeners: Array<(state: ConnectionState) => void> = [];

  constructor(hubUrl: string) {
    this.hubUrl = hubUrl;
  }

  async start(): Promise<void> {
    if (
      this.connection &&
      this.connection.state === signalR.HubConnectionState.Connected
    ) {
      console.log('[SignalR] Already connected');
      return;
    }

    const token = tokenManager.getAccessToken();
    if (!token) {
      console.warn('[SignalR] No access token found, cannot connect');
      return;
    }

    this.connection = new signalR.HubConnectionBuilder()
      .withUrl(this.hubUrl, {
        accessTokenFactory: () => token,
        // 备用方案：使用 query string（WebSocket 升级需要）
        // transport: signalR.HttpTransportType.WebSockets,
      })
      .configureLogging(
        signalR.LogLevel[
          SIGNALR_CONFIG.LOG_LEVEL as keyof typeof signalR.LogLevel
        ]
      )
      .withAutomaticReconnect(SIGNALR_CONFIG.RECONNECT_DELAYS)
      .build();

    this.setupConnectionHandlers();

    try {
      this.notifyStateChange('connecting');
      await this.connection.start();
      console.log(`[SignalR] Connected to ${this.hubUrl}`);
      this.notifyStateChange('connected');
      this.reconnectAttempt = 0;
    } catch (error) {
      console.error('[SignalR] Connection error:', error);
      this.notifyStateChange('disconnected');
      this.scheduleReconnect();
    }
  }

  async stop(): Promise<void> {
    if (this.connection) {
      await this.connection.stop();
      this.connection = null;
      this.notifyStateChange('disconnected');
      console.log('[SignalR] Disconnected');
    }
  }

  on(methodName: string, callback: (...args: any[]) => void): void {
    if (this.connection) {
      this.connection.on(methodName, callback);
    }
  }

  off(methodName: string, callback?: (...args: any[]) => void): void {
    if (this.connection && callback) {
      this.connection.off(methodName, callback);
    } else if (this.connection) {
      this.connection.off(methodName);
    }
  }

  async invoke(methodName: string, ...args: any[]): Promise<any> {
    if (
      !this.connection ||
      this.connection.state !== signalR.HubConnectionState.Connected
    ) {
      throw new Error('SignalR connection is not established');
    }

    return await this.connection.invoke(methodName, ...args);
  }

  onStateChange(listener: (state: ConnectionState) => void): () => void {
    this.stateListeners.push(listener);

    // 返回 unsubscribe 函数
    return () => {
      this.stateListeners = this.stateListeners.filter((l) => l !== listener);
    };
  }

  private setupConnectionHandlers(): void {
    if (!this.connection) return;

    this.connection.onclose((error) => {
      console.log('[SignalR] Connection closed', error);
      this.notifyStateChange('disconnected');
      this.scheduleReconnect();
    });

    this.connection.onreconnecting((error) => {
      console.log('[SignalR] Reconnecting...', error);
      this.notifyStateChange('reconnecting');
    });

    this.connection.onreconnected((connectionId) => {
      console.log('[SignalR] Reconnected', connectionId);
      this.notifyStateChange('connected');
      this.reconnectAttempt = 0;
    });
  }

  private scheduleReconnect(): void {
    if (this.reconnectAttempt >= SIGNALR_CONFIG.RECONNECT_DELAYS.length) {
      console.error('[SignalR] Max reconnect attempts reached');
      return;
    }

    const delay = SIGNALR_CONFIG.RECONNECT_DELAYS[this.reconnectAttempt];
    this.reconnectAttempt++;

    console.log(
      `[SignalR] Scheduling reconnect in ${delay}ms (attempt ${this.reconnectAttempt})`
    );

    setTimeout(() => {
      this.start();
    }, delay);
  }

  private notifyStateChange(state: ConnectionState): void {
    this.stateListeners.forEach((listener) => listener(state));
  }

  get connectionId(): string | null {
    return this.connection?.connectionId ?? null;
  }

  get state(): ConnectionState {
    if (!this.connection) return 'disconnected';

    switch (this.connection.state) {
      case signalR.HubConnectionState.Connected:
        return 'connected';
      case signalR.HubConnectionState.Connecting:
        return 'connecting';
      case signalR.HubConnectionState.Reconnecting:
        return 'reconnecting';
      default:
        return 'disconnected';
    }
  }
}