vtorio/app/lib/excel-import/websocket-server.ts

import { WebSocketServer, WebSocket } from 'ws';
import { Server } from 'http';
import { ImportProgress } from './types';

export class ImportProgressServer {
  private wss: WebSocketServer | null = null;
  private clients: Set<WebSocket> = new Set();
  private static instance: ImportProgressServer | null = null;
  private port: number = 8081;
  private isInitialized: boolean = false;

  private constructor() {
    // Private constructor for singleton pattern
  }

  public static getInstance(): ImportProgressServer {
    if (!ImportProgressServer.instance) {
      ImportProgressServer.instance = new ImportProgressServer();
    }
    return ImportProgressServer.instance;
  }

  public initialize(): void {
    if (this.isInitialized) {
      console.log('WebSocket server already initialized');
      return;
    }

    try {
      // Try to create WebSocket server on the specified port
      this.wss = new WebSocketServer({ port: this.port });

      this.setupWebSocketHandlers();
      this.isInitialized = true;
      console.log(`WebSocket server started on port ${this.port}`);

    } catch (error: any) {
      if (error.code === 'EADDRINUSE') {
        console.log(`Port ${this.port} is already in use, using existing server`);
        // Server is already running, we'll use the existing one
        this.isInitialized = true;
      } else {
        console.error('Failed to start WebSocket server:', error);
        throw error;
      }
    }
  }

  private setupWebSocketHandlers(): void {
    if (!this.wss) return;

    this.wss.on('connection', (ws: WebSocket) => {
      console.log('New WebSocket connection established');
      this.clients.add(ws);

      ws.on('close', () => {
        console.log('WebSocket connection closed');
        this.clients.delete(ws);
      });

      ws.on('error', (error) => {
        console.error('WebSocket error:', error);
        this.clients.delete(ws);
      });
    });
  }

  // Alternative method to attach to existing HTTP server
  attachToServer(server: Server): void {
    if (this.wss) {
      this.wss.close();
    }

    this.wss = new WebSocketServer({
      server,
      path: '/api/imports/progress'
    });

    this.wss.on('connection', (ws: WebSocket, request) => {
      console.log('New WebSocket connection on import progress endpoint');
      this.clients.add(ws);

      const url = new URL(request.url || '', `http://${request.headers.host}`);
      const importId = url.searchParams.get('importId');

      if (importId) {
        ws.send(JSON.stringify({
          type: 'connected',
          importId: parseInt(importId),
          message: 'Connected to import progress updates'
        }));
      }

      ws.on('close', () => {
        console.log('WebSocket connection closed');
        this.clients.delete(ws);
      });

      ws.on('error', (error) => {
        console.error('WebSocket error:', error);
        this.clients.delete(ws);
      });
    });
  }

  broadcastProgress(importId: number, progress: ImportProgress): void {
    const message = JSON.stringify({
      type: 'progress',
      importId,
      progress
    });

    this.clients.forEach(client => {
      if (client.readyState === WebSocket.OPEN) {
        client.send(message);
      }
    });
  }

  broadcastError(importId: number, error: string): void {
    const message = JSON.stringify({
      type: 'error',
      importId,
      error
    });

    this.clients.forEach(client => {
      if (client.readyState === WebSocket.OPEN) {
        client.send(message);
      }
    });
  }

  broadcastComplete(importId: number, result: any): void {
    const message = JSON.stringify({
      type: 'complete',
      importId,
      result
    });

    this.clients.forEach(client => {
      if (client.readyState === WebSocket.OPEN) {
        client.send(message);
      }
    });
  }

  close(): void {
    if (this.wss) {
      this.wss.close();
      this.clients.clear();
      this.isInitialized = false;
    }
  }

  isServerInitialized(): boolean {
    return this.isInitialized;
  }
}

// Export a singleton instance
export const progressServer = ImportProgressServer.getInstance();