import pg from 'pg';

export function registerSse(app) {
  const sseClients = [];

  app.get('/events', (req, res) => {
    res.set({
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      'Connection': 'keep-alive',
      'X-Accel-Buffering': 'no'   // 👈 desactiva el buffering en Nginx
    });

    res.flushHeaders();

    // Primer “hola”
    res.write('event: connected\ndata: {}\n\n');

    // 🔴  Mantén viva la conexión con pings cada 15 s
    const keepAlive = setInterval(() => {
      res.write(':\n\n');         // comentario SSE = ping
    }, 15000);

    sseClients.push(res);
    console.log('🟢 Cliente SSE conectado (%d)', sseClients.length);

    req.on('close', () => {
      clearInterval(keepAlive);   // limpia el intervalo
      sseClients.splice(sseClients.indexOf(res), 1);
      console.log('🔌 Cliente SSE desconectado (%d)', sseClients.length);
    });
  });



  const broadcast = (data) => {
    const payload = `data: ${data}\n\n`;
    sseClients.forEach((client) => client.write(payload));
  };

  const { Client: PgClient } = pg;
  const pgClient = new PgClient({ connectionString: process.env.DATABASE_URL });
  pgClient.connect()
    .then(() => pgClient.query('LISTEN sse_events'))
    .then(() => console.log('🛎️  Listening to Postgres channel sse_events'))
    .catch((err) => console.error('PG listen error', err));

  pgClient.on('notification', (msg) => {
    console.log('Notificación Postgres:', msg.payload);
    broadcast(msg.payload);
  });
}