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'
    });
    res.flushHeaders();
    res.write(':\n\n');
    sseClients.push(res);

    res.on('close', () => {
      const idx = sseClients.indexOf(res);
      if (idx !== -1) sseClients.splice(idx, 1);
      res.end();
    });
  });

  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);
  });
}