Webhooks SMS: Recibe Notificaciones en Tiempo Real

{
  "event": "message_delivered",
  "messageId": "sms_1234567890",
  "phone": "+56912345678",
  "status": "delivered",
  "timestamp": "2026-03-01T10:05:00Z",
  "operator": "entel"
}

const express = require('express');
const crypto = require('crypto');
require('dotenv').config();

const app = express();
app.use(express.json());

// Logger para debugging
function logWebhook(event, data) {
  const timestamp = new Date().toISOString();
  console.log(`[${timestamp}] WEBHOOK_${event}:`, JSON.stringify(data, null, 2));
}

// Verificar firma del webhook (seguridad)
function verifyWebhookSignature(payload, signature) {
  const secret = process.env.LETEL_WEBHOOK_SECRET;
  const hash = crypto
    .createHmac('sha256', secret)
    .update(JSON.stringify(payload))
    .digest('hex');
  return hash === signature;
}

// Endpoint para recibir webhooks
app.post('/webhooks/sms', (req, res) => {
  try {
    const signature = req.headers['x-letel-signature'];
    const payload = req.body;

    // Verificar autenticidad del webhook
    if (!verifyWebhookSignature(payload, signature)) {
      logWebhook('SIGNATURE_FAILED', { signature, messageId: payload.messageId });
      return res.status(401).json({ error: 'Signature inválido' });
    }

    logWebhook('RECEIVED', payload);

    // Procesar diferentes eventos
    switch (payload.event) {
      case 'message_delivered':
        handleMessageDelivered(payload);
        break;
      case 'message_failed':
        handleMessageFailed(payload);
        break;
      case 'message_bounced':
        handleMessageBounced(payload);
        break;
      case 'sms_received':
        handleSmsReceived(payload);
        break;
      default:
        console.warn('Evento desconocido:', payload.event);
    }

    // Responder rápidamente al webhook
    res.json({ received: true });

  } catch (error) {
    logWebhook('ERROR', { error: error.message });
    res.status(500).json({ error: 'Error procesando webhook' });
  }
});

// Handlers para cada tipo de evento
function handleMessageDelivered(payload) {
  // Actualizar estado en base de datos
  console.log(`✓ SMS ${payload.messageId} entregado a ${payload.phone}`);
  // db.update('messages', { messageId: payload.messageId }, { status: 'delivered' });
}

function handleMessageFailed(payload) {
  console.error(`✗ SMS ${payload.messageId} falló: ${payload.error}`);
  // Reintentar o notificar al usuario
}

function handleMessageBounced(payload) {
  console.warn(`⚠ SMS ${payload.messageId} rechazado: ${payload.reason}`);
  // Marcar número como inválido
}

function handleSmsReceived(payload) {
  console.log(`← SMS recibido de ${payload.phone}: ${payload.message}`);
  // Procesar respuesta del usuario
}

app.listen(3000, () => {
  console.log('Webhook server escuchando en puerto 3000');
});

// 1. Logger detallado para debugging
class WebhookLogger {
  static logReceived(payload) {
    console.log('\n=== WEBHOOK RECIBIDO ===');
    console.log('Evento:', payload.event);
    console.log('Teléfono:', payload.phone);
    console.log('Message ID:', payload.messageId);
    console.log('Status:', payload.status);
    console.log('Timestamp:', payload.timestamp);
    if (payload.message) console.log('Mensaje:', payload.message);
    console.log('===========================\n');
  }

  static logProcessed(event, result) {
    console.log(`[${new Date().toISOString()}] Processed ${event}: ${JSON.stringify(result)}`);
  }
}

// 2. Testing con webhooks simulados
async function testWebhook() {
  const testPayload = {
    event: 'message_delivered',
    messageId: 'test-1234567890',
    phone: '+56912345678',
    status: 'delivered',
    timestamp: new Date().toISOString(),
    operator: 'entel'
  };

  console.log('Enviando webhook de prueba...');
  try {
    const response = await fetch('http://localhost:3000/webhooks/sms', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'x-letel-signature': 'test-signature'
      },
      body: JSON.stringify(testPayload)
    });
    console.log('Respuesta:', await response.json());
  } catch (error) {
    console.error('Error en test:', error.message);
  }
}

// 3. Usar curl para testing (desde terminal)
// curl -X POST http://localhost:3000/webhooks/sms \
//   -H "Content-Type: application/json" \
//   -H "x-letel-signature: test-sig" \
//   -d '{
//     "event": "message_delivered",
//     "messageId": "msg-123",
//     "phone": "+56912345678",
//     "status": "delivered"
//   }'

// 4. Servicio de monitoreo en tiempo real
class WebhookMonitor {
  constructor() {
    this.events = [];
    this.stats = {
      delivered: 0,
      failed: 0,
      bounced: 0,
      received: 0
    };
  }

  track(payload) {
    this.events.push({
      ...payload,
      receivedAt: new Date()
    });

    if (payload.event === 'message_delivered') this.stats.delivered++;
    else if (payload.event === 'message_failed') this.stats.failed++;
    else if (payload.event === 'message_bounced') this.stats.bounced++;
    else if (payload.event === 'sms_received') this.stats.received++;
  }

  getStats() {
    return {
      totalEvents: this.events.length,
      stats: this.stats,
      lastEvents: this.events.slice(-5)
    };
  }
}

// Usar en la app
const monitor = new WebhookMonitor();

app.get('/debug/stats', (req, res) => {
  res.json(monitor.getStats());
});