WhatsApp + SMS fallback

 App event  →  WhatsApp send
                    │
         Webhook: delivered / read?    (wait up to 60 s)
                    │
          Yes                 No / timeout
                                    │
                              SMS send

import { Robase } from '@robase/node';
import WhatsApp from 'my-whatsapp-sdk';
import Bull from 'bull';

const pm = new Robase(process.env.ROBASE_API_KEY!);
const wa = new WhatsApp(process.env.WA_TOKEN);
const fallbackQueue = new Bull('wa-fallback');

async function notify(userId: string, body: { short: string; rich: string }) {
  const user = await db.users.get(userId);
  let wa_message_id: string | null = null;

  // 1. Try WhatsApp first.
  if (user.whatsapp_opted_in) {
    try {
      const { id } = await wa.send({ to: user.phone, body: body.rich });
      wa_message_id = id;
    } catch (e) {
      console.warn('wa send failed, fallback immediate', e);
      return smsFallback(user, body.short);
    }
  } else {
    return smsFallback(user, body.short);
  }

  // 2. Schedule the SMS fallback for 60s later — cancel if WhatsApp delivers.
  await fallbackQueue.add(
    { user_id: userId, message: body.short, wa_message_id },
    { delay: 60_000, jobId: `fallback-${wa_message_id}` }
  );
}

async function smsFallback(user: { phone: string }, body: string) {
  await pm.sms.send(
    { to: user.phone, from: 'SHUTTLERS', body },
    `fallback-${user.phone}-${Date.now()}`,
  );
}

// WhatsApp webhook: cancel the fallback when delivered.
app.post('/webhooks/whatsapp', async (req, res) => {
  if (!verifyWhatsApp(req)) return res.status(401).end();
  const event = req.body;
  if (event.type === 'message.delivered') {
    await fallbackQueue.removeJobs(`fallback-${event.message_id}`);
  }
  res.status(200).end();
});

// Fallback worker.
fallbackQueue.process(async (job) => {
  const { user_id, message } = job.data;
  const user = await db.users.get(user_id);
  await pm.sms.send({ to: user.phone, from: 'SHUTTLERS', body: message }, `fb-${job.id}`);
});

await notify(user.id, {
  rich:  `*Your ride is on its way* 🚗\n\nDriver: ${driver.name}\nPlate: ${vehicle.plate}\n\nTrack: https://shut.ng/t/${trip.id}`,
  short: `Your ride is here. Driver: ${driver.name}. Plate: ${vehicle.plate}. Track: shut.ng/t/${trip.id}`,
});