Receive messages with webhooks

// A RevoplyAI webhook receiver on Express 4 or 5.
//
//   npm install express
//   REVOPLY_WEBHOOK_SECRET=whsec_… node express.mjs

import express from 'express';
import { verifyRevoplySignature } from '../verify.node.mjs';

const secret = process.env.REVOPLY_WEBHOOK_SECRET;
const app = express();

// Stands in for your database: remember the event ids you have handled.
const handled = new Set();

// #region route
// express.raw() on this route, registered before any app.use(express.json()): the signature
// covers the exact bytes we sent, and a parsed-then-re-serialised body is not those bytes.
app.post('/webhooks/revoply', express.raw({ type: 'application/json' }), (req, res) => {
  if (!verifyRevoplySignature(req.body, req.get('X-Revoply-Signature'), secret)) {
    return res.status(400).send('Invalid signature');
  }

  const event = JSON.parse(req.body.toString('utf8'));

  // The same event can arrive more than once: acknowledge a repeat and do nothing.
  if (handled.has(event.id)) return res.sendStatus(200);
  handled.add(event.id);

  // Answer within 10 seconds, then do the work.
  res.sendStatus(200);
  setImmediate(() => handleEvent(event));
});
// #endregion

// #region handle
function handleEvent(event) {
  // "Send test" posts sample data about nobody real, marked "test": true.
  if (event.test) {
    console.log(`test ${event.type} received`);
    return;
  }

  switch (event.type) {
    case 'message.received': {
      const { conversation, contact, message } = event.data;
      console.log(
        `${contact?.name ?? contact?.phone ?? 'A visitor'} wrote on ${conversation.channelType}:`,
      );
      console.log(message.text ?? `[${message.type}]`);
      break;
    }
    default:
      // A type you did not expect is still acknowledged; new events may be added.
      console.log(`ignored ${event.type}`);
  }
}
// #endregion

// The rest of the app may parse JSON as usual, registered after the webhook route.
app.use(express.json());

app.listen(3000, () => console.log('Listening on port 3000, path /webhooks/revoply'));