// 1. Verifikasi Webhook Meta (GET)
app.get('/webhook/meta', (req, res) => {
  const mode = req.query['hub.mode'];
  const token = req.query['hub.verify_token'];
  const challenge = req.query['hub.challenge'];

  if (mode === 'subscribe' && token === process.env.META_VERIFY_TOKEN) {
    return res.status(200).send(challenge);
  }
  res.sendStatus(403);
});

// 2. Menerima Lead Masuk (POST)
app.post('/webhook/meta', async (req, res) => {
  const body = req.body;
  if (body.object === 'page') {
    for (const entry of body.entry) {
      for (const change of entry.changes) {
        if (change.field === 'leadgen') {
          const leadgenId = change.value.leadgen_id;
          const leadData = await fetch(`https://graph.facebook.com/v19.0/${leadgenId}?access_token=${process.env.META_ACCESS_TOKEN}`);
          const json = await leadData.json();
          saveLeadToCRM(json);
        }
      }
    }
    return res.status(200).send('EVENT_RECEIVED');
  }
  res.sendStatus(404);
});