Payments Inside Mini Apps

function invokePaymentUI(tradeNO) {
  my.tradePay({
    tradeNO: tradeNO,
    success: (res) => {
      my.hideLoading();

      // NOTE: This is INDICATIVE only!
      if (res.resultCode === '9000') {
        // Show pending state, poll for confirmation
        showPendingState();
        pollPaymentStatus();
      } else if (res.resultCode === '6001') {
        // User cancelled
        showCancelledState();
      } else {
        // Other result - still poll backend
        pollPaymentStatus();
      }
    },
    fail: (err) => {
      my.hideLoading();
      handlePaymentError(err);
    }
  });
}

app.post('/webhooks/payment', async (req, res) => {
  // 1. Verify signature
  const isValid = verifyWebhookSignature(req.headers, req.body);
  if (!isValid) {
    return res.status(401).send('Invalid signature');
  }

  // 2. Extract payment info
  const { paymentId, paymentRequestId, result } = req.body;

  // 3. Find and update order (idempotent)
  const order = await findOrderByPaymentId(paymentId);
  if (!order) {
    console.error('Order not found for payment:', paymentId);
    return res.status(200).send('OK'); // Still acknowledge
  }

  // 4. Update only if not already final
  if (order.paymentStatus !== 'SUCCESS' && order.paymentStatus !== 'FAILED') {
    await updateOrder(order.id, {
      paymentStatus: result.resultStatus === 'S' ? 'SUCCESS' : 'FAILED',
      paymentResult: result
    });
  }

  // 5. Acknowledge receipt
  res.status(200).send('OK');
});

async function pollPaymentStatus() {
  const maxAttempts = 10;
  const intervalMs = 3000;

  for (let i = 0; i < maxAttempts; i++) {
    try {
      const status = await callBackend('/orders/' + orderId + '/status');

      if (status.paymentStatus === 'SUCCESS') {
        showSuccessState();
        return;
      } else if (status.paymentStatus === 'FAILED') {
        showFailedState();
        return;
      }

      // Still pending, wait and retry
      await sleep(intervalMs);

    } catch (error) {
      console.error('Status check failed:', error);
    }
  }

  // Max attempts reached
  showUnknownState();
}