Handle a callback

try {
  const webhook = request.body;
  const invoice = await api.getInvoice(webhook.data.invoice_id);

  // Update intermediate state when useful.
  // Fulfill invoice.order_no exactly once only when status is completed.
  return response.status(200).send('OK');
} catch (error) {
  // A non-200 response causes Billions to retry the webhook.
  return response.status(500).send('Could not retrieve invoice');
}

try:
    invoice = api.get_invoice_from_webhook(webhook)

    # Update intermediate state when useful.
    # Fulfill invoice["order_no"] exactly once only when status is completed.
except Exception:
    # Return a non-200 response so Billions retries the webhook.
    raise

<?php

try {
    $webhook = json_decode(file_get_contents('php://input'), true, 512, JSON_THROW_ON_ERROR);
    $invoice = $api->getInvoice($webhook['data']['invoice_id']);

    // Update intermediate state when useful.
    // Fulfill $invoice['order_no'] exactly once only when status is completed.
} catch (Throwable $exception) {
    // Return a non-200 response so Billions retries the webhook.
}

curl --request GET \
  --url "https://api.billions.works/public/v1/invoices/$BILLIONS_INVOICE_ID" \
  --header "Content-Type: application/json" \
  --header "x-api-key: $BILLIONS_API_KEY"