Core Concepts

function handleMessage(message) {
  if (message.action === 'forceDisconnect') {
    console.log('Connection displaced:', message.reason);

    // Notify user that connection was lost
    showAlert('Connection lost - another device connected with your credentials');

    // Optionally attempt reconnection if allowed
    if (message.reconnectAllowed) {
      console.log('Reconnection allowed, will attempt to reconnect...');
      setTimeout(() => connect(), 5000);
    }
  }
}

function handlePaymentVoided(message) {
  const { transactionId, reason, originalPaymentResponse } = message;

  console.log(`Payment ${transactionId} was automatically voided`);
  console.log(`Reason: ${reason}`);
  console.log(`Original amount: ${originalPaymentResponse.amount}`);

  // Update order to require new payment
  updateOrderStatus(transactionId, 'VOIDED');

  // Alert staff with clear messaging
  showAlert(
    `Payment for ${originalPaymentResponse.amount} ${originalPaymentResponse.currency} ` +
    `was voided: Terminal reconnected too late. Please retry the payment.`
  );

  // Log for audit trail
  logVoidedPayment({
    transactionId,
    reason,
    originalAmount: originalPaymentResponse.amount,
    voidedAt: message.timestamp
  });
}

const BASE_URL = 'https://{your-api-endpoint}';

// Query transaction status after reconnection
// See Authentication docs for generateAuthHeaders implementation
async function checkTransactionStatus(transactionId) {
  const path = `/v1/transactions/${transactionId}`;
  const headers = generateAuthHeaders('GET', path);

  const response = await fetch(`${BASE_URL}${path}`, {
    method: 'GET',
    headers
  });

  const transaction = await response.json();

  if (transaction.status === 'COMPLETED') {
    console.log(`Payment was successful: ${transactionId}`);
    console.log(`Amount: ${transaction.amount} ${transaction.currency}`);
    // Update your order accordingly
    updateOrderStatus(transactionId, 'PAID');
  } else if (transaction.status === 'FAILED') {
    console.log(`Payment failed: ${transaction.errorMessage}`);
    // Prompt for retry
    promptPaymentRetry(transactionId);
  } else if (transaction.status === 'PENDING') {
    console.log('Payment still processing...');
    // Check again later
  }

  return transaction;
}

// On reconnection, check any pending transactions
async function onReconnect(pendingTransactionIds) {
  for (const txnId of pendingTransactionIds) {
    await checkTransactionStatus(txnId);
  }
}