HTTP Quick Start

const crypto = require('crypto');

const API_KEY = process.env.MODULUS_API_KEY;
const API_SECRET = process.env.MODULUS_API_SECRET;
const BASE_URL = 'https://{your-api-endpoint}';

/**
 * Generate authentication headers for HTTP API requests
 */
function generateAuthHeaders(method, path, body = null) {
  const timestamp = new Date().toISOString();

  // SHA256 hash of body (empty string for GET)
  const bodyString = body ? JSON.stringify(body) : '';
  const bodyHash = crypto
    .createHash('sha256')
    .update(bodyString)
    .digest('hex');

  // Construct string to sign
  const stringToSign = `${method}\n${path}\n${timestamp}\n${bodyHash}`;

  // Compute HMAC-SHA256 signature
  const signature = crypto
    .createHmac('sha256', API_SECRET)
    .update(stringToSign)
    .digest('base64');

  return {
    'Content-Type': 'application/json',
    'x-api-key': API_KEY,
    'x-timestamp': timestamp,
    'x-signature': signature
  };
}

/**
 * Step 1: Get available terminals
 */
async function getTerminals() {
  const path = '/v1/terminals';
  const headers = generateAuthHeaders('GET', path);

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

  if (!response.ok) {
    throw new Error(`Failed to get terminals: ${response.status}`);
  }

  return response.json();
}

/**
 * Step 2: Initiate a payment
 */
async function createPayment(terminalId, paymentData) {
  const path = `/v1/terminals/${terminalId}/payments`;
  const headers = generateAuthHeaders('POST', path, paymentData);

  const response = await fetch(`${BASE_URL}${path}`, {
    method: 'POST',
    headers,
    body: JSON.stringify(paymentData)
  });

  return response.json();
}

/**
 * Step 3: Check transaction status
 */
async function getTransaction(transactionId) {
  const path = `/v1/transactions/${transactionId}`;
  const headers = generateAuthHeaders('GET', path);

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

  return response.json();
}

// Main flow
async function main() {
  try {
    // 1. Discover terminals
    console.log('Getting terminals...');
    const terminalsResponse = await getTerminals();
    console.log(`Found ${terminalsResponse.count} terminal(s)`);

    if (terminalsResponse.terminals.length === 0) {
      console.log('No terminals available');
      return;
    }

    const terminal = terminalsResponse.terminals[0];
    console.log(`Using terminal: ${terminal.deviceId}`);

    // 2. Initiate payment
    console.log('Initiating payment...');
    const paymentResult = await createPayment(terminal.deviceId, {
      transactionId: `TXN-${Date.now()}`,
      amount: '99.99',
      currency: 'USD',
      paymentMethod: 'CARD',
      products: [
        { id: 'PROD-001', name: 'Widget', price: '99.99', quantity: 1 }
      ],
      metadata: { orderId: 'ORD-12345' }
    });

    console.log('Payment result:', paymentResult.status);

    if (paymentResult.paymentResponse) {
      console.log('Authorization:', paymentResult.paymentResponse.authorizationCode);
    }

    // 3. Optionally check transaction status
    if (paymentResult.transactionId) {
      console.log('Checking transaction status...');
      const txn = await getTransaction(paymentResult.transactionId);
      console.log('Transaction status:', txn.status);
    }

  } catch (error) {
    console.error('Error:', error.message);
  }
}

main();