Comprehensive comparison for technology in applications

const express = require('express');
const { Client, Config, CheckoutAPI } = require('@adyen/api-library');
const app = express();

app.use(express.json());

// Initialize Adyen client with configuration
const config = new Config();
config.apiKey = process.env.ADYEN_API_KEY;
config.merchantAccount = process.env.ADYEN_MERCHANT_ACCOUNT;
config.environment = 'TEST'; // Use 'LIVE' for production

const client = new Client({ config });
const checkout = new CheckoutAPI(client);

// Endpoint to create a payment session
app.post('/api/payments/sessions', async (req, res) => {
  try {
    const { amount, currency, returnUrl, reference, countryCode } = req.body;

    // Validate required fields
    if (!amount || !currency || !returnUrl || !reference) {
      return res.status(400).json({
        error: 'Missing required fields: amount, currency, returnUrl, reference'
      });
    }

    // Create payment session request
    const sessionRequest = {
      merchantAccount: config.merchantAccount,
      amount: {
        currency: currency,
        value: amount // Amount in minor units (e.g., cents)
      },
      reference: reference,
      returnUrl: returnUrl,
      countryCode: countryCode || 'US',
      shopperLocale: 'en-US',
      channel: 'Web',
      lineItems: req.body.lineItems || []
    };

    // Call Adyen API to create session
    const response = await checkout.sessions(sessionRequest);

    // Return session data to frontend
    res.json({
      sessionId: response.id,
      sessionData: response.sessionData
    });

  } catch (error) {
    console.error('Payment session creation failed:', error);
    
    // Handle specific Adyen API errors
    if (error.statusCode === 401) {
      return res.status(401).json({ error: 'Invalid API credentials' });
    }
    if (error.statusCode === 422) {
      return res.status(422).json({ error: 'Invalid payment data', details: error.message });
    }
    
    res.status(500).json({ error: 'Payment session creation failed' });
  }
});

// Webhook endpoint to handle payment notifications
app.post('/api/webhooks/adyen', async (req, res) => {
  try {
    const notificationRequest = req.body;
    const notificationItems = notificationRequest.notificationItems;

    // Process each notification item
    for (const item of notificationItems) {
      const notification = item.NotificationRequestItem;
      
      console.log('Received webhook:', {
        eventCode: notification.eventCode,
        success: notification.success,
        pspReference: notification.pspReference,
        merchantReference: notification.merchantReference
      });

      // Handle different event types
      if (notification.eventCode === 'AUTHORISATION') {
        if (notification.success === 'true') {
          // Payment authorized - fulfill order
          await fulfillOrder(notification.merchantReference);
        } else {
          // Payment failed - update order status
          await handleFailedPayment(notification.merchantReference);
        }
      }
    }

    // Always return [accepted] to acknowledge receipt
    res.status(200).send('[accepted]');

  } catch (error) {
    console.error('Webhook processing error:', error);
    res.status(500).send('[failed]');
  }
});

// Mock functions for order processing
async function fulfillOrder(reference) {
  console.log(`Fulfilling order: ${reference}`);
  // Implement your order fulfillment logic
}

async function handleFailedPayment(reference) {
  console.log(`Handling failed payment for: ${reference}`);
  // Implement your failure handling logic
}

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});