# WIA-FIN-012 Phase 4: Ecosystem Integration Specification

**Version:** 1.0.0  
**Status:** Final  
**Date:** 2025-01-15  
**Category:** Finance - Payment Systems

## Overview

This specification defines integration patterns for payment gateways, POS terminals, e-commerce platforms, mobile wallets, banking systems, and compliance frameworks.

## Payment Gateway Integration

### REST API Integration

```javascript
const paymentGateway = require('@wia/payment-gateway');

const client = new paymentGateway.Client({
  apiKey: 'sk_live_abc123',
  environment: 'production'
});

// Create payment
const payment = await client.payments.create({
  amount: 10000,
  currency: 'USD',
  payment_method: tokenId
});
```

### Webhook Integration

```javascript
app.post('/webhooks/payment', (req, res) => {
  const sig = req.headers['x-signature'];
  const event = paymentGateway.webhooks.verify(
    req.body,
    sig,
    webhookSecret
  );
  
  if (event.type === 'payment.succeeded') {
    // Handle successful payment
  }
  
  res.status(200).send('OK');
});
```

## POS Terminal Integration

### EMV Contact

```
1. Card Insertion
2. Application Selection (SELECT)
3. GPO (Get Processing Options)
4. Read Application Data
5. Cardholder Verification (PIN)
6. Terminal Risk Management
7. Card Risk Management
8. Online Authorization (ARQC)
9. Issuer Authentication (ARPC)
10. Transaction Complete (TC)
```

### Contactless (NFC)

```
1. Card Tap (< 500ms)
2. Application Selection
3. GPO with amount
4. CVM (No PIN for < $100)
5. Generate Cryptogram
6. Online/Offline Decision
7. Transaction Complete
```

## E-commerce Integration

### Hosted Payment Page

```html
<form action="https://gateway.com/checkout" method="POST">
  <input type="hidden" name="merchant_id" value="merch_123">
  <input type="hidden" name="amount" value="10000">
  <input type="hidden" name="return_url" value="https://merchant.com/callback">
  <button type="submit">Pay with Card</button>
</form>
```

### Direct API Integration

```javascript
// Client-side tokenization
const token = await wiaPayments.createToken({
  card: {
    number: cardNumber,
    exp_month: expMonth,
    exp_year: expYear,
    cvc: cvc
  }
});

// Server-side payment
const payment = await fetch('/api/charge', {
  method: 'POST',
  body: JSON.stringify({ token: token.id, amount: 10000 })
});
```

## Mobile Wallet Integration

### Apple Pay

```javascript
const paymentRequest = {
  countryCode: 'US',
  currencyCode: 'USD',
  supportedNetworks: ['visa', 'mastercard', 'amex'],
  merchantCapabilities: ['supports3DS'],
  total: {
    label: 'Merchant Name',
    amount: '100.00'
  }
};

const session = new ApplePaySession(3, paymentRequest);
session.begin();
```

### Google Pay

```javascript
const paymentDataRequest = {
  apiVersion: 2,
  apiVersionMinor: 0,
  allowedPaymentMethods: [{
    type: 'CARD',
    parameters: {
      allowedAuthMethods: ['PAN_ONLY', 'CRYPTOGRAM_3DS'],
      allowedCardNetworks: ['MASTERCARD', 'VISA']
    }
  }]
};

const paymentsClient = new google.payments.api.PaymentsClient({
  environment: 'PRODUCTION'
});
```

## PCI-DSS Compliance

### SAQ Types

- **SAQ A**: E-commerce, outsourced payment page
- **SAQ A-EP**: E-commerce, direct integration
- **SAQ B**: POS terminals only
- **SAQ C**: Payment application systems
- **SAQ D**: All other environments

### Required Controls

1. Firewall configuration
2. No default passwords
3. Protect cardholder data
4. Encrypt transmission
5. Anti-virus software
6. Secure systems
7. Restrict access
8. Unique IDs
9. Physical access restrictions
10. Track and monitor access
11. Test security systems
12. Security policy

## Testing Environments

### Test Cards

```
Visa (Approved):        4532 1234 5678 9010
Visa (Declined):        4532 1234 5678 9028
Mastercard (Approved):  5425 2334 3010 9903
Amex (Approved):        3782 822463 10005
```

### Sandbox Credentials

```
API Key: sk_test_abc123xyz789
Publishable Key: pk_test_def456uvw123
```

---

**弘익人間 - Benefit All Humanity**

*Complete integration ensures seamless payment experiences worldwide.*