Case Study: Payment System

Пример

**Payment flow с двухфазным capture:** ```typescript // Step 1: Authorize (reserve funds) const payment = await paymentService.authorize({ orderId: 'order_123', amount: { amount: 9999, currency: 'USD' }, // 99.99 paymentMethod: { type: 'card', token: 'tok_xxx' } }); // payment.status = 'authorized' // Funds reserved on customer's card // Step 2: Capture (charge) after fulfillment ready await paymentService.capture(payment.id); // payment.status = 'captured' // Money transferred // OR: Cancel if out of stock await paymentService.cancel(payment.id); // payment.status = 'cancelled' // Reservation released ```

Что вы узнали о Архитектура Payment System?

Пример

**PCI DSS requirements summary:** ``` 12 Requirements: 1. Install/maintain firewall 2. No vendor-supplied default passwords 3. Protect stored cardholder data 4. Encrypt transmission over networks 5. Use/update anti-virus 6. Develop secure systems 7. Restrict access to cardholder data 8. Assign unique IDs to users 9. Restrict physical access 10. Track/monitor network access 11. Regularly test security 12. Maintain security policy With tokenization (SAQ-A): → Only #12 applies fully → Minimal infrastructure requirements → Annual self-questionnaire (~20 questions) ```

Что вы узнали о PCI DSS Compliance?

Пример

**Stripe's idempotency implementation:** ```typescript // Stripe automatically handles idempotency const stripe = new Stripe(apiKey); // Same idempotency key = same result const payment1 = await stripe.paymentIntents.create( { amount: 1000, currency: 'usd', ... }, { idempotencyKey: 'order_123_attempt_1' } ); // Retry with same key returns cached result const payment2 = await stripe.paymentIntents.create( { amount: 1000, currency: 'usd', ... }, { idempotencyKey: 'order_123_attempt_1' } ); // payment1.id === payment2.id (same payment) ```

Что вы узнали о Idempotency: Предотвращение Дублирования?

Пример

**Daily reconciliation report:** ``` Reconciliation Report - 2024-01-15 ────────────────────────────────── Transactions processed: 1,234 Matched: 1,230 (99.7%) Unmatched: 4 Discrepancies: 2 Unmatched Internal → Stripe: • pay_abc123: $99.00 - No Stripe record (pending?) Unmatched Stripe → Internal: • ch_xyz789: $50.00 - Missing internal record • ch_def456: $25.00 - Missing internal record Amount Discrepancies: • pay_ghi012: Internal $100.00, Stripe $99.97 (diff: $0.03) Likely cause: Currency conversion rounding Status: NEEDS REVIEW Assigned to: finance-team@company.com ```

Что вы узнали о Ledger и Reconciliation?

Пример

**Chargeback prevention tips:** ```typescript // 1. Clear billing descriptor // Customer sees "MYSTORE" not "STRIPE*ABCD123" await stripe.paymentIntents.create({ amount: 1000, currency: 'usd', statement_descriptor: 'MYSTORE ORDER', statement_descriptor_suffix: '1234' // Order ID }); // 2. Send order confirmation immediately await sendEmail(customer.email, { subject: 'Order Confirmed - MyStore', body: `Thank you! Your order #${order.id} for $${order.total}...` }); // 3. Proactive communication on shipping await sendEmail(customer.email, { subject: 'Your order has shipped!', body: `Track your package: ${trackingUrl}` }); // 4. Easy refund process // Better to refund than get chargeback // Chargeback = 15-25 fee + counts toward rate ```

Что вы узнали о Refunds и Chargebacks?