Payment System

Architecture

Checkout Service
    ↓
Payment Gateway (trait)
    ├── Stripe Gateway
    ├── Airwallex Gateway
    └── Mock Gateway
    ↓
Payment Intent → Client confirms → Server verifies

Gateway trait

All payment gateways implement the PaymentGateway trait:

#[async_trait]
pub trait PaymentGateway: Send + Sync {
    fn id(&self) -> &str;
    fn name(&self) -> &str;
    async fn create_payment(&self, request: CreatePaymentRequest) -> Result<PaymentSession>;
    async fn confirm_payment(&self, payment_id: &str) -> Result<Payment>;
    async fn capture_payment(&self, payment_id: &str, amount: Option<Decimal>) -> Result<Payment>;
    async fn refund_payment(&self, payment_id: &str, amount: Option<Decimal>, reason: &str) -> Result<Refund>;
    async fn get_payment(&self, payment_id: &str) -> Result<Payment>;
}

Payment flow

1. POST /checkout/complete → create_payment() → returns client_secret
2. Client-side: mount payment element with client_secret
3. User enters card details and confirms
4. POST /checkout/confirm → get_payment() → verify status
5. If succeeded → finalize order

Stripe

• Uses Stripe Payment Intents API
• Client-side: Stripe Elements
• Supports: cards, Apple Pay, Google Pay, 3D Secure

Airwallex

• Uses Airwallex Payment Intents API
• Client-side: Airwallex Drop-in
• Supports: cards, WeChat Pay, Alipay, 3D Secure
• Amount in major currency units (not cents)

Mock gateway

For testing. Always returns success. Useful for development and CI.

Configuration

[payment]
default_gateway = "stripe"

[payment.stripe]
enabled = true
secret_key = "sk_..."
publishable_key = "pk_..."

[payment.airwallex]
enabled = true
client_id = "..."
api_key = "..."