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package billing
import (
"context"
"encoding/json"
"errors"
"fmt"
"io"
"net/http"
"strings"
"github.com/jackc/pgx/v5"
"github.com/stripe/stripe-go/v86"
"github.com/stripe/stripe-go/v86/webhook"
)
const maxWebhookBodyBytes = 1 << 20
type stripeCheckoutCreator func(context.Context, *stripe.CheckoutSessionCreateParams) (*stripe.CheckoutSession, error)
func newStripeCheckoutCreator(apiKey string) stripeCheckoutCreator {
client := stripe.NewClient(apiKey)
return client.V1CheckoutSessions.Create
}
func (s *Service) CreateCheckout(ctx context.Context, input CheckoutInput) (CheckoutResult, error) {
orderID, _, err := s.createTopUpOrder(ctx, input)
if err != nil {
return CheckoutResult{}, err
}
params := &stripe.CheckoutSessionCreateParams{
Mode: stripe.String("payment"),
ClientReferenceID: stripe.String(orderID),
IntegrationIdentifier: stripe.String(s.integrationIdentifier),
SuccessURL: stripe.String(s.stripeSuccessURL),
CancelURL: stripe.String(s.stripeCancelURL),
Metadata: map[string]string{
"aigw_topup_order_id": orderID,
"aigw_tenant_id": strings.TrimSpace(input.TenantID),
},
LineItems: []*stripe.CheckoutSessionCreateLineItemParams{{
Quantity: stripe.Int64(1),
PriceData: &stripe.CheckoutSessionCreateLineItemPriceDataParams{
Currency: stripe.String(s.currency),
UnitAmount: stripe.Int64(input.AmountMinor),
ProductData: &stripe.CheckoutSessionCreateLineItemPriceDataProductDataParams{
Name: stripe.String("AIGW prepaid balance"),
Description: stripe.String("Prepaid API usage credit"),
},
},
}},
}
params.SetIdempotencyKey("aigw_topup_" + orderID)
session, err := s.createStripeCheckout(ctx, params)
if err != nil {
_, _ = s.db.Exec(ctx, `UPDATE topup_orders SET status = 'failed' WHERE id = $1 AND status = 'pending'`, orderID)
return CheckoutResult{}, fmt.Errorf("create Stripe Checkout Session: %w", err)
}
if session.ID == "" || session.URL == "" {
return CheckoutResult{}, errors.New("Stripe returned an incomplete Checkout Session")
}
if _, err := s.db.Exec(ctx, `
UPDATE topup_orders SET stripe_session_id = $2, checkout_url = $3
WHERE id = $1`, orderID, session.ID, session.URL); err != nil {
return CheckoutResult{}, fmt.Errorf("persist Stripe Checkout Session: %w", err)
}
return CheckoutResult{OrderID: orderID, SessionID: session.ID, URL: session.URL}, nil
}
func (s *Service) WebhookHandler() http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodPost {
w.Header().Set("Allow", http.MethodPost)
http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
return
}
body, err := io.ReadAll(io.LimitReader(r.Body, maxWebhookBodyBytes+1))
if err != nil || len(body) > maxWebhookBodyBytes {
http.Error(w, "invalid webhook body", http.StatusBadRequest)
return
}
event, err := webhook.ConstructEvent(body, r.Header.Get("Stripe-Signature"), s.stripeWebhookSecret)
if err != nil {
http.Error(w, "invalid webhook signature", http.StatusBadRequest)
return
}
if err := s.processStripeEvent(r.Context(), event); err != nil {
if errors.Is(err, ErrInvalidAmount) || isNotFound(err) {
http.Error(w, "invalid checkout event", http.StatusBadRequest)
return
}
http.Error(w, "webhook processing failed", http.StatusInternalServerError)
return
}
w.Header().Set("Content-Type", "application/json")
_, _ = io.WriteString(w, `{"received":true}`+"\n")
})
}
func (s *Service) processStripeEvent(ctx context.Context, event stripe.Event) error {
typeName := string(event.Type)
switch event.Type {
case stripe.EventTypeCheckoutSessionCompleted,
stripe.EventTypeCheckoutSessionAsyncPaymentSucceeded,
stripe.EventTypeCheckoutSessionAsyncPaymentFailed,
stripe.EventTypeCheckoutSessionExpired:
default:
return nil
}
if event.Data == nil {
return ErrInvalidAmount
}
var session stripe.CheckoutSession
if err := json.Unmarshal(event.Data.Raw, &session); err != nil {
return ErrInvalidAmount
}
if event.ID == "" || session.ID == "" || session.ClientReferenceID == "" {
return ErrInvalidAmount
}
tx, err := s.db.BeginTx(ctx, pgx.TxOptions{IsoLevel: pgx.ReadCommitted})
if err != nil {
return err
}
defer tx.Rollback(ctx)
tag, err := tx.Exec(ctx, `
INSERT INTO stripe_webhook_events (event_id, event_type) VALUES ($1,$2)
ON CONFLICT (event_id) DO NOTHING`, event.ID, typeName)
if err != nil {
return fmt.Errorf("record Stripe event: %w", err)
}
if tag.RowsAffected() == 0 {
return tx.Commit(ctx)
}
var tenantID, currency, status string
var amountMinor, amountMicros int64
var storedSessionID *string
err = tx.QueryRow(ctx, `
SELECT tenant_id::text, amount_minor, amount_micros, currency, status, stripe_session_id
FROM topup_orders WHERE id = $1 FOR UPDATE`, session.ClientReferenceID,
).Scan(&tenantID, &amountMinor, &amountMicros, ¤cy, &status, &storedSessionID)
if err != nil {
return err
}
if (storedSessionID != nil && *storedSessionID != session.ID) || amountMinor != session.AmountTotal || currency != string(session.Currency) {
return ErrInvalidAmount
}
if event.Type == stripe.EventTypeCheckoutSessionAsyncPaymentFailed || event.Type == stripe.EventTypeCheckoutSessionExpired {
orderStatus := "failed"
if event.Type == stripe.EventTypeCheckoutSessionExpired {
orderStatus = "expired"
}
if _, err := tx.Exec(ctx, `UPDATE topup_orders SET status = $2, stripe_session_id = COALESCE(stripe_session_id, $3) WHERE id = $1 AND status = 'pending'`, session.ClientReferenceID, orderStatus, session.ID); err != nil {
return err
}
_, err = tx.Exec(ctx, `UPDATE stripe_webhook_events SET processed_at = now() WHERE event_id = $1`, event.ID)
if err != nil {
return err
}
return tx.Commit(ctx)
}
if session.PaymentStatus != stripe.CheckoutSessionPaymentStatusPaid {
_, err = tx.Exec(ctx, `UPDATE stripe_webhook_events SET processed_at = now() WHERE event_id = $1`, event.ID)
if err != nil {
return err
}
return tx.Commit(ctx)
}
if status != "paid" {
if _, err := tx.Exec(ctx, `
INSERT INTO tenant_wallets (tenant_id, currency) VALUES ($1,$2)
ON CONFLICT (tenant_id) DO NOTHING`, tenantID, currency); err != nil {
return err
}
var walletCurrency string
var balance int64
if err := tx.QueryRow(ctx, `SELECT currency, balance_micros FROM tenant_wallets WHERE tenant_id = $1 FOR UPDATE`, tenantID).Scan(&walletCurrency, &balance); err != nil {
return err
}
if walletCurrency != currency || amountMicros <= 0 || balance > int64(^uint64(0)>>1)-amountMicros {
return ErrInvalidAmount
}
newBalance := balance + amountMicros
if _, err := tx.Exec(ctx, `UPDATE tenant_wallets SET balance_micros = $2, updated_at = now() WHERE tenant_id = $1`, tenantID, newBalance); err != nil {
return err
}
if _, err := tx.Exec(ctx, `
INSERT INTO billing_ledger (tenant_id, currency, amount_micros, balance_after_micros, kind, source_type, source_id, description)
VALUES ($1,$2,$3,$4,'topup','stripe_checkout',$5,'Stripe balance top-up')
ON CONFLICT (source_type, source_id) DO NOTHING`, tenantID, currency, amountMicros, newBalance, session.ID); err != nil {
return err
}
if _, err := tx.Exec(ctx, `
UPDATE topup_orders SET status = 'paid', stripe_session_id = COALESCE(stripe_session_id, $2), paid_at = now()
WHERE id = $1`, session.ClientReferenceID, session.ID); err != nil {
return err
}
}
if _, err := tx.Exec(ctx, `UPDATE stripe_webhook_events SET processed_at = now() WHERE event_id = $1`, event.ID); err != nil {
return err
}
return tx.Commit(ctx)
}
|
