handle limited quantity

pkg/cart/mutation_initialize_checkout.go

@@ -2,6 +2,7 @@ package cart
 
 import (
 	"fmt"
+	"time"
 
 	messages "git.k6n.net/go-cart-actor/pkg/messages"
 )
@@ -36,6 +37,14 @@ func InitializeCheckout(g *CartGrain, m *messages.InitializeCheckout) error {
 	if m.OrderId == "" {
 		return fmt.Errorf("InitializeCheckout: missing orderId")
 	}
+	now := time.Now()
+	for _, item := range g.Items {
+		if item.ReservationEndTime != nil {
+			if now.After(*item.ReservationEndTime) {
+				return fmt.Errorf("InitializeCheckout: item id %d reservation has expired", item.Id)
+			}
+		}
+	}
 
 	g.OrderReference = m.OrderId
 	g.PaymentStatus = m.Status