add giftcards

pkg/cart/mutation_remove_giftcard.go

@@ -0,0 +1,18 @@
+package cart
+
+import (
+	"fmt"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+func RemoveGiftcard(grain *CartGrain, req *messages.RemoveGiftcard) error {
+	for i, item := range grain.Giftcards {
+		if item.Id == req.Id {
+			grain.Giftcards = append(grain.Giftcards[:i], grain.Giftcards[i+1:]...)
+			grain.UpdateTotals()
+			return nil
+		}
+	}
+	return fmt.Errorf("giftcard with ID %d not found", req.Id)
+}