handle limited quantity

pkg/cart/mutation_add_item.go

@@ -38,16 +38,24 @@ func AddItem(g *CartGrain, m *messages.AddItem) error {
 		if !sameStore {
 			continue
 		}
+		if m.ReservationEndTime != nil {
+			t := m.ReservationEndTime.AsTime()
+			if existing.ReservationEndTime == nil || existing.ReservationEndTime.Before(m.ReservationEndTime.AsTime()) {
+				existing.ReservationEndTime = &t
+				existing.Quantity = int(m.Quantity)
+			} else {
+				existing.ReservationEndTime = &t
+			}
+
+		} else {
 			existing.Quantity += int(m.Quantity)
+		}
 		existing.Stock = uint16(m.Stock)
 		// If existing had nil store but new has one, adopt it.
 		if existing.StoreId == nil && m.StoreId != nil {
 			existing.StoreId = m.StoreId
 		}
-		if m.ReservationEndTime != nil {
-			t := m.ReservationEndTime.AsTime()
-			existing.ReservationEndTime = &t
-		}
+
 		return nil
 	}
 

pkg/cart/mutation_change_quantity.go

@@ -48,8 +48,15 @@ func ChangeQuantity(g *CartGrain, m *messages.ChangeQuantity) error {
 		g.UpdateTotals()
 		return nil
 	}
-
-	g.Items[foundIndex].Quantity = int(m.Quantity)
+	item := g.Items[foundIndex]
+	if item == nil {
+		return fmt.Errorf("ChangeQuantity: item id %d not found", m.Id)
+	}
+	if item.ReservationEndTime != nil {
+		return fmt.Errorf("ChangeQuantity: cannot change quantity of reserved item id %d", m.Id)
+	} else {
+		item.Quantity = int(m.Quantity)
 		g.UpdateTotals()
+	}
 	return nil
 }

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