probably fix discounts

pkg/cart/cart-grain.go

@@ -249,19 +249,22 @@ func (c *CartGrain) UpdateTotals() {
 	for _, item := range c.Items {
 		rowTotal := MultiplyPrice(item.Price, int64(item.Quantity))
 
-		item.TotalPrice = *rowTotal
-
-		c.TotalPrice.Add(*rowTotal)
-
 		if item.OrgPrice != nil {
 			diff := NewPrice()
 			diff.Add(*item.OrgPrice)
 			diff.Subtract(item.Price)
+			diff.Multiply(int64(item.Quantity))
+			rowTotal.Subtract(*diff)
+			item.Discount = diff
 			if diff.IncVat > 0 {
 				c.TotalDiscount.Add(*diff)
 			}
 		}
 
+		item.TotalPrice = *rowTotal
+
+		c.TotalPrice.Add(*rowTotal)
+
 	}
 	for _, delivery := range c.Deliveries {
 		c.TotalPrice.Add(delivery.Price)