public void AddItem(OrderItem item, IProductInfo product)
{
switch (_state)
{
case OrderState.Cancelled:
throw new InvalidStateException(
"You can't add an item. This order is already cancelled. Place a new order.");
case OrderState.Paid:
throw new InvalidStateException("You can't change this order. It's already paid. Place a new order.");
}
var priceForNewItem = item.Quantity*product.Price;
var e = new OrderItemAdded(
Id,
_location,
_items.ToArray(),
item,
_price + priceForNewItem);
ApplyChange(e);
}
private void Apply(OrderItemAdded e)
{
_price = e.Price;
_items.Add(e.AddedItem);
}