public string CreateSale(PriceRate discount)
{
if (_vehicle == null || _compatibleAddons == null || _selectedAddons == null)
{
return("Missing key sales details");
}
OrderBuilder oBuild = new OrderBuilder();
oBuild.Add(_vehicle, VehicleType.New);
oBuild.Add(_tradeIn, VehicleType.Trade);
oBuild.SetDiscount(discount);
oBuild.Add(_selectedAddons, _compatibleAddons);
Order orders = oBuild.Prepare();
InvoiceBuilder iBuild = new InvoiceBuilder();
iBuild.Staff = _saleRep;
iBuild.Order = orders;
_sInvoice = iBuild.Prepare() as Sale;
return(_manager["Invoice"].Add(_sInvoice));
}