public void ApplyVoucher(Voucher voucher)
{
if (_appliedVouchers.Any(v => v.Id == voucher.Id))
{
return;
}
if (_appliedVouchers.Any(v => v is OfferVoucher))
{
return;
}
var result = voucher.ApplyTo(this);
_appliedVouchers.Add(voucher);
_voucherResults.Add(result);
if (!(result is VoucherIsValidResult validDiscount))
{
return;
}
DiscountedTotal -= validDiscount.ApplicableDiscount;
if (DiscountedTotal < 0)
{
DiscountedTotal = 0;
}
}
