/// <summary>
/// Calculates distribution of manual loyalty discounts across the transaction.
/// Should be called only after other discounts are calculated.
/// </summary>
/// <param name="transaction">Transaction to calculate manual loyalty discounts on.</param>
public void CalculateLoyaltyManualDiscount(SalesTransaction transaction)
{
if (transaction == null)
{
throw new ArgumentNullException("transaction");
}
Discount.ClearDiscountLinesOfType(transaction, DiscountLineType.LoyaltyDiscount);
if (transaction.LoyaltyManualDiscountAmount.HasValue)
{
this.AddLoyaltyDiscAmountLines(transaction, transaction.LoyaltyManualDiscountAmount.Value);
}
}
/// <summary>
/// This method will distribute the amountToDiscount across all the sale items in the transaction
/// proportionally except for the line item with the largest amount. The remainder will be distributed
/// to the line item with the largest amount to ensure the amount to discount is exactly applied.
/// This method currently works when the redeem loyalty points button is applied.
/// </summary>
/// <param name="transaction">The transaction receiving loyalty discount lines.</param>
/// <param name="amountToDiscount">The amount to discount the transaction.</param>
private void AddLoyaltyDiscAmountLines(
SalesTransaction transaction,
decimal amountToDiscount)
{
decimal totalAmtAvailableForDiscount = decimal.Zero;
// Build a list of the discountable items with the largest value item last
var discountableSaleItems = (from s in transaction.SalesLines
where ((s.IsEligibleForDiscount() && PriceContextHelper.IsDiscountAllowed(this.priceContext, s.ItemId)) ||
s.IsLoyaltyDiscountApplied)
orderby Math.Abs(s.NetAmount), s.LineId
select s).ToList();
// Iterate through all non voided items whether we are going to discount or not so that they get added
// back to the totals
foreach (SalesLine salesLine in transaction.SalesLines.Where(sl => !sl.IsVoided))
{
Discount.ClearDiscountLinesOfType(salesLine, DiscountLineType.LoyaltyDiscount);
SalesLineTotaller.CalculateLine(transaction, salesLine, d => this.priceContext.CurrencyAndRoundingHelper.Round(d));
if (salesLine.IsEligibleForDiscount() || salesLine.IsLoyaltyDiscountApplied)
{
// Calculate the total amount that is available for discount
totalAmtAvailableForDiscount += Math.Abs(salesLine.NetAmountWithAllInclusiveTax);
}
}
// Calculate the percentage (as a fraction) that we should attempt to discount each discountable item
// to reach the total
decimal discountFactor = totalAmtAvailableForDiscount != decimal.Zero ? (amountToDiscount / totalAmtAvailableForDiscount) : decimal.Zero;
decimal totalAmtDistributed = decimal.Zero;
// Iterate through all discountable items.
foreach (SalesLine salesLine in discountableSaleItems)
{
decimal amountToDiscountForThisItem = decimal.Zero;
if (salesLine != discountableSaleItems.Last())
{
// for every item except for the last in the list (which will have the largest value)
// discount by the rounded amount that is closest to the percentage desired for the transaction
decimal itemPrice = salesLine.NetAmount;
amountToDiscountForThisItem = this.priceContext.CurrencyAndRoundingHelper.Round(discountFactor * Math.Abs(itemPrice));
totalAmtDistributed += amountToDiscountForThisItem;
}
else
{
// Discount the last item by the remainder to ensure that the exact desired discount is applied
amountToDiscountForThisItem = amountToDiscount - totalAmtDistributed;
}
DiscountLine discountLine;
if (amountToDiscountForThisItem != decimal.Zero)
{
// Add a new loyalty points discount item
discountLine = new DiscountLine();
discountLine.Amount = salesLine.Quantity != 0 ? amountToDiscountForThisItem / salesLine.Quantity : amountToDiscountForThisItem;
discountLine.DiscountLineType = DiscountLineType.LoyaltyDiscount;
salesLine.DiscountLines.Add(discountLine);
salesLine.IsLoyaltyDiscountApplied = true;
}
SalesLineTotaller.CalculateLine(transaction, salesLine, d => this.priceContext.CurrencyAndRoundingHelper.Round(d));
}
}
