/// <summary>
/// Change composer, based on "greedy algorithm".
/// </summary>
/// <param name="walletRepository">The source wallet of the change</param>
/// <param name="changeValue">The sum of change to compose.</param>
/// <returns>The change wallet with composed change.</returns>
public static PaymentWalletRepository ChangeComposer(IWalletRepository walletRepository, Money changeValue)
{
// Collect change
PaymentWalletRepository changeCollected = new PaymentWalletRepository();
// Collect the change for big to small value
foreach (var position in walletRepository.WalletList.OrderByDescending(w => w.Item1.Nominal).Where(p => p.Item2 > 0))
{
(INotionValue money, int count) = position;
while (changeValue >= money.MoneyValue && count > 0)
{
count--;
changeValue -= money.MoneyValue;
changeCollected.AddToWallet(money, 1);
walletRepository.RemoveFromWallet(money, 1);
}
if (changeValue == Money.Zero)
{
break;
}
}
//Cannot get the change
if (changeValue != Money.Zero)
{
// return all money back
foreach (var mc in changeCollected.WalletList)
{
walletRepository.AddToWallet(mc.Item1, mc.Item2);
}
return(null);
}
return(changeCollected);
}
/// <summary>
/// Processing payment events from the coin receiver
/// </summary>
/// <param name="cmd">The event to process.</param>
/// <param name="payment">The coin received or null</param>
void PaymentAction(PaymentCmdEvent cmd, INotionValue payment)
{
if (VendingMachineState != VendingMachineState.Payment)
{
return;
}
if (cmd == PaymentCmdEvent.Cancel)
{
// Cancellation of the order or/and payment
CancelOrder();
}
else if (cmd == PaymentCmdEvent.Payment)
{
_paymentWalletRepository.AddToWallet(payment, 1);
Money total = _orderedProducts.Aggregate(Money.Zero, (m, p) => m + p.Price);
Money paid = _paymentWalletRepository.WalletList.Aggregate(Money.Zero, (m, p) => m + new Money(0, (int)p.Item1.Nominal * p.Item2));
string msg = String.Format(_vendingMessageRepository.GetMessage(MessageCode.BalancePayment), total, paid);
_displayPanel.DisplayMessage(msg);
if (paid >= total)
{
// give change or cancel
if (paid > total)
{
Money change = paid - total;
PaymentWalletRepository collectedChange = ChangeComposer(_walletRepository, change);
if (collectedChange == null)
{
DisplayMessageByCode(MessageCode.RunOutOfChange);
CancelOrder();
return;
}
foreach (var pm in collectedChange.WalletList)
{
msg = String.Format(_vendingMessageRepository.GetMessage(MessageCode.GivenChange), pm.Item1.MoneyValue, pm.Item2);
_displayPanel.DisplayMessage(msg);
}
}
// complete purchase
foreach (var p in _orderedProducts)
{
msg = String.Format(_vendingMessageRepository.GetMessage(MessageCode.CollectYourPurchase), p);
_saleRecord.Sold(p);
_displayPanel.DisplayMessage(msg);
}
_orderedProducts.Clear();
foreach (var pm in _paymentWalletRepository.WalletList)
{
_walletRepository.AddToWallet(pm.Item1, pm.Item2);
}
_paymentWalletRepository.ClearMoney();
// switch back to selling
TryToStartSelling();
_coinReceiver.Off();
}
}
}