public void CalculateChange()
{
// combine cash in hand and cash received
CashRegister newCashInHand = CashRegister.Combine(_cashInHands, _cashReceived);
_cashChange = new CashRegister(CashDenomination.ALL_DONOMINATIONS);
int change = _cashReceived.Amount - _amountDue;
// deduct from max to min denominations as needed
newCashInHand.Sort(ListSortDirection.Descending);
foreach (CashSet fromSet in newCashInHand.CashSets)
{
if (change > fromSet.Denomination.Amount)
{
int qty = (int)(change / fromSet.Denomination.Amount);
if (qty > fromSet.Quantity)
{
qty = fromSet.Quantity;
}
fromSet.Quantity = fromSet.Quantity - qty;
CashSet toSet = _cashChange.CashSets.First(s => s.Denomination.Amount == fromSet.Denomination.Amount);
toSet.Quantity = toSet.Quantity + qty;
change -= fromSet.Denomination.Amount * qty;
}
if (change <= 0)
{
break;
}
}
// if still remained, deduct from the min to max denomination to make it zero
if (change > 0)
{
newCashInHand.Sort(ListSortDirection.Ascending);
foreach (CashSet fromSet in newCashInHand.CashSets)
{
int qty = (int)(change / fromSet.Denomination.Amount) + 1;
if (qty > fromSet.Quantity)
{
qty = fromSet.Quantity;
}
fromSet.Quantity = fromSet.Quantity - qty;
CashSet toSet = _cashChange.CashSets.First(s => s.Denomination.Amount == fromSet.Denomination.Amount);
toSet.Quantity = toSet.Quantity + qty;
change -= fromSet.Denomination.Amount * qty;
if (change <= 0)
{
break;
}
}
}
}
public static CashRegister Combine(CashRegister register1, CashRegister register2)
{
CashRegister newCashRegister = new CashRegister(CashDenomination.ALL_DONOMINATIONS);
foreach (CashDenomination d in CashDenomination.ALL_DONOMINATIONS)
{
CashSet set = newCashRegister.CashSets.FirstOrDefault(s => s.Denomination.Amount == d.Amount);
CashSet s1 = register1.CashSets.FirstOrDefault(s => s.Denomination.Amount == d.Amount);
if (s1 != null)
{
set.Quantity = set.Quantity + s1.Quantity;
}
CashSet s2 = register2.CashSets.FirstOrDefault(s => s.Denomination.Amount == d.Amount);
if (s2 != null)
{
set.Quantity = set.Quantity + s2.Quantity;
}
}
return(newCashRegister);
}
