/// <summary>
/// Optimizes the change returned.
/// Gives the most efficient change back possible.
/// </summary>
/// <param name="changeValue">The change value.</param>
/// <param name="regionCurrency">The region currency.</param>
/// <returns></returns>
private List <string> OptimizedChangeReturned(decimal changeValue, IRegionCurrency regionCurrency)
{
List <string> toReturn = new List <string>();
foreach (var c in regionCurrency.GetDescendingOrderedCurrencies())
{
if (c.Value <= changeValue)
{
int times = (int)(changeValue / c.Value);
toReturn.Add(string.Format("{0} {1}", times, times > 1 ? c.PluralName : c.Name));
changeValue -= (times * c.Value);
}
}
return(toReturn);
}
/// <summary>
/// If the change due is divisible by 3, give random denominations
/// these random denominations must equal the appropriate total amount
/// of change due
/// </summary>
/// <param name="changeValue">The change value.</param>
/// <param name="regionCurrency">The region currency.</param>
/// <param name="r">The random seed</param>
/// <returns></returns>
private List <string> Mod3ChangeGeneration(decimal changeValue, IRegionCurrency regionCurrency, Random r)
{
Dictionary <Currency, int> changeDue = new Dictionary <Currency, int>();
List <string> toReturn = new List <string>();
foreach (Currency c in regionCurrency.Denominations)
{
changeDue.Add(c, 0);
}
while (changeValue > 0)
{
Currency tmp = regionCurrency.Denominations[r.Next(regionCurrency.Denominations.Count)];
if (changeValue >= tmp.Value)
{
try
{
int maxNumberOfTimes = (int)(changeValue / tmp.Value) + 1; //adding 1 because random max is exclusive
int actualTimes = r.Next(maxNumberOfTimes);
changeDue[tmp] += actualTimes;
changeValue -= (actualTimes * tmp.Value);
}
catch (OverflowException)
{
//eat the overflow exception and try again
//this happens when the initial change amount due is at or near the limit for Int32
//and we try to generate change using something less than 1 ex: a nickel.
//allow the system to try larger denominations to reduce the total change due being tracked
}
}
}
//populate the change denominations to return
foreach (Currency c in regionCurrency.GetDescendingOrderedCurrencies())
{
if (changeDue[c] > 0)
{
toReturn.Add(string.Format("{0} {1}", changeDue[c], changeDue[c] > 1 ? c.PluralName : c.Name));
}
}
return(toReturn);
}