/// <summary>
/// Get cost with discount
/// </summary>
public decimal CalculateCost(IEnumerable <IProductComparable <T> > products)
{
if (products == null)
{
throw new ArgumentNullException();
}
SetRules();
if (!ValidateAlphabet())
{
throw new Exception("repository do not contains required items");
}
var unit = new CalculateUnit <T>
{
NotCalculatedProducts = products.ToList()
};
foreach (var f in _rules)
{
unit = f(unit);
}
return(unit.Cost + unit.NotCalculatedProducts.Sum(x => x.Cost));
}
/// <summary>
/// get cost with discount by product count
/// </summary>
protected CalculateUnit <T> SaleCountProcess(CalculateUnit <T> unit, int count, decimal discount)
{
if (unit.NotCalculatedProducts.Count >= count)
{
var costTotal = unit.NotCalculatedProducts.Take(count).Sum(x => x.Cost);
unit.Cost += costTotal - costTotal * discount;
unit.NotCalculatedProducts.RemoveRange(0, count);
return(SaleCountProcess(unit, count, discount));
}
return(unit);
}
/// <summary>
/// get cost with discount by product ids
/// </summary>
protected CalculateUnit <T> SaleGroupProcess(CalculateUnit <T> unit, IEnumerable <T> ids, decimal discount)
{
var useInDiscount = new List <IProductComparable <T> >();
var tmpStorage = new List <IProductComparable <T> >(unit.NotCalculatedProducts);
foreach (var id in ids)
{
var findResult = tmpStorage.FirstOrDefault(x => x.Id.CompareTo(id) == 0);
if (findResult == null)
{
return(unit);
}
tmpStorage.Remove(findResult);
useInDiscount.Add(findResult);
}
var costTotal = useInDiscount.Sum(x => x.Cost);
unit.Cost += costTotal - costTotal * discount;
unit.NotCalculatedProducts = unit.NotCalculatedProducts.Except(useInDiscount).ToList();
return(SaleGroupProcess(unit, ids, discount));
}