protected void CreateLineItems(Product product, Special special, int scannedItemCount)
{
var scannedItems = CreateScannedItems(product, scannedItemCount);
var productSpecial = new ProductSpecial(product, special);
_lineItems = productSpecial.CreateLineItems(scannedItems);
}
/// <summary>
/// This function is to check if the special is cheaper than buying the product directly
/// </summary>
/// <param name="special"></param>
/// <param name="productPrices"></param>
/// <returns></returns>
private bool IsSpecialCheaperThanProductPrices(ProductSpecial special, List <ProductPrice> productPrices)
{
var productPrice = special.Quantities.Join(productPrices,
specialQuantity => specialQuantity.Name,
productPrice => productPrice.Name,
(specialQuantity, productPrice) => specialQuantity.Quantity * productPrice.Price).Sum();
return(special.Total < productPrice);
}
/// <summary>
/// This function updates product quantities by the number of times special can be applied for that product
/// </summary>
/// <param name="eligibleSpecial"></param>
/// <param name="productQuantities"></param>
/// <param name="products"></param>
/// <param name="TimesCanBeApplied"></param>
private void UpdateProductQuantities(ProductSpecial eligibleSpecial, List <ProductQuantity> productQuantities, List <ProductPrice> products, int TimesCanBeApplied)
{
foreach (var trolleyItem in productQuantities)
{
var product = products?.FirstOrDefault(x => x.Name.Equals(trolleyItem.Name, StringComparison.OrdinalIgnoreCase));
var productSpecial = eligibleSpecial?.Quantities.FirstOrDefault(x => x.Name.Equals(trolleyItem.Name, StringComparison.OrdinalIgnoreCase));
if (productSpecial != null && trolleyItem.Quantity >= productSpecial.Quantity)
{
trolleyItem.Quantity -= (productSpecial.Quantity * TimesCanBeApplied);
}
}
}
/// <summary>
/// This function applies passed special and checks recursively all combinations
/// with other specials to get minimum trolley value
/// </summary>
/// <param name="eligibleSpecial"></param>
/// <param name="TimesCanBeApplied"></param>
/// <param name="productQuantities"></param>
/// <param name="products"></param>
/// <param name="eligibleSpecials"></param>
/// <returns></returns>
private decimal GetSpecialTotal(ProductSpecial eligibleSpecial,
int TimesCanBeApplied,
List <ProductQuantity> productQuantities,
List <ProductPrice> products,
List <ProductSpecial> eligibleSpecials
)
{
var trolleyTotal = eligibleSpecial.Total * TimesCanBeApplied;
// updating product quantities after applying special
UpdateProductQuantities(eligibleSpecial, productQuantities, products, TimesCanBeApplied);
// getting if any other specials can be applied
var otherSpecials = GetEligibleSpecials(eligibleSpecials, productQuantities, products, false);
if (otherSpecials.Count > 0)
{
// list to get totals of other special combinations
var innerTrolleyTotals = new List <(decimal, List <ProductQuantity>)>();
foreach (var otherSpecial in otherSpecials)
{
var tempProductQuantities = GetProductQuantityCopy(productQuantities);
// getting other special total
var tempTrolleyTotal = GetSpecialTotal(otherSpecial.eligibleSpecial, otherSpecial.TimesCanBeApplied, tempProductQuantities, products, eligibleSpecials);
// if product total is greater than special then use special
innerTrolleyTotals.Add((tempTrolleyTotal, tempProductQuantities));
}
// returning the lowest trolley total of different special combinations
var lowestTotal = innerTrolleyTotals.OrderBy(x => x.Item1).First();
productQuantities = lowestTotal.Item2;
return(trolleyTotal += lowestTotal.Item1);
}
else
{
// apply product prices if no more specials are applicable
return(trolleyTotal += GetTrolleyTotalWithoutSpecials(products, productQuantities));
}
}
public decimal CalculateTotal(Trolley trolley)
{
var unitPrices = trolley.Products.ToDictionary(p => p.Name, p => p.Price);
var specials = new Dictionary <string, List <ProductSpecial> >();
foreach (var trolleySpecial in trolley.Specials)
{
foreach (var trolleySpecialQuantity in trolleySpecial.Quantities)
{
if (trolleySpecialQuantity.Quantity == 0)
{
continue;
}
if (!specials.ContainsKey(trolleySpecialQuantity.Name))
{
specials[trolleySpecialQuantity.Name] = new List <ProductSpecial>();
}
var productSpecial = new ProductSpecial
{
Quantity = trolleySpecialQuantity.Quantity, SpecialUnitPrice = trolleySpecial.Total
};
specials[trolleySpecialQuantity.Name].Add(productSpecial);
}
}
decimal total = 0;
foreach (var trolleyQuantity in trolley.Quantities)
{
var lowestTotal = CalculateTotalPrice(trolleyQuantity.Quantity, specials[trolleyQuantity.Name], unitPrices[trolleyQuantity.Name]);
total += lowestTotal;
}
return(total);
}
