private static TrolleySpecial CombineSpecials(TrolleySpecial special1, TrolleySpecial special2)
{
return(new TrolleySpecial
{
Quantities = special1.Quantities.Concat(special2.Quantities)
.GroupBy(trolleyQuantity => trolleyQuantity.Name).Select(
grouping => new TrolleyQuantity
{
Name = grouping.Key,
Quantity = grouping.Sum(trolleyQuantity => trolleyQuantity.Quantity)
}).ToList(),
Total = special1.Total + special2.Total
});
}
private Trolley CreateTrolley(TrolleyModel trolleyModel)
{
var trolley = new Trolley();
var products = trolleyModel.Products.ToDictionary(p => p.Name, p => new ProductRef
{
Name = p.Name,
Price = p.Price,
});
foreach (var item in trolleyModel.Quantities)
{
trolley.AddItem(products[item.Name], item.Quantity);
}
foreach (var item in trolleyModel.Specials.SelectMany(s => s.Quantities))
{
var special = new TrolleySpecial();
special.AddItem(products[item.Name], item.Quantity);
trolley.AddSpecial(special);
}
return(trolley);
}
/// <summary>
/// Applies the special on the trolley and returns the amount of special, also spits out the remaining items after deducting the calculated items (in <see cref="shoppedProductQuantitiesMapMinusSpecial"/>)
/// </summary>
/// <param name="trolleySpecial"></param>
/// <param name="shoppedProductQuantitiesMap"></param>
/// <param name="shoppedProductQuantitiesMapMinusSpecial">Shopped products quantities after deducting the calculated specialed items</param>
/// <returns></returns>
private decimal GetAmountOfAppliedSpecial(TrolleySpecial trolleySpecial, Dictionary <string, int> shoppedProductQuantitiesMap, out Dictionary <string, int> shoppedProductQuantitiesMapMinusSpecial)
{
var shoppedProductQuantitiesMapCopy = shoppedProductQuantitiesMap.ToDictionary(q => q.Key, q => q.Value);
var maxApplicableCount = GetMaxApplicableCount(trolleySpecial, shoppedProductQuantitiesMapCopy);
decimal totalAmount = 0;
if (maxApplicableCount == 0)
{
shoppedProductQuantitiesMapMinusSpecial = shoppedProductQuantitiesMap;
return(0m);
}
totalAmount += maxApplicableCount * trolleySpecial.Total;
foreach (var specialQuantity in trolleySpecial.Quantities)
{
shoppedProductQuantitiesMapCopy[specialQuantity.Name] -= (maxApplicableCount * specialQuantity.Quantity);
}
shoppedProductQuantitiesMapMinusSpecial = shoppedProductQuantitiesMapCopy;
return(totalAmount);
}
/// <summary>
/// This method returns a list of only the best candidate special combos, by combining as many specials as possible.
/// For example, if a trolley is eligible for special1 and special2 combined, only that special combo is returned,
/// but special1 and special2 are not returned individually.
/// </summary>
private static List <TrolleySpecial> GetBestCandidateSpecialCombos(List <TrolleyQuantity> trolleyQuantities,
TrolleySpecial eligibleSpecialCombo, List <TrolleySpecial> otherEligibleSpecialsToCombineWith)
{
var bestCandidateSpecialCombos = new List <TrolleySpecial>();
for (int i = 0; i < otherEligibleSpecialsToCombineWith.Count; i++)
{
var newSpecialCombo = CombineSpecials(eligibleSpecialCombo, otherEligibleSpecialsToCombineWith[i]);
if (IsEligible(trolleyQuantities, newSpecialCombo))
{
bestCandidateSpecialCombos.AddRange(
GetBestCandidateSpecialCombos(trolleyQuantities, newSpecialCombo,
otherEligibleSpecialsToCombineWith.Skip(i).ToList()));
}
}
if (!bestCandidateSpecialCombos.Any())
{
bestCandidateSpecialCombos.Add(eligibleSpecialCombo);
}
return(bestCandidateSpecialCombos);
}
private static decimal CalculateSavings(List <TrolleyProduct> products, TrolleySpecial special)
{
var fullPriceEquivalentOfSpecial = CalculatePrice(products, special.Quantities);
return(fullPriceEquivalentOfSpecial - special.Total);
}
private static decimal GetSpecialQuantity(TrolleySpecial special, string productName)
{
return(special.Quantities
.FirstOrDefault(quantity => quantity.Name == productName)
?.Quantity ?? 0);
}
private static List <TrolleyQuantity> GetFullPricedQuantities(Trolley trolley, TrolleySpecial special)
{
return(trolley.Quantities.Select(quantity => new TrolleyQuantity
{
Name = quantity.Name,
Quantity = quantity.Quantity - GetSpecialQuantity(special, quantity.Name)
}).ToList());
}
