private decimal GetCheapestTotal(TrolleyVM trolley, List <SpecialVM> potentialSpecials, TrolleyCheckout trolleyCheckout)
{
int indexCheapest = 0;
decimal cheapest = 0;
for (int i = 0; i < potentialSpecials.Count; i++)
{
var special = potentialSpecials[i];
var checkoutForSpecial = new TrolleyCheckout(trolleyCheckout.Total);
var trolleyForSpecial = new TrolleyVM(trolley);
checkoutForSpecial.Total += special.Total;
ApplySpecial(special, trolleyForSpecial.Quantities);
// Recursive call to continue calculating with reduced items
var totalForSpecial = GetTrolleyTotal(trolleyForSpecial, checkoutForSpecial);
if (i == 0)
{
cheapest = totalForSpecial;
}
else if (totalForSpecial < cheapest)
{
indexCheapest = i;
cheapest = totalForSpecial;
}
}
// Apply the special that has cheapest end value
return(cheapest);
}
public IActionResult CalculateTrolley(TrolleyVM trolley)
{
//var total = await _manager.CalculateTrolleyTotal(trolley);
var total = _manager.CalculateTrolleyTotal(trolley);
return(Ok(total));
}
private List <SpecialVM> GetPotentialSpecials(TrolleyVM trolley)
{
// Keep track of potential specials since there can be overlap of specials that include the same item
var potentialSpecials = new List <SpecialVM>();
// Deep clone of specials to search through below so no specials are repeated
List <SpecialVM> specialsToSearchThrough = trolley.Specials.Clone().ToList();
// In reality there can be more specials than checkout, so loop through checkout items to determine which ones apply.
foreach (ProductQuantityVM item in trolley.Quantities)
{
// Check if item applies and if it does also remove it from the specials to look through.
// Loop through backwards since removing list being iterated
for (int i = specialsToSearchThrough.Count - 1; i >= 0; i--)
{
var special = specialsToSearchThrough[i];
// Only add special to list of potentials
if (DoesSpecialIncludeItem(special, item.Name) && DoesSpecialApplyToTrolley(special, trolley.Quantities))
{
potentialSpecials.Add(special);
specialsToSearchThrough.RemoveAt(i);
}
}
}
return(potentialSpecials);
}
// Get total for current trolley - Recursive function
private decimal GetTrolleyTotal(TrolleyVM trolley, TrolleyCheckout trolleyCheckout)
{
// 1. Get all specials that apply to trolley.
var potentialSpecials = GetPotentialSpecials(trolley);
// 2. Calculate end cost of each potential special to get the cheapest result
if (potentialSpecials.Count > 0)
{
return(GetCheapestTotal(trolley, potentialSpecials, trolleyCheckout));
}
else
{
return(GetSingularItemsTotal(trolley, trolleyCheckout));
}
}
private decimal GetSingularItemsTotal(TrolleyVM trolley, TrolleyCheckout trolleyCheckout)
{
// finally calculate the remaining trolley items
foreach (ProductQuantityVM item in trolley.Quantities)
{
var product = trolley.Products.Find(p => p.Name == item.Name);
if (product == null)
{
throw new Exception("Item in trolley is not listed as a product");
}
trolleyCheckout.Total += item.Quantity * product.Price;
item.Quantity = 0;
}
return(trolleyCheckout.Total);
}
public decimal CalculateTrolleyTotal(TrolleyVM trolleyVM)
{
var trolleyCheckout = new TrolleyCheckout();
return(GetTrolleyTotal(trolleyVM, trolleyCheckout));
}
public async Task <decimal> CalculateTrolleyTotalAsync(TrolleyVM trolleyVM)
{
var trolley = _mapper.Map <Trolley>(trolleyVM);
return(await _service.CalculateTrolleyTotal(trolley));
}
