public async Task BuyItem(int amount, int id)
{
var entityToBuy = _repository.GetById(id);
var dtoProductToBuyWithDiscount = _priceCalculationService.ApplyDiscount(entityToBuy, amount);
var entityForHistory = _mapper.Map <BoughtProduct>(dtoProductToBuyWithDiscount);
entityForHistory.Id = null;
await _repository.AddToSalesHistory(entityForHistory);
await _repository.RemoveProducts(entityToBuy, amount);
}