public class OrderDiscountProcessor : IDiscountProcessor
{
    private readonly Discount _discount;

    public OrderDiscountProcessor(Discount discount)
    {
        _discount = discount;
    }

    public double ProcessDiscount(OrderViewModel order)
    {
        double discount = 0.0;
        double totalBill = order.Quantity * order.Price;

        if (order.Quantity >= _discount.MinimumItemCount && totalBill >= _discount.MinimumBillAmount)
        {
            discount = (totalBill * _discount.Percentage) / 100.0;
        }

        return discount;
    }
}