/// <summary>
/// Calculate tax for list of products using specific tax rate.
/// </summary>
/// <param name="listOfProducts">The list of product to calculate tax for.</param>
/// <param name="chargeRate">The charge rate.</param>
/// <param name="recalculateAll">Recalculate tax for each product, even if some poducts already have tax calculated.</param>
/// <returns>The list of product with calculated tax.</returns>
public static IList <IProduct> CalculateTax(IList <IProduct> listOfProducts, ChargeRate chargeRate, bool recalculateAll = false)
{
//re-calculate product tax
if (recalculateAll)
{
return(CalculateTaxForEachProduct(listOfProducts, chargeRate));
}
if (listOfProducts.Any(product => product == null))
{
throw new ArgumentNullException(nameof(listOfProducts));
}
//if tax already caclulated for all product, return the list
if (listOfProducts.All(r => r.ProductTax.HasValue))
{
return(listOfProducts.ToList());
}
//calculate tax only for products without any.
foreach (var product in listOfProducts)
{
if (!product.ProductTax.HasValue)
{
product.ProductTax = CalculateTax(product, chargeRate);
}
}
return(listOfProducts);
}
/// <summary>
/// Calculate tax for single product using specific tax rate.
/// </summary>
/// <param name="product">The product.</param>
/// <param name="chargeRate">The charge rate.</param>
/// <returns>The tax.</returns>
public static decimal CalculateTax(IProduct product, ChargeRate chargeRate)
{
if (product == null || chargeRate == null)
{
throw new ArgumentNullException();
}
var productTax = decimal.Zero;
//check if standard tax has to be applied
if (ApplyTax(product.ProductType))
{
productTax = CalculatePercentage(chargeRate.TaxRate, product.Price);
}
//add import duty if product is imported
if (product is ImportedProduct)
{
productTax += CalculatePercentage(chargeRate.ImportDutyRate, product.Price);
}
return(RoundTax(productTax));
}
/// <summary>
/// Create the receipt calculate tax an.
/// </summary>
/// <param name="listOfProducts">The list of product.</param>
/// <param name="chargeRate">The charge rate.</param>
public static void PrintReceiptWithCalculatedTax(IList <IProduct> listOfProducts, ChargeRate chargeRate)
{
if (listOfProducts == null || listOfProducts.Any(product => product == null))
{
throw new ArgumentNullException(nameof(listOfProducts));
}
if (chargeRate == null)
{
throw new ArgumentNullException(nameof(chargeRate));
}
//calculate tax
listOfProducts = TaxCalculationLogic.CalculateTax(listOfProducts, chargeRate, recalculateAll: true);
var receipt = new Receipt(listOfProducts);
PrintReceiptToConsole(receipt);
}
/// <summary>
/// Calculate tax for each product in the list.
/// </summary>
/// <param name="listOfProducts">The list of product to calculate tax for.</param>
/// <param name="chargeRate">The charge rate.</param>
/// <returns>The list of product with calculated tax.</returns>
private static IList <IProduct> CalculateTaxForEachProduct(IList <IProduct> listOfProducts, ChargeRate chargeRate)
{
foreach (var product in listOfProducts)
{
product.ProductTax = CalculateTax(product, chargeRate);
}
return(listOfProducts);
}