‫آشنایی با Refactoring - قسمت 3

using System.Collections.Generic;

namespace Refactoring.Day2.ExtractMethod.After
{
    public class Receipt
    {
        private IList<decimal> _discounts;
        private IList<decimal> _itemTotals;

        public decimal CalculateGrandTotal()
        {
            _discounts = new List<decimal> { 0.1m };
            _itemTotals = new List<decimal> { 100m, 200m };

            decimal subTotal = CalculateSubTotal();
            subTotal = CalculateDiscounts(subTotal);
            subTotal = CalculateTax(subTotal);
            return subTotal;
        }

        private decimal CalculateTax(decimal subTotal)
        {
            decimal tax = subTotal * 0.065m;
            subTotal += tax;
            return subTotal;
        }

        private decimal CalculateDiscounts(decimal subTotal)
        {
            if (_discounts.Count > 0)
            {
                foreach (decimal discount in _discounts)
                    subTotal -= discount;
            }
            return subTotal;
        }

        private decimal CalculateSubTotal()
        {
            decimal subTotal = 0m;
            foreach (decimal itemTotal in _itemTotals)
                subTotal += itemTotal;
            return subTotal;
        }
    }
}

using System.Collections.Generic;

namespace Refactoring.Day3.ExtractMethodObject.After
{
    public class Receipt
    {
        public IList<decimal> Discounts { get; set; }
        public decimal Tax { get; set; }
        public IList<decimal> ItemTotals { get; set; }

        public decimal CalculateGrandTotal()
        {
            return new ReceiptCalculator(this).CalculateGrandTotal();
        }
    }
}

using System.Collections.Generic;

namespace Refactoring.Day3.ExtractMethodObject.After
{
    public class ReceiptCalculator
    {
        Receipt _receipt;        

        public ReceiptCalculator(Receipt receipt)
        {
            _receipt = receipt;
        }

        public decimal CalculateGrandTotal()
        {
            decimal subTotal = CalculateSubTotal();
            subTotal = CalculateDiscounts(subTotal);
            subTotal = CalculateTax(subTotal);
            return subTotal;
        }

        private decimal CalculateTax(decimal subTotal)
        {
            decimal tax = subTotal * _receipt.Tax;
            subTotal += tax;
            return subTotal;
        }

        private decimal CalculateDiscounts(decimal subTotal)
        {
            if (_receipt.Discounts.Count > 0)
            {
                foreach (decimal discount in _receipt.Discounts)
                    subTotal -= discount;
            }
            return subTotal;
        }

        private decimal CalculateSubTotal()
        {
            decimal subTotal = 0m;
            foreach (decimal itemTotal in _receipt.ItemTotals)
                subTotal += itemTotal;
            return subTotal;
        }
    }
}