bnhtrade/src/bnhtrade.Core/Logic/Account/TaxCalculation.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace bnhtrade.Core.Logic.Account
{
    public class TaxCalculation
    {
        public decimal GetGrossAmount(decimal netAmount, decimal taxPercent)
        {
            return netAmount * (1 + (taxPercent / 100));
        }

        public decimal GetGrossAmount(decimal netAmount, Model.Account.TaxCodeInfo taxCodeInfo)
        {
            return GetGrossAmount(netAmount, taxCodeInfo.TaxRate);
        }

        public decimal GetNetAmount(decimal grossAmount, decimal taxPercent)
        {
            return grossAmount / (1 + (taxPercent / 100));
        }

        public decimal GetNetAmount(decimal grossAmount, Model.Account.TaxCodeInfo taxCodeInfo)
        {
            return GetNetAmount(grossAmount, taxCodeInfo.TaxRate);
        }

        public decimal GetTaxAmount(decimal amount, bool amountIsTaxInclusive, decimal taxPercent)
        {
            if (amountIsTaxInclusive)
            {
                return amount - GetNetAmount(amount, taxPercent);
            }
            else
            {
                return amount * (taxPercent / 100);
            }
        }

        public decimal GetTaxAmount(decimal amount, bool amountIsTaxInclusive, Model.Account.TaxCodeInfo taxCodeInfo)
        {
            return GetTaxAmount(amount, amountIsTaxInclusive, taxCodeInfo.TaxRate);
        }

        public decimal GetMarginTaxRate(DateTime transactionDate)
        {
            decimal vatRate = 0;
            if (transactionDate >= new DateTime(2011, 01, 04))
            {
                vatRate = 20;
            }
            else
            {
                // more coding required
                throw new Exception("Transaction is outside the current margin scheme date scope");
            }
            return vatRate;
        }

        public decimal GetMarginTaxAmount(decimal marginAmount, DateTime transactionDate)
        {
            decimal vatRate = GetMarginTaxRate(transactionDate);

            return GetTaxAmount(marginAmount, true, vatRate);
        }

        public decimal GetMarginTaxAmount(decimal purchasePrice, decimal salePrice, DateTime transactionDate)
        {
            return GetMarginTaxAmount(salePrice - purchasePrice, transactionDate);
        }

        /// <summary>
        /// Returns a value to multiply margin (sale - purchase price) by to find margin scheme tax amount
        /// </summary>
        /// <param name="transactionDate">Date of transaction</param>
        /// <returns>Value between 0 and 1</returns>
        public decimal GetMarginMultiplier(DateTime transactionDate)
        {
            decimal vatRate = GetMarginTaxRate(transactionDate);
            return vatRate / (vatRate + 100);
        }
    }
}