using System;

public class Program

{

    public static void Main()

    {

        var inputBaseAmount = 3000000;

        var inputBaseCurrency = "GBP";

        //Enter interbank ASK rate of EUR/baseCurrency - Get it from DB

        var interbankRate = 0.91691;

        var eurAccountBalance = 21411.46;

        var executionDate = new DateTimeOffset(2020, 12, 21, 23, 59, 59, TimeSpan.Zero);

        var valueDate = new DateTimeOffset(2020, 12, 30, 23, 59, 59, TimeSpan.Zero);

        var inputCurrencyBucket = "A";

        var percentage = 1.0/100;

        Console.WriteLine("!!!!Double check that you got from static table the percentage for currency bucket " +  inputCurrencyBucket +

                         " and tenor of: " + CalculateTenor(executionDate, valueDate)+ " month(s)");

        Console.WriteLine("**********");

        var initialBalance = CalculateInitialMargin(inputBaseAmount, percentage, interbankRate);

        Console.WriteLine("Initial Margin of " + inputBaseAmount + inputBaseCurrency + " is: " +

                         initialBalance + "EUR");

        var amountToFund = CalculateAmountToFund(initialBalance, eurAccountBalance);

        Console.WriteLine("Initial Balance Amount to fund is: " + amountToFund + "EUR");

    }

    private static double CalculateAmountToFund (double initialBalance, double balance)

    {

        return Math.Abs(Math.Round(balance-initialBalance,2));

    }

    private static double CalculateInitialMargin (double amount, double percentage, double interbankRate)

    {

        return CheckForMinimum(Math.Round(amount*percentage/interbankRate,2));

    }

    private static double CheckForMinimum(double initialMargin)

    {

        if(initialMargin<=5.0) return 5.0;

            else return initialMargin;

    }

    private static int CalculateTenor(DateTimeOffset executionDate, DateTimeOffset valueDate)

    {

        var deltaExecutionDateValueDate = Math.Abs((executionDate - valueDate).TotalDays);

        if(deltaExecutionDateValueDate<=30) {return 1;}

            else if(deltaExecutionDateValueDate>30 && deltaExecutionDateValueDate<=90) {return 3;}

                else if(deltaExecutionDateValueDate>90 && deltaExecutionDateValueDate<=180) {return 6;}

                    else if(deltaExecutionDateValueDate>180 && deltaExecutionDateValueDate<=360) {return 12;}

        else return 0;

    }

}