using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Payments();

    }

​

    private static void Payments()

    {

        bool proceed = true;

        string operation;

        while (proceed)

        {

            IList<string> options = new List<string>{"[Press any end to exit!]"};

            foreach (string option in options)

            {

                Console.WriteLine(option);

            }

​

            Console.Write("Choose your Option:");

            operation = Console.ReadLine();

            if (operation == "end")

            {

                return;

            }

​

            int totalDueAmount = int.Parse(operation), runningValue = totalDueAmount;

            IList<Orders> rawOrders = new List<Orders>()

            {new Orders()

            {OrderNumber = 1, DueAmount = 0, OrderAmount = 2000, OrderDate = new DateTime(2019, 12, 21, 0, 0, 0, 0)}, new Orders()

            {OrderNumber = 11, DueAmount = 0, OrderAmount = 2000, OrderDate = new DateTime(2019, 12, 23, 0, 0, 0, 0)}, new Orders()

            {OrderNumber = 21, DueAmount = 0, OrderAmount = 2000, OrderDate = new DateTime(2019, 12, 26, 0, 0, 0, 0)}, new Orders()

            {OrderNumber = 14, DueAmount = 0, OrderAmount = 2000, OrderDate = new DateTime(2019, 12, 4, 0, 0, 0, 0)}, new Orders()

            {OrderNumber = 51, DueAmount = 0, OrderAmount = 1100, OrderDate = new DateTime(2019, 12, 28, 0, 0, 0, 0)}, new Orders()

            {OrderNumber = 16, DueAmount = 0, OrderAmount = 2500, OrderDate = new DateTime(2019, 12, 6, 0, 0, 0, 0)}, new Orders()

            {OrderNumber = 71, DueAmount = 0, OrderAmount = 3000, OrderDate = new DateTime(2019, 12, 7, 0, 0, 0, 0)}, new Orders()

            {OrderNumber = 13, DueAmount = 0, OrderAmount = 2000, OrderDate = new DateTime(2019, 12, 8, 0, 0, 0, 0)}, new Orders()

            {OrderNumber = 9, DueAmount = 0, OrderAmount = 2000, OrderDate = new DateTime(2019, 12, 9, 0, 0, 0, 0)}};

            List<Orders> mappedOrders = rawOrders.Select(item => new Orders{DueAmount = item.DueAmount, Changed = false, OrderNumber = item.OrderNumber, UpdatedDueAmount = item.DueAmount, OrderAmount = item.OrderAmount, OrderDate = item.OrderDate}).OrderByDescending(a => a.OrderDate).ToList();

            foreach (Orders item in mappedOrders)

            {

                if (item.OrderAmount <= runningValue)

                {

                    runningValue = runningValue - item.OrderAmount;

                    item.UpdatedDueAmount = item.OrderAmount;

                    item.Changed = true;

                }

                else

                {

                    item.UpdatedDueAmount = runningValue;

                    item.Changed = true;

                    break;

                }

            }

​

            var filteredOrders = mappedOrders.Where(a => a.Changed == true);

            var testAllocatedAmount = 0;

            foreach (var item in filteredOrders)

            {

                testAllocatedAmount = testAllocatedAmount + item.UpdatedDueAmount;

                Console.WriteLine(item.ToString());

            }

            Console.WriteLine(String.Format("Entered Total Amount : {0}, Total Allocated Amount: {1}", totalDueAmount, testAllocatedAmount));

        }

    }

​

    private class Orders

    {

        public int OrderNumber

        {

            get;

            set;

        }

​

        public int UpdatedDueAmount

        {

            get;

            set;

        }

​

        public bool Changed

        {

            get;

            set;

        }

​

        public int DueAmount

        {

            get;

            set;

        }

​

        public int OrderAmount

        {

            get;

            set;

        }

​

        public DateTime OrderDate

        {

            get;

            set;

        }

​

        public override string ToString()

        {

            return string.Format("Order Number : {0}, Due Amount : {1}, Update Due Amount : {2}", OrderNumber, DueAmount, UpdatedDueAmount);

        }

    }

} 

​