using System;

using System.Linq;

using System.IO;

​

public class Program

{

    private const int TAGLEN = 24;

    private const Position POSITION = Position.Split;

    public static void Main()

    {

        Console.WriteLine($"Position >>> {POSITION}");

        var requestBody = POSITION switch 

        {

            Position.Front => "aaaaaaaaaaaabbbbbbbbbbbbxhjkjfgdhsgdhjklyukkutyjfhghjl;uiyuktfjghvx",

            Position.Split => "aaaaaaaaaaaaxhjkjfgdhsgdhjklyukkutyjfhghjl;uiyuktfjghvxbbbbbbbbbbbb",

            Position.Back => "xhjkjfgdhsgdhjklyukkutyjfhghjl;uiyuktfjghvxaaaaaaaaaaaabbbbbbbbbbbb"

        };

        Console.WriteLine($"RequestBody >>> {requestBody}");

        var x = GetRequestDataTag(requestBody);

        Console.WriteLine($"Tag >>> {x.Item1}");

        Console.WriteLine($"Data >>> {x.Item2}");

        var responseBody = GetResponseDataTag(x.Item1, x.Item2);

        Console.WriteLine($"ResponseBody >>> {responseBody}");

    }

    public enum Position

    {

        Front = 1,

        Split,

        Back

    }

​

    public static (string tag, string data) GetRequestDataTag(string requestBody)

    {

        return POSITION switch

        {

            Position.Front => (

                tag: requestBody[..TAGLEN],

                data: requestBody[TAGLEN..]

            ),

            Position.Split => (

                tag: requestBody[..(TAGLEN/2)] + requestBody[^(TAGLEN/2)..],

                data: requestBody[(TAGLEN/2)..^(TAGLEN/2)]

            ),

            Position.Back => (

                tag: requestBody[^TAGLEN..],

                data: requestBody[..^TAGLEN]

            ),

            _ => throw new ArgumentException("Unknown position.")

        };

    }

    public static string GetResponseDataTag(string tag, string data)

    {

        return POSITION switch

        {

            Position.Front => $"{tag}{data}",

            Position.Split => $"{tag[..(TAGLEN / 2)]}{data}{tag[^(TAGLEN / 2)..]}",

            Position.Back => $"{data}{tag}",

            _ => throw new ArgumentException("Unknown position.")

        };

    }

}

​