using System;

using System.Text.RegularExpressions;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var val = "%ABC%";

        var valFinal = val;

        if (valFinal.StartsWith("%"))

            valFinal = valFinal[1..];

        if (valFinal.EndsWith("%"))

            valFinal = valFinal[..^1];

        //Console.WriteLine(valFinal);

        (string value, string mask) obj;

        //obj = ("09945079760", "[\"###.###.###-##\", \"##.###.###/####-##\"]");

        //obj = ("04642554000143", "[\"###.###.###-##\", \"##.###.###/####-##\"]");

        //obj = ("09945079760", "###.###.###-##");

        //obj = ("04642554000143", "##.###.###/####-##");

        obj = ("A1B2C3D4", "XXXX-XXXX");

        //Console.WriteLine(Format(obj.value, obj.mask));

        Regex rg = new(@"\D");

        var s = "123.456-789";

        var x = rg.Replace(s, "");

        Console.WriteLine(x);

    }

​

    private static readonly Regex _rgxMask = new(@"([\D]+)");

​

    public static string Format(string value, string mask)

    {

        if (mask.Contains('#'))

        {

            var number = long.Parse(value);

            mask = mask.Replace("#", "0");

            var masksArr = new List<string>();

​

            if (mask.StartsWith("["))

            {

                mask = mask.Replace("[", "").Replace("]", "").Replace("\"", "");

                masksArr = mask.Split(",").Select(m => m.Trim()).ToList();

            }

            else

            {

                masksArr.Add(mask.Trim());

            }

​

            var masks = masksArr.Select(x => new { mask = _rgxMask.Replace(x, "\\$1"), noFormat = _rgxMask.Replace(x, "") });

            var maskFound = masks.FirstOrDefault(x => x.noFormat.Length == value.ToString().Length);

​

            if (maskFound == null)

            {

                mask = masks.First().mask;

            }

            else

            {

                mask = maskFound.mask;

            }

​

            return number.ToString(mask);

        }

        else

        {

            var exp = "";

            var count = 0;

            var groups = 0;

            var format = new List<char>();

​

            foreach (var c in mask)

            {

                if (c == 'X')

                {

                    if (count == 0)

                    {

                        exp += "(\\w{";

                        groups++;

                    }

                    count++;

                }

                else

                {

                    if (count > 0)

                    {

                        exp += count + "})";

                    }

                    format.Add(c);

                    count = 0;

                }

            }

            if (mask.Last() == 'X')

            {

                exp += count + "})";

            }

​

            var rgx = new Regex(exp);

            var replace = "";

​

            for (var i = 0; i < groups; i++)

            {

                replace += "$" + (i + 1);

                if (format.Count > i)

                {

                    replace += format[i];

                }

            }

​

            for (var i = groups; i < format.Count; i++)

            {

                replace += format[i];

            }

​

            return rgx.Replace(value, replace);

        }

    }

}