using System;

using System.Linq;

using System.Text.RegularExpressions;

public class Program {

  private static string MakeRegex(params string[] patterns) {

    static string SinglePattern(string pattern) => "(?:" + string.Concat(Regex

      .Split(pattern, "(x+)")

      .Select(item => item.StartsWith('x')

         ? $"[0-9]{{{item.Length}}}"

         : string.Concat(item.Select(c => Regex.Escape(c.ToString()))))) + ")";

​

     return string.Join("|", patterns.Select(pattern => SinglePattern(pattern))); 

  }

  public static void Main() {

    string phonePattern = MakeRegex(

      "+xxx xxx xxx xxx",

      "(xxx) xxx xxx xxx",

      "xxx xxx xxx",

      "xxxxxxxxx",

      "+xxxxxxxxxxxx"

    );

​

    string[] tests = new string[] {

      //TODO: Add more tests here

      "+123 456 789 777",

      "(123) 456 789 444",

      "123 456 789",

      "123456789",

      "+123456789567",

​

      "12345678",

      "1234567899",

      "1234 56 789",

    };

​

    string report = string.Join(Environment.NewLine, tests

      .Select(test => $"{test,20} : {(Regex.IsMatch(test, phonePattern) ? "Matched" : "No")}"));

​

    Console.WriteLine(report);

    Console.WriteLine();

    Console.WriteLine("Parsed Demo");

    Console.WriteLine();   

    string text = 

      @"This is the sample text with phones: +420 000 111 222,

      and (420) 555 789 567 or 123456789 and some numbers 123 or 78.";

​

    var parsed = Regex

      .Matches(text, phonePattern)

      .Cast<Match>()

      .Select(m => string.Concat(m.Value.Where(c => c >= '0' && c <= '9')))

      .Select(phone => new {

        country = phone.Length > 9 ? phone.Substring(0, 3) : "",

        number =  phone.Length > 9 ? phone.Substring(3) : phone

      });   

    Console.WriteLine(string.Join(Environment.NewLine, parsed));      

  }

}