using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;

namespace Testreg2342
{
    public class Program
    {
        static void Main(string[] args)
        {
            bool unitTestPassed = true;

            List<string> goodEntries = new List<string>
            {
                "2008-12-22"
            };

            List<string> badEntries = new List<string>
            {
                "2010-12-12X",
                "2010-12-32 12:00:00"
            };

            foreach (var entry in goodEntries)
            {
                if (entry.IsValidDateFormat())
                    Console.WriteLine("ok: good entry correctly passed: " + entry);
                else
                {
                    Console.WriteLine("**FAIL** GOOD ENTRY INCORRECTLY DID NOT PASS: " + entry);
                    unitTestPassed = false;
                }
            }

            foreach (var entry in badEntries)
            {
                if (!entry.IsValidDateFormat())
                    Console.WriteLine("ok: bad entry corrcectly did not pass : " + entry);
                else
                {
                    Console.WriteLine("**FAIL** BAD ENTRY INCORRECTLY PASSED: " + entry);
                    unitTestPassed = false;
                }
            }

            Console.WriteLine();
            if(unitTestPassed)
                Console.WriteLine("unit test passed");
            else
                Console.WriteLine("UNIT TEST FAILED, CORRECT ALL ENTRIES MARKED **FAIL** ABOVE!");

            Console.ReadLine();

        }
    }

    public static class StringHelpers
    {
        public static bool IsValidDateFormat(this string purportedDateFormat)
        {
            return RegexHelpers.Matches(purportedDateFormat, @"^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$");
        }
    }

    public static class RegexHelpers
    {

        //use if you are expecting only one match, e.g. from "id = ???"
        public static string GetMatch(string text, string regex)
        {
            Match match = Regex.Match(text, regex);
            if (match.Success)
            {
                string theMatch = match.Groups[0].Value;
                return theMatch;
            }
            else
            {
                return null;
            }
        }

        public static bool Matches(string text, string regex)
        {
            if (GetMatch(text, regex) != null)
                return true;
            else
                return false;
        }
    }
}