using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace QRCodeService.Extensions
{
    public static class StringExtension
    {
        public static byte[] ToMD5(this string value)
        {
            using (var md5 = MD5.Create())
            {
                var result = md5.ComputeHash(Encoding.UTF8.GetBytes(value));
                return result;
            }
        }
        public static DateTime? ToDate(this string dateTimeStr, string[] dateFmt)
        {
            // example: var dt = "2011-03-21 13:26".toDate(new string[]{"yyyy-MM-dd HH:mm", 
            //                                                  "M/d/yyyy h:mm:ss tt"});
            const DateTimeStyles style = DateTimeStyles.AllowWhiteSpaces;
            if (dateFmt == null)
            {
                var dateInfo = System.Threading.Thread.CurrentThread.CurrentCulture.DateTimeFormat;
                dateFmt = dateInfo.GetAllDateTimePatterns();
            }
            DateTime? result = null;
            DateTime dt;
            if (DateTime.TryParseExact(dateTimeStr, dateFmt,
               CultureInfo.InvariantCulture, style, out dt)) result = dt;
            return result;
        }

        public static DateTime? ToDate(this string dateTimeStr, string dateFmt = null)
        {
            // example:   var dt="2011-03-21 13:26".toDate("yyyy-MM-dd HH:mm");
            // or simply  var dt="2011-03-21 13:26".toDate();        
            // call overloaded function with string array param
            string[] dateFmtArr = dateFmt == null ? null : new string[] { dateFmt };
            return ToDate(dateTimeStr, dateFmtArr);
        }
    }
}