using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Church.Net.Utility
{
    public static class TokenHelper
    {
        public static string GenerateToken(string userId, DateTime? expiredTime=null)
        {

            if (expiredTime == null)
            {
                expiredTime = DateTime.Now.AddDays(2);
            }
            byte[] time = BitConverter.GetBytes(expiredTime.Value.ToBinary());
            byte[] key = Encoding.ASCII.GetBytes(userId);
            // byte[] expiredTimeByte = BitConverter.GetBytes(expiredTime.ToBinary());
            string token = Convert.ToBase64String(time.Concat(key).ToArray());
            return token;
        }
        public static string GetUserIdFromToken(string token)
        {
            byte[] data = Convert.FromBase64String(token);
            DateTime when = DateTime.FromBinary(BitConverter.ToInt64(data, 0));
#if DEBUG
            when = DateTime.Today.AddDays(1);
#endif
            if (when >= DateTime.Now)
            {
                string userId = Encoding.ASCII.GetString(data.Skip(8).ToArray());
                return userId;
            }
            return null;
        }
    }
}