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

namespace PublicLibrary.Common
{
    public class RandHelper
    {
        /// <summary>
        /// 获得三位的随机数
        /// </summary>
        /// <returns></returns>
        public static string getThreeNumRandom()
        {
            Random ro = new Random();
            int iResult;
            int iUp = 999;
            int iDown = 100;
            iResult = ro.Next(iDown, iUp);
            //Response.Write(iResult.ToString());
            return iResult.ToString().Trim();
        }

        /// <summary>
        /// 新的日期字符串
        /// </summary>
        /// <param name="oldShortDateTime"></param>
        /// <returns></returns>
        public static string generateNewLongDateTime()
        {
            string currentTime = DateTime.Now.ToString("yyyyMMddHHmmss");
            return currentTime;
        }
        /*无重复的ID生成可由上述二个函数来生成：

        既可以生成由当前日期生成的ID，也可以由以前日期来生成这样的ID

        string newid = generateNewLongDateTime() + getTreeNumRandom();
        NewDateAndTime.ToString("yyyyMMddhhmmss");  这一句有问题，如果是下午12点以后，就会产生13-12,14-12的情况，不是按24小时制来完成的。
        NewDateAndTime.ToString("yyyyMMddHHmmss");
        ToString("yyyyMMddhhmmss");  12时制
        要改成ToString("yyyyMMddHHmmss");  24时制*/
        public static long GetTimeRandId()
        {
            string newid = generateNewLongDateTime() + getThreeNumRandom();
            return Int64.Parse(newid);
        }

        public static string GetRandGuid(int length)
        {
            string newid = Guid.NewGuid().ToString("N");
            newid = newid.Substring(0, length);
            return newid;
        }

        private static char[] constant =
         {
            '0','1','2','3','4','5','6','7','8','9',
            'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',
            'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'
          };
        public static string GenerateRandomCode(int Length)
        {
            System.Text.StringBuilder newRandom = new System.Text.StringBuilder(62);
            Random rd = new Random();
            for (int i = 0; i < Length; i++)
            {
                newRandom.Append(constant[rd.Next(62)]);
            }
            return newRandom.ToString();
        }
    }
}