using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace GDZZ.Core
{
    public class InvitaCode
    {

        //自定义进制(0、O没有加入,容易混淆；同时排除X,用X补位)
        private static char[] r = new char[] { 'Q', 'W', 'E', '8', 'A', 'S', '2', 'D', 'Z', '9', 'C', '7', 'P', '5', 'I', 'K', '3', 'M', 'J', 'U', 'F', 'R', '4', 'V', 'Y', 'L', 'T', 'N', '6', 'B', 'G', 'H' };
        //不能与自定义进制有重复
        private static char b = 'X';
        //进制长度
        private static int binLen = r.Length;
        //生成的邀请码长度
        private static int length = 6;

        /// <summary>
        /// 根据ID生成六位随机邀请码
        /// </summary>
        /// <param name="id">用户id</param>
        /// <returns>返回6位邀请码</returns>
        public static string Encode(long id)
        {
            char[] buf = new char[32];
            int charPos = 32;

            while ((id / binLen) > 0)
            {
                int ind = (int)(id % binLen);
                buf[--charPos] = r[ind];
                id /= binLen;
            }
            buf[--charPos] = r[(int)(id % binLen)];
            String str = new String(buf, charPos, (32 - charPos));
            //不够长度的自动随机补全
            if (str.Length < length)
            {
                StringBuilder sb = new StringBuilder();
                sb.Append(b);
                Random rnd = new Random();
                for (int i = 1; i < length - str.Length; i++)
                {
                    sb.Append(r[rnd.Next(binLen)]);
                }
                str += sb.ToString();
            }
            return str;
        }
    }
}