Laravel如何根据用户id生成四位数唯一邀请码

<?php

namespace AppServices;// 邀请码服务class InviteCodeService{

 protected $key,$num;
 public function __construct()
 {
 $this->key = 'abcdefghjkmnpqrstuvwxyz123456789';
 // 注意这个key里面不能出现数字0 否则当 求模=0 会重复的

 // 多少进制
 $this->num = strlen($this->key);
 }

 // 传递用户id生成唯一邀请码
 public function enCode(int $user_id)
 {

 $code = ''; // 邀请码
 while ($user_id > 0) { // 转进制
 $mod = $user_id % $this->num; // 求模

 $user_id = ($user_id - $mod) / $this->num;
 $code = $this->key[$mod] . $code;
 }

 $code = str_pad($code, 4, '0', STR_PAD_LEFT); // 不足用0补充
 return $code;
 }


 // 邀请码获取用户id 一般都不需要用到
 function deCode($code)
 {

 if (strrpos($code, '0') !== false)
 $code = substr($code, strrpos($code, '0') + 1);
 $len = strlen($code);
 $code = strrev($code);
 $user_id = 0;
 for ($i = 0; $i < $len; $i++)
 $user_id += strpos($this->key, $code[$i]) * pow($this->num, $i);
 return $user_id;
 }}

 use AppServicesInviteCodeService;
 public function register()
 {
 $this->app->singleton('invite_code',InviteCodeService::class);
 }

 $max_num = 200000;

 $codes = [];
 for ($i = 1; $i <= $max_num; $i++)
 $codes[] = app('invite_code')->enCode($i);

 $i = 1;
 foreach ($codes as $code){
 $userId = app('invite_code')->deCode($code); // 邀请码获取用户id

 if( $userId != $i)
 dd("邀请码解密错误".$i);
 $i++;
 }

 $unique_count = count(array_unique($codes));
 dd($unique_count); // 不重复的总数