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<?php
namespace  App\Services;
// 邀請碼服務(wù)
class  InviteCodeService
{
 protected  $key,$num,$wordKey,$numericKey;
 public  function  __construct()
    {
 $this->key = 'X1A3B2abCDcEFGdH4eI5JfK6LgNM7OhP8QiR9SjTkUlVmWnSoYpZqrstuvwxyz';
 $this->wordKey = 'AaBbCDcdeEfFgGihHIjJlKknmLqoNrwMpsvsOuPytQRzSTUVWSYZ';
 $this->numericKey = '1234567890';
 // 注意這個key里面不能出現(xiàn)數(shù)字0  否則當(dāng) 求模=0 會重復(fù)的
 // 多少進(jìn)制
 $this->num = strlen($this->key);
    }
 // 傳遞用戶id生成唯一邀請碼
 public  function  enCode(int  $user_id, $length = 10)
    {
 $code = $end = $begin = $middle = ''; // 邀請碼
 //末尾用取模算法保證唯一
 while ($user_id > 0) { // 轉(zhuǎn)進(jìn)制
 $mod = $user_id % $this->num; // 求模
 $user_id = ($user_id - $mod) / $this->num;
 $end = $this->key[$mod] .  $end;
        }
 // 開頭使用4位隨機(jī)的數(shù)字加字母
 $begin = $this->wordKey[rand(0, strlen($this->wordKey) - 1)] .  $this->numericKey[rand(0, strlen($this->numericKey) - 1)] .  $this->wordKey[rand(0, strlen($this->wordKey) - 1)] .  $this->numericKey[rand(0, strlen($this->numericKey) - 1)];
 // 中間用隨機(jī)字符串補(bǔ)充
 while((strlen($begin)+strlen($middle)+strlen($end)) < $length){
 $middle = $this->key[rand(0, $this->num - 1)] .  $middle;
        }
 $code = $begin.$middle.$end;
 return  $code;
    }
     /**
     * 邀請碼獲取用戶id  一般都不需要用到
     * 這里的解密代碼不完整，思路是對的
     * 解密思路
     * 加密的時候最后一位記錄唯一串的長度，也就是 $end 的長度
     * 解密的時候讀取串的最后一位獲得長度，根據(jù)長度獲取 $end 字符串
     * $end 通過以下函數(shù)就能實現(xiàn)解密
     * */ 
    function deCode($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;
    }
$a = 3600;
$b = $a + 10;
for($i=$a ; $i<$b;$i++){
 echo (new  InviteCodeService)->enCode($i); echo PHP_EOL;
}

// $this->key = 'abcdefghjkmnpqrstuvwxyz123456789'; // 沒打亂的
$this->key = 'kh8sjpdazetnmb5yw7rq4gc9fuv3216x'; // 打亂的