code: static public function generate($uid = 0, $hash = false)
      {
          if ($uid) {
              $e_uid = self::encode($uid);
              $e_uid_length = strlen($e_uid);
              $e_uid_length = str_pad($e_uid_length, 2, 0, STR_PAD_LEFT);
              $e_uid_pos = rand(10, 32 - $e_uid_length - 1);
  
              if (!$hash) {
                  $hash = sha1(uniqid(rand(), true));
              }
  
              $code = $e_uid_pos . $e_uid_length;
              $code .= substr($hash, 0, $e_uid_pos - strlen($code));
              $code .= $e_uid;
              $code .= substr($hash, strlen($code));
  
              return $code;
          } else {
              return sha1(uniqid(rand(), true));
          }
      }
docs: Generates a unique hash
  
  @param int         $uid  user id
  @param bool|string $hash optional hash to implement
  
  @return string