password generator

Password.php

<?php

/**
 * @copyright Copyright (C) 2016 Max Dark maxim.dark@gmail.com
 * @license MIT; see LICENSE.txt
 */
namespace Tools{

    /**
     * Class Password
     * @package Tools
     */
    class Password
    {
        /**
         * Generate password
         *
         * @param bool $use_digs
         * @param bool $use_small
         * @param bool $use_big
         * @param bool $use_special
         * @param int  $length must be > 0
         *
         * @return string
         * @throws \Exception
         */
        public static function generate($use_digs, $use_small, $use_big, $use_special, $length)
        {
            $chars = [];
            $length = intval($length);
            if ($length < 1) {
                throw new \Exception('length must be > 0');
            }
            if ($use_digs) {
                $chars = self::append($chars, range('0', '9'));
            }
            if ($use_small) {
                $chars = self::append($chars, range('a', 'z'));
            }
            if ($use_big) {
                $chars = self::append($chars, range('A', 'Z'));
            }
            if ($use_special) {
                $chars = self::append($chars, self::charsOf('~`!@#$%^&*()-_=+\\|<,>./?:;"\''));
            }
            if (empty($chars)) {
                throw new \Exception('All options is empty');
            }
            $result = [];
            for ($i = 0; $i < $length; ++$i) {
                shuffle($chars);
                $result[] = $chars[0];
            }

            return implode('', $result);
        }

        /**
         * append $tail to $head
         *
         * @param array $head
         * @param array $tail
         *
         * @return array
         */
        private static function append($head, $tail)
        {
            array_splice($head, count($head), null, $tail);
            return $head;
        }

        /**
         * split utf-8 string to array of chars
         *
         * @param string $str
         * @return array
         */
        private static function charsOf($str)
        {
            return preg_split('/(?<!^)(?!$)/u', $str);
        }
    }
}