<?php
// +------------------------------------------------+
// |http://www.cjango.com                           |
// +------------------------------------------------+
// | 修复BUG不是一朝一夕的事情，等我喝醉了再说吧！  |
// +------------------------------------------------+
// | Author: 小陈叔叔 <Jason.Chen>                  |
// +------------------------------------------------+
namespace tools;

use think\Config as Conf;

class Crypt
{

    /**
     * 数据签名认证
     * @param  array  $data
     * @return string
     */
    public static function dataAuthSign($data = [])
    {
        ksort($data);
        $code = http_build_query($data);
        return sha1($code . Conf::get('data_auth_key'));
    }

    /**
     * 用户MD5不可逆加密
     * @param  string $string
     * @return string
     */
    public static function uMd5($string)
    {
        $key = Conf::get('data_auth_key');
        return '' === $string ? '' : md5(sha1($string) . $key);
    }

    /**
     * 长串加密
     * @param  string $string
     * @return string
     */
    public static function uSha1($string)
    {
        $key = Conf::get('data_auth_key');
        return '' === $string ? '' : sha1(md5($string) . $key);
    }

    /**
     * Discuz 经典双向加密/解密
     * @param  string $string     明文 或 密文
     * @param  string $operation  DECODE表示解密,其它表示加密
     * @param  string $key        密匙
     * @param  string $expiry     密文有效期
     */
    public static function discuz($string, $operation = 'DECODE', $key = '', $expiry = 0)
    {
        $ckey_length   = 4;
        $key           = md5($key ? $key : Conf::get('data_auth_key'));
        $keya          = md5(substr($key, 0, 16));
        $keyb          = md5(substr($key, 16, 16));
        $keyc          = $ckey_length ? ($operation == 'DECODE' ? substr($string, 0, $ckey_length) : substr(md5(microtime()), -$ckey_length)) : '';
        $cryptkey      = $keya . md5($keya . $keyc);
        $key_length    = strlen($cryptkey);
        $string        = $operation == 'DECODE' ? base64_decode(substr($string, $ckey_length)) : sprintf('%010d', $expiry ? $expiry + time() : 0) . substr(md5($string . $keyb), 0, 16) . $string;
        $string_length = strlen($string);
        $result        = '';
        $box           = range(0, 255);
        $rndkey        = [];
        for ($i = 0; $i <= 255; $i++) {
            $rndkey[$i] = ord($cryptkey[$i % $key_length]);
        }
        for ($j = $i = 0; $i < 256; $i++) {
            $j       = ($j + $box[$i] + $rndkey[$i]) % 256;
            $tmp     = $box[$i];
            $box[$i] = $box[$j];
            $box[$j] = $tmp;
        }
        for ($a = $j = $i = 0; $i < $string_length; $i++) {
            $a       = ($a + 1) % 256;
            $j       = ($j + $box[$a]) % 256;
            $tmp     = $box[$a];
            $box[$a] = $box[$j];
            $box[$j] = $tmp;
            $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
        }
        if ($operation == 'DECODE') {
            if ((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26) . $keyb), 0, 16)) {
                return substr($result, 26);
            } else {
                return '';
            }
        } else {
            return $keyc . str_replace('=', '', base64_encode($result));
        }
    }

}