<?php

namespace LdapRecord;

class Utilities
{
    /**
     * Converts a DN string into an array of RDNs.
     *
     * This will also decode hex characters into their true
     * UTF-8 representation embedded inside the DN as well.
     *
     * @param string $dn
     * @param bool   $removeAttributePrefixes
     *
     * @return array|false
     */
    public static function explodeDn($dn, $removeAttributePrefixes = true)
    {
        $dn = ldap_explode_dn($dn, ($removeAttributePrefixes ? 1 : 0));

        if (! is_array($dn)) {
            return false;
        }

        if (! array_key_exists('count', $dn)) {
            return false;
        }

        unset($dn['count']);

        foreach ($dn as $rdn => $value) {
            $dn[$rdn] = static::unescape($value);
        }

        return $dn;
    }

    /**
     * Un-escapes a hexadecimal string into its original string representation.
     *
     * @param string $value
     *
     * @return string
     */
    public static function unescape($value)
    {
        return preg_replace_callback('/\\\([0-9A-Fa-f]{2})/', function ($matches) {
            return chr(hexdec($matches[1]));
        }, $value);
    }

    /**
     * Convert a binary SID to a string SID.
     *
     * @author Chad Sikorra
     *
     * @see https://github.com/ChadSikorra
     * @see https://stackoverflow.com/questions/39533560/php-ldap-get-user-sid
     *
     * @param string $value The Binary SID
     *
     * @return string|null
     */
    public static function binarySidToString($value)
    {
        // Revision - 8bit unsigned int (C1)
        // Count - 8bit unsigned int (C1)
        // 2 null bytes
        // ID - 32bit unsigned long, big-endian order
        $sid = @unpack('C1rev/C1count/x2/N1id', $value);

        if (! isset($sid['id']) || ! isset($sid['rev'])) {
            return;
        }

        $revisionLevel = $sid['rev'];

        $identifierAuthority = $sid['id'];

        $subs = isset($sid['count']) ? $sid['count'] : 0;

        $sidHex = $subs ? bin2hex($value) : '';

        $subAuthorities = [];

        // The sub-authorities depend on the count, so only get as
        // many as the count, regardless of data beyond it.
        for ($i = 0; $i < $subs; $i++) {
            $data = implode(array_reverse(
                str_split(
                    substr($sidHex, 16 + ($i * 8), 8),
                    2
                )
            ));

            $subAuthorities[] = hexdec($data);
        }

        // Tack on the 'S-' and glue it all together...
        return 'S-'.$revisionLevel.'-'.$identifierAuthority.implode(
            preg_filter('/^/', '-', $subAuthorities)
        );
    }

    /**
     * Convert a binary GUID to a string GUID.
     *
     * @param string $binGuid
     *
     * @return string|null
     */
    public static function binaryGuidToString($binGuid)
    {
        if (trim($binGuid) == '' || is_null($binGuid)) {
            return;
        }

        $hex = unpack('H*hex', $binGuid)['hex'];

        $hex1 = substr($hex, -26, 2).substr($hex, -28, 2).substr($hex, -30, 2).substr($hex, -32, 2);
        $hex2 = substr($hex, -22, 2).substr($hex, -24, 2);
        $hex3 = substr($hex, -18, 2).substr($hex, -20, 2);
        $hex4 = substr($hex, -16, 4);
        $hex5 = substr($hex, -12, 12);

        return sprintf('%s-%s-%s-%s-%s', $hex1, $hex2, $hex3, $hex4, $hex5);
    }

    /**
     * Converts a string GUID to it's hex variant.
     *
     * @param string $string
     *
     * @return string
     */
    public static function stringGuidToHex($string)
    {
        $hex = '\\'.substr($string, 6, 2).'\\'.substr($string, 4, 2).'\\'.substr($string, 2, 2).'\\'.substr($string, 0, 2);
        $hex = $hex.'\\'.substr($string, 11, 2).'\\'.substr($string, 9, 2);
        $hex = $hex.'\\'.substr($string, 16, 2).'\\'.substr($string, 14, 2);
        $hex = $hex.'\\'.substr($string, 19, 2).'\\'.substr($string, 21, 2);
        $hex = $hex.'\\'.substr($string, 24, 2).'\\'.substr($string, 26, 2).'\\'.substr($string, 28, 2).'\\'.substr($string, 30, 2).'\\'.substr($string, 32, 2).'\\'.substr($string, 34, 2);

        return $hex;
    }

    /**
     * Round a Windows timestamp down to seconds and remove
     * the seconds between 1601-01-01 and 1970-01-01.
     *
     * @param float $windowsTime
     *
     * @return float
     */
    public static function convertWindowsTimeToUnixTime($windowsTime)
    {
        return round($windowsTime / 10000000) - 11644473600;
    }

    /**
     * Convert a Unix timestamp to Windows timestamp.
     *
     * @param float $unixTime
     *
     * @return float
     */
    public static function convertUnixTimeToWindowsTime($unixTime)
    {
        return ($unixTime + 11644473600) * 10000000;
    }

    /**
     * Validates that the inserted string is an object SID.
     *
     * @param string $sid
     *
     * @return bool
     */
    public static function isValidSid($sid)
    {
        return (bool) preg_match("/^S-\d(-\d{1,10}){1,16}$/i", $sid);
    }

    /**
     * Validates that the inserted string is an object GUID.
     *
     * @param string $guid
     *
     * @return bool
     */
    public static function isValidGuid($guid)
    {
        return (bool) preg_match('/^([0-9a-fA-F]){8}(-([0-9a-fA-F]){4}){3}-([0-9a-fA-F]){12}$/', $guid);
    }
}