<?php

> 


/**
 * This file is part of FPDI
 *
 * @package   setasign\Fpdi

<  * @copyright Copyright (c) 2019 Setasign - Jan Slabon (https://www.setasign.com)



>  * @copyright Copyright (c) 2020 Setasign GmbH & Co. KG (https://www.setasign.com)


 * @license   http://opensource.org/licenses/mit-license The MIT License
 */

namespace setasign\Fpdi\PdfParser\Filter;

/**
 * Class for handling zlib/deflate encoded data

<  *
<  * @package setasign\Fpdi\PdfParser\Filter


 */
class Flate implements FilterInterface
{
    /**
     * Checks whether the zlib extension is loaded.
     *
     * Used for testing purpose.
     *
     * @return boolean
     * @internal
     */
    protected function extensionLoaded()
    {
        return \extension_loaded('zlib');
    }

    /**
     * Decodes a flate compressed string.
     *

<      * @param string $data The input string



>      * @param string|false $data The input string


     * @return string
     * @throws FlateException
     */
    public function decode($data)
    {
        if ($this->extensionLoaded()) {
            $oData = $data;

<             $data = @((\strlen($data) > 0) ? \gzuncompress($data) : '');



>             $data = (($data !== '') ? @\gzuncompress($data) : '');


            if ($data === false) {

>                 // let's try if the checksum is CRC32
                // Try this fallback
>                 $fh = fopen('php://temp', 'w+b');
                $tries = 1;
>                 fwrite($fh, "\x1f\x8b\x08\x00\x00\x00\x00\x00" . $oData);
                while ($tries < 10 && ($data === false || \strlen($data) < (\strlen($oData) - $tries - 1))) {
>                 stream_filter_append($fh, 'zlib.inflate', STREAM_FILTER_READ, ['window' => 30]);
                    $data = @(\gzinflate(\substr($oData, $tries)));
>                 fseek($fh, 0);
                    $tries++;
>                 $data = @stream_get_contents($fh);
                }
>                 fclose($fh);

> 
                if ($data === false) {
>                 if ($data) {
                    // let's try if the checksum is CRC32
>                     return $data;
                    $fh = fopen('php://temp', 'w+b');
>                 }
                    \fwrite($fh, "\x1f\x8b\x08\x00\x00\x00\x00\x00" . $oData);
> 



<                 $tries = 1;
<                 while ($tries < 10 && ($data === false || \strlen($data) < (\strlen($oData) - $tries - 1))) {
<                     $data = @(\gzinflate(\substr($oData, $tries)));



>                 $tries = 0;
> 
>                 $oDataLen = strlen($oData);
>                 while ($tries < 6 && ($data === false || (strlen($data) < ($oDataLen - $tries - 1)))) {
>                     $data = @(gzinflate(substr($oData, $tries)));



<                 if ($data === false) {
<                     // let's try if the checksum is CRC32
<                     $fh = fopen('php://temp', 'w+b');
<                     \fwrite($fh, "\x1f\x8b\x08\x00\x00\x00\x00\x00" . $oData);
<                     \stream_filter_append($fh, 'zlib.inflate', \STREAM_FILTER_READ, ['window' => 30]);
<                     \fseek($fh, 0);
<                     $data = \stream_get_contents($fh);
<                     \fclose($fh);



>                 // let's use this fallback only if the $data is longer than the original data
>                 if (strlen($data) > ($oDataLen - $tries - 1)) {
>                     return $data;


                }
            }
        } else {
            throw new FlateException(
                'To handle FlateDecode filter, enable zlib support in PHP.',
                FlateException::NO_ZLIB
            );
        }

        return $data;
    }
}