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<?php

namespace GuzzleHttp\Psr7;

use Psr\Http\Message\StreamInterface;

/**

 * Uses PHP's zlib.inflate filter to inflate deflate or gzipped content.

 *

 * This stream decorator skips the first 10 bytes of the given stream to remove

 * the gzip header, converts the provided stream to a PHP stream resource,

 * then appends the zlib.inflate filter. The stream is then converted back

 * to a Guzzle stream resource to be used as a Guzzle stream.

 *

 * @link http://tools.ietf.org/html/rfc1952

 * @link http://php.net/manual/en/filters.compression.php

 */

class InflateStream implements StreamInterface

{

    use StreamDecoratorTrait;

    public function __construct(StreamInterface $stream)

    {

        // read the first 10 bytes, ie. gzip header

        $header = $stream->read(10);

        $filenameHeaderLength = $this->getLengthOfPossibleFilenameHeader($stream, $header);

        // Skip the header, that is 10 + length of filename + 1 (nil) bytes

        $stream = new LimitStream($stream, -1, 10 + $filenameHeaderLength);

        $resource = StreamWrapper::getResource($stream);

        stream_filter_append($resource, 'zlib.inflate', STREAM_FILTER_READ);

        $this->stream = new Stream($resource);

    }

    /**

     * @param StreamInterface $stream

     * @param $header

     * @return int

     */

    private function getLengthOfPossibleFilenameHeader(StreamInterface $stream, $header)

    {

        $filename_header_length = 0;

        if (substr(bin2hex($header), 6, 2) === '08') {

            // we have a filename, read until nil

            $filename_header_length = 1;

            while ($stream->read(1) !== chr(0)) {

                $filename_header_length++;

            }

        }

        return $filename_header_length;

    }

}