<?php
/**
 * @package     Joomla.Platform
 * @subpackage  Archive
 *
 * @copyright   Copyright (C) 2005 - 2016 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE
 */

defined('JPATH_PLATFORM') or die;

jimport('joomla.filesystem.file');

/**
 * Gzip format adapter for the JArchive class
 *
 * This class is inspired from and draws heavily in code and concept from the Compress package of
 * The Horde Project <https://www.horde.org>
 *
 * @contributor  Michael Slusarz <slusarz@horde.org>
 * @contributor  Michael Cochrane <mike@graftonhall.co.nz>
 *
 * @since  11.1
 */
class JArchiveGzip implements JArchiveExtractable
{
	/**
	 * Gzip file flags.
	 *
	 * @var    array
	 * @since  11.1
	 */
	private $_flags = array('FTEXT' => 0x01, 'FHCRC' => 0x02, 'FEXTRA' => 0x04, 'FNAME' => 0x08, 'FCOMMENT' => 0x10);

	/**
	 * Gzip file data buffer
	 *
	 * @var    string
	 * @since  11.1
	 */
	private $_data = null;

	/**
	 * Extract a Gzip compressed file to a given path
	 *
	 * @param   string  $archive      Path to ZIP archive to extract
	 * @param   string  $destination  Path to extract archive to
	 * @param   array   $options      Extraction options [unused]
	 *
	 * @return  boolean  True if successful
	 *
	 * @since   11.1
	 * @throws  RuntimeException
	 */
	public function extract($archive, $destination, array $options = array())
	{
		$this->_data = null;

		if (!extension_loaded('zlib'))
		{
			return $this->raiseWarning(100, 'The zlib extension is not available.');
		}

		if (isset($options['use_streams']) && $options['use_streams'] != false)
		{
			return $this->extractStream($archive, $destination, $options);
		}

		$this->_data = file_get_contents($archive);

		if (!$this->_data)
		{
			return $this->raiseWarning(100, 'Unable to read archive');
		}

		$position = $this->_getFilePosition();
		$buffer = gzinflate(substr($this->_data, $position, strlen($this->_data) - $position));

		if (empty($buffer))
		{
			return $this->raiseWarning(100, 'Unable to decompress data');
		}

		if (JFile::write($destination, $buffer) === false)
		{
			return $this->raiseWarning(100, 'Unable to write archive');
		}

		return true;
	}

	/**
	 * Method to extract archive using stream objects
	 *
	 * @param   string  $archive      Path to ZIP archive to extract
	 * @param   string  $destination  Path to extract archive to
	 * @param   array   $options      Extraction options [unused]
	 *
	 * @return  boolean  True if successful
	 */
	protected function extractStream($archive, $destination, $options = array())
	{
		// New style! streams!
		$input = JFactory::getStream();

		// Use gz
		$input->set('processingmethod', 'gz');

		if (!$input->open($archive))
		{
			return $this->raiseWarning(100, 'Unable to read archive (gz)');
		}

		$output = JFactory::getStream();

		if (!$output->open($destination, 'w'))
		{
			$input->close();

			return $this->raiseWarning(100, 'Unable to write archive (gz)');
		}

		do
		{
			$this->_data = $input->read($input->get('chunksize', 8196));

			if ($this->_data && !$output->write($this->_data))
			{
				$input->close();

				return $this->raiseWarning(100, 'Unable to write file (gz)');
			}
		}

		while ($this->_data);

		$output->close();
		$input->close();

		return true;
	}

	/**
	 * Temporary private method to isolate JError from the extract method
	 * This code should be removed when JError is removed.
	 *
	 * @param   int     $code  The application-internal error code for this error
	 * @param   string  $msg   The error message, which may also be shown the user if need be.
	 *
	 * @return  JException  JException instance if JError class exists
	 *
	 * @throws  RuntimeException if JError class does not exist
	 */
	private function raiseWarning($code, $msg)
	{
		if (class_exists('JError'))
		{
			return JError::raiseWarning($code, $msg);
		}

		throw new RuntimeException($msg);
	}

	/**
	 * Tests whether this adapter can unpack files on this computer.
	 *
	 * @return  boolean  True if supported
	 *
	 * @since   11.3
	 */
	public static function isSupported()
	{
		return extension_loaded('zlib');
	}

	/**
	 * Get file data offset for archive
	 *
	 * @return  integer  Data position marker for archive
	 *
	 * @since   11.1
	 * @throws  RuntimeException
	 */
	public function _getFilePosition()
	{
		// Gzipped file... unpack it first
		$position = 0;
		$info = @ unpack('CCM/CFLG/VTime/CXFL/COS', substr($this->_data, $position + 2));

		if (!$info)
		{
			return $this->raiseWarning(100, 'Unable to decompress data.');
		}

		$position += 10;

		if ($info['FLG'] & $this->_flags['FEXTRA'])
		{
			$XLEN = unpack('vLength', substr($this->_data, $position + 0, 2));
			$XLEN = $XLEN['Length'];
			$position += $XLEN + 2;
		}

		if ($info['FLG'] & $this->_flags['FNAME'])
		{
			$filenamePos = strpos($this->_data, "\x0", $position);
			$position = $filenamePos + 1;
		}

		if ($info['FLG'] & $this->_flags['FCOMMENT'])
		{
			$commentPos = strpos($this->_data, "\x0", $position);
			$position = $commentPos + 1;
		}

		if ($info['FLG'] & $this->_flags['FHCRC'])
		{
			$hcrc = unpack('vCRC', substr($this->_data, $position + 0, 2));
			$hcrc = $hcrc['CRC'];
			$position += 2;
		}

		return $position;
	}
}
