<?php
/**
 * @package LiveUpdate
 * @copyright Copyright ©2011 Nicholas K. Dionysopoulos / AkeebaBackup.com
 * @license GNU LGPLv3 or later <http://www.gnu.org/copyleft/lesser.html>
 */

defined('_JEXEC') or die();

/**
 * Allows downloading packages over the web to your server 
 */
class LiveUpdateDownloadHelper
{
	/**
	 * Downloads from a URL and saves the result as a local file
	 * @param <type> $url
	 * @param <type> $target
	 * @return bool True on success
	 */
	public static function download($url, $target)
	{
		// Import Joomla! libraries
		jimport('joomla.filesystem.file');

		/** @var bool Did we try to force permissions? */
		$hackPermissions = false;

		// Make sure the target does not exist
		if(JFile::exists($target)) {
			if(!@unlink($target)) {
				JFile::delete($target);
			}
		}

		// Try to open the output file for writing
		$fp = @fopen($target, 'wb');
		if($fp === false) {
			// The file can not be opened for writing. Let's try a hack.
			if( JFile::write($target, '') ) {
				if( self::chmod($target, 511) ) {
					$fp = @fopen($target, 'wb');
					$hackPermissions = true;
				}
			}
		}
		
		$result = false;
		if($fp !== false)
		{
			// First try to download directly to file if $fp !== false
			$adapters = self::getAdapters();
			$result = false;
			while(!empty($adapters) && ($result === false)) {
				// Run the current download method
				$method = 'get' . strtoupper( array_shift($adapters) );
				$result = self::$method($url, $fp);
				
				// Check if we have a download
				if($result === true) {
					// The download is complete, close the file pointer
					@fclose($fp);
					// If the filesize is not at least 1 byte, we consider it failed.
					clearstatcache();
					$filesize = @filesize($target);
					if($filesize <= 0) {
						$result = false;
						$fp = @fopen($target, 'wb');
					}
				}
			}
			
			// If we have no download, close the file pointer
			if($result === false) {
				@fclose($fp);
			}
		}

		if($result === false)
		{
			// Delete the target file if it exists
			if(file_exists($target)) {
				if( !@unlink($target) ) {
					JFile::delete($target);
				}
			}
			// Download and write using JFile::write();
			$result = JFile::write($target, self::downloadAndReturn($url) );
		}
		
		return $result;
	}

	/**
	 * Downloads from a URL and returns the result as a string
	 * @param <type> $url
	 * @return mixed Result string on success, false on failure
	 */
	public static function downloadAndReturn($url)
	{
		$adapters = self::getAdapters();
		$result = false;
		
		while(!empty($adapters) && ($result === false)) {
			// Run the current download method
			$method = 'get' . strtoupper( array_shift($adapters) );
			$result = self::$method($url, null);
		}
		
		return $result;
	}

	/**
	 * Does the server support PHP's cURL extension?
	 * @return bool True if it is supported
	 */
	private static function hasCURL()
	{
		static $result = null;

		if(is_null($result))
		{
			$result = function_exists('curl_init');
		}

		return $result;
	}
	
	/**
	 * Downloads the contents of a URL and writes them to disk (if $fp is not null)
	 * or returns them as a string (if $fp is null)
	 * @param string $url The URL to download from
	 * @param resource $fp The file pointer to download to. Omit to return the contents.
	 * @return bool|string False on failure, true on success ($fp not null) or the URL contents (if $fp is null)
	 */
	private static function &getCURL($url, $fp = null, $nofollow = false)
	{
		$result = false;
		
		$ch = curl_init($url);
		$config = new LiveUpdateConfig();
		$config->applyCACert($ch);
		
		if( !@curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1) && !$nofollow ) {
			// Safe Mode is enabled. We have to fetch the headers and
			// parse any redirections present in there.
			curl_setopt($ch, CURLOPT_AUTOREFERER, true);
			curl_setopt($ch, CURLOPT_FAILONERROR, true);
			curl_setopt($ch, CURLOPT_HEADER, true);
			curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
			curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
			curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
			curl_setopt($ch, CURLOPT_TIMEOUT, 30);

			// Get the headers
			$data = curl_exec($ch);
			curl_close($ch);
			
			// Init
			$newURL = $url;
			
			// Parse the headers
			$lines = explode("\n", $data);
			foreach($lines as $line) {
				if(substr($line, 0, 9) == "Location:") {
					$newURL = trim(substr($line,9));
				}
			}

			// Download from the new URL
			if($url != $newURL) {
				return self::getCURL($newURL, $fp);
			} else {
				return self::getCURL($newURL, $fp, true);
			}
		} else {
			@curl_setopt($ch, CURLOPT_MAXREDIRS, 20);
		}
		
		curl_setopt($ch, CURLOPT_AUTOREFERER, true);
		curl_setopt($ch, CURLOPT_FAILONERROR, true);
		curl_setopt($ch, CURLOPT_HEADER, false);
		curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
		curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
		curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
		curl_setopt($ch, CURLOPT_TIMEOUT, 30);
		// Pretend we are IE7, so that webservers play nice with us
		curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0)');
		
		if(is_resource($fp)) {
			curl_setopt($ch, CURLOPT_FILE, $fp);
		}
		
		$result = curl_exec($ch);
		curl_close($ch);
		
		return $result;
	}

	/**
	 * Does the server support URL fopen() wrappers?
	 * @return bool
	 */
	private static function hasFOPEN()
	{
		static $result = null;

		if(is_null($result))
		{
			// If we are not allowed to use ini_get, we assume that URL fopen is
			// disabled.
			if(!function_exists('ini_get')) {
				$result = false;
			} else {
				$result = ini_get('allow_url_fopen');
			}
		}

		return $result;
	}
	
	private static function &getFOPEN($url, $fp = null)
	{
		$result = false;
		
		// Track errors
		if( function_exists('ini_set') ) {
			$track_errors = ini_set('track_errors',true);
		}
		
		// Open the URL for reading
		if(function_exists('stream_context_create')) {
			// PHP 5+ way (best)
			$httpopts = Array('user_agent'=>'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0)');
			$context = stream_context_create( array( 'http' => $httpopts ) );
			$ih = @fopen($url, 'r', false, $context);
		} else {
			// PHP 4 way (actually, it's just a fallback as we can't run Admin Tools in PHP4)
			if( function_exists('ini_set') ) {
				ini_set('user_agent', 'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0)');
			}
			$ih = @fopen($url, 'r');
		}
		
		// If fopen() fails, abort
		if( !is_resource($ih) ) {
			return $result;
		}
		
		// Try to download
		$bytes = 0;
		$result = true;
		$return = '';
		while (!feof($ih) && $result)
		{
			$contents = fread($ih, 4096);
			if ($contents === false) {
				@fclose($ih);
				$result = false;
				return $result;
			} else {
				$bytes += strlen($contents);
				if(is_resource($fp)) {
					$result = @fwrite($fp, $contents);
				} else {
					$return .= $contents;
					unset($contents);
				}
			}
		}
		
		@fclose($ih);
		
		if(is_resource($fp)) {
			return $result;
		} elseif( $result === true ) {
			return $return;
		} else {
			return $result;
		}
	}

	/**
	 * Detect and return available download adapters
	 * @return array
	 */
	private static function getAdapters()
	{
		// Detect available adapters
		$adapters = array();
		if(self::hasCURL()) $adapters[] = 'curl';
		if(self::hasFOPEN()) $adapters[] = 'fopen';
		return $adapters;
	}

	/**
	 * Change the permissions of a file, optionally using FTP
	 * @param string $file Absolute path to file
	 * @param int $mode Permissions, e.g. 0755
	 */
	private static function chmod($path, $mode)
	{
		if(is_string($mode))
		{
			$mode = octdec($mode);
			if( ($mode < 0600) || ($mode > 0777) ) $mode = 0755;
		}

		// Initialize variables
		jimport('joomla.client.helper');
		$ftpOptions = JClientHelper::getCredentials('ftp');

		// Check to make sure the path valid and clean
		$path = JPath::clean($path);

		if ($ftpOptions['enabled'] == 1) {
			// Connect the FTP client
			jimport('joomla.client.ftp');
			$ftp = &JFTP::getInstance(
				$ftpOptions['host'], $ftpOptions['port'], null,
				$ftpOptions['user'], $ftpOptions['pass']
			);
		}

		if(@chmod($path, $mode))
		{
			$ret = true;
		} elseif ($ftpOptions['enabled'] == 1) {
			// Translate path and delete
			jimport('joomla.client.ftp');
			$path = JPath::clean(str_replace(JPATH_ROOT, $ftpOptions['root'], $path), '/');
			// FTP connector throws an error
			$ret = $ftp->chmod($path, $mode);
		} else {
			return false;
		}
	}

}