<?php
  /**
   * Copyright (c) 2011 Bart Visscher bartv@thisnet.nl
   * This file is licensed under the Affero General Public License version 3 or
   * later.
   * See the COPYING-README file.
   */
  
  class OC_Response {

  	const STATUS_FOUND = 304;

  	const STATUS_NOT_MODIFIED = 304;
  	const STATUS_TEMPORARY_REDIRECT = 307;

  	const STATUS_BAD_REQUEST = 400;

  	const STATUS_NOT_FOUND = 404;

  	const STATUS_INTERNAL_SERVER_ERROR = 500;

  	const STATUS_SERVICE_UNAVAILABLE = 503;

  
  	/**

  	* Enable response caching by sending correct HTTP headers
  	* @param integer $cache_time time to cache the response

  	*  >0		cache time in seconds
  	*  0 and <0	enable default browser caching
  	*  null		cache indefinitly
  	*/
  	static public function enableCaching($cache_time = null) {
  		if (is_numeric($cache_time)) {
  			header('Pragma: public');// enable caching in IE
  			if ($cache_time > 0) {
  				self::setExpiresHeader('PT'.$cache_time.'S');
  				header('Cache-Control: max-age='.$cache_time.', must-revalidate');
  			}
  			else {
  				self::setExpiresHeader(0);
  				header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
  			}
  		}
  		else {
  			header('Cache-Control: cache');
  			header('Pragma: cache');
  		}
  
  	}
  
  	/**

  	* disable browser caching

  	* @see enableCaching with cache_time = 0
  	*/
  	static public function disableCaching() {
  		self::enableCaching(0);
  	}
  
  	/**

  	* Set response status
  	* @param int $status a HTTP status code, see also the STATUS constants

  	*/
  	static public function setStatus($status) {
  		$protocol = $_SERVER['SERVER_PROTOCOL'];
  		switch($status) {
  			case self::STATUS_NOT_MODIFIED:
  				$status = $status . ' Not Modified';
  				break;
  			case self::STATUS_TEMPORARY_REDIRECT:
  				if ($protocol == 'HTTP/1.1') {
  					$status = $status . ' Temporary Redirect';
  					break;
  				} else {
  					$status = self::STATUS_FOUND;
  					// fallthrough
  				}
  			case self::STATUS_FOUND;
  				$status = $status . ' Found';
  				break;
  			case self::STATUS_NOT_FOUND;
  				$status = $status . ' Not Found';
  				break;

  			case self::STATUS_INTERNAL_SERVER_ERROR;
  				$status = $status . ' Internal Server Error';
  				break;

  			case self::STATUS_SERVICE_UNAVAILABLE;
  				$status = $status . ' Service Unavailable';
  				break;

  		}
  		header($protocol.' '.$status);
  	}
  
  	/**

  	* Send redirect response
  	* @param string $location to redirect to

  	*/
  	static public function redirect($location) {
  		self::setStatus(self::STATUS_TEMPORARY_REDIRECT);
  		header('Location: '.$location);
  	}
  
  	/**

  	* Set reponse expire time
  	* @param string|DateTime $expires date-time when the response expires

  	*  string for DateInterval from now
  	*  DateTime object when to expire response
  	*/
  	static public function setExpiresHeader($expires) {
  		if (is_string($expires) && $expires[0] == 'P') {
  			$interval = $expires;
  			$expires = new DateTime('now');
  			$expires->add(new DateInterval($interval));
  		}
  		if ($expires instanceof DateTime) {
  			$expires->setTimezone(new DateTimeZone('GMT'));
  			$expires = $expires->format(DateTime::RFC2822);
  		}
  		header('Expires: '.$expires);
  	}
  
  	/**
  	* Checks and set ETag header, when the request matches sends a
  	* 'not modified' response

  	* @param string $etag token to use for modification check

  	*/
  	static public function setETagHeader($etag) {
  		if (empty($etag)) {
  			return;
  		}
  		$etag = '"'.$etag.'"';
  		if (isset($_SERVER['HTTP_IF_NONE_MATCH']) &&
  		    trim($_SERVER['HTTP_IF_NONE_MATCH']) == $etag) {
  			self::setStatus(self::STATUS_NOT_MODIFIED);
  			exit;
  		}
  		header('ETag: '.$etag);
  	}
  
  	/**
  	* Checks and set Last-Modified header, when the request matches sends a
  	* 'not modified' response

  	* @param int|DateTime|string $lastModified time when the reponse was last modified

  	*/
  	static public function setLastModifiedHeader($lastModified) {
  		if (empty($lastModified)) {
  			return;
  		}
  		if (is_int($lastModified)) {
  			$lastModified = gmdate(DateTime::RFC2822, $lastModified);
  		}
  		if ($lastModified instanceof DateTime) {
  			$lastModified = $lastModified->format(DateTime::RFC2822);
  		}
  		if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) &&
  		    trim($_SERVER['HTTP_IF_MODIFIED_SINCE']) == $lastModified) {
  			self::setStatus(self::STATUS_NOT_MODIFIED);
  			exit;
  		}
  		header('Last-Modified: '.$lastModified);
  	}
  
  	/**

  	 * Sets the content disposition header (with possible workarounds)
  	 * @param string $filename file name
  	 * @param string $type disposition type, either 'attachment' or 'inline'
  	 */
  	static public function setContentDispositionHeader( $filename, $type = 'attachment' ) {

  		if (OC_Request::isUserAgent(array(
  				OC_Request::USER_AGENT_IE,
  				OC_Request::USER_AGENT_ANDROID_MOBILE_CHROME,
  				OC_Request::USER_AGENT_FREEBOX
  			))) {

  			header( 'Content-Disposition: ' . rawurlencode($type) . '; filename="' . rawurlencode( $filename ) . '"' );
  		} else {
  			header( 'Content-Disposition: ' . rawurlencode($type) . '; filename*=UTF-8\'\'' . rawurlencode( $filename )
  												 . '; filename="' . rawurlencode( $filename ) . '"' );
  		}
  	}
  
  	/**

  	* Send file as response, checking and setting caching headers
  	* @param string $filepath of file to send

  	*/
  	static public function sendFile($filepath) {
  		$fp = fopen($filepath, 'rb');
  		if ($fp) {
  			self::setLastModifiedHeader(filemtime($filepath));
  			self::setETagHeader(md5_file($filepath));
  
  			header('Content-Length: '.filesize($filepath));
  			fpassthru($fp);
  		}
  		else {
  			self::setStatus(self::STATUS_NOT_FOUND);
  		}
  	}

  
  	/*
  	 * This function adds some security related headers to all requests served via base.php
  	 * The implementation of this function has to happen here to ensure that all third-party
  	 * components (e.g. SabreDAV) also benefit from this headers.
  	 */
  	public static function addSecurityHeaders() {
  		header('X-XSS-Protection: 1; mode=block'); // Enforce browser based XSS filters
  		header('X-Content-Type-Options: nosniff'); // Disable sniffing the content type for IE
  
  		// iFrame Restriction Policy
  		$xFramePolicy = OC_Config::getValue('xframe_restriction', true);
  		if ($xFramePolicy) {
  			header('X-Frame-Options: Sameorigin'); // Disallow iFraming from other domains
  		}
  
  		// Content Security Policy
  		// If you change the standard policy, please also change it in config.sample.php
  		$policy = OC_Config::getValue('custom_csp_policy',
  			'default-src \'self\'; '
  			. 'script-src \'self\' \'unsafe-eval\'; '
  			. 'style-src \'self\' \'unsafe-inline\'; '
  			. 'frame-src *; '
  			. 'img-src *; '
  			. 'font-src \'self\' data:; '
  			. 'media-src *');
  		header('Content-Security-Policy:' . $policy);
  
  		// https://developers.google.com/webmasters/control-crawl-index/docs/robots_meta_tag
  		header('X-Robots-Tag: none');
  	}

  }