<?php
  
  /**
   * ownCloud - App Framework
   *
   * @author Bernhard Posselt
   * @copyright 2012 Bernhard Posselt nukeawhale@gmail.com
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
   * License as published by the Free Software Foundation; either
   * version 3 of the License, or any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU AFFERO GENERAL PUBLIC LICENSE for more details.
   *
   * You should have received a copy of the GNU Affero General Public
   * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
   *
   */
  
  
  namespace OC\AppFramework\Middleware\Security;
  
  use OC\AppFramework\Http;
  use OC\AppFramework\Http\RedirectResponse;
  use OC\AppFramework\Utility\MethodAnnotationReader;
  use OCP\AppFramework\Middleware;
  use OCP\AppFramework\Http\Response;
  use OCP\AppFramework\Http\JSONResponse;
  use OCP\AppFramework\IAppContainer;
  use OCP\IRequest;
  
  
  /**
   * Used to do all the authentication and checking stuff for a controller method
   * It reads out the annotations of a controller method and checks which if
   * security things should be checked and also handles errors in case a security
   * check fails
   */
  class SecurityMiddleware extends Middleware {
  
  	/**
  	 * @var \OCP\AppFramework\IAppContainer
  	 */
  	private $app;
  
  	/**
  	 * @var \OCP\IRequest
  	 */
  	private $request;
  
  	/**
  	 * @param IAppContainer $app
  	 * @param IRequest $request
  	 */
  	public function __construct(IAppContainer $app, IRequest $request){
  		$this->app = $app;
  		$this->request = $request;
  	}
  
  
  	/**
  	 * This runs all the security checks before a method call. The
  	 * security checks are determined by inspecting the controller method
  	 * annotations
  	 * @param string/Controller $controller the controllername or string
  	 * @param string $methodName the name of the method
  	 * @throws SecurityException when a security check fails
  	 */
  	public function beforeController($controller, $methodName){
  
  		// get annotations from comments
  		$annotationReader = new MethodAnnotationReader($controller, $methodName);
  
  		// this will set the current navigation entry of the app, use this only
  		// for normal HTML requests and not for AJAX requests
  		$this->app->getServer()->getNavigationManager()->setActiveEntry($this->app->getAppName());
  
  		// security checks
  		$isPublicPage = $annotationReader->hasAnnotation('PublicPage');
  		if(!$isPublicPage) {
  			if(!$this->app->isLoggedIn()) {
  				throw new SecurityException('Current user is not logged in', Http::STATUS_UNAUTHORIZED);
  			}
  
  			if(!$annotationReader->hasAnnotation('NoAdminRequired')) {
  				if(!$this->app->isAdminUser()) {
  					throw new SecurityException('Logged in user must be an admin', Http::STATUS_FORBIDDEN);
  				}
  			}
  		}
  
  		if(!$annotationReader->hasAnnotation('NoCSRFRequired')) {
  			if(!$this->request->passesCSRFCheck()) {
  				throw new SecurityException('CSRF check failed', Http::STATUS_PRECONDITION_FAILED);
  			}
  		}
  
  	}
  
  
  	/**
  	 * If an SecurityException is being caught, ajax requests return a JSON error
  	 * response and non ajax requests redirect to the index
  	 * @param Controller $controller the controller that is being called
  	 * @param string $methodName the name of the method that will be called on
  	 *                           the controller
  	 * @param \Exception $exception the thrown exception
  	 * @throws \Exception the passed in exception if it cant handle it
  	 * @return Response a Response object or null in case that the exception could not be handled
  	 */
  	public function afterException($controller, $methodName, \Exception $exception){
  		if($exception instanceof SecurityException){
  
  			if (stripos($this->request->getHeader('Accept'),'html')===false) {
  
  				$response = new JSONResponse(
  					array('message' => $exception->getMessage()),
  					$exception->getCode()
  				);
  				$this->app->log($exception->getMessage(), 'debug');
  			} else {
  
  				// TODO: replace with link to route
  				$url = $this->app->getServer()->getURLGenerator()->getAbsoluteURL('index.php');
  				$response = new RedirectResponse($url);
  				$this->app->log($exception->getMessage(), 'debug');
  			}
  
  			return $response;
  
  		}
  
  		throw $exception;
  	}
  
  }