<?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;
  
  use OCP\AppFramework\Controller;
  use OCP\AppFramework\Http\Response;
  use OCP\AppFramework\MiddleWare;
  
  /**
   * This class is used to store and run all the middleware in correct order
   */
  class MiddlewareDispatcher {
  
  	/**
  	 * @var array array containing all the middlewares
  	 */
  	private $middlewares;
  
  	/**
  	 * @var int counter which tells us what middlware was executed once an
  	 *                  exception occurs
  	 */
  	private $middlewareCounter;
  
  
  	/**
  	 * Constructor
  	 */
  	public function __construct(){
  		$this->middlewares = array();
  		$this->middlewareCounter = 0;
  	}
  
  
  	/**
  	 * Adds a new middleware
  	 * @param Middleware $middleware the middleware which will be added
  	 */
  	public function registerMiddleware(Middleware $middleWare){
  		array_push($this->middlewares, $middleWare);
  	}
  
  
  	/**
  	 * returns an array with all middleware elements
  	 * @return array the middlewares
  	 */
  	public function getMiddlewares(){
  		return $this->middlewares;
  	}
  
  
  	/**
  	 * This is being run in normal order before the controller is being
  	 * called which allows several modifications and checks
  	 *
  	 * @param Controller $controller the controller that is being called
  	 * @param string $methodName the name of the method that will be called on
  	 *                           the controller
  	 */
  	public function beforeController(Controller $controller, $methodName){
  		// we need to count so that we know which middlewares we have to ask in
  		// case theres an exception
  		for($i=0; $i<count($this->middlewares); $i++){
  			$this->middlewareCounter++;
  			$middleware = $this->middlewares[$i];
  			$middleware->beforeController($controller, $methodName);
  		}
  	}
  
  
  	/**
  	 * This is being run when either the beforeController method or the
  	 * controller method itself is throwing an exception. The middleware is asked
  	 * in reverse order to handle the exception and to return a response.
  	 * If the response is null, it is assumed that the exception could not be
  	 * handled and the error will be thrown again
  	 *
  	 * @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
  	 * @return Response a Response object if the middleware can handle the
  	 * exception
  	 * @throws \Exception the passed in exception if it cant handle it
  	 */
  	public function afterException(Controller $controller, $methodName, \Exception $exception){
  		for($i=$this->middlewareCounter-1; $i>=0; $i--){
  			$middleware = $this->middlewares[$i];
  			try {
  				return $middleware->afterException($controller, $methodName, $exception);
  			} catch(\Exception $exception){
  				continue;
  			}
  		}
  		throw $exception;
  	}
  
  
  	/**
  	 * This is being run after a successful controllermethod call and allows
  	 * the manipulation of a Response object. The middleware is run in reverse order
  	 *
  	 * @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 Response $response the generated response from the controller
  	 * @return Response a Response object
  	 */
  	public function afterController(Controller $controller, $methodName, Response $response){
  		for($i=count($this->middlewares)-1; $i>=0; $i--){
  			$middleware = $this->middlewares[$i];
  			$response = $middleware->afterController($controller, $methodName, $response);
  		}
  		return $response;
  	}
  
  
  	/**
  	 * This is being run after the response object has been rendered and
  	 * allows the manipulation of the output. The middleware is run in reverse order
  	 *
  	 * @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 string $output the generated output from a response
  	 * @return string the output that should be printed
  	 */
  	public function beforeOutput(Controller $controller, $methodName, $output){
  		for($i=count($this->middlewares)-1; $i>=0; $i--){
  			$middleware = $this->middlewares[$i];
  			$output = $middleware->beforeOutput($controller, $methodName, $output);
  		}
  		return $output;
  	}
  
  }