<?php
/**
 * @author Bernhard Posselt <dev@bernhard-posselt.com>
 * @author Georg Ehrke <georg@owncloud.com>
 * @author Lukas Reschke <lukas@statuscode.ch>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 * @author Thomas Tanghus <thomas@tanghus.net>
 *
 * @copyright Copyright (c) 2018, ownCloud GmbH
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * This program 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, version 3,
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

namespace OC\AppFramework\Http;

use \OC\AppFramework\Middleware\MiddlewareDispatcher;
use \OC\AppFramework\Http;
use \OC\AppFramework\Utility\ControllerMethodReflector;

use OCP\AppFramework\Controller;
use OCP\AppFramework\Http\Response;
use OCP\AppFramework\Http\DataResponse;
use OCP\IRequest;

/**
 * Class to dispatch the request to the middleware dispatcher
 */
class Dispatcher {
	private $middlewareDispatcher;
	private $protocol;
	private $reflector;
	private $request;

	/**
	 * @param Http $protocol the http protocol with contains all status headers
	 * @param MiddlewareDispatcher $middlewareDispatcher the dispatcher which
	 * runs the middleware
	 * @param ControllerMethodReflector $reflector the reflector that is used to inject
	 * the arguments for the controller
	 * @param IRequest $request the incoming request
	 */
	public function __construct(
		Http $protocol,
		MiddlewareDispatcher $middlewareDispatcher,
		ControllerMethodReflector $reflector,
		IRequest $request
	) {
		$this->protocol = $protocol;
		$this->middlewareDispatcher = $middlewareDispatcher;
		$this->reflector = $reflector;
		$this->request = $request;
	}

	/**
	 * Handles a request and calls the dispatcher on the controller
	 * @param Controller $controller the controller which will be called
	 * @param string $methodName the method name which will be called on
	 * the controller
	 * @return array $array[0] contains a string with the http main header,
	 * $array[1] contains headers in the form: $key => value, $array[2] contains
	 * the response output
	 * @throws \Exception
	 */
	public function dispatch(Controller $controller, $methodName) {
		$out = [null, [], null];

		try {
			// prefill reflector with everything thats needed for the
			// middlewares
			$this->reflector->reflect($controller, $methodName);

			$this->middlewareDispatcher->beforeController(
				$controller,
				$methodName
			);
			$response = $this->executeController($controller, $methodName);

			// if an exception appears, the middleware checks if it can handle the
			// exception and creates a response. If no response is created, it is
			// assumed that theres no middleware who can handle it and the error is
			// thrown again
		} catch (\Exception $exception) {
			$response = $this->middlewareDispatcher->afterException(
				$controller,
				$methodName,
				$exception
			);
			if ($response === null) {
				throw $exception;
			}
		}

		$response = $this->middlewareDispatcher->afterController(
			$controller,
			$methodName,
			$response
		);

		// depending on the cache object the headers need to be changed
		$out[0] = $this->protocol->getStatusHeader(
			$response->getStatus(),
			$response->getLastModified(),
			$response->getETag()
		);
		$out[1] = \array_merge($response->getHeaders());
		$out[2] = $response->getCookies();
		$out[3] = $this->middlewareDispatcher->beforeOutput(
			$controller,
			$methodName,
			$response->render()
		);
		$out[4] = $response;

		return $out;
	}

	/**
	 * Uses the reflected parameters, types and request parameters to execute
	 * the controller
	 * @param Controller $controller the controller to be executed
	 * @param string $methodName the method on the controller that should be executed
	 * @return Response
	 */
	private function executeController($controller, $methodName) {
		$arguments = [];

		// valid types that will be casted
		$types = ['int', 'integer', 'bool', 'boolean', 'float'];

		foreach ($this->reflector->getParameters() as $param => $default) {
			// try to get the parameter from the request object and cast
			// it to the type annotated in the @param annotation
			$value = $this->request->getParam($param, $default);
			$type = $this->reflector->getType($param);

			// if this is submitted using GET or a POST form, 'false' should be
			// converted to false
			if (($type === 'bool' || $type === 'boolean') &&
				$value === 'false' &&
				(
					$this->request->method === 'GET' ||
					\strpos(
						$this->request->getHeader('Content-Type') ?? '',
						'application/x-www-form-urlencoded'
					) !== false
				)
			) {
				$value = false;
			} elseif ($value !== null && \in_array($type, $types)) {
				\settype($value, $type);
			}

			$arguments[] = $value;
		}

		$response = \call_user_func_array([$controller, $methodName], $arguments);

		// format response
		if ($response instanceof DataResponse || !($response instanceof Response)) {
			// get format from the url format or request format parameter
			$format = $this->request->getParam('format');

			// if none is given try the first Accept header
			if ($format === null) {
				$headers = $this->request->getHeader('Accept') ?? '';
				$format = $controller->getResponderByHTTPHeader($headers);
			}

			$response = $controller->buildResponse($response, $format);
		}

		return $response;
	}
}
