1 files changed, 142 insertions, 0 deletions
diff --git a/lib/private/AppFramework/Middleware/MiddlewareDispatcher.php b/lib/private/AppFramework/Middleware/MiddlewareDispatcher.php
new file mode 100644
index 00000000000..c9b51f26f34
--- /dev/null
+++ b/lib/private/AppFramework/Middleware/MiddlewareDispatcher.php
@@ -0,0 +1,142 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+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 Middleware[] array containing all the middlewares
+	 */
+	private array $middlewares;
+
+	/**
+	 * @var int counter which tells us what middleware was executed once an
+	 *          exception occurs
+	 */
+	private int $middlewareCounter;
+
+
+	/**
+	 * Constructor
+	 */
+	public function __construct() {
+		$this->middlewares = [];
+		$this->middlewareCounter = 0;
+	}
+
+
+	/**
+	 * Adds a new middleware
+	 * @param Middleware $middleWare the middleware which will be added
+	 */
+	public function registerMiddleware(Middleware $middleWare): void {
+		$this->middlewares[] = $middleWare;
+	}
+
+
+	/**
+	 * returns an array with all middleware elements
+	 * @return Middleware[] the middlewares
+	 */
+	public function getMiddlewares(): array {
+		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, string $methodName): void {
+		// we need to count so that we know which middlewares we have to ask in
+		// case there is an exception
+		$middlewareCount = \count($this->middlewares);
+		for ($i = 0; $i < $middlewareCount; $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 can't handle it
+	 */
+	public function afterException(Controller $controller, string $methodName, \Exception $exception): Response {
+		for ($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, string $methodName, Response $response): Response {
+		for ($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, string $methodName, string $output): string {
+		for ($i = \count($this->middlewares) - 1; $i >= 0; $i--) {
+			$middleware = $this->middlewares[$i];
+			$output = $middleware->beforeOutput($controller, $methodName, $output);
+		}
+		return $output;
+	}
+}