1 files changed, 141 insertions, 0 deletions
diff --git a/apps/dav/lib/CalDAV/WebcalCaching/Plugin.php b/apps/dav/lib/CalDAV/WebcalCaching/Plugin.php
new file mode 100644
index 00000000000..e07be39c7b4
--- /dev/null
+++ b/apps/dav/lib/CalDAV/WebcalCaching/Plugin.php
@@ -0,0 +1,141 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2018 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\DAV\CalDAV\WebcalCaching;
+
+use OCA\DAV\CalDAV\CalendarRoot;
+use OCP\IRequest;
+use Sabre\DAV\Exception\NotFound;
+use Sabre\DAV\Server;
+use Sabre\DAV\ServerPlugin;
+use Sabre\HTTP\RequestInterface;
+use Sabre\HTTP\ResponseInterface;
+
+class Plugin extends ServerPlugin {
+
+	/**
+	 * list of regular expressions for calendar user agents,
+	 * that do not support subscriptions on their own
+	 *
+	 * /^MSFT-WIN-3/ - Windows 10 Calendar
+	 * /Evolution/ - Gnome Calendar/Evolution
+	 * /KIO/ - KDE PIM/Akonadi
+	 * @var string[]
+	 */
+	public const ENABLE_FOR_CLIENTS = [
+		'/^MSFT-WIN-3/',
+		'/Evolution/',
+		'/KIO/'
+	];
+
+	/**
+	 * @var bool
+	 */
+	private $enabled = false;
+
+	/**
+	 * @var Server
+	 */
+	private $server;
+
+	/**
+	 * Plugin constructor.
+	 *
+	 * @param IRequest $request
+	 */
+	public function __construct(IRequest $request) {
+		if ($request->isUserAgent(self::ENABLE_FOR_CLIENTS)) {
+			$this->enabled = true;
+		}
+
+		$magicHeader = $request->getHeader('X-NC-CalDAV-Webcal-Caching');
+		if ($magicHeader === 'On') {
+			$this->enabled = true;
+		}
+
+		$isExportRequest = $request->getMethod() === 'GET' && array_key_exists('export', $request->getParams());
+		if ($isExportRequest) {
+			$this->enabled = true;
+		}
+	}
+
+	/**
+	 * This initializes the plugin.
+	 *
+	 * This function is called by Sabre\DAV\Server, after
+	 * addPlugin is called.
+	 *
+	 * This method should set up the required event subscriptions.
+	 *
+	 * @param Server $server
+	 */
+	public function initialize(Server $server) {
+		$this->server = $server;
+		$server->on('beforeMethod:*', [$this, 'beforeMethod'], 15);
+	}
+
+	/**
+	 * @param RequestInterface $request
+	 * @param ResponseInterface $response
+	 */
+	public function beforeMethod(RequestInterface $request, ResponseInterface $response) {
+		if (!$this->enabled) {
+			return;
+		}
+
+		$path = $request->getPath();
+		if (!str_starts_with($path, 'calendars/')) {
+			return;
+		}
+
+		$pathParts = explode('/', ltrim($path, '/'));
+		if (\count($pathParts) < 2) {
+			return;
+		}
+
+		try {
+			$calendarRoot = $this->server->tree->getNodeForPath($pathParts[0]);
+			if ($calendarRoot instanceof CalendarRoot) {
+				$calendarRoot->enableReturnCachedSubscriptions($pathParts[1]);
+			}
+		} catch (NotFound $ex) {
+			return;
+		}
+	}
+
+	/**
+	 * @return bool
+	 */
+	public function isCachingEnabledForThisRequest():bool {
+		return $this->enabled;
+	}
+
+	/**
+	 * This method should return a list of server-features.
+	 *
+	 * This is for example 'versioning' and is added to the DAV: header
+	 * in an OPTIONS response.
+	 *
+	 * @return string[]
+	 */
+	public function getFeatures():array {
+		return ['nc-calendar-webcal-cache'];
+	}
+
+	/**
+	 * Returns a plugin name.
+	 *
+	 * Using this name other plugins will be able to access other plugins
+	 * using Sabre\DAV\Server::getPlugin
+	 *
+	 * @return string
+	 */
+	public function getPluginName():string {
+		return 'nc-calendar-webcal-cache';
+	}
+}