Allow apps to provide Calendars in user's calendarHome

Signed-off-by: Georg Ehrke <developer@georgehrke.com>

3 files changed, 239 insertions, 2 deletions

diff --git a/apps/dav/lib/CalDAV/CalendarHome.php b/apps/dav/lib/CalDAV/CalendarHome.php
index b491c2304d2..ce29ed12db6 100644
--- a/apps/dav/lib/CalDAV/CalendarHome.php
+++ b/apps/dav/lib/CalDAV/CalendarHome.php
@@ -26,6 +26,9 @@
 
 namespace OCA\DAV\CalDAV;
 
+use OCA\DAV\AppInfo\PluginManager;
+use OCA\DAV\CalDAV\Integration\ExternalCalendar;
+use OCA\DAV\CalDAV\Integration\ICalendarProvider;
 use Sabre\CalDAV\Backend\BackendInterface;
 use Sabre\CalDAV\Backend\NotificationSupport;
 use Sabre\CalDAV\Backend\SchedulingSupport;
@@ -44,6 +47,9 @@ class CalendarHome extends \Sabre\CalDAV\CalendarHome {
 	/** @var \OCP\IConfig */
 	private $config;
 
+	/** @var PluginManager */
+	private $pluginManager;
+
 	/** @var bool */
 	private $returnCachedSubscriptions=false;
 
@@ -51,6 +57,10 @@ class CalendarHome extends \Sabre\CalDAV\CalendarHome {
 		parent::__construct($caldavBackend, $principalInfo);
 		$this->l10n = \OC::$server->getL10N('dav');
 		$this->config = \OC::$server->getConfig();
+		$this->pluginManager = new PluginManager(
+			\OC::$server,
+			\OC::$server->getAppManager()
+		);
 	}
 
 	/**
@@ -66,7 +76,7 @@ class CalendarHome extends \Sabre\CalDAV\CalendarHome {
 	function createExtendedCollection($name, MkCol $mkCol) {
 		$reservedNames = [BirthdayService::BIRTHDAY_CALENDAR_URI];
 
-		if (in_array($name, $reservedNames)) {
+		if (\in_array($name, $reservedNames, true) || ExternalCalendar::doesViolateReservedName($name)) {
 			throw new MethodNotAllowed('The resource you tried to create has a reserved name');
 		}
 
@@ -104,6 +114,14 @@ class CalendarHome extends \Sabre\CalDAV\CalendarHome {
 			}
 		}
 
+		foreach ($this->pluginManager->getCalendarPlugins() as $calendarPlugin) {
+			/** @var ICalendarProvider $calendarPlugin */
+			$calendars = $calendarPlugin->fetchAllForCalendarHome($this->principalInfo['uri']);
+			foreach ($calendars as $calendar) {
+				$objects[] = $calendar;
+			}
+		}
+
 		return $objects;
 	}
 
@@ -139,7 +157,21 @@ class CalendarHome extends \Sabre\CalDAV\CalendarHome {
 					return new Subscription($this->caldavBackend, $subscription);
 				}
 			}
+		}
+
+		if (ExternalCalendar::isAppGeneratedCalendar($name)) {
+			[$appId, $calendarUri] = ExternalCalendar::splitAppGeneratedCalendarUri($name);
 
+			foreach ($this->pluginManager->getCalendarPlugins() as $calendarPlugin) {
+				/** @var ICalendarProvider $calendarPlugin */
+				if ($calendarPlugin->getAppId() !== $appId) {
+					continue;
+				}
+
+				if ($calendarPlugin->hasCalendarInCalendarHome($this->principalInfo['uri'], $calendarUri)) {
+					return $calendarPlugin->getCalendarInCalendarHome($this->principalInfo['uri'], $calendarUri);
+				}
+			}
 		}
 
 		throw new NotFound('Node with name \'' . $name . '\' could not be found');
@@ -155,7 +187,7 @@ class CalendarHome extends \Sabre\CalDAV\CalendarHome {
 		return $this->caldavBackend->calendarSearch($principalUri, $filters, $limit, $offset);
 	}
 
-	
+
 	public function enableCachedSubscriptionsForThisRequest() {
 		$this->returnCachedSubscriptions = true;
 	}
diff --git a/apps/dav/lib/CalDAV/Integration/ExternalCalendar.php b/apps/dav/lib/CalDAV/Integration/ExternalCalendar.php
new file mode 100644
index 00000000000..88d43f0bb55
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Integration/ExternalCalendar.php
@@ -0,0 +1,132 @@
+<?php
+/**
+ * @copyright 2020, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * 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
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+namespace OCA\DAV\CalDAV\Integration;
+
+use Sabre\CalDAV;
+use Sabre\DAV;
+
+/**
+ * Class ExternalCalendar
+ *
+ * @package OCA\DAV\CalDAV\Integration
+ * @since 19.0.0
+ */
+abstract class ExternalCalendar implements CalDAV\ICalendar, DAV\IProperties {
+
+	/** @var string */
+	private const PREFIX = 'app-generated';
+
+	/**
+	 * @var string
+	 *
+	 * Double dash is a valid delimiter,
+	 * because it will always split the calendarURIs correctly:
+	 * - our prefix contains only one dash and won't be split
+	 * - appIds are not allowed to contain dashes as per spec:
+	 * > must contain only lowercase ASCII characters and underscore
+	 * - explode has a limit of three, so even if the app-generated
+	 *   calendar uri has double dashes, it won't be split
+	 */
+	private const DELIMITER = '--';
+
+	/** @var string */
+	private $appId;
+
+	/** @var string */
+	private $calendarUri;
+
+	/**
+	 * ExternalCalendar constructor.
+	 *
+	 * @param string $appId
+	 * @param string $calendarUri
+	 */
+	public function __construct(string $appId, string $calendarUri) {
+		$this->appId = $appId;
+		$this->calendarUri = $calendarUri;
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	final public function getName() {
+		return implode(self::DELIMITER, [
+			self::PREFIX,
+			$this->appId,
+			$this->calendarUri,
+		]);
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	final public function setName($name) {
+		throw new DAV\Exception\MethodNotAllowed('Renaming calendars is not yet supported');
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	final public function createDirectory($name) {
+		throw new DAV\Exception\MethodNotAllowed('Creating collections in calendar objects is not allowed');
+
+	}
+
+	/**
+	 * Checks whether the calendar uri is app-generated
+	 *
+	 * @param string $calendarUri
+	 * @return bool
+	 */
+	public static function isAppGeneratedCalendar(string $calendarUri):bool {
+		return strpos($calendarUri, self::PREFIX) === 0 && substr_count($calendarUri, self::DELIMITER) >= 2;
+	}
+
+	/**
+	 * Splits an app-generated calendar-uri into appId and calendarUri
+	 *
+	 * @param string $calendarUri
+	 * @return array
+	 */
+	public static function splitAppGeneratedCalendarUri(string $calendarUri):array {
+		$array = array_slice(explode(self::DELIMITER, $calendarUri, 3), 1);
+		// Check the array has expected amount of elements
+		// and none of them is an empty string
+		if (\count($array) !== 2 || \in_array('', $array, true)) {
+			throw new \InvalidArgumentException('Provided calendar uri was not app-generated');
+		}
+
+		return $array;
+	}
+
+	/**
+	 * Checks whether a calendar-name, the user wants to create, violates
+	 * the reserved name for calendar uris
+	 *
+	 * @param string $calendarUri
+	 * @return bool
+	 */
+	public static function doesViolateReservedName(string $calendarUri):bool {
+		return strpos($calendarUri, self::PREFIX) === 0;
+	}
+}
diff --git a/apps/dav/lib/CalDAV/Integration/ICalendarProvider.php b/apps/dav/lib/CalDAV/Integration/ICalendarProvider.php
new file mode 100644
index 00000000000..29f5f113ef5
--- /dev/null
+++ b/apps/dav/lib/CalDAV/Integration/ICalendarProvider.php
@@ -0,0 +1,73 @@
+<?php
+/**
+ * @copyright 2020, Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * 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
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+namespace OCA\DAV\CalDAV\Integration;
+
+use Sabre\CalDAV\ICalendar;
+
+/**
+ * Interface ICalendarProvider
+ *
+ * @package OCA\DAV\CalDAV\Integration
+ * @since 19.0.0
+ */
+interface ICalendarProvider {
+
+	/**
+	 * Provides the appId of the plugin
+	 *
+	 * @since 19.0.0
+	 * @return string AppId
+	 */
+	public function getAppId(): string;
+
+	/**
+	 * Fetches all calendars for a given principal uri
+	 *
+	 * @since 19.0.0
+	 * @param string $principalUri E.g. principals/users/user1
+	 * @return ExternalCalendar[] Array of all calendars
+	 */
+	public function fetchAllForCalendarHome(string $principalUri): array;
+
+	/**
+	 * Checks whether plugin has a calendar for a given principalUri and calendarUri
+	 *
+	 * @since 19.0.0
+	 * @param string $principalUri E.g. principals/users/user1
+	 * @param string $calendarUri E.g. personal
+	 * @return bool True if calendar for principalUri and calendarUri exists, false otherwise
+	 */
+	public function hasCalendarInCalendarHome(string $principalUri, string $calendarUri): bool;
+
+	/**
+	 * Fetches a calendar for a given principalUri and calendarUri
+	 * Returns null if calendar does not exist
+	 *
+	 * @since 19.0.0
+	 * @param string $principalUri E.g. principals/users/user1
+	 * @param string $calendarUri E.g. personal
+	 * @return ExternalCalendar|null Calendar if it exists, null otherwise
+	 */
+	public function getCalendarInCalendarHome(string $principalUri, string $calendarUri): ?ExternalCalendar;
+
+}