Use recurrence instance to build iMip email

instead of the main VEVENT of a repeating event

Fixes part of https://github.com/nextcloud/calendar/issues/3919

Signed-off-by: Anna Larch <anna@nextcloud.com>

1 files changed, 123 insertions, 0 deletions

diff --git a/apps/dav/lib/CalDAV/EventComparisonService.php b/apps/dav/lib/CalDAV/EventComparisonService.php
new file mode 100644
index 00000000000..0fd4d08e83e
--- /dev/null
+++ b/apps/dav/lib/CalDAV/EventComparisonService.php
@@ -0,0 +1,123 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright 2022 Anna Larch <anna.larch@gmx.net>
+ *
+ * @author 2022 Anna Larch <anna.larch@gmx.net>
+ *
+ * @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;
+
+use OCA\DAV\AppInfo\Application;
+use OCA\DAV\CalDAV\Schedule\IMipService;
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\IConfig;
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Component\VEvent;
+use Sabre\VObject\Component\VTimeZone;
+use Sabre\VObject\Component\VTodo;
+use function max;
+
+class EventComparisonService {
+
+	/** @var string[] */
+	private const EVENT_DIFF = [
+		'RECURRENCE-ID',
+		'RRULE',
+		'SEQUENCE',
+		'LAST-MODIFIED'
+	];
+
+
+	/**
+	 * If found, remove the event from $eventsToFilter that
+	 * is identical to the passed $filterEvent
+	 * and return whether an identical event was found
+	 *
+	 * This function takes into account the SEQUENCE,
+	 * RRULE, RECURRENCE-ID and LAST-MODIFIED parameters
+	 *
+	 * @param VEvent $filterEvent
+	 * @param array $eventsToFilter
+	 * @return bool true if there was an identical event found and removed, false if there wasn't
+	 */
+	private function removeIfUnchanged(VEvent $filterEvent, array &$eventsToFilter): bool {
+		$filterEventData = [];
+		foreach(self::EVENT_DIFF as $eventDiff) {
+			$filterEventData[] = IMipService::readPropertyWithDefault($filterEvent, $eventDiff, '');
+		}
+
+		/** @var VEvent $component */
+		foreach ($eventsToFilter as $k => $eventToFilter) {
+			$eventToFilterData = [];
+			foreach(self::EVENT_DIFF as $eventDiff) {
+				$eventToFilterData[] = IMipService::readPropertyWithDefault($eventToFilter, $eventDiff, '');
+			}
+			// events are identical and can be removed
+			if (empty(array_diff($filterEventData, $eventToFilterData))) {
+				unset($eventsToFilter[$k]);
+				return true;
+			}
+		}
+		return false;
+	}
+
+	/**
+	 * Compare two VCalendars with each other and find all changed elements
+	 *
+	 * Returns an array of old and new events
+	 *
+	 * Old events are only detected if they are also changed
+	 * If there is no corresponding old event for a VEvent, it
+	 * has been newly created
+	 *
+	 * @param VCalendar $new
+	 * @param VCalendar|null $old
+	 * @return array<string, VEvent[]>
+	 */
+	public function findModified(VCalendar $new, ?VCalendar $old): array {
+		$newEventComponents = $new->getComponents();
+
+		foreach ($newEventComponents as $k => $event) {
+			if(!$event instanceof VEvent) {
+				unset($newEventComponents[$k]);
+			}
+		}
+
+		if(empty($old)) {
+			return ['old' => null, 'new' => $newEventComponents];
+		}
+
+		$oldEventComponents = $old->getComponents();
+		if(is_array($oldEventComponents) && !empty($oldEventComponents)) {
+			foreach ($oldEventComponents as $k => $event) {
+				if(!$event instanceof VEvent) {
+					unset($oldEventComponents[$k]);
+					continue;
+				}
+				if($this->removeIfUnchanged($event, $newEventComponents)) {
+					unset($oldEventComponents[$k]);
+				}
+			}
+		}
+
+		return ['old' => array_values($oldEventComponents), 'new' => array_values($newEventComponents)];
+	}
+}