1 files changed, 93 insertions, 0 deletions
diff --git a/apps/dav/lib/CalDAV/TimezoneService.php b/apps/dav/lib/CalDAV/TimezoneService.php
new file mode 100644
index 00000000000..a7709bde0f9
--- /dev/null
+++ b/apps/dav/lib/CalDAV/TimezoneService.php
@@ -0,0 +1,93 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2023 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\DAV\CalDAV;
+
+use OCA\DAV\Db\PropertyMapper;
+use OCP\Calendar\ICalendar;
+use OCP\Calendar\IManager;
+use OCP\IConfig;
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Component\VTimeZone;
+use Sabre\VObject\Reader;
+use function array_reduce;
+
+class TimezoneService {
+
+	public function __construct(
+		private IConfig $config,
+		private PropertyMapper $propertyMapper,
+		private IManager $calendarManager,
+	) {
+	}
+
+	public function getUserTimezone(string $userId): ?string {
+		$fromConfig = $this->config->getUserValue(
+			$userId,
+			'core',
+			'timezone',
+		);
+		if ($fromConfig !== '') {
+			return $fromConfig;
+		}
+
+		$availabilityPropPath = 'calendars/' . $userId . '/inbox';
+		$availabilityProp = '{' . Plugin::NS_CALDAV . '}calendar-availability';
+		$availabilities = $this->propertyMapper->findPropertyByPathAndName($userId, $availabilityPropPath, $availabilityProp);
+		if (!empty($availabilities)) {
+			$availability = $availabilities[0]->getPropertyvalue();
+			/** @var VCalendar $vCalendar */
+			$vCalendar = Reader::read($availability);
+			/** @var VTimeZone $vTimezone */
+			$vTimezone = $vCalendar->VTIMEZONE;
+			// Sabre has a fallback to date_default_timezone_get
+			return $vTimezone->getTimeZone()->getName();
+		}
+
+		$principal = 'principals/users/' . $userId;
+		$uri = $this->config->getUserValue($userId, 'dav', 'defaultCalendar', CalDavBackend::PERSONAL_CALENDAR_URI);
+		$calendars = $this->calendarManager->getCalendarsForPrincipal($principal);
+
+		/** @var ?VTimeZone $personalCalendarTimezone */
+		$personalCalendarTimezone = array_reduce($calendars, function (?VTimeZone $acc, ICalendar $calendar) use ($uri) {
+			if ($acc !== null) {
+				return $acc;
+			}
+			if ($calendar->getUri() === $uri && !$calendar->isDeleted() && $calendar instanceof CalendarImpl) {
+				return $calendar->getSchedulingTimezone();
+			}
+			return null;
+		});
+		if ($personalCalendarTimezone !== null) {
+			return $personalCalendarTimezone->getTimeZone()->getName();
+		}
+
+		// No timezone in the personalCalendarTimezone calendar or no personalCalendarTimezone calendar
+		// Loop through all calendars until we find a timezone.
+		/** @var ?VTimeZone $firstTimezone */
+		$firstTimezone = array_reduce($calendars, function (?VTimeZone $acc, ICalendar $calendar) {
+			if ($acc !== null) {
+				return $acc;
+			}
+			if (!$calendar->isDeleted() && $calendar instanceof CalendarImpl) {
+				return $calendar->getSchedulingTimezone();
+			}
+			return null;
+		});
+		if ($firstTimezone !== null) {
+			return $firstTimezone->getTimeZone()->getName();
+		}
+		return null;
+	}
+
+	public function getDefaultTimezone(): string {
+		return $this->config->getSystemValueString('default_timezone', 'UTC');
+	}
+
+}