1 files changed, 72 insertions, 0 deletions
diff --git a/apps/dav/lib/CalDAV/ICSExportPlugin/ICSExportPlugin.php b/apps/dav/lib/CalDAV/ICSExportPlugin/ICSExportPlugin.php
new file mode 100644
index 00000000000..08dc10f7bf4
--- /dev/null
+++ b/apps/dav/lib/CalDAV/ICSExportPlugin/ICSExportPlugin.php
@@ -0,0 +1,72 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2019 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\DAV\CalDAV\ICSExportPlugin;
+
+use OCP\IConfig;
+use Psr\Log\LoggerInterface;
+use Sabre\HTTP\ResponseInterface;
+use Sabre\VObject\DateTimeParser;
+use Sabre\VObject\InvalidDataException;
+use Sabre\VObject\Property\ICalendar\Duration;
+
+/**
+ * Class ICSExportPlugin
+ *
+ * @package OCA\DAV\CalDAV\ICSExportPlugin
+ */
+class ICSExportPlugin extends \Sabre\CalDAV\ICSExportPlugin {
+	/** @var string */
+	private const DEFAULT_REFRESH_INTERVAL = 'PT4H';
+
+	/**
+	 * ICSExportPlugin constructor.
+	 */
+	public function __construct(
+		private IConfig $config,
+		private LoggerInterface $logger,
+	) {
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	protected function generateResponse($path, $start, $end, $expand, $componentType, $format, $properties, ResponseInterface $response) {
+		if (!isset($properties['{http://nextcloud.com/ns}refresh-interval'])) {
+			$value = $this->config->getAppValue('dav', 'defaultRefreshIntervalExportedCalendars', self::DEFAULT_REFRESH_INTERVAL);
+			$properties['{http://nextcloud.com/ns}refresh-interval'] = $value;
+		}
+
+		return parent::generateResponse($path, $start, $end, $expand, $componentType, $format, $properties, $response);
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public function mergeObjects(array $properties, array $inputObjects) {
+		$vcalendar = parent::mergeObjects($properties, $inputObjects);
+
+		if (isset($properties['{http://nextcloud.com/ns}refresh-interval'])) {
+			$refreshIntervalValue = $properties['{http://nextcloud.com/ns}refresh-interval'];
+			try {
+				DateTimeParser::parseDuration($refreshIntervalValue);
+			} catch (InvalidDataException $ex) {
+				$this->logger->debug('Invalid refresh interval for exported calendar, falling back to default value ...');
+				$refreshIntervalValue = self::DEFAULT_REFRESH_INTERVAL;
+			}
+
+			// https://tools.ietf.org/html/rfc7986#section-5.7
+			$refreshInterval = new Duration($vcalendar, 'REFRESH-INTERVAL', $refreshIntervalValue);
+			$refreshInterval->add('VALUE', 'DURATION');
+			$vcalendar->add($refreshInterval);
+
+			// Legacy property for compatibility
+			$vcalendar->{'X-PUBLISHED-TTL'} = $refreshIntervalValue;
+		}
+
+		return $vcalendar;
+	}
+}