Merge pull request #30963 from nextcloud/feat/calendar-migration

21 files changed, 1283 insertions, 0 deletions

diff --git a/apps/dav/composer/composer/autoload_classmap.php b/apps/dav/composer/composer/autoload_classmap.php
index 9cfefaed1c8..f4b17814817 100644
--- a/apps/dav/composer/composer/autoload_classmap.php
+++ b/apps/dav/composer/composer/autoload_classmap.php
@@ -299,4 +299,7 @@ return array(
     'OCA\\DAV\\Upload\\UploadFile' => $baseDir . '/../lib/Upload/UploadFile.php',
     'OCA\\DAV\\Upload\\UploadFolder' => $baseDir . '/../lib/Upload/UploadFolder.php',
     'OCA\\DAV\\Upload\\UploadHome' => $baseDir . '/../lib/Upload/UploadHome.php',
+    'OCA\\DAV\\UserMigration\\CalendarMigrator' => $baseDir . '/../lib/UserMigration/CalendarMigrator.php',
+    'OCA\\DAV\\UserMigration\\CalendarMigratorException' => $baseDir . '/../lib/UserMigration/CalendarMigratorException.php',
+    'OCA\\DAV\\UserMigration\\InvalidCalendarException' => $baseDir . '/../lib/UserMigration/InvalidCalendarException.php',
 );
diff --git a/apps/dav/composer/composer/autoload_static.php b/apps/dav/composer/composer/autoload_static.php
index 01c24fe38c8..d164ab2b1ce 100644
--- a/apps/dav/composer/composer/autoload_static.php
+++ b/apps/dav/composer/composer/autoload_static.php
@@ -314,6 +314,9 @@ class ComposerStaticInitDAV
         'OCA\\DAV\\Upload\\UploadFile' => __DIR__ . '/..' . '/../lib/Upload/UploadFile.php',
         'OCA\\DAV\\Upload\\UploadFolder' => __DIR__ . '/..' . '/../lib/Upload/UploadFolder.php',
         'OCA\\DAV\\Upload\\UploadHome' => __DIR__ . '/..' . '/../lib/Upload/UploadHome.php',
+        'OCA\\DAV\\UserMigration\\CalendarMigrator' => __DIR__ . '/..' . '/../lib/UserMigration/CalendarMigrator.php',
+        'OCA\\DAV\\UserMigration\\CalendarMigratorException' => __DIR__ . '/..' . '/../lib/UserMigration/CalendarMigratorException.php',
+        'OCA\\DAV\\UserMigration\\InvalidCalendarException' => __DIR__ . '/..' . '/../lib/UserMigration/InvalidCalendarException.php',
     );
 
     public static function getInitializer(ClassLoader $loader)
diff --git a/apps/dav/lib/AppInfo/Application.php b/apps/dav/lib/AppInfo/Application.php
index 99521b61e8b..f29161d6976 100644
--- a/apps/dav/lib/AppInfo/Application.php
+++ b/apps/dav/lib/AppInfo/Application.php
@@ -80,6 +80,7 @@ use OCA\DAV\Listener\CardListener;
 use OCA\DAV\Search\ContactsSearchProvider;
 use OCA\DAV\Search\EventsSearchProvider;
 use OCA\DAV\Search\TasksSearchProvider;
+use OCA\DAV\UserMigration\CalendarMigrator;
 use OCP\AppFramework\App;
 use OCP\AppFramework\Bootstrap\IBootContext;
 use OCP\AppFramework\Bootstrap\IBootstrap;
@@ -165,6 +166,8 @@ class Application extends App implements IBootstrap {
 		$context->registerNotifierService(Notifier::class);
 
 		$context->registerCalendarProvider(CalendarProvider::class);
+
+		$context->registerUserMigrator(CalendarMigrator::class);
 	}
 
 	public function boot(IBootContext $context): void {
diff --git a/apps/dav/lib/CalDAV/CalendarImpl.php b/apps/dav/lib/CalDAV/CalendarImpl.php
index 1c36db68cca..406389e3a3d 100644
--- a/apps/dav/lib/CalDAV/CalendarImpl.php
+++ b/apps/dav/lib/CalDAV/CalendarImpl.php
@@ -70,6 +70,13 @@ class CalendarImpl implements ICreateFromString {
 	}
 
 	/**
+	 * {@inheritDoc}
+	 */
+	public function getUri(): string {
+		return $this->calendarInfo['uri'];
+	}
+
+	/**
 	 * In comparison to getKey() this function returns a human readable (maybe translated) name
 	 * @return null|string
 	 * @since 13.0.0
diff --git a/apps/dav/lib/UserMigration/CalendarMigrator.php b/apps/dav/lib/UserMigration/CalendarMigrator.php
new file mode 100644
index 00000000000..d0d9e94351b
--- /dev/null
+++ b/apps/dav/lib/UserMigration/CalendarMigrator.php
@@ -0,0 +1,460 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright 2022 Christopher Ng <chrng8@gmail.com>
+ *
+ * @author Christopher Ng <chrng8@gmail.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\UserMigration;
+
+use function Safe\substr;
+use OCA\DAV\AppInfo\Application;
+use OCA\DAV\CalDAV\CalDavBackend;
+use OCA\DAV\CalDAV\ICSExportPlugin\ICSExportPlugin;
+use OCA\DAV\CalDAV\Plugin as CalDAVPlugin;
+use OCA\DAV\Connector\Sabre\CachingTree;
+use OCA\DAV\Connector\Sabre\Server as SabreDavServer;
+use OCA\DAV\RootCollection;
+use OCP\Calendar\ICalendar;
+use OCP\Calendar\IManager as ICalendarManager;
+use OCP\Defaults;
+use OCP\IL10N;
+use OCP\IUser;
+use OCP\UserMigration\IExportDestination;
+use OCP\UserMigration\IImportSource;
+use OCP\UserMigration\IMigrator;
+use OCP\UserMigration\TMigratorBasicVersionHandling;
+use Sabre\VObject\Component as VObjectComponent;
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Component\VTimeZone;
+use Sabre\VObject\Property\ICalendar\DateTime;
+use Sabre\VObject\Reader as VObjectReader;
+use Sabre\VObject\UUIDUtil;
+use Safe\Exceptions\StringsException;
+use Symfony\Component\Console\Output\OutputInterface;
+use Throwable;
+
+class CalendarMigrator implements IMigrator {
+
+	use TMigratorBasicVersionHandling;
+
+	private CalDavBackend $calDavBackend;
+
+	private ICalendarManager $calendarManager;
+
+	// ICSExportPlugin is injected as the mergeObjects() method is required and is not to be used as a SabreDAV server plugin
+	private ICSExportPlugin $icsExportPlugin;
+
+	private Defaults $defaults;
+
+	private IL10N $l10n;
+
+	private SabreDavServer $sabreDavServer;
+
+	private const USERS_URI_ROOT = 'principals/users/';
+
+	private const FILENAME_EXT = '.ics';
+
+	private const MIGRATED_URI_PREFIX = 'migrated-';
+
+	private const EXPORT_ROOT = Application::APP_ID . '/calendars/';
+
+	public function __construct(
+		CalDavBackend $calDavBackend,
+		ICalendarManager $calendarManager,
+		ICSExportPlugin $icsExportPlugin,
+		Defaults $defaults,
+		IL10N $l10n
+	) {
+		$this->calDavBackend = $calDavBackend;
+		$this->calendarManager = $calendarManager;
+		$this->icsExportPlugin = $icsExportPlugin;
+		$this->defaults = $defaults;
+		$this->l10n = $l10n;
+
+		$root = new RootCollection();
+		$this->sabreDavServer = new SabreDavServer(new CachingTree($root));
+		$this->sabreDavServer->addPlugin(new CalDAVPlugin());
+	}
+
+	private function getPrincipalUri(IUser $user): string {
+		return CalendarMigrator::USERS_URI_ROOT . $user->getUID();
+	}
+
+	/**
+	 * @return array{name: string, vCalendar: VCalendar}
+	 *
+	 * @throws CalendarMigratorException
+	 * @throws InvalidCalendarException
+	 */
+	private function getCalendarExportData(IUser $user, ICalendar $calendar, OutputInterface $output): array {
+		$userId = $user->getUID();
+		$calendarId = $calendar->getKey();
+		$calendarInfo = $this->calDavBackend->getCalendarById($calendarId);
+
+		if (empty($calendarInfo)) {
+			throw new CalendarMigratorException("Invalid info for calendar ID $calendarId");
+		}
+
+		$uri = $calendarInfo['uri'];
+		$path = CalDAVPlugin::CALENDAR_ROOT . "/$userId/$uri";
+
+		/**
+		 * @see \Sabre\CalDAV\ICSExportPlugin::httpGet() implementation reference
+		 */
+
+		$properties = $this->sabreDavServer->getProperties($path, [
+			'{DAV:}resourcetype',
+			'{DAV:}displayname',
+			'{http://sabredav.org/ns}sync-token',
+			'{DAV:}sync-token',
+			'{http://apple.com/ns/ical/}calendar-color',
+		]);
+
+		// Filter out invalid (e.g. deleted) calendars
+		if (!isset($properties['{DAV:}resourcetype']) || !$properties['{DAV:}resourcetype']->is('{' . CalDAVPlugin::NS_CALDAV . '}calendar')) {
+			throw new InvalidCalendarException();
+		}
+
+		/**
+		 * @see \Sabre\CalDAV\ICSExportPlugin::generateResponse() implementation reference
+		 */
+
+		$calDataProp = '{' . CalDAVPlugin::NS_CALDAV . '}calendar-data';
+		$calendarNode = $this->sabreDavServer->tree->getNodeForPath($path);
+		$nodes = $this->sabreDavServer->getPropertiesIteratorForPath($path, [$calDataProp], 1);
+
+		$blobs = [];
+		foreach ($nodes as $node) {
+			if (isset($node[200][$calDataProp])) {
+				$blobs[$node['href']] = $node[200][$calDataProp];
+			}
+		}
+
+		$mergedCalendar = $this->icsExportPlugin->mergeObjects(
+			$properties,
+			$blobs,
+		);
+
+		$problems = $mergedCalendar->validate();
+		if (!empty($problems)) {
+			$output->writeln('Skipping calendar "' . $properties['{DAV:}displayname'] . '" containing invalid calendar data');
+			throw new InvalidCalendarException();
+		}
+
+		return [
+			'name' => $calendarNode->getName(),
+			'vCalendar' => $mergedCalendar,
+		];
+	}
+
+	/**
+	 * @return array<int, array{name: string, vCalendar: VCalendar}>
+	 *
+	 * @throws CalendarMigratorException
+	 */
+	private function getCalendarExports(IUser $user, OutputInterface $output): array {
+		$principalUri = $this->getPrincipalUri($user);
+
+		return array_values(array_filter(array_map(
+			function (ICalendar $calendar) use ($user, $output) {
+				try {
+					return $this->getCalendarExportData($user, $calendar, $output);
+				} catch (InvalidCalendarException $e) {
+					// Allow this exception as invalid (e.g. deleted) calendars are not to be exported
+					return null;
+				}
+			},
+			$this->calendarManager->getCalendarsForPrincipal($principalUri),
+		)));
+	}
+
+	private function getUniqueCalendarUri(IUser $user, string $initialCalendarUri): string {
+		$principalUri = $this->getPrincipalUri($user);
+		try {
+			$initialCalendarUri = substr($initialCalendarUri, 0, strlen(CalendarMigrator::MIGRATED_URI_PREFIX)) === CalendarMigrator::MIGRATED_URI_PREFIX
+				? $initialCalendarUri
+				: CalendarMigrator::MIGRATED_URI_PREFIX . $initialCalendarUri;
+		} catch (StringsException $e) {
+			throw new CalendarMigratorException('Failed to get unique calendar URI', 0, $e);
+		}
+
+		$existingCalendarUris = array_map(
+			fn (ICalendar $calendar) => $calendar->getUri(),
+			$this->calendarManager->getCalendarsForPrincipal($principalUri),
+		);
+
+		$calendarUri = $initialCalendarUri;
+		$acc = 1;
+		while (in_array($calendarUri, $existingCalendarUris, true)) {
+			$calendarUri = $initialCalendarUri . "-$acc";
+			++$acc;
+		}
+
+		return $calendarUri;
+	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	public function export(IUser $user, IExportDestination $exportDestination, OutputInterface $output): void {
+		$output->writeln('Exporting calendars into ' . CalendarMigrator::EXPORT_ROOT . '…');
+
+		$calendarExports = $this->getCalendarExports($user, $output);
+
+		if (empty($calendarExports)) {
+			$output->writeln('No calendars to export…');
+		}
+
+		/**
+		 * @var string $name
+		 * @var VCalendar $vCalendar
+		 */
+		foreach ($calendarExports as ['name' => $name, 'vCalendar' => $vCalendar]) {
+			// Set filename to sanitized calendar name appended with the date
+			$filename = preg_replace('/[^a-zA-Z0-9-_ ]/um', '', $name) . '_' . date('Y-m-d') . CalendarMigrator::FILENAME_EXT;
+			$exportPath = CalendarMigrator::EXPORT_ROOT . $filename;
+
+			if ($exportDestination->addFileContents($exportPath, $vCalendar->serialize()) === false) {
+				throw new CalendarMigratorException('Could not export calendars');
+			}
+		}
+	}
+
+	/**
+	 * @return array<string, VTimeZone>
+	 */
+	private function getCalendarTimezones(VCalendar $vCalendar): array {
+		/** @var VTimeZone[] $calendarTimezones */
+		$calendarTimezones = array_filter(
+			$vCalendar->getComponents(),
+			fn ($component) => $component->name === 'VTIMEZONE',
+		);
+
+		/** @var array<string, VTimeZone> $calendarTimezoneMap */
+		$calendarTimezoneMap = [];
+		foreach ($calendarTimezones as $vTimeZone) {
+			$calendarTimezoneMap[$vTimeZone->getTimeZone()->getName()] = $vTimeZone;
+		}
+
+		return $calendarTimezoneMap;
+	}
+
+	/**
+	 * @return VTimeZone[]
+	 */
+	private function getTimezonesForComponent(VCalendar $vCalendar, VObjectComponent $component): array {
+		$componentTimezoneIds = [];
+
+		foreach ($component->children() as $child) {
+			if ($child instanceof DateTime && isset($child->parameters['TZID'])) {
+				$timezoneId = $child->parameters['TZID']->getValue();
+				if (!in_array($timezoneId, $componentTimezoneIds, true)) {
+					$componentTimezoneIds[] = $timezoneId;
+				}
+			}
+		}
+
+		$calendarTimezoneMap = $this->getCalendarTimezones($vCalendar);
+
+		return array_values(array_filter(array_map(
+			fn (string $timezoneId) => $calendarTimezoneMap[$timezoneId],
+			$componentTimezoneIds,
+		)));
+	}
+
+	private function sanitizeComponent(VObjectComponent $component): VObjectComponent {
+		// Operate on the component clone to prevent mutation of the original
+		$component = clone $component;
+
+		// Remove RSVP parameters to prevent automatically sending invitation emails to attendees on import
+		foreach ($component->children() as $child) {
+			if (
+				$child->name === 'ATTENDEE'
+				&& isset($child->parameters['RSVP'])
+			) {
+				unset($child->parameters['RSVP']);
+			}
+		}
+
+		return $component;
+	}
+
+	/**
+	 * @return VObjectComponent[]
+	 */
+	private function getRequiredImportComponents(VCalendar $vCalendar, VObjectComponent $component): array {
+		$component = $this->sanitizeComponent($component);
+		/** @var array<int, VTimeZone> $timezoneComponents */
+		$timezoneComponents = $this->getTimezonesForComponent($vCalendar, $component);
+		return [
+			...$timezoneComponents,
+			$component,
+		];
+	}
+
+	private function initCalendarObject(): VCalendar {
+		$vCalendarObject = new VCalendar();
+		$vCalendarObject->PRODID = '-//IDN nextcloud.com//Migrated calendar//EN';
+		return $vCalendarObject;
+	}
+
+	private function importCalendarObject(int $calendarId, VCalendar $vCalendarObject, OutputInterface $output): void {
+		try {
+			$this->calDavBackend->createCalendarObject(
+				$calendarId,
+				UUIDUtil::getUUID() . CalendarMigrator::FILENAME_EXT,
+				$vCalendarObject->serialize(),
+				CalDavBackend::CALENDAR_TYPE_CALENDAR,
+			);
+		} catch (Throwable $e) {
+			// Rollback creation of calendar on error
+			$output->writeln('Error creating calendar object, rolling back creation of calendar…');
+			$this->calDavBackend->deleteCalendar($calendarId, true);
+		}
+	}
+
+	/**
+	 * @throws CalendarMigratorException
+	 */
+	private function importCalendar(IUser $user, string $filename, string $initialCalendarUri, VCalendar $vCalendar, OutputInterface $output): void {
+		$principalUri = $this->getPrincipalUri($user);
+		$calendarUri = $this->getUniqueCalendarUri($user, $initialCalendarUri);
+
+		$calendarId = $this->calDavBackend->createCalendar($principalUri, $calendarUri, [
+			'{DAV:}displayname' => isset($vCalendar->{'X-WR-CALNAME'}) ? $vCalendar->{'X-WR-CALNAME'}->getValue() : $this->l10n->t('Migrated calendar (%1$s)', [$filename]),
+			'{http://apple.com/ns/ical/}calendar-color' => isset($vCalendar->{'X-APPLE-CALENDAR-COLOR'}) ? $vCalendar->{'X-APPLE-CALENDAR-COLOR'}->getValue() : $this->defaults->getColorPrimary(),
+			'components' => implode(
+				',',
+				array_reduce(
+					$vCalendar->getComponents(),
+					function (array $componentNames, VObjectComponent $component) {
+						/** @var array<int, string> $componentNames */
+						return !in_array($component->name, $componentNames, true)
+							? [...$componentNames, $component->name]
+							: $componentNames;
+					},
+					[],
+				)
+			),
+		]);
+
+		/** @var VObjectComponent[] $calendarComponents */
+		$calendarComponents = array_values(array_filter(
+			$vCalendar->getComponents(),
+			// VTIMEZONE components are handled separately and added to the calendar object only if depended on by the component
+			fn (VObjectComponent $component) => $component->name !== 'VTIMEZONE',
+		));
+
+		/** @var array<string, VObjectComponent[]> $groupedCalendarComponents */
+		$groupedCalendarComponents = [];
+		/** @var VObjectComponent[] $ungroupedCalendarComponents */
+		$ungroupedCalendarComponents = [];
+
+		foreach ($calendarComponents as $component) {
+			if (isset($component->UID)) {
+				$uid = $component->UID->getValue();
+				// Components with the same UID (e.g. recurring events) are grouped together into a single calendar object
+				if (isset($groupedCalendarComponents[$uid])) {
+					$groupedCalendarComponents[$uid][] = $component;
+				} else {
+					$groupedCalendarComponents[$uid] = [$component];
+				}
+			} else {
+				$ungroupedCalendarComponents[] = $component;
+			}
+		}
+
+		foreach ($groupedCalendarComponents as $uid => $components) {
+			// Construct and import a calendar object containing all components of a group
+			$vCalendarObject = $this->initCalendarObject();
+			foreach ($components as $component) {
+				foreach ($this->getRequiredImportComponents($vCalendar, $component) as $component) {
+					$vCalendarObject->add($component);
+				}
+			}
+			$this->importCalendarObject($calendarId, $vCalendarObject, $output);
+		}
+
+		foreach ($ungroupedCalendarComponents as $component) {
+			// Construct and import a calendar object for a single component
+			$vCalendarObject = $this->initCalendarObject();
+			foreach ($this->getRequiredImportComponents($vCalendar, $component) as $component) {
+				$vCalendarObject->add($component);
+			}
+			$this->importCalendarObject($calendarId, $vCalendarObject, $output);
+		}
+	}
+
+	/**
+	 * {@inheritDoc}
+	 *
+	 * @throws CalendarMigratorException
+	 */
+	public function import(IUser $user, IImportSource $importSource, OutputInterface $output): void {
+		if ($importSource->getMigratorVersion(static::class) === null) {
+			$output->writeln('No version for ' . static::class . ', skipping import…');
+			return;
+		}
+
+		$output->writeln('Importing calendars from ' . CalendarMigrator::EXPORT_ROOT . '…');
+
+		$calendarImports = $importSource->getFolderListing(CalendarMigrator::EXPORT_ROOT);
+		if (empty($calendarImports)) {
+			$output->writeln('No calendars to import…');
+		}
+
+		foreach ($calendarImports as $filename) {
+			$importPath = CalendarMigrator::EXPORT_ROOT . $filename;
+			try {
+				/** @var VCalendar $vCalendar */
+				$vCalendar = VObjectReader::read(
+					$importSource->getFileAsStream($importPath),
+					VObjectReader::OPTION_FORGIVING,
+				);
+			} catch (Throwable $e) {
+				throw new CalendarMigratorException("Failed to read file \"$importPath\"", 0, $e);
+			}
+
+			$problems = $vCalendar->validate();
+			if (!empty($problems)) {
+				throw new CalendarMigratorException("Invalid calendar data contained in \"$importPath\"");
+			}
+
+			$splitFilename = explode('_', $filename, 2);
+			if (count($splitFilename) !== 2) {
+				throw new CalendarMigratorException("Invalid filename \"$filename\", expected filename of the format \"<calendar_name>_YYYY-MM-DD" . CalendarMigrator::FILENAME_EXT . '"');
+			}
+			[$initialCalendarUri, $suffix] = $splitFilename;
+
+			$this->importCalendar(
+				$user,
+				$filename,
+				$initialCalendarUri,
+				$vCalendar,
+				$output,
+			);
+
+			$vCalendar->destroy();
+		}
+	}
+}
diff --git a/apps/dav/lib/UserMigration/CalendarMigratorException.php b/apps/dav/lib/UserMigration/CalendarMigratorException.php
new file mode 100644
index 00000000000..91bac58ffac
--- /dev/null
+++ b/apps/dav/lib/UserMigration/CalendarMigratorException.php
@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright 2022 Christopher Ng <chrng8@gmail.com>
+ *
+ * @author Christopher Ng <chrng8@gmail.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\UserMigration;
+
+use Exception;
+
+class CalendarMigratorException extends Exception {
+}
diff --git a/apps/dav/lib/UserMigration/InvalidCalendarException.php b/apps/dav/lib/UserMigration/InvalidCalendarException.php
new file mode 100644
index 00000000000..0e42ef1bc20
--- /dev/null
+++ b/apps/dav/lib/UserMigration/InvalidCalendarException.php
@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright 2022 Christopher Ng <chrng8@gmail.com>
+ *
+ * @author Christopher Ng <chrng8@gmail.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\UserMigration;
+
+use Exception;
+
+class InvalidCalendarException extends Exception {
+}
diff --git a/apps/dav/tests/integration/UserMigration/CalendarMigratorTest.php b/apps/dav/tests/integration/UserMigration/CalendarMigratorTest.php
new file mode 100644
index 00000000000..f1ad6dda22e
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/CalendarMigratorTest.php
@@ -0,0 +1,137 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright 2022 Christopher Ng <chrng8@gmail.com>
+ *
+ * @author Christopher Ng <chrng8@gmail.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\Tests\integration\UserMigration;
+
+use function Safe\scandir;
+use OCA\DAV\AppInfo\Application;
+use OCA\DAV\UserMigration\CalendarMigrator;
+use OCP\AppFramework\App;
+use OCP\IUserManager;
+use Sabre\VObject\Component as VObjectComponent;
+use Sabre\VObject\Component\VCalendar;
+use Sabre\VObject\Property as VObjectProperty;
+use Sabre\VObject\Reader as VObjectReader;
+use Sabre\VObject\UUIDUtil;
+use Symfony\Component\Console\Output\OutputInterface;
+use Test\TestCase;
+
+/**
+ * @group DB
+ */
+class CalendarMigratorTest extends TestCase {
+
+	private IUserManager $userManager;
+
+	private CalendarMigrator $migrator;
+
+	private OutputInterface $output;
+
+	private const ASSETS_DIR = __DIR__ . '/assets/';
+
+	protected function setUp(): void {
+		$app = new App(Application::APP_ID);
+		$container = $app->getContainer();
+
+		$this->userManager = $container->get(IUserManager::class);
+		$this->migrator = $container->get(CalendarMigrator::class);
+		$this->output = $this->createMock(OutputInterface::class);
+	}
+
+	public function dataAssets(): array {
+		return array_map(
+			function (string $filename) {
+				/** @var VCalendar $vCalendar */
+				$vCalendar = VObjectReader::read(
+					fopen(self::ASSETS_DIR . $filename, 'r'),
+					VObjectReader::OPTION_FORGIVING,
+				);
+				[$initialCalendarUri, $ext] = explode('.', $filename, 2);
+				return [UUIDUtil::getUUID(), $filename, $initialCalendarUri, $vCalendar];
+			},
+			array_diff(
+				scandir(self::ASSETS_DIR),
+				// Exclude current and parent directories
+				['.', '..'],
+			),
+		);
+	}
+
+	private function getProperties(VCalendar $vCalendar): array {
+		return array_map(
+			fn (VObjectProperty $property) => $property->serialize(),
+			array_values(array_filter(
+				$vCalendar->children(),
+				fn (mixed $child) => $child instanceof VObjectProperty,
+			)),
+		);
+	}
+
+	private function getComponents(VCalendar $vCalendar): array {
+		return array_map(
+			// Elements of the serialized blob are sorted
+			fn (VObjectComponent $component) => $component->serialize(),
+			$vCalendar->getComponents(),
+		);
+	}
+
+	private function getSanitizedComponents(VCalendar $vCalendar): array {
+		return array_map(
+			// Elements of the serialized blob are sorted
+			fn (VObjectComponent $component) => $this->invokePrivate($this->migrator, 'sanitizeComponent', [$component])->serialize(),
+			$vCalendar->getComponents(),
+		);
+	}
+
+	/**
+	 * @dataProvider dataAssets
+	 */
+	public function testImportExportAsset(string $userId, string $filename, string $initialCalendarUri, VCalendar $importCalendar): void {
+		$user = $this->userManager->createUser($userId, 'topsecretpassword');
+
+		$problems = $importCalendar->validate();
+		$this->assertEmpty($problems);
+
+		$this->invokePrivate($this->migrator, 'importCalendar', [$user, $filename, $initialCalendarUri, $importCalendar, $this->output]);
+
+		$calendarExports = $this->invokePrivate($this->migrator, 'getCalendarExports', [$user, $this->output]);
+		$this->assertCount(1, $calendarExports);
+
+		/** @var VCalendar $exportCalendar */
+		['vCalendar' => $exportCalendar] = reset($calendarExports);
+
+		$this->assertEqualsCanonicalizing(
+			$this->getProperties($importCalendar),
+			$this->getProperties($exportCalendar),
+		);
+
+		$this->assertEqualsCanonicalizing(
+			// Components are expected to be sanitized on import
+			$this->getSanitizedComponents($importCalendar),
+			$this->getComponents($exportCalendar),
+		);
+	}
+}
diff --git a/apps/dav/tests/integration/UserMigration/assets/event-alarms.ics b/apps/dav/tests/integration/UserMigration/assets/event-alarms.ics
new file mode 100644
index 00000000000..5dc6acbb605
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/event-alarms.ics
@@ -0,0 +1,42 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//SabreDAV//SabreDAV//EN
+CALSCALE:GREGORIAN
+X-WR-CALNAME:Alarms
+X-APPLE-CALENDAR-COLOR:#0082c9
+BEGIN:VTIMEZONE
+TZID:Europe/Berlin
+BEGIN:DAYLIGHT
+TZOFFSETFROM:+0100
+RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
+DTSTART:19810329T020000
+TZNAME:GMT+2
+TZOFFSETTO:+0200
+END:DAYLIGHT
+BEGIN:STANDARD
+TZOFFSETFROM:+0200
+RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
+DTSTART:19961027T030000
+TZNAME:GMT+1
+TZOFFSETTO:+0100
+END:STANDARD
+END:VTIMEZONE
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+DTEND;TZID=Europe/Berlin:20160816T100000
+TRANSP:OPAQUE
+SUMMARY:Test Europe Berlin
+DTSTART;TZID=Europe/Berlin:20160816T090000
+DTSTAMP:20160809T163632Z
+SEQUENCE:0
+BEGIN:VALARM
+ACTION:DISPLAY
+TRIGGER;RELATED=START:P1DT9H
+END:VALARM
+BEGIN:VALARM
+ACTION:DISPLAY
+TRIGGER;VALUE=DATE-TIME:20200306T083000Z
+END:VALARM
+END:VEVENT
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/event-attendees.ics b/apps/dav/tests/integration/UserMigration/assets/event-attendees.ics
new file mode 100644
index 00000000000..4100365926c
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/event-attendees.ics
@@ -0,0 +1,39 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//SabreDAV//SabreDAV//EN
+CALSCALE:GREGORIAN
+X-WR-CALNAME:Attendees
+X-APPLE-CALENDAR-COLOR:#0082c9
+BEGIN:VTIMEZONE
+TZID:Europe/Berlin
+BEGIN:DAYLIGHT
+TZOFFSETFROM:+0100
+RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
+DTSTART:19810329T020000
+TZNAME:GMT+2
+TZOFFSETTO:+0200
+END:DAYLIGHT
+BEGIN:STANDARD
+TZOFFSETFROM:+0200
+RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
+DTSTART:19961027T030000
+TZNAME:GMT+1
+TZOFFSETTO:+0100
+END:STANDARD
+END:VTIMEZONE
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+DTEND;TZID=Europe/Berlin:20160816T100000
+TRANSP:OPAQUE
+SUMMARY:Test Europe Berlin
+DTSTART;TZID=Europe/Berlin:20160816T090000
+DTSTAMP:20160809T163632Z
+SEQUENCE:0
+ORGANIZER;CN=John Smith:mailto:jsmith@example.com
+ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT:mailto:jsmith@example.com
+ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=TENTATIVE;CN=Henry Cabot:mailto:hcabot@example.com
+ATTENDEE;ROLE=REQ-PARTICIPANT;DELEGATED-FROM="mailto:bob@example.com";PARTSTAT=ACCEPTED;CN=Jane Doe:mailto:jdoe@example.com
+ATTENDEE;ROLE=NON-PARTICIPANT;PARTSTAT=DELEGATED;DELEGATED-TO="mailto:hcabot@example.com";CN=The Big Cheese:mailto:iamboss@example.com
+END:VEVENT
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/event-categories.ics b/apps/dav/tests/integration/UserMigration/assets/event-categories.ics
new file mode 100644
index 00000000000..7e7054d0251
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/event-categories.ics
@@ -0,0 +1,35 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//SabreDAV//SabreDAV//EN
+CALSCALE:GREGORIAN
+X-WR-CALNAME:Categories
+X-APPLE-CALENDAR-COLOR:#0082c9
+BEGIN:VTIMEZONE
+TZID:Europe/Berlin
+BEGIN:DAYLIGHT
+TZOFFSETFROM:+0100
+RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
+DTSTART:19810329T020000
+TZNAME:GMT+2
+TZOFFSETTO:+0200
+END:DAYLIGHT
+BEGIN:STANDARD
+TZOFFSETFROM:+0200
+RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
+DTSTART:19961027T030000
+TZNAME:GMT+1
+TZOFFSETTO:+0100
+END:STANDARD
+END:VTIMEZONE
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+DTEND;TZID=Europe/Berlin:20160816T100000
+TRANSP:OPAQUE
+SUMMARY:Test Europe Berlin
+DTSTART;TZID=Europe/Berlin:20160816T090000
+DTSTAMP:20160809T163632Z
+SEQUENCE:0
+CATEGORIES:BUSINESS,HUMAN RESOURCES
+END:VEVENT
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/event-complex-alarm-recurring.ics b/apps/dav/tests/integration/UserMigration/assets/event-complex-alarm-recurring.ics
new file mode 100644
index 00000000000..8aa8e085c63
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/event-complex-alarm-recurring.ics
@@ -0,0 +1,33 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+CALSCALE:GREGORIAN
+PRODID:-//SabreDAV//SabreDAV//EN
+X-WR-CALNAME:Complex alarm recurring
+X-APPLE-CALENDAR-COLOR:#0082c9
+BEGIN:VEVENT
+CREATED:20220218T031205Z
+DTSTAMP:20220218T031409Z
+LAST-MODIFIED:20220218T031409Z
+SEQUENCE:2
+UID:b78f3a65-413d-4fa7-b125-1232bc6a2c72
+DTSTART;VALUE=DATE:20220217
+DTEND;VALUE=DATE:20220218
+STATUS:TENTATIVE
+SUMMARY:Complex recurring event
+LOCATION:Antarctica
+DESCRIPTION:Event description
+CLASS:CONFIDENTIAL
+TRANSP:TRANSPARENT
+CATEGORIES:Personal,Travel,Special occasion
+COLOR:khaki
+RRULE:FREQ=MONTHLY;COUNT=10;BYDAY=WE;BYSETPOS=2
+BEGIN:VALARM
+ACTION:DISPLAY
+TRIGGER;RELATED=START:-P6DT15H
+END:VALARM
+BEGIN:VALARM
+ACTION:DISPLAY
+TRIGGER;RELATED=START:-PT15H
+END:VALARM
+END:VEVENT
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/event-complex-recurrence.ics b/apps/dav/tests/integration/UserMigration/assets/event-complex-recurrence.ics
new file mode 100644
index 00000000000..45fb5540af6
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/event-complex-recurrence.ics
@@ -0,0 +1,87 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//SabreDAV//SabreDAV//EN
+CALSCALE:GREGORIAN
+X-WR-CALNAME:Complex recurrence
+X-APPLE-CALENDAR-COLOR:#0082c9
+BEGIN:VTIMEZONE
+TZID:Europe/Berlin
+BEGIN:DAYLIGHT
+TZOFFSETFROM:+0100
+RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
+DTSTART:19810329T020000
+TZNAME:GMT+2
+TZOFFSETTO:+0200
+END:DAYLIGHT
+BEGIN:STANDARD
+TZOFFSETFROM:+0200
+RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
+DTSTART:19961027T030000
+TZNAME:GMT+1
+TZOFFSETTO:+0100
+END:STANDARD
+END:VTIMEZONE
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST
+RRULE:FREQ=WEEKLY
+DTSTART;TZID=Europe/Berlin:20200301T150000
+DTEND;TZID=Europe/Berlin:20200301T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST EX 1
+RECURRENCE-ID;TZID=Europe/Berlin:20200308T150000
+DTSTART;TZID=Europe/Berlin:20200401T150000
+DTEND;TZID=Europe/Berlin:20200401T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST EX 2
+RECURRENCE-ID;TZID=Europe/Berlin:20200315T150000
+DTSTART;TZID=Europe/Berlin:20201101T150000
+DTEND;TZID=Europe/Berlin:20201101T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST EX 3
+RECURRENCE-ID;TZID=Europe/Berlin:20200405T150000
+DTSTART;TZID=Europe/Berlin:20200406T150000
+DTEND;TZID=Europe/Berlin:20200406T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST EX 4
+RECURRENCE-ID;TZID=Europe/Berlin:20200412T150000
+DTSTART;TZID=Europe/Berlin:20201201T150000
+DTEND;TZID=Europe/Berlin:20201201T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST EX 5
+RECURRENCE-ID;TZID=Europe/Berlin:20200426T150000
+DTSTART;TZID=Europe/Berlin:20200410T150000
+DTEND;TZID=Europe/Berlin:20200410T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:INVALID RECURRENCE-ID
+RECURRENCE-ID;TZID=Europe/Berlin:20200427T150000
+DTSTART;TZID=Europe/Berlin:20200420T150000
+DTEND;TZID=Europe/Berlin:20200420T160000
+END:VEVENT
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/event-custom-color.ics b/apps/dav/tests/integration/UserMigration/assets/event-custom-color.ics
new file mode 100644
index 00000000000..012ec9fbc17
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/event-custom-color.ics
@@ -0,0 +1,34 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//SabreDAV//SabreDAV//EN
+X-WR-CALNAME:Personal
+X-APPLE-CALENDAR-COLOR:#f264ab
+CALSCALE:GREGORIAN
+BEGIN:VTIMEZONE
+TZID:Europe/Berlin
+BEGIN:DAYLIGHT
+TZOFFSETFROM:+0100
+RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
+DTSTART:19810329T020000
+TZNAME:GMT+2
+TZOFFSETTO:+0200
+END:DAYLIGHT
+BEGIN:STANDARD
+TZOFFSETFROM:+0200
+RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
+DTSTART:19961027T030000
+TZNAME:GMT+1
+TZOFFSETTO:+0100
+END:STANDARD
+END:VTIMEZONE
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+DTEND;TZID=Europe/Berlin:20160816T100000
+TRANSP:OPAQUE
+SUMMARY:Test Europe Berlin
+DTSTART;TZID=Europe/Berlin:20160816T090000
+DTSTAMP:20160809T163632Z
+SEQUENCE:0
+END:VEVENT
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/event-multiple-recurring.ics b/apps/dav/tests/integration/UserMigration/assets/event-multiple-recurring.ics
new file mode 100644
index 00000000000..a9e748b5252
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/event-multiple-recurring.ics
@@ -0,0 +1,74 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+CALSCALE:GREGORIAN
+PRODID:-//SabreDAV//SabreDAV//EN
+X-WR-CALNAME:Multiple and recurring
+X-APPLE-CALENDAR-COLOR:#795AAB
+BEGIN:VEVENT
+CREATED:20220218T044833Z
+DTSTAMP:20220218T044837Z
+LAST-MODIFIED:20220218T044837Z
+SEQUENCE:2
+UID:dc343863-b57c-43a5-9ba4-19ae2740cd7e
+DTSTART;VALUE=DATE:20220607
+DTEND;VALUE=DATE:20220608
+STATUS:CONFIRMED
+SUMMARY:Event 4
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20220218T044806Z
+DTSTAMP:20220218T044809Z
+LAST-MODIFIED:20220218T044809Z
+SEQUENCE:2
+UID:ae28b642-7e11-4e16-818a-06c89ae74f44
+DTSTART;VALUE=DATE:20220218
+DTEND;VALUE=DATE:20220219
+STATUS:CONFIRMED
+SUMMARY:Event 1
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20220218T044820Z
+DTSTAMP:20220218T044827Z
+LAST-MODIFIED:20220218T044827Z
+SEQUENCE:2
+UID:5edfb90e-44b3-47c6-863b-f632327f46f0
+DTSTART;VALUE=DATE:20220518
+DTEND;VALUE=DATE:20220519
+STATUS:CONFIRMED
+SUMMARY:Event 3
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20220218T044810Z
+DTSTAMP:20220218T044814Z
+LAST-MODIFIED:20220218T044814Z
+SEQUENCE:2
+UID:9789f684-1cf9-4ee7-90cb-54cdec6a6f03
+DTSTART;VALUE=DATE:20220223
+DTEND;VALUE=DATE:20220224
+STATUS:CONFIRMED
+SUMMARY:Event 2
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20220218T044932Z
+DTSTAMP:20220218T044945Z
+LAST-MODIFIED:20220218T044945Z
+SEQUENCE:2
+UID:d5bdaf0e-d6c7-4e30-a730-04928976a1d2
+DTSTART;VALUE=DATE:20221102
+DTEND;VALUE=DATE:20221103
+STATUS:CONFIRMED
+SUMMARY:Recurring event
+RRULE:FREQ=WEEKLY;BYDAY=WE
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20220218T044915Z
+DTSTAMP:20220218T044918Z
+LAST-MODIFIED:20220218T044918Z
+SEQUENCE:2
+UID:11c3d9fd-fb54-4384-ab68-40b5d6acef6f
+DTSTART;VALUE=DATE:20221010
+DTEND;VALUE=DATE:20221011
+STATUS:CONFIRMED
+SUMMARY:Event 5
+END:VEVENT
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/event-multiple.ics b/apps/dav/tests/integration/UserMigration/assets/event-multiple.ics
new file mode 100644
index 00000000000..ba0f5457052
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/event-multiple.ics
@@ -0,0 +1,62 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+CALSCALE:GREGORIAN
+PRODID:-//SabreDAV//SabreDAV//EN
+X-WR-CALNAME:Multiple
+X-APPLE-CALENDAR-COLOR:#795AAB
+BEGIN:VEVENT
+CREATED:20220218T044833Z
+DTSTAMP:20220218T044837Z
+LAST-MODIFIED:20220218T044837Z
+SEQUENCE:2
+UID:dc343863-b57c-43a5-9ba4-19ae2740cd7e
+DTSTART;VALUE=DATE:20220607
+DTEND;VALUE=DATE:20220608
+STATUS:CONFIRMED
+SUMMARY:Event 4
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20220218T044806Z
+DTSTAMP:20220218T044809Z
+LAST-MODIFIED:20220218T044809Z
+SEQUENCE:2
+UID:ae28b642-7e11-4e16-818a-06c89ae74f44
+DTSTART;VALUE=DATE:20220218
+DTEND;VALUE=DATE:20220219
+STATUS:CONFIRMED
+SUMMARY:Event 1
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20220218T044820Z
+DTSTAMP:20220218T044827Z
+LAST-MODIFIED:20220218T044827Z
+SEQUENCE:2
+UID:5edfb90e-44b3-47c6-863b-f632327f46f0
+DTSTART;VALUE=DATE:20220518
+DTEND;VALUE=DATE:20220519
+STATUS:CONFIRMED
+SUMMARY:Event 3
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20220218T044810Z
+DTSTAMP:20220218T044814Z
+LAST-MODIFIED:20220218T044814Z
+SEQUENCE:2
+UID:9789f684-1cf9-4ee7-90cb-54cdec6a6f03
+DTSTART;VALUE=DATE:20220223
+DTEND;VALUE=DATE:20220224
+STATUS:CONFIRMED
+SUMMARY:Event 2
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20220218T044915Z
+DTSTAMP:20220218T044918Z
+LAST-MODIFIED:20220218T044918Z
+SEQUENCE:2
+UID:11c3d9fd-fb54-4384-ab68-40b5d6acef6f
+DTSTART;VALUE=DATE:20221010
+DTEND;VALUE=DATE:20221011
+STATUS:CONFIRMED
+SUMMARY:Event 5
+END:VEVENT
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/event-recurring.ics b/apps/dav/tests/integration/UserMigration/assets/event-recurring.ics
new file mode 100644
index 00000000000..d59627b4a6c
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/event-recurring.ics
@@ -0,0 +1,87 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//SabreDAV//SabreDAV//EN
+CALSCALE:GREGORIAN
+X-WR-CALNAME:Recurring
+X-APPLE-CALENDAR-COLOR:#0082c9
+BEGIN:VTIMEZONE
+TZID:Europe/Berlin
+BEGIN:DAYLIGHT
+TZOFFSETFROM:+0100
+RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
+DTSTART:19810329T020000
+TZNAME:GMT+2
+TZOFFSETTO:+0200
+END:DAYLIGHT
+BEGIN:STANDARD
+TZOFFSETFROM:+0200
+RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
+DTSTART:19961027T030000
+TZNAME:GMT+1
+TZOFFSETTO:+0100
+END:STANDARD
+END:VTIMEZONE
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST
+RRULE:FREQ=WEEKLY
+DTSTART;TZID=Europe/Berlin:20200301T150000
+DTEND;TZID=Europe/Berlin:20200301T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST EX 1
+RECURRENCE-ID;TZID=Europe/Berlin:20200308T150000
+DTSTART;TZID=Europe/Berlin:20200401T150000
+DTEND;TZID=Europe/Berlin:20200401T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST EX 2
+RECURRENCE-ID;TZID=Europe/Berlin:20200315T150000
+DTSTART;TZID=Europe/Berlin:20201101T150000
+DTEND;TZID=Europe/Berlin:20201101T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST EX 3
+RECURRENCE-ID;TZID=Europe/Berlin:20200405T150000
+DTSTART;TZID=Europe/Berlin:20200406T150000
+DTEND;TZID=Europe/Berlin:20200406T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST EX 4
+RECURRENCE-ID;TZID=Europe/Berlin:20200412T150000
+DTSTART;TZID=Europe/Berlin:20201201T150000
+DTEND;TZID=Europe/Berlin:20201201T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:TEST EX 5
+RECURRENCE-ID;TZID=Europe/Berlin:20200426T150000
+DTSTART;TZID=Europe/Berlin:20200410T150000
+DTEND;TZID=Europe/Berlin:20200410T160000
+END:VEVENT
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+DTSTAMP:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+SUMMARY:INVALID RECURRENCE-ID
+RECURRENCE-ID;TZID=Europe/Berlin:20200427T150000
+DTSTART;TZID=Europe/Berlin:20200420T150000
+DTEND;TZID=Europe/Berlin:20200420T160000
+END:VEVENT
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/event-timed.ics b/apps/dav/tests/integration/UserMigration/assets/event-timed.ics
new file mode 100644
index 00000000000..980a290a4f7
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/event-timed.ics
@@ -0,0 +1,34 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//SabreDAV//SabreDAV//EN
+X-WR-CALNAME:Timed
+X-APPLE-CALENDAR-COLOR:#0082c9
+CALSCALE:GREGORIAN
+BEGIN:VTIMEZONE
+TZID:Europe/Berlin
+BEGIN:DAYLIGHT
+TZOFFSETFROM:+0100
+RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
+DTSTART:19810329T020000
+TZNAME:GMT+2
+TZOFFSETTO:+0200
+END:DAYLIGHT
+BEGIN:STANDARD
+TZOFFSETFROM:+0200
+RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
+DTSTART:19961027T030000
+TZNAME:GMT+1
+TZOFFSETTO:+0100
+END:STANDARD
+END:VTIMEZONE
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+DTEND;TZID=Europe/Berlin:20160816T100000
+TRANSP:OPAQUE
+SUMMARY:Test Europe Berlin
+DTSTART;TZID=Europe/Berlin:20160816T090000
+DTSTAMP:20160809T163632Z
+SEQUENCE:0
+END:VEVENT
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/journal-todo-event.ics b/apps/dav/tests/integration/UserMigration/assets/journal-todo-event.ics
new file mode 100644
index 00000000000..6a74aface84
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/journal-todo-event.ics
@@ -0,0 +1,41 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+CALSCALE:GREGORIAN
+PRODID:-//SabreDAV//SabreDAV//EN
+X-WR-CALNAME:Journal Todo Event
+X-APPLE-CALENDAR-COLOR:#0082c9
+BEGIN:VJOURNAL
+UID:19970901T130000Z-123405@example.com
+DTSTAMP:19970901T130000Z
+DTSTART;VALUE=DATE:19970317
+SUMMARY:Staff meeting minutes
+DESCRIPTION:1. Staff meeting: Participants include Joe\,
+  Lisa\, and Bob. Aurora project plans were reviewed.
+  There is currently no budget reserves for this project.
+  Lisa will escalate to management. Next meeting on Tuesday.\n
+  2. Telephone Conference: ABC Corp. sales representative
+  called to discuss new printer. Promised to get us a demo by
+  Friday.\n3. Henry Miller (Handsoff Insurance): Car was
+  totaled by tree. Is looking into a loaner car. 555-2323
+  (tel).
+END:VJOURNAL
+BEGIN:VTODO
+UID:20070313T123432Z-456553@example.com
+DTSTAMP:20070313T123432Z
+DUE;VALUE=DATE:20070501
+SUMMARY:Submit Quebec Income Tax Return for 2006
+CLASS:CONFIDENTIAL
+CATEGORIES:FAMILY,FINANCE
+STATUS:NEEDS-ACTION
+END:VTODO
+BEGIN:VEVENT
+CREATED:20160809T163629Z
+UID:0AD16F58-01B3-463B-A215-FD09FC729A02
+DTEND:20160816T100000
+TRANSP:OPAQUE
+SUMMARY:Test Event
+DTSTART:20160816T090000
+DTSTAMP:20160809T163632Z
+SEQUENCE:0
+END:VEVENT
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/journal.ics b/apps/dav/tests/integration/UserMigration/assets/journal.ics
new file mode 100644
index 00000000000..4add335f075
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/journal.ics
@@ -0,0 +1,22 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//SabreDAV//SabreDAV//EN
+CALSCALE:GREGORIAN
+X-WR-CALNAME:Journal
+X-APPLE-CALENDAR-COLOR:#0082c9
+BEGIN:VJOURNAL
+UID:19970901T130000Z-123405@example.com
+DTSTAMP:19970901T130000Z
+DTSTART;VALUE=DATE:19970317
+SUMMARY:Staff meeting minutes
+DESCRIPTION:1. Staff meeting: Participants include Joe\,
+ Lisa\, and Bob. Aurora project plans were reviewed.
+ There is currently no budget reserves for this project.
+ Lisa will escalate to management. Next meeting on Tuesday.\n
+ 2. Telephone Conference: ABC Corp. sales representative
+ called to discuss new printer. Promised to get us a demo by
+ Friday.\n3. Henry Miller (Handsoff Insurance): Car was
+ totaled by tree. Is looking into a loaner car. 555-2323
+ (tel).
+END:VJOURNAL
+END:VCALENDAR
diff --git a/apps/dav/tests/integration/UserMigration/assets/todo.ics b/apps/dav/tests/integration/UserMigration/assets/todo.ics
new file mode 100644
index 00000000000..48f00e6315a
--- /dev/null
+++ b/apps/dav/tests/integration/UserMigration/assets/todo.ics
@@ -0,0 +1,16 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//SabreDAV//SabreDAV//EN
+CALSCALE:GREGORIAN
+X-WR-CALNAME:Todo
+X-APPLE-CALENDAR-COLOR:#0082c9
+BEGIN:VTODO
+UID:20070313T123432Z-456553@example.com
+DTSTAMP:20070313T123432Z
+DUE;VALUE=DATE:20070501
+SUMMARY:Submit Quebec Income Tax Return for 2006
+CLASS:CONFIDENTIAL
+CATEGORIES:FAMILY,FINANCE
+STATUS:NEEDS-ACTION
+END:VTODO
+END:VCALENDAR