16 files changed, 476 insertions, 21 deletions

diff --git a/apps/dav/composer/composer/autoload_classmap.php b/apps/dav/composer/composer/autoload_classmap.php
index 0572fe3cff8..daf2cff3161 100644
--- a/apps/dav/composer/composer/autoload_classmap.php
+++ b/apps/dav/composer/composer/autoload_classmap.php
@@ -43,6 +43,7 @@ return array(
     'OCA\\DAV\\CalDAV\\CalendarImpl' => $baseDir . '/../lib/CalDAV/CalendarImpl.php',
     'OCA\\DAV\\CalDAV\\CalendarManager' => $baseDir . '/../lib/CalDAV/CalendarManager.php',
     'OCA\\DAV\\CalDAV\\CalendarObject' => $baseDir . '/../lib/CalDAV/CalendarObject.php',
+    'OCA\\DAV\\CalDAV\\CalendarProvider' => $baseDir . '/../lib/CalDAV/CalendarProvider.php',
     'OCA\\DAV\\CalDAV\\CalendarRoot' => $baseDir . '/../lib/CalDAV/CalendarRoot.php',
     'OCA\\DAV\\CalDAV\\ICSExportPlugin\\ICSExportPlugin' => $baseDir . '/../lib/CalDAV/ICSExportPlugin/ICSExportPlugin.php',
     'OCA\\DAV\\CalDAV\\IRestorable' => $baseDir . '/../lib/CalDAV/IRestorable.php',
diff --git a/apps/dav/composer/composer/autoload_static.php b/apps/dav/composer/composer/autoload_static.php
index 01a5df8c1b8..d00299ed047 100644
--- a/apps/dav/composer/composer/autoload_static.php
+++ b/apps/dav/composer/composer/autoload_static.php
@@ -58,6 +58,7 @@ class ComposerStaticInitDAV
         'OCA\\DAV\\CalDAV\\CalendarImpl' => __DIR__ . '/..' . '/../lib/CalDAV/CalendarImpl.php',
         'OCA\\DAV\\CalDAV\\CalendarManager' => __DIR__ . '/..' . '/../lib/CalDAV/CalendarManager.php',
         'OCA\\DAV\\CalDAV\\CalendarObject' => __DIR__ . '/..' . '/../lib/CalDAV/CalendarObject.php',
+        'OCA\\DAV\\CalDAV\\CalendarProvider' => __DIR__ . '/..' . '/../lib/CalDAV/CalendarProvider.php',
         'OCA\\DAV\\CalDAV\\CalendarRoot' => __DIR__ . '/..' . '/../lib/CalDAV/CalendarRoot.php',
         'OCA\\DAV\\CalDAV\\ICSExportPlugin\\ICSExportPlugin' => __DIR__ . '/..' . '/../lib/CalDAV/ICSExportPlugin/ICSExportPlugin.php',
         'OCA\\DAV\\CalDAV\\IRestorable' => __DIR__ . '/..' . '/../lib/CalDAV/IRestorable.php',
diff --git a/apps/dav/lib/CalDAV/CalDavBackend.php b/apps/dav/lib/CalDAV/CalDavBackend.php
index 5f0c1bf3c48..64ee76f94d1 100644
--- a/apps/dav/lib/CalDAV/CalDavBackend.php
+++ b/apps/dav/lib/CalDAV/CalDavBackend.php
@@ -1845,17 +1845,19 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 				$outerQuery->createNamedParameter(self::CALENDAR_TYPE_CALENDAR)));
 
 		// only return public items for shared calendars for now
-		if ($calendarInfo['principaluri'] !== $calendarInfo['{http://owncloud.org/ns}owner-principal']) {
+		if (isset($calendarInfo['{http://owncloud.org/ns}owner-principal']) === false || $calendarInfo['principaluri'] !== $calendarInfo['{http://owncloud.org/ns}owner-principal']) {
 			$innerQuery->andWhere($innerQuery->expr()->eq('c.classification',
 				$outerQuery->createNamedParameter(self::CLASSIFICATION_PUBLIC)));
 		}
 
-		$or = $innerQuery->expr()->orX();
-		foreach ($searchProperties as $searchProperty) {
-			$or->add($innerQuery->expr()->eq('op.name',
-				$outerQuery->createNamedParameter($searchProperty)));
+		if (!empty($searchProperties)) {
+			$or = $innerQuery->expr()->orX();
+			foreach ($searchProperties as $searchProperty) {
+				$or->add($innerQuery->expr()->eq('op.name',
+					$outerQuery->createNamedParameter($searchProperty)));
+			}
+			$innerQuery->andWhere($or);
 		}
-		$innerQuery->andWhere($or);
 
 		if ($pattern !== '') {
 			$innerQuery->andWhere($innerQuery->expr()->iLike('op.value',
@@ -1878,7 +1880,7 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 			}
 		}
 
-		if (isset($options['types'])) {
+		if (!empty($options['types'])) {
 			$or = $outerQuery->expr()->orX();
 			foreach ($options['types'] as $type) {
 				$or->add($outerQuery->expr()->eq('componenttype',
@@ -1887,8 +1889,7 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 			$outerQuery->andWhere($or);
 		}
 
-		$outerQuery->andWhere($outerQuery->expr()->in('c.id',
-			$outerQuery->createFunction($innerQuery->getSQL())));
+		$outerQuery->andWhere($outerQuery->expr()->in('c.id', $outerQuery->createFunction($innerQuery->getSQL())));
 
 		if ($offset) {
 			$outerQuery->setFirstResult($offset);
diff --git a/apps/dav/lib/CalDAV/CalendarImpl.php b/apps/dav/lib/CalDAV/CalendarImpl.php
index 4f34e604c81..356f2800031 100644
--- a/apps/dav/lib/CalDAV/CalendarImpl.php
+++ b/apps/dav/lib/CalDAV/CalendarImpl.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 /**
  * @copyright 2017, Georg Ehrke <oc.list@georgehrke.com>
  *
@@ -51,7 +54,7 @@ class CalendarImpl implements ICalendar {
 		$this->calendarInfo = $calendarInfo;
 		$this->backend = $backend;
 	}
-	
+
 	/**
 	 * @return string defining the technical unique key
 	 * @since 13.0.0
diff --git a/apps/dav/lib/CalDAV/CalendarProvider.php b/apps/dav/lib/CalDAV/CalendarProvider.php
new file mode 100644
index 00000000000..30eb6ae4268
--- /dev/null
+++ b/apps/dav/lib/CalDAV/CalendarProvider.php
@@ -0,0 +1,72 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright 2021 Anna Larch <anna.larch@gmx.net>
+ *
+ * @author 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 OCP\Calendar\ICalendarProvider;
+use OCP\IConfig;
+use OCP\IL10N;
+
+class CalendarProvider implements ICalendarProvider {
+
+	/** @var CalDavBackend */
+	private $calDavBackend;
+
+	/** @var IL10N */
+	private $l10n;
+
+	/** @var IConfig */
+	private $config;
+
+	public function __construct(CalDavBackend $calDavBackend, IL10N $l10n, IConfig $config) {
+		$this->calDavBackend = $calDavBackend;
+		$this->l10n = $l10n;
+		$this->config = $config;
+	}
+
+	public function getCalendars(string $principalUri, array $calendarUris = []): array {
+		$calendarInfos = [];
+		if (empty($calendarUris)) {
+			$calendarInfos[] = $this->calDavBackend->getCalendarsForUser($principalUri);
+		} else {
+			foreach ($calendarUris as $calendarUri) {
+				$calendarInfos[] = $this->calDavBackend->getCalendarByUri($principalUri, $calendarUri);
+			}
+		}
+
+		$calendarInfos = array_filter($calendarInfos);
+
+		$iCalendars = [];
+		foreach ($calendarInfos as $calendarInfo) {
+			$calendar = new Calendar($this->calDavBackend, $calendarInfo, $this->l10n, $this->config);
+			$iCalendars[] = new CalendarImpl(
+				$calendar,
+				$calendarInfo,
+				$this->calDavBackend,
+			);
+		}
+		return $iCalendars;
+	}
+}
diff --git a/lib/composer/composer/autoload_classmap.php b/lib/composer/composer/autoload_classmap.php
index 823eef1fde3..353fc22d486 100644
--- a/lib/composer/composer/autoload_classmap.php
+++ b/lib/composer/composer/autoload_classmap.php
@@ -117,6 +117,8 @@ return array(
     'OCP\\Broadcast\\Events\\IBroadcastEvent' => $baseDir . '/lib/public/Broadcast/Events/IBroadcastEvent.php',
     'OCP\\Calendar\\BackendTemporarilyUnavailableException' => $baseDir . '/lib/public/Calendar/BackendTemporarilyUnavailableException.php',
     'OCP\\Calendar\\ICalendar' => $baseDir . '/lib/public/Calendar/ICalendar.php',
+    'OCP\\Calendar\\ICalendarProvider' => $baseDir . '/lib/public/Calendar/ICalendarProvider.php',
+    'OCP\\Calendar\\ICalendarQuery' => $baseDir . '/lib/public/Calendar/ICalendarQuery.php',
     'OCP\\Calendar\\IManager' => $baseDir . '/lib/public/Calendar/IManager.php',
     'OCP\\Calendar\\IMetadataProvider' => $baseDir . '/lib/public/Calendar/IMetadataProvider.php',
     'OCP\\Calendar\\Resource\\IBackend' => $baseDir . '/lib/public/Calendar/Resource/IBackend.php',
@@ -759,6 +761,7 @@ return array(
     'OC\\Broadcast\\Events\\BroadcastEvent' => $baseDir . '/lib/private/Broadcast/Events/BroadcastEvent.php',
     'OC\\Cache\\CappedMemoryCache' => $baseDir . '/lib/private/Cache/CappedMemoryCache.php',
     'OC\\Cache\\File' => $baseDir . '/lib/private/Cache/File.php',
+    'OC\\Calendar\\CalendarQuery' => $baseDir . '/lib/private/Calendar/CalendarQuery.php',
     'OC\\Calendar\\Manager' => $baseDir . '/lib/private/Calendar/Manager.php',
     'OC\\Calendar\\Resource\\Manager' => $baseDir . '/lib/private/Calendar/Resource/Manager.php',
     'OC\\Calendar\\Room\\Manager' => $baseDir . '/lib/private/Calendar/Room/Manager.php',
diff --git a/lib/composer/composer/autoload_static.php b/lib/composer/composer/autoload_static.php
index 81cd22b0570..f7c541d8c31 100644
--- a/lib/composer/composer/autoload_static.php
+++ b/lib/composer/composer/autoload_static.php
@@ -146,6 +146,8 @@ class ComposerStaticInit53792487c5a8370acc0b06b1a864ff4c
         'OCP\\Broadcast\\Events\\IBroadcastEvent' => __DIR__ . '/../../..' . '/lib/public/Broadcast/Events/IBroadcastEvent.php',
         'OCP\\Calendar\\BackendTemporarilyUnavailableException' => __DIR__ . '/../../..' . '/lib/public/Calendar/BackendTemporarilyUnavailableException.php',
         'OCP\\Calendar\\ICalendar' => __DIR__ . '/../../..' . '/lib/public/Calendar/ICalendar.php',
+        'OCP\\Calendar\\ICalendarProvider' => __DIR__ . '/../../..' . '/lib/public/Calendar/ICalendarProvider.php',
+        'OCP\\Calendar\\ICalendarQuery' => __DIR__ . '/../../..' . '/lib/public/Calendar/ICalendarQuery.php',
         'OCP\\Calendar\\IManager' => __DIR__ . '/../../..' . '/lib/public/Calendar/IManager.php',
         'OCP\\Calendar\\IMetadataProvider' => __DIR__ . '/../../..' . '/lib/public/Calendar/IMetadataProvider.php',
         'OCP\\Calendar\\Resource\\IBackend' => __DIR__ . '/../../..' . '/lib/public/Calendar/Resource/IBackend.php',
@@ -788,6 +790,7 @@ class ComposerStaticInit53792487c5a8370acc0b06b1a864ff4c
         'OC\\Broadcast\\Events\\BroadcastEvent' => __DIR__ . '/../../..' . '/lib/private/Broadcast/Events/BroadcastEvent.php',
         'OC\\Cache\\CappedMemoryCache' => __DIR__ . '/../../..' . '/lib/private/Cache/CappedMemoryCache.php',
         'OC\\Cache\\File' => __DIR__ . '/../../..' . '/lib/private/Cache/File.php',
+        'OC\\Calendar\\CalendarQuery' => __DIR__ . '/../../..' . '/lib/private/Calendar/CalendarQuery.php',
         'OC\\Calendar\\Manager' => __DIR__ . '/../../..' . '/lib/private/Calendar/Manager.php',
         'OC\\Calendar\\Resource\\Manager' => __DIR__ . '/../../..' . '/lib/private/Calendar/Resource/Manager.php',
         'OC\\Calendar\\Room\\Manager' => __DIR__ . '/../../..' . '/lib/private/Calendar/Room/Manager.php',
diff --git a/lib/private/AppFramework/Bootstrap/RegistrationContext.php b/lib/private/AppFramework/Bootstrap/RegistrationContext.php
index 30ac63281d1..8eed6a5bde4 100644
--- a/lib/private/AppFramework/Bootstrap/RegistrationContext.php
+++ b/lib/private/AppFramework/Bootstrap/RegistrationContext.php
@@ -35,6 +35,7 @@ use OCP\AppFramework\Bootstrap\IRegistrationContext;
 use OCP\AppFramework\Middleware;
 use OCP\AppFramework\Services\InitialStateProvider;
 use OCP\Authentication\IAlternativeLogin;
+use OCP\Calendar\ICalendarProvider;
 use OCP\Capabilities\ICapability;
 use OCP\Dashboard\IManager;
 use OCP\Dashboard\IWidget;
@@ -95,6 +96,9 @@ class RegistrationContext {
 	/** @var ServiceRegistration<\OCP\Authentication\TwoFactorAuth\IProvider>[] */
 	private $twoFactorProviders = [];
 
+	/** @var ServiceRegistration<ICalendarProvider>[] */
+	private $calendarProviders = [];
+
 	/** @var LoggerInterface */
 	private $logger;
 
@@ -225,6 +229,13 @@ class RegistrationContext {
 					$twoFactorProviderClass
 				);
 			}
+
+			public function registerCalendarProvider(string $class): void {
+				$this->context->registerCalendarProvider(
+					$this->appId,
+					$class
+				);
+			}
 		};
 	}
 
@@ -300,6 +311,10 @@ class RegistrationContext {
 		$this->twoFactorProviders[] = new ServiceRegistration($appId, $class);
 	}
 
+	public function registerCalendarProvider(string $appId, string $class): void {
+		$this->calendarProviders[] = new ServiceRegistration($appId, $class);
+	}
+
 	/**
 	 * @param App[] $apps
 	 */
@@ -530,4 +545,11 @@ class RegistrationContext {
 	public function getTwoFactorProviders(): array {
 		return $this->twoFactorProviders;
 	}
+
+	/**
+	 * @return ServiceRegistration<ICalendarProvider>[]
+	 */
+	public function getCalendarProviders(): array {
+		return $this->calendarProviders;
+	}
 }
diff --git a/lib/private/Calendar/CalendarQuery.php b/lib/private/Calendar/CalendarQuery.php
new file mode 100644
index 00000000000..6b4e2b3be16
--- /dev/null
+++ b/lib/private/Calendar/CalendarQuery.php
@@ -0,0 +1,124 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright 2021 Anna Larch <anna.larch@gmx.net>
+ *
+ * @author 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 OC\Calendar;
+
+use OCP\Calendar\ICalendarQuery;
+
+class CalendarQuery implements ICalendarQuery {
+
+	/** @var string */
+	private $principalUri;
+
+	/** @var array */
+	public $searchProperties;
+
+	/** @var string|null */
+	private $searchPattern;
+
+	/** @var array */
+	private $options;
+
+	/** @var int|null */
+	private $offset;
+
+	/** @var int|null */
+	private $limit;
+
+	/** @var array */
+	private $calendarUris;
+
+	public function __construct(string $principalUri) {
+		$this->principalUri = $principalUri;
+		$this->searchProperties = [];
+		$this->options = [
+			'types' => [],
+		];
+	}
+
+	public function getPrincipalUri(): string {
+		return $this->principalUri;
+	}
+
+	public function setPrincipalUri(string $principalUri): void {
+		$this->principalUri = $principalUri;
+	}
+
+	public function setSearchPattern(string $pattern): void {
+		$this->searchPattern = $pattern;
+	}
+
+	public function getSearchPattern(): ?string {
+		return $this->searchPattern;
+	}
+
+	public function addSearchProperty(string $value): void {
+		$this->searchProperties[] = $value;
+	}
+
+	public function getSearchProperties(): array {
+		return $this->searchProperties;
+	}
+
+	public function addSearchCalendar(string $calendarUri): void {
+		$this->calendarUris[] = $calendarUri;
+	}
+
+	public function getCalendarUris(): array {
+		return $this->calendarUris;
+	}
+
+	public function getLimit(): ?int {
+		return $this->limit;
+	}
+
+	public function setLimit(int $limit): void {
+		$this->limit = $limit;
+	}
+
+	public function getOffset(): ?int {
+		return $this->offset;
+	}
+
+	public function setOffset(int $offset): void {
+		$this->offset = $offset;
+	}
+
+	public function addType(string $value): void {
+		$this->options['types'][] = $value;
+	}
+
+	public function setTimerangeStart(\DateTimeImmutable $startTime): void {
+		$this->options['timerange']['start'] = $startTime;
+	}
+
+	public function setTimerangeEnd(\DateTimeImmutable $endTime): void {
+		$this->options['timerange']['end'] = $endTime;
+	}
+
+	public function getOptions(): array {
+		return $this->options;
+	}
+}
diff --git a/lib/private/Calendar/Manager.php b/lib/private/Calendar/Manager.php
index ab22c3ba7b8..30ee60e4943 100644
--- a/lib/private/Calendar/Manager.php
+++ b/lib/private/Calendar/Manager.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 /**
  * @copyright 2017, Georg Ehrke <oc.list@georgehrke.com>
  *
@@ -23,9 +26,13 @@
  */
 namespace OC\Calendar;
 
+use OC\AppFramework\Bootstrap\Coordinator;
 use OCP\Calendar\ICalendar;
+use OCP\Calendar\ICalendarProvider;
+use OCP\Calendar\ICalendarQuery;
+use OCP\Calendar\IManager;
 
-class Manager implements \OCP\Calendar\IManager {
+class Manager implements IManager {
 
 	/**
 	 * @var ICalendar[] holds all registered calendars
@@ -37,6 +44,13 @@ class Manager implements \OCP\Calendar\IManager {
 	 */
 	private $calendarLoaders = [];
 
+	/** @var Coordinator */
+	private $coordinator;
+
+	public function __construct(Coordinator $coordinator) {
+		$this->coordinator = $coordinator;
+	}
+
 	/**
 	 * This function is used to search and find objects within the user's calendars.
 	 * In case $pattern is empty all events/journals/todos will be returned.
@@ -137,4 +151,38 @@ class Manager implements \OCP\Calendar\IManager {
 		}
 		$this->calendarLoaders = [];
 	}
+
+	public function searchForPrincipal(ICalendarQuery $query): array {
+		$context = $this->coordinator->getRegistrationContext();
+		if ($context === null) {
+			return [];
+		}
+
+		/** @var CalendarQuery $query */
+		$calendars = array_merge(...array_map(static function (ICalendarProvider $p) use ($query) {
+			return $p->getCalendars($query->getPrincipalUri(), $query->getCalendarUris());
+		}, $context->getCalendarProviders()));
+
+		$results = [];
+		/** @var ICalendar $calendar */
+		foreach ($calendars as $calendar) {
+			$r = $calendar->search(
+				$query->getSearchPattern() ?? '',
+				$query->getSearchProperties(),
+				$query->getOptions(),
+				$query->getLimit(),
+				$query->getOffset()
+			);
+
+			foreach ($r as $o) {
+				$o['calendar-key'] = $calendar->getKey();
+				$results[] = $o;
+			}
+		}
+		return $results;
+	}
+
+	public function newQuery(string $principalUri): ICalendarQuery {
+		return new CalendarQuery($principalUri);
+	}
 }
diff --git a/lib/public/AppFramework/Bootstrap/IRegistrationContext.php b/lib/public/AppFramework/Bootstrap/IRegistrationContext.php
index 589140d3edd..d396c619923 100644
--- a/lib/public/AppFramework/Bootstrap/IRegistrationContext.php
+++ b/lib/public/AppFramework/Bootstrap/IRegistrationContext.php
@@ -228,4 +228,13 @@ interface IRegistrationContext {
 	 * @since 22.0.0
 	 */
 	public function registerTwoFactorProvider(string $twoFactorProviderClass): void;
+
+	/**
+	 * Register a calendar provider
+	 *
+	 * @param string $class
+	 * @psalm-param class-string<IProvider> $class
+	 * @since 23.0.0
+	 */
+	public function registerCalendarProvider(string $class): void;
 }
diff --git a/lib/public/Calendar/ICalendar.php b/lib/public/Calendar/ICalendar.php
index ebaa7c50f84..551870de20e 100644
--- a/lib/public/Calendar/ICalendar.php
+++ b/lib/public/Calendar/ICalendar.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 /**
  * @copyright 2017, Georg Ehrke <oc.list@georgehrke.com>
  *
diff --git a/lib/public/Calendar/ICalendarProvider.php b/lib/public/Calendar/ICalendarProvider.php
new file mode 100644
index 00000000000..d135910b08c
--- /dev/null
+++ b/lib/public/Calendar/ICalendarProvider.php
@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright 2021 Anna Larch <anna.larch@gmx.net>
+ *
+ * @author 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 OCP\Calendar;
+
+/**
+ * This interface defines a lazy loading mechanism for
+ * calendars for Public Consumption
+ *
+ * @since 23.0.0
+ */
+interface ICalendarProvider {
+
+	/**
+	 * @param string $principalUri
+	 * @param string[] $calendarUris
+	 * @return ICalendar[]
+	 * @since 23.0.0
+	 */
+	public function getCalendars(string $principalUri, array $calendarUris = []): array;
+}
diff --git a/lib/public/Calendar/ICalendarQuery.php b/lib/public/Calendar/ICalendarQuery.php
new file mode 100644
index 00000000000..142810d3fb9
--- /dev/null
+++ b/lib/public/Calendar/ICalendarQuery.php
@@ -0,0 +1,82 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright 2021 Anna Larch <anna.larch@gmx.net>
+ *
+ * @author 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 OCP\Calendar;
+
+use DateTimeImmutable;
+
+/**
+ * Build a flexible, extendable query to the CalDAV backend
+ *
+ * @since 23.0.0
+ */
+interface ICalendarQuery {
+
+	/**
+	 * Limit the results to the calendar uri(s)
+	 *
+	 * @since 23.0.0
+	 */
+	public function addSearchCalendar(string $calendarUri): void;
+
+	/**
+	 * Search the property values
+	 *
+	 * @since 23.0.0
+	 */
+	public function setSearchPattern(string $pattern): void;
+
+	/**
+	 * Define the property name(s) to search for
+	 *
+	 * @since 23.0.0
+	 */
+	public function addSearchProperty(string $value): void;
+
+	/**
+	 * @since 23.0.0
+	 */
+	public function addType(string $value): void;
+
+	/**
+	 * @since 23.0.0
+	 */
+	public function setTimerangeStart(DateTimeImmutable $startTime): void;
+
+	/**
+	 * @since 23.0.0
+	 */
+	public function setTimerangeEnd(DateTimeImmutable $endTime): void;
+
+	/**
+	 * @since 23.0.0
+	 */
+	public function setLimit(int $limit): void;
+
+	/**
+	 * @since 23.0.0
+	 */
+	public function setOffset(int $offset): void;
+}
diff --git a/lib/public/Calendar/IManager.php b/lib/public/Calendar/IManager.php
index df4c993b2b5..eb4113bba99 100644
--- a/lib/public/Calendar/IManager.php
+++ b/lib/public/Calendar/IManager.php
@@ -1,9 +1,13 @@
 <?php
+
+declare(strict_types=1);
+
 /**
  * @copyright 2017, Georg Ehrke <oc.list@georgehrke.com>
  *
  * @author Christoph Wurst <christoph@winzerhof-wurst.at>
  * @author Georg Ehrke <oc.list@georgehrke.com>
+ * @author Anna Larch <anna.larch@gmx.net>
  *
  * @license GNU AGPL version 3 or any later version
  *
@@ -67,6 +71,7 @@ interface IManager {
 	 * @param integer|null $offset - offset for paging of search results
 	 * @return array an array of events/journals/todos which are arrays of arrays of key-value-pairs
 	 * @since 13.0.0
+	 * @deprecated 23.0.0 use \OCP\Calendar\IManager::searchForPrincipal
 	 */
 	public function search($pattern, array $searchProperties = [], array $options = [], $limit = null, $offset = null);
 
@@ -75,6 +80,7 @@ interface IManager {
 	 *
 	 * @return bool true if enabled, false if not
 	 * @since 13.0.0
+	 * @deprecated 23.0.0
 	 */
 	public function isEnabled();
 
@@ -84,6 +90,7 @@ interface IManager {
 	 * @param ICalendar $calendar
 	 * @return void
 	 * @since 13.0.0
+	 * @deprecated 23.0.0 use \OCP\AppFramework\Bootstrap\IRegistrationContext::registerCalendarProvider
 	 */
 	public function registerCalendar(ICalendar $calendar);
 
@@ -93,6 +100,7 @@ interface IManager {
 	 * @param ICalendar $calendar
 	 * @return void
 	 * @since 13.0.0
+	 * @deprecated 23.0.0
 	 */
 	public function unregisterCalendar(ICalendar $calendar);
 
@@ -103,19 +111,40 @@ interface IManager {
 	 * @param \Closure $callable
 	 * @return void
 	 * @since 13.0.0
+	 * @deprecated 23.0.0 use \OCP\AppFramework\Bootstrap\IRegistrationContext::registerCalendarProvider
 	 */
 	public function register(\Closure $callable);
 
 	/**
 	 * @return ICalendar[]
 	 * @since 13.0.0
+	 * @deprecated 23.0.0
 	 */
 	public function getCalendars();
 
 	/**
 	 * removes all registered calendar instances
+	 *
 	 * @return void
 	 * @since 13.0.0
+	 * @deprecated 23.0.0
 	 */
 	public function clear();
+
+	/**
+	 * Query a principals calendar(s)
+	 *
+	 * @param ICalendarQuery $query
+	 * @return array[]
+	 * @since 23.0.0
+	 */
+	public function searchForPrincipal(ICalendarQuery $query): array;
+
+	/**
+	 * Build a new query for searchForPrincipal
+	 *
+	 * @return ICalendarQuery
+	 * @since 23.0.0
+	 */
+	public function newQuery(string $principalUri) : ICalendarQuery;
 }
diff --git a/tests/lib/Calendar/ManagerTest.php b/tests/lib/Calendar/ManagerTest.php
index e686e82adf0..70f7dbe2437 100644
--- a/tests/lib/Calendar/ManagerTest.php
+++ b/tests/lib/Calendar/ManagerTest.php
@@ -23,26 +23,35 @@
 
 namespace Test\Calendar;
 
+use OC\AppFramework\Bootstrap\Coordinator;
 use OC\Calendar\Manager;
 use OCP\Calendar\ICalendar;
+use PHPUnit\Framework\MockObject\MockObject;
 use Test\TestCase;
 
 class ManagerTest extends TestCase {
 
+	/** @var Coordinator|MockObject */
+	private $coordinator;
+
 	/** @var Manager */
 	private $manager;
 
 	protected function setUp(): void {
 		parent::setUp();
 
-		$this->manager = new Manager();
+		$this->coordinator = $this->createMock(Coordinator::class);
+
+		$this->manager = new Manager(
+			$this->coordinator
+		);
 	}
 
 	/**
 	 * @dataProvider searchProvider
 	 */
 	public function testSearch($search1, $search2, $expected) {
-		/** @var ICalendar | \PHPUnit\Framework\MockObject\MockObject $calendar1 */
+		/** @var ICalendar | MockObject $calendar1 */
 		$calendar1 = $this->createMock(ICalendar::class);
 		$calendar1->method('getKey')->willReturn('simple:1');
 		$calendar1->expects($this->once())
@@ -50,7 +59,7 @@ class ManagerTest extends TestCase {
 			->with('', [], [], null, null)
 			->willReturn($search1);
 
-		/** @var ICalendar | \PHPUnit\Framework\MockObject\MockObject $calendar2 */
+		/** @var ICalendar | MockObject $calendar2 */
 		$calendar2 = $this->createMock(ICalendar::class);
 		$calendar2->method('getKey')->willReturn('simple:2');
 		$calendar2->expects($this->once())
@@ -69,7 +78,7 @@ class ManagerTest extends TestCase {
 	 * @dataProvider searchProvider
 	 */
 	public function testSearchOptions($search1, $search2, $expected) {
-		/** @var ICalendar | \PHPUnit\Framework\MockObject\MockObject $calendar1 */
+		/** @var ICalendar | MockObject $calendar1 */
 		$calendar1 = $this->createMock(ICalendar::class);
 		$calendar1->method('getKey')->willReturn('simple:1');
 		$calendar1->expects($this->once())
@@ -78,7 +87,7 @@ class ManagerTest extends TestCase {
 				['timerange' => ['start' => null, 'end' => null]], 5, 20)
 			->willReturn($search1);
 
-		/** @var ICalendar | \PHPUnit\Framework\MockObject\MockObject $calendar2 */
+		/** @var ICalendar | MockObject $calendar2 */
 		$calendar2 = $this->createMock(ICalendar::class);
 		$calendar2->method('getKey')->willReturn('simple:2');
 		$calendar2->expects($this->once())
@@ -150,11 +159,11 @@ class ManagerTest extends TestCase {
 	}
 
 	public function testRegisterUnregister() {
-		/** @var ICalendar | \PHPUnit\Framework\MockObject\MockObject $calendar1 */
+		/** @var ICalendar | MockObject $calendar1 */
 		$calendar1 = $this->createMock(ICalendar::class);
 		$calendar1->method('getKey')->willReturn('key1');
 
-		/** @var ICalendar | \PHPUnit\Framework\MockObject\MockObject $calendar2 */
+		/** @var ICalendar | MockObject $calendar2 */
 		$calendar2 = $this->createMock(ICalendar::class);
 		$calendar2->method('getKey')->willReturn('key2');
 
@@ -174,11 +183,11 @@ class ManagerTest extends TestCase {
 	}
 
 	public function testGetCalendars() {
-		/** @var ICalendar | \PHPUnit\Framework\MockObject\MockObject $calendar1 */
+		/** @var ICalendar | MockObject $calendar1 */
 		$calendar1 = $this->createMock(ICalendar::class);
 		$calendar1->method('getKey')->willReturn('key1');
 
-		/** @var ICalendar | \PHPUnit\Framework\MockObject\MockObject $calendar2 */
+		/** @var ICalendar | MockObject $calendar2 */
 		$calendar2 = $this->createMock(ICalendar::class);
 		$calendar2->method('getKey')->willReturn('key2');
 
@@ -203,7 +212,7 @@ class ManagerTest extends TestCase {
 	}
 
 	public function testIfEnabledIfSo() {
-		/** @var ICalendar | \PHPUnit\Framework\MockObject\MockObject $calendar */
+		/** @var ICalendar | MockObject $calendar */
 		$calendar = $this->createMock(ICalendar::class);
 		$this->manager->registerCalendar($calendar);