diff --git a/lib/DAV/Calendar.php b/lib/DAV/Calendar.php
index 8563c3679..6c97e8446 100644
--- a/lib/DAV/Calendar.php
+++ b/lib/DAV/Calendar.php
@@ -24,72 +24,44 @@ namespace OCA\Deck\DAV;
 
 use OCA\DAV\CalDAV\Integration\ExternalCalendar;
 use OCA\DAV\CalDAV\Plugin;
-use OCA\DAV\DAV\Sharing\IShareable;
+use OCA\Deck\Db\Acl;
 use OCA\Deck\Db\Board;
-use OCA\Deck\Db\Card;
-use OCA\Deck\Db\Stack;
-use OCA\Deck\Service\CardService;
-use OCA\Deck\Service\StackService;
 use Sabre\CalDAV\Xml\Property\SupportedCalendarComponentSet;
+use Sabre\DAV\Exception\Forbidden;
 use Sabre\DAV\PropPatch;
 
-class Calendar extends ExternalCalendar implements IShareable {
+class Calendar extends ExternalCalendar {
 
 	/** @var string */
 	private $principalUri;
-
-	/** @var string */
-	private $calendarUri;
-
 	/** @var string[] */
 	private $children;
-	/**
-	 * @var \stdClass
-	 */
-	private $cardService;
+	/** @var DeckCalendarBackend */
+	private $backend;
+	/**  @var Board */
+	private $board;
 
-	/**
-	 * Calendar constructor.
-	 *
-	 * @param string $principalUri
-	 * @param string $calendarUri
-	 */
-	public function __construct(string $principalUri, string $calendarUri, Board $board = null) {
+	public function __construct(string $principalUri, string $calendarUri, Board $board, DeckCalendarBackend $backend) {
 		parent::__construct('deck', $calendarUri);
 
+		$this->backend = $backend;
 		$this->board = $board;
 
 		$this->principalUri = $principalUri;
-		$this->calendarUri = $calendarUri;
-
 
 		if ($board) {
-			/** @var CardService $cardService */
-			$cardService = \OC::$server->query(CardService::class);
-			/** @var StackService $stackService */
-			$stackService = \OC::$server->query(StackService::class);
-			$this->children = array_merge(
-				$cardService->findCalendarEntries($board->getId()),
-				$stackService->findCalendarEntries($board->getId())
-			);
+			$this->children = $this->backend->getChildren($board->getId());
 		} else {
 			$this->children = [];
 		}
 	}
 
-
-	/**
-	 * @inheritDoc
-	 */
-	function getOwner() {
+	public function getOwner() {
 		return $this->principalUri;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getACL() {
-		return [
+	public function getACL() {
+		$acl = [
 			[
 				'privilege' => '{DAV:}read',
 				'principal' => $this->getOwner(),
@@ -106,43 +78,41 @@ class Calendar extends ExternalCalendar implements IShareable {
 				'protected' => true,
 			],
 		];
+		if ($this->backend->checkBoardPermission($this->board->getId(), Acl::PERMISSION_EDIT)) {
+			$acl[] = [
+				'privilege' => '{DAV:}write',
+				'principal' => $this->getOwner(),
+				'protected' => true,
+			];
+			$acl[] = [
+				'privilege' => '{DAV:}write-properties',
+				'principal' => $this->getOwner(),
+				'protected' => true,
+			];
+		}
+		return $acl;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function setACL(array $acl) {
-		throw new \Sabre\DAV\Exception\Forbidden('Setting ACL is not supported on this node');
+	public function setACL(array $acl) {
+		throw new Forbidden('Setting ACL is not supported on this node');
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getSupportedPrivilegeSet() {
+	public function getSupportedPrivilegeSet() {
 		return null;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function calendarQuery(array $filters) {
-		// In a real implementation this should actually filter
+	public function calendarQuery(array $filters) {
+		// FIXME: In a real implementation this should actually filter
 		return array_map(function ($card) {
 			return $card->getCalendarPrefix() . '-' . $card->getId() . '.ics';
 		}, $this->children);
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function createFile($name, $data = null) {
-		return null;
+	public function createFile($name, $data = null) {
+		throw new \Sabre\DAV\Exception\Forbidden('Creating a new entry is not implemented');
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getChild($name) {
+	public function getChild($name) {
 		if ($this->childExists($name)) {
 			$card = array_values(array_filter(
 				$this->children,
@@ -151,15 +121,12 @@ class Calendar extends ExternalCalendar implements IShareable {
 				}
 			));
 			if (count($card) > 0) {
-				return new CalendarObject($this, $name, $card[0]);
+				return new CalendarObject($this, $name, $card[0], $this->backend);
 			}
 		}
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getChildren() {
+	public function getChildren() {
 		$childNames = array_map(function ($card) {
 			return $card->getCalendarPrefix() . '-' . $card->getId() . '.ics';
 		}, $this->children);
@@ -173,10 +140,7 @@ class Calendar extends ExternalCalendar implements IShareable {
 		return $children;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function childExists($name) {
+	public function childExists($name) {
 		return count(array_filter(
 			$this->children,
 			function ($card) use (&$name) {
@@ -185,64 +149,51 @@ class Calendar extends ExternalCalendar implements IShareable {
 		)) > 0;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function delete() {
+
+	public function delete() {
 		return null;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getLastModified() {
+	public function getLastModified() {
 		return $this->board->getLastModified();
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getGroup() {
+	public function getGroup() {
 		return [];
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function propPatch(PropPatch $propPatch) {
+	public function propPatch(PropPatch $propPatch) {
+		$properties = [
+			'{DAV:}displayname',
+			'{http://apple.com/ns/ical/}calendar-color'
+		];
+		$propPatch->handle($properties, function ($properties) {
+			foreach ($properties as $key => $value) {
+				switch ($key) {
+					case '{DAV:}displayname':
+						if (mb_substr($value, 0, strlen('Deck: '))) {
+							$value = mb_substr($value, strlen('Deck: '));
+						}
+						$this->board->setTitle($value);
+						break;
+					case '{http://apple.com/ns/ical/}calendar-color':
+						$this->board->setColor(substr($value, 1));
+						break;
+				}
+			}
+			return $this->backend->updateBoard($this->board);
+		});
 		// We can just return here and let oc_properties handle everything
 	}
 
 	/**
 	 * @inheritDoc
 	 */
-	function getProperties($properties) {
-		// A backend should provide at least minimum properties
+	public function getProperties($properties) {
 		return [
 			'{DAV:}displayname' => 'Deck: ' . ($this->board ? $this->board->getTitle() : 'no board object provided'),
 			'{http://apple.com/ns/ical/}calendar-color'  => '#' . $this->board->getColor(),
-			'{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet(['VTODO', 'VEVENT']),
+			'{' . Plugin::NS_CALDAV . '}supported-calendar-component-set' => new SupportedCalendarComponentSet(['VTODO']),
 		];
 	}
-
-	/**
-	 * @inheritDoc
-	 */
-	function updateShares(array $add, array $remove) {
-		// TODO: Implement updateShares() method.
-	}
-
-	/**
-	 * @inheritDoc
-	 */
-	function getShares() {
-		return [];
-	}
-
-	/**
-	 * @inheritDoc
-	 */
-	public function getResourceId() {
-		// TODO: Implement getResourceId() method.
-	}
 }
diff --git a/lib/DAV/CalendarObject.php b/lib/DAV/CalendarObject.php
index 82633dd30..2a4d3e041 100644
--- a/lib/DAV/CalendarObject.php
+++ b/lib/DAV/CalendarObject.php
@@ -23,130 +23,88 @@
 namespace OCA\Deck\DAV;
 
 use OCA\Deck\Db\Card;
-use OCA\Deck\Service\CardService;
+use OCA\Deck\Db\Stack;
+use Sabre\CalDAV\ICalendarObject;
+use Sabre\DAV\Exception\Forbidden;
+use Sabre\DAVACL\IACL;
 use Sabre\VObject\Component\VCalendar;
 
-class CalendarObject implements \Sabre\CalDAV\ICalendarObject, \Sabre\DAVACL\IACL {
+class CalendarObject implements ICalendarObject, IACL {
 
 	/** @var Calendar */
 	private $calendar;
-
 	/** @var string */
 	private $name;
-	/**
-	 * @var Card
-	 */
+	/** @var Card|Stack */
 	private $sourceItem;
+	/** @var DeckCalendarBackend */
+	private $backend;
+	/** @var VCalendar */
+	private $calendarObject;
 
-	/**
-	 * CalendarObject constructor.
-	 *
-	 * @param Calendar $calendar
-	 * @param string $name
-	 */
-	public function __construct(Calendar $calendar, string $name, $sourceItem = null) {
+	public function __construct(Calendar $calendar, string $name, $sourceItem = null, DeckCalendarBackend $backend) {
 		$this->calendar = $calendar;
 		$this->name = $name;
 		$this->sourceItem = $sourceItem;
+		$this->backend = $backend;
+		$this->calendarObject = $this->sourceItem->getCalendarObject();
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getOwner() {
+	public function getOwner() {
 		return null;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getGroup() {
+	public function getGroup() {
 		return null;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getACL() {
+	public function getACL() {
 		return $this->calendar->getACL();
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function setACL(array $acl) {
-		throw new \Sabre\DAV\Exception\Forbidden('Setting ACL is not supported on this node');
+	public function setACL(array $acl) {
+		throw new Forbidden('Setting ACL is not supported on this node');
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getSupportedPrivilegeSet() {
+	public function getSupportedPrivilegeSet() {
 		return null;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function put($data) {
-		throw new \Sabre\DAV\Exception\Forbidden('This calendar-object is read-only');
+	public function put($data) {
+		throw new Forbidden('This calendar-object is read-only');
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function get() {
+	public function get() {
 		if ($this->sourceItem) {
-			return $this->sourceItem->getCalendarObject()->serialize();
+			return $this->calendarObject->serialize();
 		}
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getContentType() {
+	public function getContentType() {
 		return 'text/calendar; charset=utf-8';
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getETag() {
-		return '"' . md5($this->get()) . '"';
+	public function getETag() {
+		return '"' . md5($this->sourceItem->getLastModified()) . '"';
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getSize() {
-		return strlen($this->get());
+	public function getSize() {
+		return mb_strlen($this->calendarObject->serialize());
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function delete() {
-		throw new \Sabre\DAV\Exception\Forbidden('This calendar-object is read-only');
+	public function delete() {
+		throw new Forbidden('This calendar-object is read-only');
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getName() {
+	public function getName() {
 		return $this->name;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function setName($name) {
-		throw new \Sabre\DAV\Exception\Forbidden('This calendar-object is read-only');
+	public function setName($name) {
+		throw new Forbidden('This calendar-object is read-only');
 	}
 
-	/**
-	 * @inheritDoc
-	 */
-	function getLastModified() {
+	public function getLastModified() {
 		return $this->sourceItem->getLastModified();
 	}
 }
diff --git a/lib/DAV/CalendarPlugin.php b/lib/DAV/CalendarPlugin.php
index ba5226827..e0f614995 100644
--- a/lib/DAV/CalendarPlugin.php
+++ b/lib/DAV/CalendarPlugin.php
@@ -26,53 +26,37 @@ namespace OCA\Deck\DAV;
 use OCA\DAV\CalDAV\Integration\ExternalCalendar;
 use OCA\DAV\CalDAV\Integration\ICalendarProvider;
 use OCA\Deck\Db\Board;
-use OCA\Deck\Service\BoardService;
 
 class CalendarPlugin implements ICalendarProvider {
 
-	/**
-	 * @var BoardService
-	 */
-	private $boardService;
+	/** @var DeckCalendarBackend */
+	private $backend;
 
-	public function __construct(BoardService $boardService) {
-		$this->boardService = $boardService;
+	public function __construct(DeckCalendarBackend $backend) {
+		$this->backend = $backend;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
 	public function getAppId(): string {
 		return 'deck';
 	}
 
-	/**
-	 * @inheritDoc
-	 */
 	public function fetchAllForCalendarHome(string $principalUri): array {
-		$boards = $this->boardService->findAll();
 		return array_map(function (Board $board) use ($principalUri) {
-			return new Calendar($principalUri, 'board-' . $board->getId(), $board);
-		}, $boards);
+			return new Calendar($principalUri, 'board-' . $board->getId(), $board, $this->backend);
+		}, $this->backend->getBoards());
 	}
 
-	/**
-	 * @inheritDoc
-	 */
 	public function hasCalendarInCalendarHome(string $principalUri, string $calendarUri): bool {
-		$boards = array_map(function(Board $board) {
+		$boards = array_map(static function (Board $board) {
 			return 'board-' . $board->getId();
-		}, $this->boardService->findAll());
+		}, $this->backend->getBoards());
 		return in_array($calendarUri, $boards, true);
 	}
 
-	/**
-	 * @inheritDoc
-	 */
 	public function getCalendarInCalendarHome(string $principalUri, string $calendarUri): ?ExternalCalendar {
 		if ($this->hasCalendarInCalendarHome($principalUri, $calendarUri)) {
-			$board = $this->boardService->find(str_replace('board-', '', $calendarUri));
-			return new Calendar($principalUri, $calendarUri, $board);
+			$board = $this->backend->getBoard((int)str_replace('board-', '', $calendarUri));
+			return new Calendar($principalUri, $calendarUri, $board, $this->backend);
 		}
 
 		return null;
diff --git a/lib/DAV/DeckCalendarBackend.php b/lib/DAV/DeckCalendarBackend.php
new file mode 100644
index 000000000..2e001cc08
--- /dev/null
+++ b/lib/DAV/DeckCalendarBackend.php
@@ -0,0 +1,84 @@
+<?php
+/**
+ * @copyright Copyright (c) 2020 Julius Härtl <jus@bitgrid.net>
+ *
+ * @author Julius Härtl <jus@bitgrid.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/>.
+ *
+ */
+
+declare(strict_types=1);
+
+
+namespace OCA\Deck\DAV;
+
+use OCA\Deck\Db\Board;
+use OCA\Deck\Db\BoardMapper;
+use OCA\Deck\Service\BoardService;
+use OCA\Deck\Service\CardService;
+use OCA\Deck\Service\PermissionService;
+use OCA\Deck\Service\StackService;
+
+class DeckCalendarBackend {
+
+	/** @var BoardService */
+	private $boardService;
+	/** @var StackService */
+	private $stackService;
+	/** @var CardService */
+	private $cardService;
+	/** @var PermissionService */
+	private $permissionService;
+	/** @var BoardMapper */
+	private $boardMapper;
+
+	public function __construct(
+		BoardService $boardService, StackService $stackService, CardService $cardService, PermissionService $permissionService,
+		BoardMapper $boardMapper
+	) {
+		$this->boardService = $boardService;
+		$this->stackService = $stackService;
+		$this->cardService = $cardService;
+		$this->permissionService = $permissionService;
+		$this->boardMapper = $boardMapper;
+	}
+
+	public function getBoards(): array {
+		return $this->boardService->findAll();
+	}
+
+	public function getBoard(int $id): Board {
+		return $this->boardService->find($id);
+	}
+
+	public function checkBoardPermission(int $id, int $permission): bool {
+		$permissions = $this->permissionService->getPermissions($id);
+		return isset($permissions[$permission]) ? $permissions[$permission] : false;
+	}
+
+	public function updateBoard(Board $board): bool {
+		$this->boardMapper->update($board);
+		return true;
+	}
+
+	public function getChildren(int $id): array {
+		return array_merge(
+			$this->cardService->findCalendarEntries($id),
+			$this->stackService->findCalendarEntries($id)
+		);
+	}
+}
diff --git a/lib/Db/Card.php b/lib/Db/Card.php
index 0b157fd56..1bb927d41 100644
--- a/lib/Db/Card.php
+++ b/lib/Db/Card.php
@@ -159,5 +159,4 @@ class Card extends RelationalEntity {
 	public function getCalendarPrefix(): string {
 		return 'card';
 	}
-
 }
diff --git a/lib/Db/Stack.php b/lib/Db/Stack.php
index 7dc9310ba..1cc679240 100644
--- a/lib/Db/Stack.php
+++ b/lib/Db/Stack.php
@@ -65,5 +65,4 @@ class Stack extends RelationalEntity {
 	public function getCalendarPrefix(): string {
 		return 'stack';
 	}
-
 }