diff --git a/appinfo/application.php b/appinfo/application.php
index 4572e58d..e3dc7ee1 100644
--- a/appinfo/application.php
+++ b/appinfo/application.php
@@ -28,6 +28,7 @@ use \OCA\Tasks\Controller\CollectionsController;
 use \OCA\Tasks\Controller\ListsController;
 use \OCA\Tasks\Controller\SettingsController;
 use \OCA\Tasks\Controller\TasksController;
+use \OCA\Tasks\Service\TasksService;
 
 class Application extends App {
 
@@ -79,6 +80,17 @@ class Application extends App {
 			return new TasksController(
 				$c->query('AppName'), 
 				$c->query('Request'),
+				$c->query('TasksService'),
+				$c->query('UserId')
+			);
+		});
+
+
+		/**
+		 * Services
+		 */
+		$container->registerService('TasksService', function($c) {
+			return new TasksService(
 				$c->query('UserId')
 			);
 		});
@@ -104,4 +116,4 @@ class Application extends App {
 	}
 
 
-}
\ No newline at end of file
+}
diff --git a/controller/taskscontroller.php b/controller/taskscontroller.php
index 5b333b1e..20745e26 100644
--- a/controller/taskscontroller.php
+++ b/controller/taskscontroller.php
@@ -32,214 +32,69 @@ use \OCA\Tasks\Controller\Helper;
 class TasksController extends Controller {
 
 	private $userId;
+	private $tasksService;
 
-	public function __construct($appName, IRequest $request, $userId){
+	public function __construct($appName, IRequest $request, TasksService $tasksService, $userId){
 		parent::__construct($appName, $request);
-		$this->userId = $userId;
+		$this->tasksService = $tasksService;
+		$this->userId = $userId;		
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
 	public function getTasks($listID = 'all', $type = 'all'){
-		
-		$user_timezone = \OC_Calendar_App::getTimezone();
-		if ($listID == 'all'){
-			$calendars = \OC_Calendar_Calendar::allCalendars($this->userId, true);
-		} else {
-			$calendar = \OC_Calendar_App::getCalendar($listID, true, false);
-			$calendars = array($calendar);
-		}
-
-		$tasks = array();
-		$lists = array();
-		foreach( $calendars as $calendar ) {
-			$calendar_entries = \OC_Calendar_Object::all($calendar['id']);
-			$tasks_selected = array();
-			foreach( $calendar_entries as $task ) {
-				if($task['objecttype']!='VTODO') {
-					continue;
-				}
-				if(is_null($task['summary'])) {
-					continue;
-				}
-				$vtodo = Helper::parseVTODO($task['calendardata']);
-				try {
-					$task_data = Helper::arrayForJSON($task['id'], $vtodo, $user_timezone, $calendar['id']);
-					switch($type){
-						case 'all':
-							$tasks[] = $task_data;
-							break;
-						case 'init':
-							if (!$task_data['completed']){
-								$tasks[] = $task_data;
-							} else {
-								$tasks_selected[] = $task_data;
-							}
-							break;
-						case 'completed':
-							if ($task_data['completed']){
-								$tasks[] = $task_data;
-							}
-							break;
-						case 'uncompleted':
-							if (!$task_data['completed']){
-								$tasks[] = $task_data;
-							}
-							break;
-					}
-				} catch(\Exception $e) {
-					\OCP\Util::writeLog('tasks', $e->getMessage(), \OCP\Util::ERROR);
-				}
-			}
-			$nrCompleted = 0;
-			$notLoaded = 0;
-			usort($tasks_selected, array($this, 'sort_completed'));
-			foreach( $tasks_selected as $task_selected){
-				$nrCompleted++;
-				if ($nrCompleted > 5){
-					$notLoaded++;
-					continue;
-				}
-				$tasks[] = $task_selected;
-			}
-			$lists[] = array(
-				'id' 		=> $calendar['id'],
-				'notLoaded' => $notLoaded
-				);
-		}
-		$result = array(
-			'data' => array(
-				'tasks' => $tasks,
-				'lists' => $lists
-				)
-			);
-		$response = new JSONResponse();
-		$response->setData($result);
-		return $response;
+		$result = $this->tasksService->getAll($listID, $type);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
 	public function getTask($taskID){
-		$object = \OC_Calendar_App::getEventObject($taskID);
-		$user_timezone = \OC_Calendar_App::getTimezone();
-		$task = array();
-		if($object['objecttype']=='VTODO' && !is_null($object['summary'])) {
-			$vtodo = Helper::parseVTODO($object['calendardata']);
-			try {
-				$task_data = Helper::arrayForJSON($object['id'], $vtodo, $user_timezone, $object['calendarid']);
-				$task[] = $task_data;
-			} catch(\Exception $e) {
-				\OCP\Util::writeLog('tasks', $e->getMessage(), \OCP\Util::ERROR);
-			}	
-		}
-		$result = array(
+		$result = $this->tasksService->get($taskID);
+		$response = array(
 			'data' => array(
-				'tasks' => $task
-				)
-			);
-		$response = new JSONResponse();
-		$response->setData($result);
-		return $response;
-	}
-
-	private static function sort_completed($a, $b){
-		$t1 = \DateTime::createFromFormat('Ymd\THis', $a['completed_date']);
-		$t2 = \DateTime::createFromFormat('Ymd\THis', $b['completed_date']);
-		if ($t1 == $t2) {
-			return 0;
-		}
-		return $t1 < $t2 ? 1 : -1;
-	}
-
-	/**
-	 * @param boolean $isStarred
-	 */
-	private function setStarred($isStarred){
-		$taskId = (int) $this->params('taskID');
-		try {
-			$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-			$vtodo = $vcalendar->VTODO;
-			if($isStarred){
-				$vtodo->PRIORITY = 1;
-			}else{
-				$vtodo->__unset('PRIORITY');
-			}
-			\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-		} catch(\Exception $e) {
-			// throw new BusinessLayerException($e->getMessage());
-		}
+				'task' => $result
+			)
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function starTask(){
-		$response = new JSONResponse();
-		try {
-			$this->setStarred(true);
-			return $response;
-		} catch(\Exception $e) {
-			return $response;
-			// return $this->renderJSON(array(), $e->getMessage());
-		}
+	public function starTask($taskID){
+		$result = $this->tasksService->setStarred($taskID, true);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function unstarTask(){
-		$response = new JSONResponse();
-		try {
-			$this->setStarred(false);
-			return $response;
-		} catch(\Exception $e) {
-			return $response;
-			// return $this->renderJSON(array(), $e->getMessage());
-		}
-	}
-
-	private function setPercentComplete($percent_complete){
-		$taskId = (int) $this->params('taskID');
-		try {
-			$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-			$vtodo = $vcalendar->VTODO;
-			if (!empty($percent_complete)) {
-				$vtodo->{'PERCENT-COMPLETE'} = $percent_complete;
-			}else{
-				$vtodo->__unset('PERCENT-COMPLETE');
-			}
-			if ($percent_complete == 100) {
-				$vtodo->STATUS = 'COMPLETED';
-				$vtodo->COMPLETED = new \DateTime('now', new \DateTimeZone('UTC'));
-			} elseif ($percent_complete != 0) {
-				$vtodo->STATUS = 'IN-PROCESS';
-				unset($vtodo->COMPLETED);
-			} else{
-				$vtodo->STATUS = 'NEEDS-ACTION';
-				unset($vtodo->COMPLETED);
-			}
-			\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-		} catch(\Exception $e) {
-			// throw new BusinessLayerException($e->getMessage());
-		}
+	public function unstarTask($taskID){
+		$result = $this->tasksService->setStarred($taskID, false);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function percentComplete(){
-		$response = new JSONResponse();
-		try{
-			$percent_complete = $this->params('complete');
-			$this->setPercentComplete( $percent_complete );
-			return $response;
-		} catch(\Exception $e) {
-			return $response;
-			// return $this->renderJSON(array(), $e->getMessage());
-		}
+	public function percentComplete($taskID, $complete){
+		$result = $this->tasksService->setPercentComplete($taskID, $complete);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 
@@ -247,437 +102,168 @@ class TasksController extends Controller {
 	 * @NoAdminRequired
 	 */
 	public function completeTask(){
-		$response = new JSONResponse();
-		try {
-			$this->setPercentComplete(100);
-			return $response;
-		} catch(\Exception $e) {
-			return $response;
-			// return $this->renderJSON(array(), $e->getMessage());
-		}
+		$result = $this->tasksService->setPercentComplete($taskID, 100);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
 	public function uncompleteTask(){
-		$response = new JSONResponse();
-		try {
-			$this->setPercentComplete(0);
-			return $response;
-		} catch(\Exception $e) {
-			return $response;
-			// return $this->renderJSON(array(), $e->getMessage());
-		}
-	}
-
-	/**
-	 * @NoAdminRequired
-	 */
-	public function addTask(){
-		$taskName = $this->params('name');
-		$calendarId = $this->params('calendarID');
-		$starred = $this->params('starred');
-		$due = $this->params('due');
-		$start = $this->params('start');
-		$response = new JSONResponse();
-		$user_timezone = \OC_Calendar_App::getTimezone();
-		$request = array(
-				'summary'			=> $taskName,
-				'categories'		=> null,
-				'priority'			=> $starred,
-				'location' 			=> null,
-				'due'				=> $due,
-				'start'				=> $start,
-				'description'		=> null
-			);
-		$vcalendar = Helper::createVCalendarFromRequest($request);
-		$taskId = \OC_Calendar_Object::add($calendarId, $vcalendar->serialize());
-
-		$task = Helper::arrayForJSON($taskId, $vcalendar->VTODO, $user_timezone, $calendarId);
-
-		$task['tmpID'] = $this->params('tmpID');
-		$result = array(
-			'data' => array(
-				'task' => $task
-				)
+		$result = $this->tasksService->setPercentComplete($taskID, 0);
+		$response = array(
+			'data' => $result
 		);
-		$response->setData($result);
-		return $response;
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function deleteTask(){
-		$response = new JSONResponse();
-		$taskId = $this->params('taskID');
-		\OC_Calendar_Object::delete($taskId);
-		return $response;
+	public function addTask($taskName, $calendarId, $starred, $due, $start, $tmpID){
+		$result = $this->tasksService->add($taskName, $calendarId, $starred, $due, $start, $tmpID);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function setTaskName(){
-		$taskId = (int) $this->params('taskID');
-		$taskName = $this->params('name');
-		$response = new JSONResponse();
-		try {
-			$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-			$vtodo = $vcalendar->VTODO;
-			$vtodo->SUMMARY = $taskName;
-			\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-		} catch(\Exception $e) {
-			// throw new BusinessLayerException($e->getMessage());
-		}
-		return $response;
+	public function deleteTask($taskID){
+		$result = $this->tasksService->delete($taskID);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function setTaskCalendar(){
-		$taskId = $this->params('taskID');
-		$calendarId = $this->params('calendarID');
-		$response = new JSONResponse();
-		try {
-			$data = \OC_Calendar_App::getEventObject($taskId);
-			if ($data['calendarid'] != $calendarId) {
-				\OC_Calendar_Object::moveToCalendar($taskId, $calendarId);
-			}
-		} catch(\Exception $e) {
-			// throw new BusinessLayerException($e->getMessage());
-		}
-		return $response;
+	public function setTaskName($taskID, $name){
+		$result = $this->tasksService->setName($taskID, $name);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function setTaskNote(){
-		$taskId = $this->params('taskID');
-		$note = $this->params('note');
-		$response = new JSONResponse();
-		try {
-			$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-			$vtodo = $vcalendar->VTODO;
-			$vtodo->DESCRIPTION = $note;
-			\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-		} catch(\Exception $e) {
-			// throw new BusinessLayerException($e->getMessage());
-		}
-		return $response;
+	public function setTaskCalendar($taskID, $calendarID){
+		$result = $this->tasksService->setCalendarId($taskID, $calendarID);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function setDueDate(){
-		$taskId = $this->params('taskID');
-		$due = $this->params('due');
-		$response = new JSONResponse();
-		try{
-			$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-			$vtodo = $vcalendar->VTODO;
-			if ($due != false) {
-				$timezone = \OC_Calendar_App::getTimezone();
-				$timezone = new \DateTimeZone($timezone);
-
-				$due = new \DateTime('@'.$due);
-				$due->setTimezone($timezone);
-				$vtodo->DUE = $due;
-			} else {
-				unset($vtodo->DUE);
-			}
-			\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-		} catch (\Exception $e) {
-
-		}
-		return $response;
+	public function setTaskNote($taskID, $note){
+		$result = $this->tasksService->setDescription($taskID, $note);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function setStartDate(){
-		$taskId = $this->params('taskID');
-		$start = $this->params('start');
-		$response = new JSONResponse();
-
-		try{
-			$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-			$vtodo = $vcalendar->VTODO;
-			if ($start != false) {
-				$timezone = \OC_Calendar_App::getTimezone();
-				$timezone = new \DateTimeZone($timezone);
-
-				$start = new \DateTime('@'.$start);
-				$start->setTimezone($timezone);
-				$vtodo->DTSTART = $start;
-			} else {
-				unset($vtodo->DTSTART);
-			}
-			\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-		} catch (\Exception $e) {
-
-		}
-		return $response;
+	public function setDueDate($taskID, $due){
+		$result = $this->tasksService->setDueDate($taskID, $due);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function setReminderDate(){
-		$taskId = $this->params('taskID');
-		$type = $this->params('type');
-		$action = $this->params('action');
-		$response = new JSONResponse();
-
-		$types = array('DATE-TIME','DURATION');
-
-		$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-		$vtodo = $vcalendar->VTODO;
-		$valarm = $vtodo->VALARM;
-
-		if ($type == false){
-			unset($vtodo->VALARM);
-			$vtodo->__get('LAST-MODIFIED')->setValue(new \DateTime('now', new \DateTimeZone('UTC')));
-			$vtodo->DTSTAMP = new \DateTime('now', new \DateTimeZone('UTC'));
-			\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-		}
-		elseif (in_array($type,$types)) {
-			try{
-				if($valarm == null) {
-					$valarm = $vcalendar->createComponent('VALARM');
-					$valarm->ACTION = $action;
-					$valarm->DESCRIPTION = 'Default Event Notification';
-					$vtodo->add($valarm);
-				} else {
-					unset($valarm->TRIGGER);
-				}
-				$tv = '';
-				$related = null;
-				if ($type == 'DATE-TIME') {
-					$date = new \DateTime('@'.$this->params('date'));
-					$tv = $date->format('Ymd\THis\Z');
-				} elseif ($type == 'DURATION') {
-					$invert = $this->params('invert');
-					$related= $this->params('related');
-					$week 	= (int)$this->params('week');
-					$day 	= (int)$this->params('day');
-					$hour 	= (int)$this->params('hour');
-					$minute = (int)$this->params('minute');
-					$second = (int)$this->params('second');
-
-					// Create duration string
-					if($week || $day || $hour || $minute || $second) {
-						if ($invert){
-							$tv.='-';
-						}
-						$tv.='P';
-						if ($week){
-							$tv.=$week.'W';
-						}
-						if ($day){
-							$tv.=$day.'D';
-						}
-						$tv.='T';
-						if ($hour){
-							$tv.=$hour.'H';
-						}
-						if ($minute){
-							$tv.=$minute.'M';
-						}
-						if ($second){
-							$tv.=$second.'S';
-						}
-					}else{
-						$tv = 'PT0S';
-					}
-				}
-				if($related == 'END'){
-					$valarm->add('TRIGGER', $tv, array('VALUE' => $type, 'RELATED' => $related));
-				} else {
-					$valarm->add('TRIGGER', $tv, array('VALUE' => $type));
-				}
-				$vtodo->__get('LAST-MODIFIED')->setValue(new \DateTime('now', new \DateTimeZone('UTC')));
-				$vtodo->DTSTAMP = new \DateTime('now', new \DateTimeZone('UTC'));
-				\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-			} catch (\Exception $e) {
-
-			}
-		}
-		return $response;
+	public function setStartDate($taskID, $start){
+		$result = $this->tasksService->setStartDate($taskID, $start);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function addCategory(){
-		$taskId = $this->params('taskID');
-		$category = $this->params('category');
-		$response = new JSONResponse();
-		try {
-			$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-			$vtodo = $vcalendar->VTODO;
-			// fetch categories from TODO
-			$categories = $vtodo->CATEGORIES;
-			if ($categories){
-				$taskcategories = $categories->getParts();
-			}
-			// add category
-			if (!in_array($category, $taskcategories)){
-				$taskcategories[] = $category;
-				$vtodo->CATEGORIES = $taskcategories;
-				\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-			}
-		} catch(\Exception $e) {
-			// throw new BusinessLayerException($e->getMessage());
-		}
-		return $response;
+	public function setReminderDate($taskID, $type, $action, $date, $invert, $related = null, $week, $day, $hour, $minute, $second){
+		$result = $this->tasksService->setReminderDate($taskID, $type, $action, $date, $invert, $related = null, $week, $day, $hour, $minute, $second);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function removeCategory(){
-		$taskId = $this->params('taskID');
-		$category = $this->params('category');
-		$response = new JSONResponse();
-		try {
-			$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-			$vtodo = $vcalendar->VTODO;
-			// fetch categories from TODO
-			$categories = $vtodo->CATEGORIES;
-			if ($categories){
-				$taskcategories = $categories->getParts();
-			}
-			// remove category
-			$key = array_search($category, $taskcategories);
-			if ($key !== null && $key !== false){
-				unset($taskcategories[$key]);
-				if(count($taskcategories)){
-					$vtodo->CATEGORIES = $taskcategories;
-				} else{
-					$vtodo->__unset('CATEGORIES');
-				}
-				\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-			}
-		} catch(\Exception $e) {
-			// throw new BusinessLayerException($e->getMessage());
-		}
-		return $response;
+	public function addCategory($taskID, $category){
+		$result = $this->tasksService->addCategory($taskID, $category);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function setLocation(){
-		$taskId = $this->params('taskID');
-		$location = $this->params('location');
-		$response = new JSONResponse();
-		try {
-			$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-			$vtodo = $vcalendar->VTODO;
-			$vtodo->LOCATION = $location;
-			\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-		} catch(\Exception $e) {
-			// throw new BusinessLayerException($e->getMessage());
-		}
-		return $response;
+	public function removeCategory($taskID, $category){
+		$result = $this->tasksService->removeCategory($taskID, $category);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function addComment(){
-		$taskId = $this->params('taskID');
-		$comment = $this->params('comment');
-		$response = new JSONResponse();
-		try {
-			$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-			$vtodo = $vcalendar->VTODO;
-
-			if($vtodo->COMMENT == "") {
-				// if this is the first comment set the id to 0
-				$commentId = 0;
-			} else {
-				// Determine new commentId by looping through all comments
-				$commentIds = array();
-				foreach($vtodo->COMMENT as $com) {
-					$commentIds[] = (int)$com['X-OC-ID']->getValue();
-				}
-				$commentId = 1+max($commentIds);
-			}
-
-			$now = 	new \DateTime();
-			$vtodo->add('COMMENT',$comment,
-				array(
-					'X-OC-ID' => $commentId,
-					'X-OC-USERID' => $this->userId,
-					'X-OC-DATE-TIME' => $now->format('Ymd\THis\Z')
-					)
-				);
-			\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-			$user_timezone = \OC_Calendar_App::getTimezone();
-			$now->setTimezone(new \DateTimeZone($user_timezone));
-			$comment = array(
-				'taskID' => $taskId,
-				'id' => $commentId,
-				'tmpID' => $this->params('tmpID'),
-				'name' => \OCP\User::getDisplayName(),
-				'userID' => $this->userId,
-				'comment' => $comment,
-				'time' => $now->format('Ymd\THis')
-				);
-			$result = array(
-				'data' => array(
-					'comment' => $comment
-					)
-				);
-			$response->setData($result);
-		} catch(\Exception $e) {
-			// throw new BusinessLayerException($e->getMessage());
-		}
-		return $response;
+	public function setLocation($taskID, $location){
+		$result = $this->tasksService->setLocation($taskID, $location);
+		$response = array(
+			'data' => $result
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function deleteComment(){
-		$taskId = $this->params('taskID');
-		$commentId = $this->params('commentID');
-		$response = new JSONResponse();
-		try {
-			$vcalendar = \OC_Calendar_App::getVCalendar($taskId);
-			$vtodo = $vcalendar->VTODO;
-			$commentIndex = $this->getCommentById($vtodo,$commentId);
-			$comment = $vtodo->children[$commentIndex];
-			if($comment['X-OC-USERID']->getValue() == $this->userId){
-				unset($vtodo->children[$commentIndex]);
-				\OC_Calendar_Object::edit($taskId, $vcalendar->serialize());
-			}else{
-				throw new \Exception('Not allowed.');
-			}
-		} catch(\Exception $e) {
-			// throw new BusinessLayerException($e->getMessage());
-		}
-		return $response;
+	public function addComment($taskID, $comment, $tmpID){
+		$result = $this->tasksService->addComment($taskID, $comment);
+		$response = array(
+			'data' => array(
+				'comment' => $result
+			)
+		);
+		return (new JSONResponse())->setData($response);
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
-	public function getCommentById($vtodo,$commentId) {
-		$idx = 0;
-		foreach ($vtodo->children as $i => &$property) {
-			if ( $property->name == 'COMMENT' && $property['X-OC-ID']->getValue() == $commentId ) {
-				return $idx;
-			}
-			$idx += 1;
-		}
-		throw new \Exception('Commment not found.');
+	public function deleteComment($taskID, $commentID){
+		$result = $this->tasksService->deleteComment($taskID, $commentID);
+		$response = array(
+			'data' => array(
+				'comment' => $result
+			)
+		);
+		return (new JSONResponse())->setData($response);
 	}
 }
diff --git a/service/tasksservice.php b/service/tasksservice.php
new file mode 100644
index 00000000..7bcdefc8
--- /dev/null
+++ b/service/tasksservice.php
@@ -0,0 +1,577 @@
+<?php
+namespace OCA\Tasks\Service;
+
+use \OCA\Tasks\Controller\Helper;
+
+class TasksService {
+
+	private $userId;
+
+	public function __construct($userId){
+		$this->userId = $userId;
+	}
+
+	/**
+	 * get a list of Tasks filtered by listID and type
+	 * 
+	 * @param  string $listID
+	 * @param  string $type
+	 * @return array
+	 */
+	public function getAll($listID = 'all', $type = 'all'){
+		
+		$user_timezone = \OC_Calendar_App::getTimezone();
+		if ($listID == 'all'){
+			$calendars = \OC_Calendar_Calendar::allCalendars($this->userId, true);
+		} else {
+			$calendar = \OC_Calendar_App::getCalendar($listID, true, false);
+			$calendars = array($calendar);
+		}
+
+		$tasks = array();
+		$lists = array();
+		foreach( $calendars as $calendar ) {
+			$calendar_entries = \OC_Calendar_Object::all($calendar['id']);
+			$tasks_selected = array();
+			foreach( $calendar_entries as $task ) {
+				if($task['objecttype']!='VTODO') {
+					continue;
+				}
+				if(is_null($task['summary'])) {
+					continue;
+				}
+				$vtodo = Helper::parseVTODO($task['calendardata']);
+				try {
+					$task_data = Helper::arrayForJSON($task['id'], $vtodo, $user_timezone, $calendar['id']);
+					switch($type){
+						case 'all':
+							$tasks[] = $task_data;
+							break;
+						case 'init':
+							if (!$task_data['completed']){
+								$tasks[] = $task_data;
+							} else {
+								$tasks_selected[] = $task_data;
+							}
+							break;
+						case 'completed':
+							if ($task_data['completed']){
+								$tasks[] = $task_data;
+							}
+							break;
+						case 'uncompleted':
+							if (!$task_data['completed']){
+								$tasks[] = $task_data;
+							}
+							break;
+					}
+				} catch(\Exception $e) {
+					\OCP\Util::writeLog('tasks', $e->getMessage(), \OCP\Util::ERROR);
+				}
+			}
+			$nrCompleted = 0;
+			$notLoaded = 0;
+			usort($tasks_selected, array($this, 'sort_completed'));
+			foreach( $tasks_selected as $task_selected){
+				$nrCompleted++;
+				if ($nrCompleted > 5){
+					$notLoaded++;
+					continue;
+				}
+				$tasks[] = $task_selected;
+			}
+			$lists[] = array(
+				'id' 		=> $calendar['id'],
+				'notLoaded' => $notLoaded
+				);
+		}
+		return array(
+			'tasks' => $tasks,
+			'lists' => $lists
+		);
+	}
+
+	/**
+	 * get task by id
+	 * 
+	 * @param  string $taskID
+	 * @return array
+	 */
+	public function get($taskID){
+		$object = \OC_Calendar_App::getEventObject($taskID);
+		$user_timezone = \OC_Calendar_App::getTimezone();
+		$task = array();
+		if($object['objecttype']=='VTODO' && !is_null($object['summary'])) {
+			$vtodo = Helper::parseVTODO($object['calendardata']);
+			try {
+				$task_data = Helper::arrayForJSON($object['id'], $vtodo, $user_timezone, $object['calendarid']);
+				$task[] = $task_data;
+			} catch(\Exception $e) {
+				\OCP\Util::writeLog('tasks', $e->getMessage(), \OCP\Util::ERROR);
+			}	
+		}
+		$result = array(
+			'tasks' => $task
+		);
+	}
+
+	/**
+	 * create new task
+	 * 
+	 * @param  string $taskName
+	 * @param  int    $calendarId
+	 * @param  bool   $starred
+	 * @param  mixed  $due
+	 * @param  mixed  $start
+	 * @param  int    $tmpID
+	 * @return array
+	 */
+	public function add($taskName, $calendarId, $starred, $due, $start, $tmpID){
+		$user_timezone = \OC_Calendar_App::getTimezone();
+		$request = array(
+				'summary'			=> $taskName,
+				'categories'		=> null,
+				'priority'			=> $starred,
+				'location' 			=> null,
+				'due'				=> $due,
+				'start'				=> $start,
+				'description'		=> null
+			);
+		$vcalendar = Helper::createVCalendarFromRequest($request);
+		$taskID = \OC_Calendar_Object::add($calendarId, $vcalendar->serialize());
+
+		$task = Helper::arrayForJSON($taskID, $vcalendar->VTODO, $user_timezone, $calendarId);
+
+		$task['tmpID'] = $tmpID;
+		return $task;
+	}
+
+	/**
+	 * delete task by id
+	 * 
+	 * @param  int   $taskID
+	 * @return bool
+	 */
+	public function delete($taskID) {
+		return \OC_Calendar_Object::delete($taskID);
+	}
+
+	/**
+	 * set name of task by id
+	 * @param  int    $taskID
+	 * @param  string $name
+	 * @return bool
+	 */
+	public function setName($taskID, $name) {
+		try {
+			$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+			$vtodo = $vcalendar->VTODO;
+			$vtodo->SUMMARY = $taskName;
+			return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+		} catch(\Exception $e) {
+			// throw new BusinessLayerException($e->getMessage());
+			return false;
+		}
+	}
+
+	/**
+	 * set calendar id of task by id
+	 * 
+	 * @param  int    $taskID
+	 * @param  int    $calendarID
+	 * @return bool
+	 */
+	public function setCalendarId($taskID, $calendarID) {
+		try {
+			$data = \OC_Calendar_App::getEventObject($taskID);
+			if ($data['calendarid'] != $calendarId) {
+				return \OC_Calendar_Object::moveToCalendar($taskID, $calendarId);
+			} else {
+				return true;
+			}
+		} catch(\Exception $e) {
+			// throw new BusinessLayerException($e->getMessage());
+			return false;
+		}
+	}
+
+	/**
+	 * star or unstar task by id
+	 * 
+	 * @param int    $taskID
+	 * @param bool   $isStarred
+	 */
+	public function setStarred($taskID, $isStarred) {
+		try {
+			$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+			$vtodo = $vcalendar->VTODO;
+			if($isStarred) {
+				$vtodo->PRIORITY = 5; // prio: medium
+			} else {
+				$vtodo->PRIORITY = 0;
+			}
+			return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+		} catch(\Exception $e) {
+			return false;
+		}
+	}
+
+	/**
+	 * set completeness of task in percent by id
+	 * 
+	 * @param  int    $taskID
+	 * @param  int    $percent_complete
+	 * @return bool
+	 */
+	public function setPercentComplete($taskID, $percent_complete) {
+		try {
+			$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+			$vtodo = $vcalendar->VTODO;
+			if (!empty($percent_complete)) {
+				$vtodo->{'PERCENT-COMPLETE'} = $percent_complete;
+			}else{
+				$vtodo->__unset('PERCENT-COMPLETE');
+			}
+			if ($percent_complete == 100) {
+				$vtodo->STATUS = 'COMPLETED';
+				$vtodo->COMPLETED = new \DateTime('now', new \DateTimeZone('UTC'));
+			} elseif ($percent_complete != 0) {
+				$vtodo->STATUS = 'IN-PROCESS';
+				unset($vtodo->COMPLETED);
+			} else{
+				$vtodo->STATUS = 'NEEDS-ACTION';
+				unset($vtodo->COMPLETED);
+			}
+			return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+		} catch(\Exception $e) {
+			return false;// throw new BusinessLayerException($e->getMessage());
+		}
+	}
+
+	/**
+	 * set due date of task by id
+	 * 
+	 * @param  int    $taskID
+	 * @param  mixed  $dueDate
+	 * @return bool
+	 */
+	public function setDueDate($taskID, $dueDate) {
+		try{
+			$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+			$vtodo = $vcalendar->VTODO;
+			if ($dueDate != false) {
+				$timezone = \OC_Calendar_App::getTimezone();
+				$timezone = new \DateTimeZone($timezone);
+
+				$dueDate = new \DateTime('@'.$dueDate);
+				$dueDate->setTimezone($timezone);
+				$vtodo->DUE = $dueDate;
+			} else {
+				unset($vtodo->DUE);
+			}
+			return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+		} catch (\Exception $e) {
+			return false;
+		}
+	}
+
+	public function setStartDate($taskID, $startDate) {
+		try{
+			$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+			$vtodo = $vcalendar->VTODO;
+			if ($startDate != false) {
+				$timezone = \OC_Calendar_App::getTimezone();
+				$timezone = new \DateTimeZone($timezone);
+
+				$startDate = new \DateTime('@'.$startDate);
+				$startDate->setTimezone($timezone);
+				$vtodo->DTSTART = $startDate;
+			} else {
+				unset($vtodo->DTSTART);
+			}
+			return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+		} catch (\Exception $e) {
+			return false;
+		}
+	}
+
+	/**
+	 * set reminder date of task by id
+	 * @param  int    $taskID
+	 * @param  string $type
+	 * @param  mixed  $action
+	 * @param  mixed  $date
+	 * @param  bool   $invert
+	 * @param  string $related
+	 * @param  mixed  $week
+	 * @param  mixed  $day
+	 * @param  mixed  $hour
+	 * @param  mixed  $minute
+	 * @param  mixed  $second
+	 * @return bool
+	 */
+	public function setReminderDate($taskID, $type, $action, $date, $invert, $related = null, $week, $day, $hour, $minute, $second){
+		$types = array('DATE-TIME','DURATION');
+
+		$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+		$vtodo = $vcalendar->VTODO;
+		$valarm = $vtodo->VALARM;
+
+		if ($type == false){
+			unset($vtodo->VALARM);
+			$vtodo->__get('LAST-MODIFIED')->setValue(new \DateTime('now', new \DateTimeZone('UTC')));
+			$vtodo->DTSTAMP = new \DateTime('now', new \DateTimeZone('UTC'));
+			return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+		}
+		elseif (in_array($type,$types)) {
+			try{
+				if($valarm == null) {
+					$valarm = $vcalendar->createComponent('VALARM');
+					$valarm->ACTION = $action;
+					$valarm->DESCRIPTION = 'Default Event Notification';
+					$vtodo->add($valarm);
+				} else {
+					unset($valarm->TRIGGER);
+				}
+				$tv = '';
+				if ($type == 'DATE-TIME') {
+					$date = new \DateTime('@'.$this->params('date'));
+					$tv = $date->format('Ymd\THis\Z');
+				} elseif ($type == 'DURATION') {
+					// Create duration string
+					if($week || $day || $hour || $minute || $second) {
+						if ($invert){
+							$tv.='-';
+						}
+						$tv.='P';
+						if ($week){
+							$tv.=$week.'W';
+						}
+						if ($day){
+							$tv.=$day.'D';
+						}
+						$tv.='T';
+						if ($hour){
+							$tv.=$hour.'H';
+						}
+						if ($minute){
+							$tv.=$minute.'M';
+						}
+						if ($second){
+							$tv.=$second.'S';
+						}
+					}else{
+						$tv = 'PT0S';
+					}
+				}
+				if($related == 'END'){
+					$valarm->add('TRIGGER', $tv, array('VALUE' => $type, 'RELATED' => $related));
+				} else {
+					$valarm->add('TRIGGER', $tv, array('VALUE' => $type));
+				}
+				$vtodo->__get('LAST-MODIFIED')->setValue(new \DateTime('now', new \DateTimeZone('UTC')));
+				$vtodo->DTSTAMP = new \DateTime('now', new \DateTimeZone('UTC'));
+				return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+			} catch (\Exception $e) {
+				return false;
+			}
+		}
+	}
+
+	/**
+	 * add category to task by id
+	 * @param  int    $taskID
+	 * @param  string $category
+	 * @return bool
+	 */
+	public function addCategory($taskID, $category){
+		$taskID = $this->params('taskID');
+		$category = $this->params('category');
+		try {
+			$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+			$vtodo = $vcalendar->VTODO;
+			// fetch categories from TODO
+			$categories = $vtodo->CATEGORIES;
+			if ($categories){
+				$taskcategories = $categories->getParts();
+			}
+			// add category
+			if (!in_array($category, $taskcategories)){
+				$taskcategories[] = $category;
+				$vtodo->CATEGORIES = $taskcategories;
+				return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+			} else {
+				return true;
+			}
+		} catch(\Exception $e) {
+			// throw new BusinessLayerException($e->getMessage());
+			return false;
+		}
+	}
+
+	/**
+	 * remove category from task by id
+	 * @param  int    $taskID
+	 * @param  string $category
+	 * @return bool
+	 */
+	public function removeCategory($taskID, $category){
+		try {
+			$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+			$vtodo = $vcalendar->VTODO;
+			// fetch categories from TODO
+			$categories = $vtodo->CATEGORIES;
+			if ($categories){
+				$taskcategories = $categories->getParts();
+			}
+			// remove category
+			$key = array_search($category, $taskcategories);
+			if ($key !== null && $key !== false){
+				unset($taskcategories[$key]);
+				if(count($taskcategories)){
+					$vtodo->CATEGORIES = $taskcategories;
+				} else{
+					$vtodo->__unset('CATEGORIES');
+				}
+				return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+			}
+		} catch(\Exception $e) {
+			// throw new BusinessLayerException($e->getMessage());
+			return false;
+		}
+	}
+
+	/**
+	 * set location of task by id
+	 * @param  int    $taskID
+	 * @param  string $location
+	 * @return bool
+	 */
+	public function setLocation($taskID, $location){
+		try {
+			$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+			$vtodo = $vcalendar->VTODO;
+			$vtodo->LOCATION = $location;
+			return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+		} catch(\Exception $e) {
+			// throw new BusinessLayerException($e->getMessage());
+			return false;
+		}
+	}
+
+	/**
+	 * set description of task by id
+	 * 
+	 * @param  int    $taskID
+	 * @param  string $description
+	 * @return bool
+	 */
+	public function setDescription($taskID, $description){
+		try {
+			$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+			$vtodo = $vcalendar->VTODO;
+			$vtodo->DESCRIPTION = $description;
+			return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+		} catch(\Exception $e) {
+			// throw new BusinessLayerException($e->getMessage());
+			return false;
+		}
+	}
+
+	/**
+	 * add comment to task by id
+	 * @param  int    $taskID
+	 * @param  string $comment
+	 * @param  int    $tmpID
+	 * @return array
+	 */
+	public function addComment($taskID, $comment, $tmpID){
+		try {
+			$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+			$vtodo = $vcalendar->VTODO;
+
+			if($vtodo->COMMENT == "") {
+				// if this is the first comment set the id to 0
+				$commentId = 0;
+			} else {
+				// Determine new commentId by looping through all comments
+				$commentIds = array();
+				foreach($vtodo->COMMENT as $com) {
+					$commentIds[] = (int)$com['X-OC-ID']->getValue();
+				}
+				$commentId = 1+max($commentIds);
+			}
+
+			$now = 	new \DateTime();
+			$vtodo->add('COMMENT',$comment,
+				array(
+					'X-OC-ID' => $commentId,
+					'X-OC-USERID' => $this->userId,
+					'X-OC-DATE-TIME' => $now->format('Ymd\THis\Z')
+					)
+				);
+			\OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+			$user_timezone = \OC_Calendar_App::getTimezone();
+			$now->setTimezone(new \DateTimeZone($user_timezone));
+			$comment = array(
+				'taskID' => $taskID,
+				'id' => $commentId,
+				'tmpID' => $tmpID,
+				'name' => \OCP\User::getDisplayName(),
+				'userID' => $this->userId,
+				'comment' => $comment,
+				'time' => $now->format('Ymd\THis')
+				);
+		} catch(\Exception $e) {
+			// throw new BusinessLayerException($e->getMessage());
+		}
+		return $comment;
+	}
+
+	/**
+	 * delete comment of task by id
+	 * @param  int   $taskID
+	 * @param  int   $commentID
+	 * @return bool
+	 */
+	public function deleteComment($taskID, $commentID){
+		try {
+			$vcalendar = \OC_Calendar_App::getVCalendar($taskID);
+			$vtodo = $vcalendar->VTODO;
+			$commentIndex = $this->getCommentById($vtodo,$commentID);
+			$comment = $vtodo->children[$commentIndex];
+			if($comment['X-OC-USERID']->getValue() == $this->userId){
+				unset($vtodo->children[$commentIndex]);
+				return \OC_Calendar_Object::edit($taskID, $vcalendar->serialize());
+			}else{
+				throw new \Exception('Not allowed.');
+			}
+		} catch(\Exception $e) {
+			// throw new BusinessLayerException($e->getMessage());
+			return false;
+		}
+		return $response;
+	}
+
+
+	private static function sort_completed($a, $b) {
+		$t1 = \DateTime::createFromFormat('Ymd\THis', $a['completed_date']);
+		$t2 = \DateTime::createFromFormat('Ymd\THis', $b['completed_date']);
+		if ($t1 == $t2) {
+			return 0;
+		}
+		return $t1 < $t2 ? 1 : -1;
+	}
+
+	private function getCommentById($vtodo,$commentId) {
+		$idx = 0;
+		foreach ($vtodo->children as $i => &$property) {
+			if ( $property->name == 'COMMENT' && $property['X-OC-ID']->getValue() == $commentId ) {
+				return $idx;
+			}
+			$idx += 1;
+		}
+		throw new \Exception('Commment not found.');
+	}
+
+}
\ No newline at end of file