nextcloud / circles

	 * @return array

	 * @throws \Exception

	 */

	public function linkGroup($circleUniqueId, $groupId) {

		try {

			$circle = $this->circlesRequest->getCircle($circleUniqueId, $this->userId);

			$circle->getHigherViewer()

				   ->hasToBeAdmin();

			$group = $this->getFreshNewMember($circleUniqueId, $groupId);

		} catch (\Exception $e) {

			throw $e;

		}

		$group->setLevel(Member::LEVEL_MEMBER);

		$this->membersRequest->updateGroup($group);

		$this->eventsService->onGroupLink($circle, $group);

		return $this->membersRequest->getGroupsFromCircle(

			$circleUniqueId, $circle->getHigherViewer()

		);

	}

	/**

	 * @return null|Member

	 * @throws \Exception

	 */

	public function joinCircle($circleUniqueId) {

		try {

			$circle = $this->circlesRequest->getCircle($circleUniqueId, $this->userId);

			$member = $this->membersRequest->getFreshNewMember(

				$circleUniqueId, $this->userId, Member::TYPE_USER

			);

			$member->hasToBeAbleToJoinTheCircle();

			$member->joinCircle($circle->getType());

			$this->membersRequest->updateMember($member);

			$this->eventsService->onMemberNew($circle, $member);

		} catch (\Exception $e) {

			throw $e;

		}

		return $member;

	}

	 * @return null|Member

	 * @throws \Exception

	 */

	public function leaveCircle($circleUniqueId) {

		try {

			$circle = $this->circlesRequest->getCircle($circleUniqueId, $this->userId);

			$member = $circle->getViewer();

			$member->hasToBeMemberOrAlmost();

			$member->cantBeOwner();

			$this->eventsService->onMemberLeaving($circle, $member);

			$member->setStatus(Member::STATUS_NONMEMBER);

			$member->setLevel(Member::LEVEL_NONE);

			$this->membersRequest->updateMember($member);

		} catch (\Exception $e) {

			throw $e;

		}

		return $member;

	}

	/**

	 * destroy a circle.