<?php
declare(strict_types=1);
/**
 * @copyright Copyright (c) 2016, ownCloud, Inc.
 *
 * @author Arthur Schiwon <blizzz@arthur-schiwon.de>
 * @author Bjoern Schiessle <bjoern@schiessle.org>
 * @author Joas Schilling <coding@schilljs.com>
 * @author Lukas Reschke <lukas@statuscode.ch>
 * @author michag86 <micha_g@arcor.de>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Roeland Jago Douma <roeland@famdouma.nl>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 * @author Tom Needham <tom@owncloud.com>
 * @author John Molakvoæ <skjnldsv@protonmail.com>
 *
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * 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, version 3,
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

namespace OCA\Provisioning_API\Controller;

use OC\Accounts\AccountManager;
use OC\HintException;
use OC\Settings\Mailer\NewUserMailHelper;
use OCA\Provisioning_API\FederatedFileSharingFactory;
use OCP\App\IAppManager;
use OCP\AppFramework\Http\DataResponse;
use OCP\AppFramework\OCS\OCSException;
use OCP\AppFramework\OCS\OCSForbiddenException;
use OCP\IConfig;
use OCP\IGroup;
use OCP\IGroupManager;
use OCP\ILogger;
use OCP\IRequest;
use OCP\IUserManager;
use OCP\IUserSession;
use OCP\L10N\IFactory;
use OCP\Security\ISecureRandom;

class UsersController extends AUserData {

	/** @var IAppManager */
	private $appManager;
	/** @var ILogger */
	private $logger;
	/** @var IFactory */
	private $l10nFactory;
	/** @var NewUserMailHelper */
	private $newUserMailHelper;
	/** @var FederatedFileSharingFactory */
	private $federatedFileSharingFactory;
	/** @var ISecureRandom */
	private $secureRandom;

	/**
	 * @param string $appName
	 * @param IRequest $request
	 * @param IUserManager $userManager
	 * @param IConfig $config
	 * @param IAppManager $appManager
	 * @param IGroupManager $groupManager
	 * @param IUserSession $userSession
	 * @param AccountManager $accountManager
	 * @param ILogger $logger
	 * @param IFactory $l10nFactory
	 * @param NewUserMailHelper $newUserMailHelper
	 * @param FederatedFileSharingFactory $federatedFileSharingFactory
	 * @param ISecureRandom $secureRandom
	 */
	public function __construct(string $appName,
								IRequest $request,
								IUserManager $userManager,
								IConfig $config,
								IAppManager $appManager,
								IGroupManager $groupManager,
								IUserSession $userSession,
								AccountManager $accountManager,
								ILogger $logger,
								IFactory $l10nFactory,
								NewUserMailHelper $newUserMailHelper,
								FederatedFileSharingFactory $federatedFileSharingFactory,
								ISecureRandom $secureRandom) {
		parent::__construct($appName,
							$request,
							$userManager,
							$config,
							$groupManager,
							$userSession,
							$accountManager);

		$this->appManager = $appManager;
		$this->logger = $logger;
		$this->l10nFactory = $l10nFactory;
		$this->newUserMailHelper = $newUserMailHelper;
		$this->federatedFileSharingFactory = $federatedFileSharingFactory;
		$this->secureRandom = $secureRandom;
	}

	/**
	 * @NoAdminRequired
	 *
	 * returns a list of users
	 *
	 * @param string $search
	 * @param int $limit
	 * @param int $offset
	 * @return DataResponse
	 */
	public function getUsers(string $search = '', $limit = null, $offset = 0): DataResponse {
		$user = $this->userSession->getUser();
		$users = [];

		// Admin? Or SubAdmin?
		$uid = $user->getUID();
		$subAdminManager = $this->groupManager->getSubAdmin();
		if ($this->groupManager->isAdmin($uid)){
			$users = $this->userManager->search($search, $limit, $offset);
		} else if ($subAdminManager->isSubAdmin($user)) {
			$subAdminOfGroups = $subAdminManager->getSubAdminsGroups($user);
			foreach ($subAdminOfGroups as $key => $group) {
				$subAdminOfGroups[$key] = $group->getGID();
			}

			$users = [];
			foreach ($subAdminOfGroups as $group) {
				$users = array_merge($users, $this->groupManager->displayNamesInGroup($group, $search, $limit, $offset));
			}
		}

		$users = array_keys($users);

		return new DataResponse([
			'users' => $users
		]);
	}

	/**
	 * @NoAdminRequired
	 *
	 * returns a list of users and their data
	 */
	public function getUsersDetails(string $search = '', $limit = null, $offset = 0): DataResponse {
		$user = $this->userSession->getUser();
		$users = [];

		// Admin? Or SubAdmin?
		$uid = $user->getUID();
		$subAdminManager = $this->groupManager->getSubAdmin();
		if ($this->groupManager->isAdmin($uid)){
			$users = $this->userManager->search($search, $limit, $offset);
		} else if ($subAdminManager->isSubAdmin($user)) {
			$subAdminOfGroups = $subAdminManager->getSubAdminsGroups($user);
			foreach ($subAdminOfGroups as $key => $group) {
				$subAdminOfGroups[$key] = $group->getGID();
			}

			$users = [];
			foreach ($subAdminOfGroups as $group) {
				$users = array_merge($users, $this->groupManager->displayNamesInGroup($group, $search, $limit, $offset));
			}
		}

		$users = array_keys($users);
		$usersDetails = [];
		foreach ($users as $key => $userId) {
			$userData = $this->getUserData($userId);
			// Do not insert empty entry
			if (!empty($userData)) {
				$usersDetails[$userId] = $userData;
			}
		}

		return new DataResponse([
			'users' => $usersDetails
		]);
	}

	/**
	 * @PasswordConfirmationRequired
	 * @NoAdminRequired
	 *
	 * @param string $userid
	 * @param string $password
	 * @param string $email
	 * @param array $groups
	 * @param array $subadmins
	 * @param string $quota
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function addUser(string $userid,
							string $password = '',
							string $email = '',
							array $groups = [],
							array $subadmin = [],
							string $quota = ''): DataResponse {
		$user = $this->userSession->getUser();
		$isAdmin = $this->groupManager->isAdmin($user->getUID());
		$subAdminManager = $this->groupManager->getSubAdmin();

		if ($this->userManager->userExists($userid)) {
			$this->logger->error('Failed addUser attempt: User already exists.', ['app' => 'ocs_api']);
			throw new OCSException('User already exists', 102);
		}

		if ($groups !== []) {
			foreach ($groups as $group) {
				if (!$this->groupManager->groupExists($group)) {
					throw new OCSException('group '.$group.' does not exist', 104);
				}
				if (!$isAdmin && !$subAdminManager->isSubAdminOfGroup($user, $this->groupManager->get($group))) {
					throw new OCSException('insufficient privileges for group '. $group, 105);
				}
			}
		} else {
			if (!$isAdmin) {
				throw new OCSException('no group specified (required for subadmins)', 106);
			}
		}

		$subadminGroups = [];
		if ($subadmin !== []) {
			foreach ($subadmin as $groupid) {
				$group = $this->groupManager->get($groupid);
				// Check if group exists
				if ($group === null) {
					throw new OCSException('Subadmin group does not exist',  102);
				}
				// Check if trying to make subadmin of admin group
				if ($group->getGID() === 'admin') {
					throw new OCSException('Cannot create subadmins for admin group', 103);
				}
				// Check if has permission to promote subadmins
				if (!$subAdminManager->isSubAdminOfGroup($user, $group) && !$isAdmin) {
					throw new OCSForbiddenException('No permissions to promote subadmins');
				}
				$subadminGroups[] = $group;
			}
		}

		$generatePasswordResetToken = false;
		if ($password === '') {
			if ($email === '') {
				throw new OCSException('To send a password link to the user an email address is required.', 108);
			}

			$password = $this->secureRandom->generate(10);
			// Make sure we pass the password_policy
			$password .= $this->secureRandom->generate(2, '$!.,;:-~+*[]{}()');
			$generatePasswordResetToken = true;
		}

		try {
			$newUser = $this->userManager->createUser($userid, $password);
			$this->logger->info('Successful addUser call with userid: ' . $userid, ['app' => 'ocs_api']);

			foreach ($groups as $group) {
				$this->groupManager->get($group)->addUser($newUser);
				$this->logger->info('Added userid ' . $userid . ' to group ' . $group, ['app' => 'ocs_api']);
			}
			foreach ($subadminGroups as $group) {
				$subAdminManager->createSubAdmin($newUser, $group);
			}

			if ($quota !== '') {
				$this->editUser($userid, 'quota', $quota);
			}

			// Send new user mail only if a mail is set
			if ($email !== '') {
				$newUser->setEMailAddress($email);
				try {
					$emailTemplate = $this->newUserMailHelper->generateTemplate($newUser, $generatePasswordResetToken);
					$this->newUserMailHelper->sendMail($newUser, $emailTemplate);
				} catch (\Exception $e) {
					$this->logger->logException($e, [
						'message' => "Can't send new user mail to $email",
						'level' => \OCP\Util::ERROR,
						'app' => 'ocs_api',
					]);
					throw new OCSException('Unable to send the invitation mail', 109);
				}
			}

			return new DataResponse();

		} catch (HintException $e ) {
			$this->logger->logException($e, [
				'message' => 'Failed addUser attempt with hint exception.',
				'level' => \OCP\Util::WARN,
				'app' => 'ocs_api',
			]);
			throw new OCSException($e->getHint(), 107);
		} catch (\Exception $e) {
			$this->logger->logException($e, [
				'message' => 'Failed addUser attempt with exception.',
				'level' => \OCP\Util::ERROR,
				'app' => 'ocs_api',
			]);
			throw new OCSException('Bad request', 101);
		}
	}

	/**
	 * @NoAdminRequired
	 * @NoSubAdminRequired
	 *
	 * gets user info
	 *
	 * @param string $userId
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function getUser(string $userId): DataResponse {
		$data = $this->getUserData($userId);
		// getUserData returns empty array if not enough permissions
		if (empty($data)) {
			throw new OCSException('', \OCP\API::RESPOND_UNAUTHORISED);
		}
		return new DataResponse($data);
	}

	/**
	 * @NoAdminRequired
	 * @NoSubAdminRequired
	 *
	 * gets user info from the currently logged in user
	 *
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function getCurrentUser(): DataResponse {
		$user = $this->userSession->getUser();
		if ($user) {
			$data =  $this->getUserData($user->getUID());
			// rename "displayname" to "display-name" only for this call to keep
			// the API stable.
			$data['display-name'] = $data['displayname'];
			unset($data['displayname']);
			return new DataResponse($data);

		}

		throw new OCSException('', \OCP\API::RESPOND_UNAUTHORISED);
	}

	/**
	 * @NoAdminRequired
	 * @NoSubAdminRequired
	 */
	public function getEditableFields(): DataResponse {
		$permittedFields = [];

		// Editing self (display, email)
		if ($this->config->getSystemValue('allow_user_to_change_display_name', true) !== false) {
			$permittedFields[] = AccountManager::PROPERTY_DISPLAYNAME;
			$permittedFields[] = AccountManager::PROPERTY_EMAIL;
		}

		if ($this->appManager->isEnabledForUser('federatedfilesharing')) {
			$federatedFileSharing = $this->federatedFileSharingFactory->get();
			$shareProvider = $federatedFileSharing->getFederatedShareProvider();
			if ($shareProvider->isLookupServerUploadEnabled()) {
				$permittedFields[] = AccountManager::PROPERTY_PHONE;
				$permittedFields[] = AccountManager::PROPERTY_ADDRESS;
				$permittedFields[] = AccountManager::PROPERTY_WEBSITE;
				$permittedFields[] = AccountManager::PROPERTY_TWITTER;
			}
		}

		return new DataResponse($permittedFields);
	}

	/**
	 * @NoAdminRequired
	 * @NoSubAdminRequired
	 * @PasswordConfirmationRequired
	 *
	 * edit users
	 *
	 * @param string $userId
	 * @param string $key
	 * @param string $value
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function editUser(string $userId, string $key, string $value): DataResponse {
		$currentLoggedInUser = $this->userSession->getUser();

		$targetUser = $this->userManager->get($userId);
		if ($targetUser === null) {
			throw new OCSException('', \OCP\API::RESPOND_UNAUTHORISED);
		}

		$permittedFields = [];
		if ($targetUser->getUID() === $currentLoggedInUser->getUID()) {
			// Editing self (display, email)
			if ($this->config->getSystemValue('allow_user_to_change_display_name', true) !== false) {
				$permittedFields[] = 'display';
				$permittedFields[] = AccountManager::PROPERTY_DISPLAYNAME;
				$permittedFields[] = AccountManager::PROPERTY_EMAIL;
			}

			$permittedFields[] = 'password';
			if ($this->config->getSystemValue('force_language', false) === false ||
				$this->groupManager->isAdmin($currentLoggedInUser->getUID())) {
				$permittedFields[] = 'language';
			}

			if ($this->appManager->isEnabledForUser('federatedfilesharing')) {
				$federatedFileSharing = new \OCA\FederatedFileSharing\AppInfo\Application();
				$shareProvider = $federatedFileSharing->getFederatedShareProvider();
				if ($shareProvider->isLookupServerUploadEnabled()) {
					$permittedFields[] = AccountManager::PROPERTY_PHONE;
					$permittedFields[] = AccountManager::PROPERTY_ADDRESS;
					$permittedFields[] = AccountManager::PROPERTY_WEBSITE;
					$permittedFields[] = AccountManager::PROPERTY_TWITTER;
				}
			}

			// If admin they can edit their own quota
			if ($this->groupManager->isAdmin($currentLoggedInUser->getUID())) {
				$permittedFields[] = 'quota';
			}
		} else {
			// Check if admin / subadmin
			$subAdminManager = $this->groupManager->getSubAdmin();
			if ($subAdminManager->isUserAccessible($currentLoggedInUser, $targetUser)
			|| $this->groupManager->isAdmin($currentLoggedInUser->getUID())) {
				// They have permissions over the user
				$permittedFields[] = 'display';
				$permittedFields[] = AccountManager::PROPERTY_DISPLAYNAME;
				$permittedFields[] = AccountManager::PROPERTY_EMAIL;
				$permittedFields[] = 'password';
				$permittedFields[] = 'language';
				$permittedFields[] = AccountManager::PROPERTY_PHONE;
				$permittedFields[] = AccountManager::PROPERTY_ADDRESS;
				$permittedFields[] = AccountManager::PROPERTY_WEBSITE;
				$permittedFields[] = AccountManager::PROPERTY_TWITTER;
				$permittedFields[] = 'quota';
			} else {
				// No rights
				throw new OCSException('', \OCP\API::RESPOND_UNAUTHORISED);
			}
		}
		// Check if permitted to edit this field
		if (!in_array($key, $permittedFields)) {
			throw new OCSException('', \OCP\API::RESPOND_UNAUTHORISED);
		}
		// Process the edit
		switch($key) {
			case 'display':
			case AccountManager::PROPERTY_DISPLAYNAME:
				$targetUser->setDisplayName($value);
				break;
			case 'quota':
				$quota = $value;
				if ($quota !== 'none' && $quota !== 'default') {
					if (is_numeric($quota)) {
						$quota = (float) $quota;
					} else {
						$quota = \OCP\Util::computerFileSize($quota);
					}
					if ($quota === false) {
						throw new OCSException('Invalid quota value '.$value, 103);
					}
					if ($quota === 0) {
						$quota = 'default';
					}else if ($quota === -1) {
						$quota = 'none';
					} else {
						$quota = \OCP\Util::humanFileSize($quota);
					}
				}
				$targetUser->setQuota($quota);
				break;
			case 'password':
				$targetUser->setPassword($value);
				break;
			case 'language':
				$languagesCodes = $this->l10nFactory->findAvailableLanguages();
				if (!in_array($value, $languagesCodes, true) && $value !== 'en') {
					throw new OCSException('Invalid language', 102);
				}
				$this->config->setUserValue($targetUser->getUID(), 'core', 'lang', $value);
				break;
			case AccountManager::PROPERTY_EMAIL:
				if (filter_var($value, FILTER_VALIDATE_EMAIL) || $value === '') {
					$targetUser->setEMailAddress($value);
				} else {
					throw new OCSException('', 102);
				}
				break;
			case AccountManager::PROPERTY_PHONE:
			case AccountManager::PROPERTY_ADDRESS:
			case AccountManager::PROPERTY_WEBSITE:
			case AccountManager::PROPERTY_TWITTER:
				$userAccount = $this->accountManager->getUser($targetUser);
				if ($userAccount[$key]['value'] !== $value) {
					$userAccount[$key]['value'] = $value;
					$this->accountManager->updateUser($targetUser, $userAccount);
				}
				break;
			default:
				throw new OCSException('', 103);
		}
		return new DataResponse();
	}

	/**
	 * @PasswordConfirmationRequired
	 * @NoAdminRequired
	 *
	 * @param string $userId
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function deleteUser(string $userId): DataResponse {
		$currentLoggedInUser = $this->userSession->getUser();

		$targetUser = $this->userManager->get($userId);

		if ($targetUser === null || $targetUser->getUID() === $currentLoggedInUser->getUID()) {
			throw new OCSException('', 101);
		}

		// If not permitted
		$subAdminManager = $this->groupManager->getSubAdmin();
		if (!$this->groupManager->isAdmin($currentLoggedInUser->getUID()) && !$subAdminManager->isUserAccessible($currentLoggedInUser, $targetUser)) {
			throw new OCSException('', \OCP\API::RESPOND_UNAUTHORISED);
		}

		// Go ahead with the delete
		if ($targetUser->delete()) {
			return new DataResponse();
		} else {
			throw new OCSException('', 101);
		}
	}

	/**
	 * @PasswordConfirmationRequired
	 * @NoAdminRequired
	 *
	 * @param string $userId
	 * @return DataResponse
	 * @throws OCSException
	 * @throws OCSForbiddenException
	 */
	public function disableUser(string $userId): DataResponse {
		return $this->setEnabled($userId, false);
	}

	/**
	 * @PasswordConfirmationRequired
	 * @NoAdminRequired
	 *
	 * @param string $userId
	 * @return DataResponse
	 * @throws OCSException
	 * @throws OCSForbiddenException
	 */
	public function enableUser(string $userId): DataResponse {
		return $this->setEnabled($userId, true);
	}

	/**
	 * @param string $userId
	 * @param bool $value
	 * @return DataResponse
	 * @throws OCSException
	 */
	private function setEnabled(string $userId, bool $value): DataResponse {
		$currentLoggedInUser = $this->userSession->getUser();

		$targetUser = $this->userManager->get($userId);
		if ($targetUser === null || $targetUser->getUID() === $currentLoggedInUser->getUID()) {
			throw new OCSException('', 101);
		}

		// If not permitted
		$subAdminManager = $this->groupManager->getSubAdmin();
		if (!$this->groupManager->isAdmin($currentLoggedInUser->getUID()) && !$subAdminManager->isUserAccessible($currentLoggedInUser, $targetUser)) {
			throw new OCSException('', \OCP\API::RESPOND_UNAUTHORISED);
		}

		// enable/disable the user now
		$targetUser->setEnabled($value);
		return new DataResponse();
	}

	/**
	 * @NoAdminRequired
	 * @NoSubAdminRequired
	 *
	 * @param string $userId
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function getUsersGroups(string $userId): DataResponse {
		$loggedInUser = $this->userSession->getUser();

		$targetUser = $this->userManager->get($userId);
		if ($targetUser === null) {
			throw new OCSException('', \OCP\API::RESPOND_NOT_FOUND);
		}

		if ($targetUser->getUID() === $loggedInUser->getUID() || $this->groupManager->isAdmin($loggedInUser->getUID())) {
			// Self lookup or admin lookup
			return new DataResponse([
				'groups' => $this->groupManager->getUserGroupIds($targetUser)
			]);
		} else {
			$subAdminManager = $this->groupManager->getSubAdmin();

			// Looking up someone else
			if ($subAdminManager->isUserAccessible($loggedInUser, $targetUser)) {
				// Return the group that the method caller is subadmin of for the user in question
				/** @var IGroup[] $getSubAdminsGroups */
				$getSubAdminsGroups = $subAdminManager->getSubAdminsGroups($loggedInUser);
				foreach ($getSubAdminsGroups as $key => $group) {
					$getSubAdminsGroups[$key] = $group->getGID();
				}
				$groups = array_intersect(
					$getSubAdminsGroups,
					$this->groupManager->getUserGroupIds($targetUser)
				);
				return new DataResponse(['groups' => $groups]);
			} else {
				// Not permitted
				throw new OCSException('', \OCP\API::RESPOND_UNAUTHORISED);
			}
		}

	}

	/**
	 * @PasswordConfirmationRequired
	 * @NoAdminRequired
	 *
	 * @param string $userId
	 * @param string $groupid
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function addToGroup(string $userId, string $groupid = ''): DataResponse {
		if ($groupid === '') {
			throw new OCSException('', 101);
		}

		$group = $this->groupManager->get($groupid);
		$targetUser = $this->userManager->get($userId);
		if ($group === null) {
			throw new OCSException('', 102);
		}
		if ($targetUser === null) {
			throw new OCSException('', 103);
		}

		// If they're not an admin, check they are a subadmin of the group in question
		$loggedInUser = $this->userSession->getUser();
		$subAdminManager = $this->groupManager->getSubAdmin();
		if (!$this->groupManager->isAdmin($loggedInUser->getUID()) && !$subAdminManager->isSubAdminOfGroup($loggedInUser, $group)) {
			throw new OCSException('', 104);
		}

		// Add user to group
		$group->addUser($targetUser);
		return new DataResponse();
	}

	/**
	 * @PasswordConfirmationRequired
	 * @NoAdminRequired
	 *
	 * @param string $userId
	 * @param string $groupid
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function removeFromGroup(string $userId, string $groupid): DataResponse {
		$loggedInUser = $this->userSession->getUser();

		if ($groupid === null || trim($groupid) === '') {
			throw new OCSException('', 101);
		}

		$group = $this->groupManager->get($groupid);
		if ($group === null) {
			throw new OCSException('', 102);
		}

		$targetUser = $this->userManager->get($userId);
		if ($targetUser === null) {
			throw new OCSException('', 103);
		}

		// If they're not an admin, check they are a subadmin of the group in question
		$subAdminManager = $this->groupManager->getSubAdmin();
		if (!$this->groupManager->isAdmin($loggedInUser->getUID()) && !$subAdminManager->isSubAdminOfGroup($loggedInUser, $group)) {
			throw new OCSException('', 104);
		}

		// Check they aren't removing themselves from 'admin' or their 'subadmin; group
		if ($targetUser->getUID() === $loggedInUser->getUID()) {
			if ($this->groupManager->isAdmin($loggedInUser->getUID())) {
				if ($group->getGID() === 'admin') {
					throw new OCSException('Cannot remove yourself from the admin group', 105);
				}
			} else {
				// Not an admin, so the user must be a subadmin of this group, but that is not allowed.
				throw new OCSException('Cannot remove yourself from this group as you are a SubAdmin', 105);
			}

		} else if (!$this->groupManager->isAdmin($loggedInUser->getUID())) {
			/** @var IGroup[] $subAdminGroups */
			$subAdminGroups = $subAdminManager->getSubAdminsGroups($loggedInUser);
			$subAdminGroups = array_map(function (IGroup $subAdminGroup) {
				return $subAdminGroup->getGID();
			}, $subAdminGroups);
			$userGroups = $this->groupManager->getUserGroupIds($targetUser);
			$userSubAdminGroups = array_intersect($subAdminGroups, $userGroups);

			if (count($userSubAdminGroups) <= 1) {
				// Subadmin must not be able to remove a user from all their subadmin groups.
				throw new OCSException('Cannot remove user from this group as this is the only remaining group you are a SubAdmin of', 105);
			}
		}

		// Remove user from group
		$group->removeUser($targetUser);
		return new DataResponse();
	}

	/**
	 * Creates a subadmin
	 *
	 * @PasswordConfirmationRequired
	 *
	 * @param string $userId
	 * @param string $groupid
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function addSubAdmin(string $userId, string $groupid): DataResponse {
		$group = $this->groupManager->get($groupid);
		$user = $this->userManager->get($userId);

		// Check if the user exists
		if ($user === null) {
			throw new OCSException('User does not exist', 101);
		}
		// Check if group exists
		if ($group === null) {
			throw new OCSException('Group does not exist',  102);
		}
		// Check if trying to make subadmin of admin group
		if ($group->getGID() === 'admin') {
			throw new OCSException('Cannot create subadmins for admin group', 103);
		}

		$subAdminManager = $this->groupManager->getSubAdmin();

		// We cannot be subadmin twice
		if ($subAdminManager->isSubAdminOfGroup($user, $group)) {
			return new DataResponse();
		}
		// Go
		if ($subAdminManager->createSubAdmin($user, $group)) {
			return new DataResponse();
		} else {
			throw new OCSException('Unknown error occurred', 103);
		}
	}

	/**
	 * Removes a subadmin from a group
	 *
	 * @PasswordConfirmationRequired
	 *
	 * @param string $userId
	 * @param string $groupid
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function removeSubAdmin(string $userId, string $groupid): DataResponse {
		$group = $this->groupManager->get($groupid);
		$user = $this->userManager->get($userId);
		$subAdminManager = $this->groupManager->getSubAdmin();

		// Check if the user exists
		if ($user === null) {
			throw new OCSException('User does not exist', 101);
		}
		// Check if the group exists
		if ($group === null) {
			throw new OCSException('Group does not exist', 101);
		}
		// Check if they are a subadmin of this said group
		if (!$subAdminManager->isSubAdminOfGroup($user, $group)) {
			throw new OCSException('User is not a subadmin of this group', 102);
		}

		// Go
		if ($subAdminManager->deleteSubAdmin($user, $group)) {
			return new DataResponse();
		} else {
			throw new OCSException('Unknown error occurred', 103);
		}
	}

	/**
	 * Get the groups a user is a subadmin of
	 *
	 * @param string $userId
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function getUserSubAdminGroups(string $userId): DataResponse {
		$groups = $this->getUserSubAdminGroupsData($userId);
		return new DataResponse($groups);
	}

	/**
	 * @NoAdminRequired
	 * @PasswordConfirmationRequired
	 *
	 * resend welcome message
	 *
	 * @param string $userId
	 * @return DataResponse
	 * @throws OCSException
	 */
	public function resendWelcomeMessage(string $userId): DataResponse {
		$currentLoggedInUser = $this->userSession->getUser();

		$targetUser = $this->userManager->get($userId);
		if ($targetUser === null) {
			throw new OCSException('', \OCP\API::RESPOND_NOT_FOUND);
		}

		// Check if admin / subadmin
		$subAdminManager = $this->groupManager->getSubAdmin();
		if (!$subAdminManager->isUserAccessible($currentLoggedInUser, $targetUser)
			&& !$this->groupManager->isAdmin($currentLoggedInUser->getUID())) {
			// No rights
			throw new OCSException('', \OCP\API::RESPOND_UNAUTHORISED);
		}

		$email = $targetUser->getEMailAddress();
		if ($email === '' || $email === null) {
			throw new OCSException('Email address not available', 101);
		}
		$username = $targetUser->getUID();
		$lang = $this->config->getUserValue($username, 'core', 'lang', 'en');
		if (!$this->l10nFactory->languageExists('settings', $lang)) {
			$lang = 'en';
		}

		$l10n = $this->l10nFactory->get('settings', $lang);

		try {
			$this->newUserMailHelper->setL10N($l10n);
			$emailTemplate = $this->newUserMailHelper->generateTemplate($targetUser, false);
			$this->newUserMailHelper->sendMail($targetUser, $emailTemplate);
		} catch(\Exception $e) {
			$this->logger->logException($e, [
				'message' => "Can't send new user mail to $email",
				'level' => \OCP\Util::ERROR,
				'app' => 'settings',
			]);
			throw new OCSException('Sending email failed', 102);
		}

		return new DataResponse();
	}
}