<?php

declare(strict_types=1);

/**
 * @copyright Copyright (c) 2017 Julius Härtl <jus@bitgrid.net>
 * @copyright Copyright (c) 2017 Pellaeon Lin <pellaeon@hs.ntnu.edu.tw>
 * @copyright Copyright (c) 2017 Lukas Reschke <lukas@statuscode.ch>
 *
 * @author Julius Härtl <jus@bitgrid.net>
 * @author Pellaeon Lin <pellaeon@hs.ntnu.edu.tw>
 * @author Lukas Reschke <lukas@statuscode.ch>
 *
 * @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\Registration\Service;

use OC\Authentication\Exceptions\InvalidTokenException;
use OC\Authentication\Exceptions\PasswordlessTokenException;
use OC\Authentication\Token\IProvider;
use OC\Authentication\Token\IToken;
use OCA\Registration\Db\Registration;
use OCA\Registration\Db\RegistrationMapper;
use OCP\AppFramework\Db\DoesNotExistException;
use OCP\ILogger;
use OCP\IRequest;
use OCP\ISession;
use OCP\IURLGenerator;
use OCP\IUser;
use OCP\Security\ICrypto;
use OCP\Session\Exceptions\SessionNotAvailableException;
use \OCP\IUserManager;
use \OCP\IUserSession;
use \OCP\IGroupManager;
use \OCP\IL10N;
use \OCP\IConfig;
use \OCP\Security\ISecureRandom;

class RegistrationService {

	/** @var string */
	private $appName;
	/** @var MailService */
	private $mailService;
	/** @var IL10N */
	private $l10n;
	/** @var IURLGenerator */
	private $urlGenerator;
	/** @var RegistrationMapper */
	private $registrationMapper;
	/** @var IUserManager */
	private $userManager;
	/** @var IConfig */
	private $config;
	/** @var IGroupManager */
	private $groupManager;
	/** @var ISecureRandom */
	private $random;
	/** @var IUserSession  */
	private $userSession;
	/** @var IRequest */
	private $request;
	/** @var ILogger */
	private $logger;
	/** @var ISession */
	private $session;
	/** @var IProvider */
	private $tokenProvider;
	/** @var ICrypto */
	private $crypto;

	public function __construct(
		string $appName,
		MailService $mailService,
		IL10N $l10n,
		IURLGenerator $urlGenerator,
		RegistrationMapper $registrationMapper,
		IUserManager $userManager,
		IConfig $config,
		IGroupManager $groupManager,
		ISecureRandom $random,
		IUserSession $userSession,
		IRequest $request,
		ILogger $logger,
		ISession $session,
		IProvider $tokenProvider,
		ICrypto $crypto
	) {
		$this->appName = $appName;
		$this->mailService = $mailService;
		$this->l10n = $l10n;
		$this->urlGenerator = $urlGenerator;
		$this->registrationMapper = $registrationMapper;
		$this->userManager = $userManager;
		$this->config = $config;
		$this->groupManager = $groupManager;
		$this->random = $random;
		$this->userSession = $userSession;
		$this->request = $request;
		$this->logger = $logger;
		$this->session = $session;
		$this->tokenProvider = $tokenProvider;
		$this->crypto = $crypto;
	}

	public function confirmEmail(Registration $registration): void {
		$registration->setEmailConfirmed(true);
		$this->registrationMapper->update($registration);
	}

	public function generateNewToken(Registration $registration): void {
		$this->registrationMapper->generateNewToken($registration);
		$this->registrationMapper->update($registration);
	}

	/**
	 * Create registration request, used by both the API and form
	 * @param string $email
	 * @param string $username
	 * @param string $password
	 * @param string $displayname
	 * @return Registration
	 */
	public function createRegistration(string $email, string $username = '', string $password = '', string $displayname = ''): Registration {
		$registration = new Registration();
		$registration->setEmail($email);
		$registration->setUsername($username);
		$registration->setDisplayname($displayname);
		if ($password !== "") {
			$password = $this->crypto->encrypt($password);
			$registration->setPassword($password);
		}
		$this->registrationMapper->generateNewToken($registration);
		$this->registrationMapper->generateClientSecret($registration);
		$this->registrationMapper->insert($registration);
		return $registration;
	}

	/**
	 * @param string $email
	 * @throws RegistrationException
	 */
	public function validateEmail(string $email): void {
		$this->mailService->validateEmail($email);

		// check for pending registrations
		try {
			$this->registrationMapper->find($email);//if not found DB will throw a exception
			throw new RegistrationException(
				$this->l10n->t('A user has already taken this email, maybe you already have an account?')
			);
		} catch (DoesNotExistException $e) {
		}

		if ($this->userManager->getByEmail($email)) {
			throw new RegistrationException(
				$this->l10n->t('A user has already taken this email, maybe you already have an account?'),
				$this->l10n->t('You can <a href="%s">log in now</a>.', [$this->urlGenerator->getAbsoluteURL('/')])
			);
		}

		if (!$this->checkAllowedDomains($email)) {
			throw new RegistrationException(
				$this->l10n->t(
					'Registration is only allowed for the following domains: ' .
					$this->config->getAppValue($this->appName, 'allowed_domains', '')
				)
			);
		}
	}

	/**
	 * @param string $displayname
	 * @throws RegistrationException
	 */
	public function validateDisplayname(string $displayname): void {
		if ($displayname === '') {
			throw new RegistrationException($this->l10n->t('Please provide a valid display name.'));
		}
	}

	/**
	 * @param string $username
	 * @throws RegistrationException
	 */
	public function validateUsername(string $username): void {
		if ($username === "") {
			throw new RegistrationException($this->l10n->t('Please provide a valid user name.'));
		}

		if ($this->registrationMapper->usernameIsPending($username) || $this->userManager->get($username) !== null) {
			throw new RegistrationException($this->l10n->t('The username you have chosen already exists.'));
		}
	}

	/**
	 * check if email domain is allowed
	 *
	 * @param string $email
	 * @return bool
	 */
	public function checkAllowedDomains(string $email): bool {
		$allowedDomains = $this->config->getAppValue($this->appName, 'allowed_domains', '');
		if ($allowedDomains !== '') {
			[,$mailDomain] = explode('@', strtolower($email), 2);
			$allowedDomains = explode(';', strtolower($allowedDomains));

			foreach ($allowedDomains as $domain) {
				// valid domain, everything's fine
				if ($mailDomain === $domain) {
					return true;
				}
			}
			return false;
		}
		return true;
	}

	/**
	 * @return string[]
	 */
	public function getAllowedDomains(): array {
		$allowedDomains = $this->config->getAppValue($this->appName, 'allowed_domains', '');
		$allowedDomains = explode(';', $allowedDomains);
		return $allowedDomains;
	}

	/**
	 * Find registration entity for token
	 *
	 * @param string $token
	 * @return Registration
	 * @throws RegistrationException
	 */
	public function verifyToken(string $token): Registration {
		try {
			return $this->registrationMapper->findByToken($token);
		} catch (DoesNotExistException $exception) {
			throw new RegistrationException($this->l10n->t('Invalid verification URL. No registration request with this verification URL is found.', 404));
		}
	}

	/**
	 * @param $registration
	 * @param string|null $username
	 * @param string|null $password
	 * @return IUser
	 * @throws RegistrationException|InvalidTokenException
	 */
	public function createAccount(Registration $registration, ?string $username = null, ?string $password = null): IUser {
		if ($password === null && $registration->getPassword() === null) {
			$generatedPassword = $this->generateRandomDeviceToken();
			$registration->setPassword($this->crypto->encrypt($generatedPassword));
		}

		if ($username === null) {
			$username = $registration->getUsername();
		}

		if ($registration->getPassword() !== null) {
			$password = $this->crypto->decrypt($registration->getPassword());
		}

		$this->validateUsername($username);

		/* TODO
		 * createUser tests username validity once, but validateUsername already checked it,
		 * but createUser doesn't check if there is a pending registration with that name
		 *
		 * And validateUsername will throw RegistrationException while
		 * createUser throws \InvalidTokenException in NC, \Exception in OC
		 */
		$user = $this->userManager->createUser($username, $password);
		if ($user === false) {
			throw new RegistrationException($this->l10n->t('Unable to create user, there are problems with the user backend.'));
		}
		$userId = $user->getUID();

		// Set user email
		try {
			$user->setEMailAddress($registration->getEmail());
		} catch (\Exception $e) {
			throw new RegistrationException($this->l10n->t('Unable to set user email: ' . $e->getMessage()));
		}

		// Add user to group
		$registeredUserGroup = $this->config->getAppValue($this->appName, 'registered_user_group', 'none');
		if ($registeredUserGroup !== 'none') {
			$group = $this->groupManager->get($registeredUserGroup);
			if ($group === null) {
				// This might happen if $registered_user_group is deleted after setting the value
				// Here I choose to log error instead of stopping the user to register
				$this->logger->error("You specified newly registered users be added to '$registeredUserGroup' group, but it does not exist.");
				$groupId = '';
			} else {
				$group->addUser($user);
				$groupId = $group->getGID();
			}
		} else {
			$groupId = '';
		}

		// disable user if this is requested by config
		$adminApprovalRequired = $this->config->getAppValue($this->appName, 'admin_approval_required', 'no');
		if ($adminApprovalRequired === 'yes') {
			$user->setEnabled(false);
		}

		$this->mailService->notifyAdmins($userId, $user->isEnabled(), $groupId);
		return $user;
	}

	/**
	 * @param string $email
	 * @return Registration
	 * @throws DoesNotExistException
	 */
	public function getRegistrationForEmail(string $email): Registration {
		return $this->registrationMapper->find($email);
	}

	/**
	 * @param string $token
	 * @return Registration
	 * @throws DoesNotExistException
	 */
	public function getRegistrationForToken(string $token): Registration {
		return $this->registrationMapper->findByToken($token);
	}

	/**
	 * @param string $secret
	 * @return Registration
	 * @throws DoesNotExistException
	 */
	public function getRegistrationForSecret(string $secret): Registration {
		return $this->registrationMapper->findBySecret($secret);
	}

	public function getUserAccount(Registration $registration): ?IUser {
		return $this->userManager->get($registration->getUsername());
	}

	public function deleteRegistration(Registration $registration): void {
		$this->registrationMapper->delete($registration);
	}

	/**
	 * Return a 25 digit device password
	 *
	 * Example: AbCdE-fGhIj-KlMnO-pQrSt-12345
	 *
	 * @return string
	 */
	private function generateRandomDeviceToken(): string {
		$groups = [];
		for ($i = 0; $i < 5; $i++) {
			$groups[] = $this->random->generate(5, ISecureRandom::CHAR_HUMAN_READABLE);
		}
		return implode('-', $groups);
	}

	/**
	 * @param string $uid
	 * @return string
	 * @throws RegistrationException
	 */
	public function generateAppPassword(string $uid): string {
		$name = $this->l10n->t('Registration app auto setup');
		try {
			$sessionId = $this->session->getId();
		} catch (SessionNotAvailableException $ex) {
			throw new RegistrationException('Failed to generate an app token.');
		}

		try {
			$sessionToken = $this->tokenProvider->getToken($sessionId);
			$loginName = $sessionToken->getLoginName();
			try {
				$password = $this->tokenProvider->getPassword($sessionToken, $sessionId);
			} catch (PasswordlessTokenException $ex) {
				$password = null;
			}
		} catch (InvalidTokenException $ex) {
			throw new RegistrationException('Failed to generate an app token.');
		}

		$token = $this->generateRandomDeviceToken();
		$this->tokenProvider->generateToken($token, $uid, $loginName, $password, $name, IToken::PERMANENT_TOKEN);
		return $token;
	}

	/**
	 * @param string $userId
	 * @param string $username
	 * @param string $password
	 * @param bool $decrypt
	 */
	public function loginUser(string $userId, string $username, string $password, bool $decrypt = false): void {
		if ($decrypt) {
			$password = $this->crypto->decrypt($password);
		}

		$this->userSession->login($username, $password);
		$this->userSession->createSessionToken($this->request, $userId, $username, $password);
	}

	/**
	 * Replicates OC::cleanupLoginTokens() since it's protected
	 * @param string $userId
	 */
	public function cleanupLoginTokens(string $userId): void {
		$cutoff = time() - $this->config->getSystemValue('remember_login_cookie_lifetime', 60 * 60 * 24 * 15);
		$tokens = $this->config->getUserKeys($userId, 'login_token');
		foreach ($tokens as $token) {
			$time = $this->config->getUserValue($userId, 'login_token', $token);
			if ($time < $cutoff) {
				$this->config->deleteUserValue($userId, 'login_token', $token);
			}
		}
	}
}