<?php
/**
 * @copyright Copyright (c) 2016, ownCloud, Inc.
 *
 * @author Arthur Schiwon <blizzz@arthur-schiwon.de>
 * @author Bjoern Schiessle <bjoern@schiessle.org>
 * @author Björn Schießle <bjoern@schiessle.org>
 * @author Christoph Wurst <christoph@winzerhof-wurst.at>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Roeland Jago Douma <roeland@famdouma.nl>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 *
 * @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\Federation;

use OCA\Federation\BackgroundJob\RequestSharedSecret;
use OCP\AppFramework\Http;
use OCP\AppFramework\Utility\ITimeFactory;
use OCP\BackgroundJob\IJobList;
use OCP\HintException;
use OCP\Http\Client\IClientService;
use OCP\IConfig;
use OCP\ILogger;
use OCP\Security\ISecureRandom;
use Symfony\Component\EventDispatcher\EventDispatcherInterface;
use Symfony\Component\EventDispatcher\GenericEvent;

class TrustedServers {

	/** after a user list was exchanged at least once successfully */
	public const STATUS_OK = 1;
	/** waiting for shared secret or initial user list exchange */
	public const STATUS_PENDING = 2;
	/** something went wrong, misconfigured server, software bug,... user interaction needed */
	public const STATUS_FAILURE = 3;
	/** remote server revoked access */
	public const STATUS_ACCESS_REVOKED = 4;

	/** @var  dbHandler */
	private $dbHandler;

	/** @var  IClientService */
	private $httpClientService;

	/** @var ILogger */
	private $logger;

	/** @var IJobList */
	private $jobList;

	/** @var ISecureRandom */
	private $secureRandom;

	/** @var IConfig */
	private $config;

	/** @var EventDispatcherInterface */
	private $dispatcher;

	/** @var ITimeFactory */
	private $timeFactory;

	/**
	 * @param DbHandler $dbHandler
	 * @param IClientService $httpClientService
	 * @param ILogger $logger
	 * @param IJobList $jobList
	 * @param ISecureRandom $secureRandom
	 * @param IConfig $config
	 * @param EventDispatcherInterface $dispatcher
	 * @param ITimeFactory $timeFactory
	 */
	public function __construct(
		DbHandler $dbHandler,
		IClientService $httpClientService,
		ILogger $logger,
		IJobList $jobList,
		ISecureRandom $secureRandom,
		IConfig $config,
		EventDispatcherInterface $dispatcher,
		ITimeFactory $timeFactory
	) {
		$this->dbHandler = $dbHandler;
		$this->httpClientService = $httpClientService;
		$this->logger = $logger;
		$this->jobList = $jobList;
		$this->secureRandom = $secureRandom;
		$this->config = $config;
		$this->dispatcher = $dispatcher;
		$this->timeFactory = $timeFactory;
	}

	/**
	 * add server to the list of trusted servers
	 *
	 * @param $url
	 * @return int server id
	 */
	public function addServer($url) {
		$url = $this->updateProtocol($url);
		$result = $this->dbHandler->addServer($url);
		if ($result) {
			$token = $this->secureRandom->generate(16);
			$this->dbHandler->addToken($url, $token);
			$this->jobList->add(
				RequestSharedSecret::class,
				[
					'url' => $url,
					'token' => $token,
					'created' => $this->timeFactory->getTime()
				]
			);
		}

		return $result;
	}

	/**
	 * get shared secret for the given server
	 *
	 * @param string $url
	 * @return string
	 */
	public function getSharedSecret($url) {
		return $this->dbHandler->getSharedSecret($url);
	}

	/**
	 * add shared secret for the given server
	 *
	 * @param string $url
	 * @param $sharedSecret
	 */
	public function addSharedSecret($url, $sharedSecret) {
		$this->dbHandler->addSharedSecret($url, $sharedSecret);
	}

	/**
	 * remove server from the list of trusted servers
	 *
	 * @param int $id
	 */
	public function removeServer($id) {
		$server = $this->dbHandler->getServerById($id);
		$this->dbHandler->removeServer($id);
		$event = new GenericEvent($server['url_hash']);
		$this->dispatcher->dispatch('OCP\Federation\TrustedServerEvent::remove', $event);
	}

	/**
	 * get all trusted servers
	 *
	 * @return array
	 */
	public function getServers() {
		return $this->dbHandler->getAllServer();
	}

	/**
	 * check if given server is a trusted Nextcloud server
	 *
	 * @param string $url
	 * @return bool
	 */
	public function isTrustedServer($url) {
		return $this->dbHandler->serverExists($url);
	}

	/**
	 * set server status
	 *
	 * @param string $url
	 * @param int $status
	 */
	public function setServerStatus($url, $status) {
		$this->dbHandler->setServerStatus($url, $status);
	}

	/**
	 * @param string $url
	 * @return int
	 */
	public function getServerStatus($url) {
		return $this->dbHandler->getServerStatus($url);
	}

	/**
	 * check if URL point to a ownCloud/Nextcloud server
	 *
	 * @param string $url
	 * @return bool
	 */
	public function isOwnCloudServer($url) {
		$isValidOwnCloud = false;
		$client = $this->httpClientService->newClient();
		try {
			$result = $client->get(
				$url . '/status.php',
				[
					'timeout' => 3,
					'connect_timeout' => 3,
				]
			);
			if ($result->getStatusCode() === Http::STATUS_OK) {
				$isValidOwnCloud = $this->checkOwnCloudVersion($result->getBody());
			}
		} catch (\Exception $e) {
			\OC::$server->getLogger()->logException($e, [
				'message' => 'No Nextcloud server.',
				'level' => ILogger::DEBUG,
				'app' => 'federation',
			]);
			return false;
		}

		return $isValidOwnCloud;
	}

	/**
	 * check if ownCloud version is >= 9.0
	 *
	 * @param $status
	 * @return bool
	 * @throws HintException
	 */
	protected function checkOwnCloudVersion($status) {
		$decoded = json_decode($status, true);
		if (!empty($decoded) && isset($decoded['version'])) {
			if (!version_compare($decoded['version'], '9.0.0', '>=')) {
				throw new HintException('Remote server version is too low. 9.0 is required.');
			}
			return true;
		}
		return false;
	}

	/**
	 * check if the URL contain a protocol, if not add https
	 *
	 * @param string $url
	 * @return string
	 */
	protected function updateProtocol($url) {
		if (
			strpos($url, 'https://') === 0
			|| strpos($url, 'http://') === 0
		) {
			return $url;
		}

		return 'https://' . $url;
	}
}
