<?php
/**
 * @author Arthur Schiwon <blizzz@arthur-schiwon.de>
 * @author Bart Visscher <bartv@thisnet.nl>
 * @author Christopher Schäpers <kondou@ts.unde.re>
 * @author Joas Schilling <coding@schilljs.com>
 * @author Jörn Friedrich Dreyer <jfd@butonic.de>
 * @author Lukas Reschke <lukas@statuscode.ch>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Robin McCorkell <robin@mccorkell.me.uk>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 *
 * @copyright Copyright (c) 2016, ownCloud GmbH.
 * @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\User_LDAP;

use OCA\User_LDAP\Mapping\UserMapping;
use OCA\User_LDAP\Mapping\GroupMapping;
use OCA\User_LDAP\User\Manager;

abstract class Proxy {
	private static $accesses = [];
	private $ldap = null;

	/** @var \OCP\ICache|null */
	private $cache;

	/**
	 * @param ILDAPWrapper $ldap
	 */
	public function __construct(ILDAPWrapper $ldap) {
		$this->ldap = $ldap;
		$memcache = \OC::$server->getMemCacheFactory();
		if ($memcache->isAvailable()) {
			$this->cache = $memcache->create();
		}
	}

	/**
	 * @param string $configPrefix
	 */
	private function addAccess($configPrefix) {
		static $coreConfig;
		static $fs;
		static $logger;
		static $avatarM;
		static $userMap;
		static $groupMap;
		static $db;
		static $coreUserManager;
		static $helper;
		if ($fs === null) {
			$coreConfig = \OC::$server->getConfig();
			$fs       = new FilesystemHelper();
			$logger   = \OC::$server->getLogger();
			$avatarM  = \OC::$server->getAvatarManager();
			$db       = \OC::$server->getDatabaseConnection();
			$userMap  = new UserMapping($db);
			$groupMap = new GroupMapping($db);
			$coreUserManager = \OC::$server->getUserManager();
			$helper   = new Helper();
		}
		$userManager =
			new Manager($coreConfig, $fs, $logger, $avatarM, $db, $coreUserManager);

		$configuration = new Configuration($coreConfig, $configPrefix);
		$connector = new Connection($this->ldap, $configuration);

		$access = new Access($connector, $userManager);
		$access->setUserMapper($userMap);
		$access->setGroupMapper($groupMap);
		self::$accesses[$configPrefix] = $access;
	}

	/**
	 * @param string $configPrefix
	 * @return Access
	 */
	protected function getAccess($configPrefix) {
		if (!isset(self::$accesses[$configPrefix])) {
			$this->addAccess($configPrefix);
		}
		return self::$accesses[$configPrefix];
	}

	/**
	 * @param string $uid
	 * @return string
	 */
	protected function getUserCacheKey($uid) {
		return "user-$uid-lastSeenOn";
	}

	/**
	 * @param string $gid
	 * @return string
	 */
	protected function getGroupCacheKey($gid) {
		return "group-$gid-lastSeenOn";
	}

	/**
	 * @param string $id
	 * @param string $method
	 * @param array $parameters
	 * @param bool $passOnWhen
	 * @return mixed
	 */
	abstract protected function callOnLastSeenOn($id, $method, $parameters, $passOnWhen);

	/**
	 * @param string $id
	 * @param string $method
	 * @param array $parameters
	 * @return mixed
	 */
	abstract protected function walkBackends($id, $method, $parameters);

	/**
	 * Takes care of the request to the User backend
	 * @param string $id
	 * @param string $method string, the method of the user backend that shall be called
	 * @param array $parameters an array of parameters to be passed
	 * @param bool $passOnWhen
	 * @return mixed, the result of the specified method
	 */
	protected function handleRequest($id, $method, $parameters, $passOnWhen = false) {
		$result = $this->callOnLastSeenOn($id, $method, $parameters, $passOnWhen);
		if ($result === $passOnWhen) {
			$result = $this->walkBackends($id, $method, $parameters);
		}// FIXME return null if result is false ... the user then is unknown. Exception?
		return $result;
	}

	/**
	 * @param string|null $key
	 * @return string
	 */
	private function getCacheKey($key) {
		$prefix = 'LDAP-Proxy-';
		if ($key === null) {
			return $prefix;
		}
		return $prefix.\md5($key);
	}

	/**
	 * @param string $key
	 * @return mixed|null
	 */
	public function getFromCache($key) {
		if ($this->cache === null || !$this->isCached($key)) {
			return null;
		}
		$key = $this->getCacheKey($key);

		return \json_decode(\base64_decode($this->cache->get($key)));
	}

	/**
	 * @param string $key
	 * @return bool
	 */
	public function isCached($key) {
		if ($this->cache === null) {
			return false;
		}
		$key = $this->getCacheKey($key);
		return $this->cache->hasKey($key);
	}

	/**
	 * @param string $key
	 * @param mixed $value
	 */
	public function writeToCache($key, $value) {
		if ($this->cache === null) {
			return;
		}
		$key   = $this->getCacheKey($key);
		$value = \base64_encode(\json_encode($value));
		$this->cache->set($key, $value, '2592000');
	}

	public function clearCache() {
		if ($this->cache === null) {
			return;
		}
		$this->cache->clear($this->getCacheKey(null));
	}
}