<?php

/**
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; under version 2
 * of the License (non-upgradable).
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright (c) 2013 (original work) Open Assessment Technologies SA (under the project TAO-PRODUCT);
 *
 */

use oat\oatbox\service\ConfigurableService;

/**
 * Session implementation as a Key Value storage and using the persistence
 *
 * @author Joel Bout <joel@taotesting.com>
 * @package generis
 */
class common_session_php_KeyValueSessionHandler extends ConfigurableService implements common_session_php_SessionHandler
{
    public const OPTION_PERSISTENCE = 'persistence';
    public const OPTION_SESSION_TTL = 'session_ttl';

    public const KEY_NAMESPACE = 'generis:session:';

    /** @var common_persistence_KeyValuePersistence */
    private $sessionPersistence;

    protected function getPersistence()
    {
        if (is_null($this->sessionPersistence)) {
            $this->sessionPersistence = common_persistence_KeyValuePersistence::getPersistence($this->getOption(self::OPTION_PERSISTENCE));
        }

        return $this->sessionPersistence;
    }

    /**
     * (non-PHPdoc)
     * @see common_session_storage_SessionStorage::open()
     */
    public function open($savePath, $sessionName)
    {
           return true;
    }

    /**
     * (non-PHPdoc)
     * @see common_session_storage_SessionStorage::close()
     */
    public function close()
    {
        return true;
    }

    /**
     * (non-PHPdoc)
     * @see common_session_storage_SessionStorage::read()
     */
    public function read($id)
    {
        $session = $this->getPersistence()->get(self::KEY_NAMESPACE . $id);
        return is_string($session) ? $session : '';
    }

    /**
     * (non-PHPdoc)
     * @see common_session_storage_SessionStorage::write()
     */
    public function write($id, $data)
    {
        return $this->getPersistence()->set(self::KEY_NAMESPACE . $id, $data, $this->getSessionTtl());
    }

    /**
     * (non-PHPdoc)
     * @see common_session_storage_SessionStorage::destroy()
     */
    public function destroy($id)
    {
        $this->getPersistence()->del(self::KEY_NAMESPACE . $id);
        return true;
    }

    /**
     * (non-PHPdoc)
     * @see common_session_storage_SessionStorage::gc()
     */
    public function gc($maxlifetime)
    {
        //
        //problem here either
        // solution 1 : do two explicit handlers for each specific persistence (Redis, SQL)
        // solution 2 : Check if the eprsistence is capable of autonomous garbage
        //
        return true;
    }

    private function getSessionTtl(): int
    {
        return $this->getOption(self::OPTION_SESSION_TTL) ?? (int)ini_get('session.gc_maxlifetime');
    }
}