<?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\ServiceManager;
use oat\oatbox\service\ConfigurableService;
use oat\tao\model\state\StateStorage;

/**
 * Persistence for the item delivery service
 *
 * @access public
 * @author Joel Bout, <joel@taotesting.com>
 * @package tao
 */
class tao_models_classes_service_StateStorage extends ConfigurableService implements StateStorage
{
    /**
     * @var string name of former hardcoded persistence
     * @deprecated
     */
    const PERSISTENCE_ID = 'serviceState';
    
    const KEY_NAMESPACE = 'tao:state:';
    
    const OPTION_PERSISTENCE = 'persistence';
    
    /**
     * @deprecated
     */
    public static function singleton()
    {
        return ServiceManager::getServiceManager()->getServiceManager()->get(StateStorage::SERVICE_ID);
    }
    
    /**
     * Persistence to store service states to
     *
     * @var common_persistence_KeyValuePersistence
     */
    private $persistence;
    
    /**
     * protected constructor to ensure singleton pattern
     */
    protected function getPersistence()
    {
        if (is_null($this->persistence)) {
            $this->persistence = common_persistence_KeyValuePersistence::getPersistence($this->getOption(self::OPTION_PERSISTENCE));
        }
        return $this->persistence;
    }
    
    /**
     * Store the state of the service call
     *
     * @param string $userId
     * @param string $callId
     * @param string $data
     * @return boolean
     */
    public function set($userId, $callId, $data)
    {
        $key = $this->getSerial($userId, $callId);
        return $this->getPersistence()->set($key, $data);
    }
    
    /**
     * Retore the state of the service call
     * Returns null if no state is found
     *
     * @param string $userId
     * @param string $callId
     * @return string
     */
    public function get($userId, $callId)
    {
        $key = $this->getSerial($userId, $callId);
        $returnValue = $this->getPersistence()->get($key);
        if ($returnValue === false && !$this->has($userId, $callId)) {
            $returnValue = null;
        }
        return $returnValue;
    }
    
    /**
     * Whenever or not a state for this service call exists
     *
     * @param string $userId
     * @param string $callId
     * @return boolean
     */
    public function has($userId, $callId)
    {
        $key = $this->getSerial($userId, $callId);
        return $this->getPersistence()->exists($key);
    }
    
    /**
     * Remove the state for this service call
     *
     * @param string $userId
     * @param string $callId
     * @return boolean
     */
    public function del($userId, $callId)
    {
        $key = $this->getSerial($userId, $callId);
        return $this->getPersistence()->del($key);
    }
    
    /**
     * Generate a storage key using the provide user and serial
     *
     * @param string $userId
     * @param string $callId
     * @return string
     */
    private function getSerial($userId, $callId)
    {
        if (is_object($userId)) {
            common_Logger::w('Object as userid: ' . get_class($userId));
            if ($userId instanceof core_kernel_classes_Resource) {
                $userId = $userId->getUri();
            }
        }
        return self::KEY_NAMESPACE . $userId . '_' . $callId;
        ;
    }
}