<?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) 2002-2008 (original work) Public Research Centre Henri Tudor & University of Luxembourg (under the project TAO & TAO2);
 *               2008-2010 (update and modification) Deutsche Institut für Internationale Pädagogische Forschung (under the project TAO-TRANSFER);
 *               2009-2012 (update and modification) Public Research Centre Henri Tudor (under the project TAO-SUSTAIN & TAO-DEV);
 *
 */

use oat\oatbox\service\ServiceManager;
use oat\oatbox\cache\SimpleCache;

/**
 * A facade aiming at helping client code to put User data in the Cache memory.
 *
 * @access public
 * @author Jerome Bogaerts, <jerome.bogaerts@tudor.lu>
 * @package generis

 */
class core_kernel_users_Cache
{
    // --- ASSOCIATIONS ---


    // --- ATTRIBUTES ---

    /**
     * Short description of attribute SERIAL_PREFIX_INCLUDED_ROLES
     *
     * @access public
     * @var string
     */
    const SERIAL_PREFIX_INCLUDED_ROLES = 'roles-ir';
    // --- OPERATIONS ---

    /**
     * Retrieve roles included in a given Generis Role from the Cache memory.
     *
     * @access public
     * @author Jerome Bogaerts, <jerome.bogaerts@tudor.lu>
     *
     * @param  core_kernel_classes_Resource $role A Generis Role Resource.
     *
     * @return array
     * @throws \oat\oatbox\service\ServiceNotFoundException
     * @throws common_Exception
     * @throws core_kernel_users_CacheException
     */
    public static function retrieveIncludedRoles(core_kernel_classes_Resource $role)
    {
        $returnValue = [];
        $serial = self::buildIncludedRolesSerial($role);
        $fromCache = ServiceManager::getServiceManager()->get(SimpleCache::SERVICE_ID)->get($serial);
        // array of URIs.
        if (is_null($fromCache)) {
            $roleUri = $role->getUri();
            $msg = "Includes roles related to Role with URI '${roleUri}' is not in the Cache memory.";
            throw new core_kernel_users_CacheException($msg);
        }

        foreach ($fromCache as $uri) {
            $returnValue[$uri] = new core_kernel_classes_Resource($uri);
        }

        return (array) $returnValue;
    }

    /**
     * Put roles included in a Generis Role in the Cache memory.
     *
     * @access public
     * @author Jerome Bogaerts, <jerome.bogaerts@tudor.lu>
     *
     * @param  core_kernel_classes_Resource $role
     * @param  array $includedRoles
     *
     * @return bool
     * @throws \oat\oatbox\service\ServiceNotFoundException
     * @throws common_Exception
     * @throws core_kernel_users_CacheException
     */
    public static function cacheIncludedRoles(core_kernel_classes_Resource $role, $includedRoles)
    {
        // Make a simple array of URIs with the included roles.
        $toCache = [];
        foreach ($includedRoles as $resource) {
            $toCache[] = $resource->getUri();
        }
        
        $serial = self::buildIncludedRolesSerial($role);
        /** @var SimpleCache $cache */
        $cache = ServiceManager::getServiceManager()->get(SimpleCache::SERVICE_ID);
        try {
            $cache->set($serial, $toCache);
            $returnValue = true;
        } catch (common_Exception $e) {
            $roleUri = $role->getUri();
            $msg = "An error occurred while writing included roles in the cache memory for Role '${roleUri}': ";
            $msg .= $e->getMessage();
            throw new core_kernel_users_CacheException($msg);
        }
        

        return (bool) $returnValue;
    }

    /**
     * Remove roles included in a Generis Role from the Cache memory.
     *
     * @access public
     * @author Jerome Bogaerts, <jerome.bogaerts@tudor.lu>
     * @param  core_kernel_classes_Resource $role A Generis Role as a Resource.
     * @return boolean
     */
    public static function removeIncludedRoles(core_kernel_classes_Resource $role)
    {
        $serial = self::buildIncludedRolesSerial($role);
        ServiceManager::getServiceManager()->get('generis/cache')->remove($serial);
        ;

        // -- note: the cache might exist even if it was successfully
        // removed due to race conditions.
        // $returnValue = (file_exists(GENERIS_CACHE_PATH . $serial)) ? false : true;
        return true;
    }

    /**
     * Returns true if the roles included in a given Generis Role are in the
     * memory.
     *
     * @access public
     * @author Jerome Bogaerts, <jerome.bogaerts@tudor.lu>
     * @param  core_kernel_classes_Resource $role The Generis Role you want to check if its included roles are in the cache memory.
     * @return boolean
     */
    public static function areIncludedRolesInCache(core_kernel_classes_Resource $role)
    {

        $serial = self::buildIncludedRolesSerial($role);
        return ServiceManager::getServiceManager()->get('generis/cache')->has($serial);
    }

    /**
     * Build a serial aiming at identifying the includes roles of a given
     * Role in the Cache memory.
     *
     * @access private
     * @author Jerome Bogaerts, <jerome.bogaerts@tudor.lu>
     * @param  core_kernel_classes_Resource $role The role you want to create a serial for.
     * @return string
     */
    private static function buildIncludedRolesSerial(core_kernel_classes_Resource $role)
    {
        return self::SERIAL_PREFIX_INCLUDED_ROLES . urlencode($role->getUri());
    }

    /**
     * Removes all entries related to included roles from the Cache memory.
     *
     * @access public
     * @author Jerome Bogaerts, <jerome.bogaerts@tudor.lu>
     * @return void
     */
    public static function flush()
    {
        ServiceManager::getServiceManager()->get('generis/cache')->purge();
    }
}