<?php

/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package	CodeIgniter
 * @author	EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
 * @license	http://opensource.org/licenses/MIT	MIT License
 * @link	https://codeigniter.com
 * @since	Version 2.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * CodeIgniter Memcached Caching Class
 *
 * @package		CodeIgniter
 * @subpackage	Libraries
 * @category	Core
 * @author		EllisLab Dev Team
 * @link
 */
class CI_Cache_memcached extends CI_Driver {

    /**
     * Holds the memcached object
     *
     * @var object
     */
    protected $_memcached;

    /**
     * Memcached configuration
     *
     * @var array
     */
    protected $_config = array(
        'default' => array(
            'host' => '127.0.0.1',
            'port' => 11211,
            'weight' => 1
        )
    );

    // ------------------------------------------------------------------------

    /**
     * Class constructor
     *
     * Setup Memcache(d)
     *
     * @return	void
     */
    public function __construct() {
        // Try to load memcached server info from the config file.
        $CI = & get_instance();
        $defaults = $this->_config['default'];

        if ($CI->config->load('memcached', TRUE, TRUE)) {
            $this->_config = $CI->config->config['memcached'];
        }

        if (class_exists('Memcached', FALSE)) {
            $this->_memcached = new Memcached();
        } elseif (class_exists('Memcache', FALSE)) {
            $this->_memcached = new Memcache();
        } else {
            log_message('error', 'Cache: Failed to create Memcache(d) object; extension not loaded?');
            return;
        }

        foreach ($this->_config as $cache_server) {
            isset($cache_server['hostname']) OR $cache_server['hostname'] = $defaults['host'];
            isset($cache_server['port']) OR $cache_server['port'] = $defaults['port'];
            isset($cache_server['weight']) OR $cache_server['weight'] = $defaults['weight'];

            if ($this->_memcached instanceof Memcache) {
                // Third parameter is persistence and defaults to TRUE.
                $this->_memcached->addServer(
                        $cache_server['hostname'], $cache_server['port'], TRUE, $cache_server['weight']
                );
            } elseif ($this->_memcached instanceof Memcached) {
                $this->_memcached->addServer(
                        $cache_server['hostname'], $cache_server['port'], $cache_server['weight']
                );
            }
        }
    }

    // ------------------------------------------------------------------------

    /**
     * Fetch from cache
     *
     * @param	string	$id	Cache ID
     * @return	mixed	Data on success, FALSE on failure
     */
    public function get($id) {
        $data = $this->_memcached->get($id);

        return is_array($data) ? $data[0] : $data;
    }

    // ------------------------------------------------------------------------

    /**
     * Save
     *
     * @param	string	$id	Cache ID
     * @param	mixed	$data	Data being cached
     * @param	int	$ttl	Time to live
     * @param	bool	$raw	Whether to store the raw value
     * @return	bool	TRUE on success, FALSE on failure
     */
    public function save($id, $data, $ttl = 60, $raw = FALSE) {
        if ($raw !== TRUE) {
            $data = array($data, time(), $ttl);
        }

        if ($this->_memcached instanceof Memcached) {
            return $this->_memcached->set($id, $data, $ttl);
        } elseif ($this->_memcached instanceof Memcache) {
            return $this->_memcached->set($id, $data, 0, $ttl);
        }

        return FALSE;
    }

    // ------------------------------------------------------------------------

    /**
     * Delete from Cache
     *
     * @param	mixed	$id	key to be deleted.
     * @return	bool	true on success, false on failure
     */
    public function delete($id) {
        return $this->_memcached->delete($id);
    }

    // ------------------------------------------------------------------------

    /**
     * Increment a raw value
     *
     * @param	string	$id	Cache ID
     * @param	int	$offset	Step/value to add
     * @return	mixed	New value on success or FALSE on failure
     */
    public function increment($id, $offset = 1) {
        return $this->_memcached->increment($id, $offset);
    }

    // ------------------------------------------------------------------------

    /**
     * Decrement a raw value
     *
     * @param	string	$id	Cache ID
     * @param	int	$offset	Step/value to reduce by
     * @return	mixed	New value on success or FALSE on failure
     */
    public function decrement($id, $offset = 1) {
        return $this->_memcached->decrement($id, $offset);
    }

    // ------------------------------------------------------------------------

    /**
     * Clean the Cache
     *
     * @return	bool	false on failure/true on success
     */
    public function clean() {
        return $this->_memcached->flush();
    }

    // ------------------------------------------------------------------------

    /**
     * Cache Info
     *
     * @return	mixed	array on success, false on failure
     */
    public function cache_info() {
        return $this->_memcached->getStats();
    }

    // ------------------------------------------------------------------------

    /**
     * Get Cache Metadata
     *
     * @param	mixed	$id	key to get cache metadata on
     * @return	mixed	FALSE on failure, array on success.
     */
    public function get_metadata($id) {
        $stored = $this->_memcached->get($id);

        if (count($stored) !== 3) {
            return FALSE;
        }

        list($data, $time, $ttl) = $stored;

        return array(
            'expire' => $time + $ttl,
            'mtime' => $time,
            'data' => $data
        );
    }

    // ------------------------------------------------------------------------

    /**
     * Is supported
     *
     * Returns FALSE if memcached is not supported on the system.
     * If it is, we setup the memcached object & return TRUE
     *
     * @return	bool
     */
    public function is_supported() {
        return (extension_loaded('memcached') OR extension_loaded('memcache'));
    }

    // ------------------------------------------------------------------------

    /**
     * Class destructor
     *
     * Closes the connection to Memcache(d) if present.
     *
     * @return	void
     */
    public function __destruct() {
        if ($this->_memcached instanceof Memcache) {
            $this->_memcached->close();
        } elseif ($this->_memcached instanceof Memcached && method_exists($this->_memcached, 'quit')) {
            $this->_memcached->quit();
        }
    }

}
