<?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 2.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * CodeIgniter Caching Class
 *
 * @package		CodeIgniter
 * @subpackage	Libraries
 * @category	Core
 * @author		EllisLab Dev Team
 * @link
 */
class CI_Cache extends CI_Driver_Library {

    /**
     * Valid cache drivers
     *
     * @var array
     */
    protected $valid_drivers = array(
        'apc',
        'dummy',
        'file',
        'memcached',
        'redis',
        'wincache'
    );

    /**
     * Path of cache files (if file-based cache)
     *
     * @var string
     */
    protected $_cache_path = NULL;

    /**
     * Reference to the driver
     *
     * @var mixed
     */
    protected $_adapter = 'dummy';

    /**
     * Fallback driver
     *
     * @var string
     */
    protected $_backup_driver = 'dummy';

    /**
     * Cache key prefix
     *
     * @var	string
     */
    public $key_prefix = '';

    /**
     * Constructor
     *
     * Initialize class properties based on the configuration array.
     *
     * @param	array	$config = array()
     * @return	void
     */
    public function __construct($config = array()) {
        isset($config['adapter']) && $this->_adapter = $config['adapter'];
        isset($config['backup']) && $this->_backup_driver = $config['backup'];
        isset($config['key_prefix']) && $this->key_prefix = $config['key_prefix'];

        // If the specified adapter isn't available, check the backup.
        if (!$this->is_supported($this->_adapter)) {
            if (!$this->is_supported($this->_backup_driver)) {
                // Backup isn't supported either. Default to 'Dummy' driver.
                log_message('error', 'Cache adapter "' . $this->_adapter . '" and backup "' . $this->_backup_driver . '" are both unavailable. Cache is now using "Dummy" adapter.');
                $this->_adapter = 'dummy';
            } else {
                // Backup is supported. Set it to primary.
                log_message('debug', 'Cache adapter "' . $this->_adapter . '" is unavailable. Falling back to "' . $this->_backup_driver . '" backup adapter.');
                $this->_adapter = $this->_backup_driver;
            }
        }
    }

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

    /**
     * Get
     *
     * Look for a value in the cache. If it exists, return the data
     * if not, return FALSE
     *
     * @param	string	$id
     * @return	mixed	value matching $id or FALSE on failure
     */
    public function get($id) {
        return $this->{$this->_adapter}->get($this->key_prefix . $id);
    }

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

    /**
     * Cache Save
     *
     * @param	string	$id	Cache ID
     * @param	mixed	$data	Data to store
     * @param	int	$ttl	Cache TTL (in seconds)
     * @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) {
        return $this->{$this->_adapter}->save($this->key_prefix . $id, $data, $ttl, $raw);
    }

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

    /**
     * Delete from Cache
     *
     * @param	string	$id	Cache ID
     * @return	bool	TRUE on success, FALSE on failure
     */
    public function delete($id) {
        return $this->{$this->_adapter}->delete($this->key_prefix . $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 $this->{$this->_adapter}->increment($this->key_prefix . $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 $this->{$this->_adapter}->decrement($this->key_prefix . $id, $offset);
    }

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

    /**
     * Clean the cache
     *
     * @return	bool	TRUE on success, FALSE on failure
     */
    public function clean() {
        return $this->{$this->_adapter}->clean();
    }

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

    /**
     * Cache Info
     *
     * @param	string	$type = 'user'	user/filehits
     * @return	mixed	array containing cache info on success OR FALSE on failure
     */
    public function cache_info($type = 'user') {
        return $this->{$this->_adapter}->cache_info($type);
    }

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

    /**
     * Get Cache Metadata
     *
     * @param	string	$id	key to get cache metadata on
     * @return	mixed	cache item metadata
     */
    public function get_metadata($id) {
        return $this->{$this->_adapter}->get_metadata($this->key_prefix . $id);
    }

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

    /**
     * Is the requested driver supported in this environment?
     *
     * @param	string	$driver	The driver to test
     * @return	array
     */
    public function is_supported($driver) {
        static $support;

        if (!isset($support, $support[$driver])) {
            $support[$driver] = $this->{$driver}->is_supported();
        }

        return $support[$driver];
    }

}
