<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 4.3.2 or newer
 *
 * @package        CodeIgniter
 * @author        ExpressionEngine Dev Team
 * @copyright    Copyright (c) 2006 - 2012 EllisLab, Inc.
 * @license        http://codeigniter.com/user_guide/license.html
 * @link        http://codeigniter.com
 * @since        Version 2.0
 * @filesource    
 */

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

/**
 * CodeIgniter Caching Class 
 *
 * @package        CodeIgniter
 * @subpackage    Libraries
 * @category    Core
 * @author        ExpressionEngine Dev Team
 * @link        
 */
class CI_Cache extends CI_Driver_Library {
    
    protected $valid_drivers     = array(
        'cache_apc', 'cache_file', 'cache_memcached', 'cache_dummy'
    );

    protected $_cache_path        = NULL;        // Path of cache files (if file-based cache)
    protected $_adapter            = 'dummy';
    protected $_backup_driver;
    
    // ------------------------------------------------------------------------

    /**
     * Constructor
     *
     * @param array
     */
    public function __construct($config = array())
    {
        if ( ! empty($config))
        {
            $this->_initialize($config);
        }
    }

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

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

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

    /**
     * Cache Save
     *
     * @param     string        Unique Key
     * @param     mixed        Data to store
     * @param     int            Length of time (in seconds) to cache the data
     *
     * @return     boolean        true on success/false on failure
     */
    public function save($id, $data, $ttl = 60)
    {
        return $this->{$this->_adapter}->save($id, $data, $ttl);
    }

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

    /**
     * Delete from Cache
     *
     * @param     mixed        unique identifier of the item in the cache
     * @return     boolean        true on success/false on failure
     */
    public function delete($id)
    {
        return $this->{$this->_adapter}->delete($id);
    }

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

    /**
     * Clean the cache
     *
     * @return     boolean        false on failure/true on success
     */
    public function clean()
    {
        return $this->{$this->_adapter}->clean();
    }

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

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

    // ------------------------------------------------------------------------
    
    /**
     * Get Cache Metadata
     *
     * @param     mixed        key to get cache metadata on
     * @return     mixed        return value from child method
     */
    public function get_metadata($id)
    {
        return $this->{$this->_adapter}->get_metadata($id);
    }
    
    // ------------------------------------------------------------------------

    /**
     * Initialize
     *
     * Initialize class properties based on the configuration array.
     *
     * @param    array     
     * @return     void
     */
    private function _initialize($config)
    {        
        $default_config = array(
                'adapter',
                'memcached'
            );

        foreach ($default_config as $key)
        {
            if (isset($config[$key]))
            {
                $param = '_'.$key;

                $this->{$param} = $config[$key];
            }
        }

        if (isset($config['backup']))
        {
            if (in_array('cache_'.$config['backup'], $this->valid_drivers))
            {
                $this->_backup_driver = $config['backup'];
            }
        }
    }

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

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

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

        return $support[$driver];
    }

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

    /**
     * __get()
     *
     * @param     child
     * @return     object
     */
    public function __get($child)
    {
        $obj = parent::__get($child);

        if ( ! $this->is_supported($child))
        {
            $this->_adapter = $this->_backup_driver;
        }

        return $obj;
    }
    
    // ------------------------------------------------------------------------
}
// End Class

/* End of file Cache.php */
/* Location: ./system/libraries/Cache/Cache.php */