<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

/**

 * CodeIgniter

 *

 * An open source application development framework for PHP 5.1.6 or newer

 *

 * @package		CodeIgniter

 * @author		ExpressionEngine Dev Team

 * @copyright	Copyright (c) 2008 - 2011, EllisLab, Inc.

 * @license		http://codeigniter.com/user_guide/license.html

 * @link		http://codeigniter.com

 * @since		Version 1.0

 * @filesource

 */



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



/**

 * Database Cache Class

 *

 * @category	Database

 * @author		ExpressionEngine Dev Team

 * @link		http://codeigniter.com/user_guide/database/

 */

class CI_DB_Cache {



	var $CI;

	var $db;	// allows passing of db object so that multiple database connections and returned db objects can be supported



	/**

	 * Constructor

	 *

	 * Grabs the CI super object instance so we can access it.

	 *

	 */

	function __construct(&$db)

	{

		// Assign the main CI object to $this->CI

		// and load the file helper since we use it a lot

		$this->CI =& get_instance();

		$this->db =& $db;

		$this->CI->load->helper('file');

	}



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



	/**

	 * Set Cache Directory Path

	 *

	 * @access	public

	 * @param	string	the path to the cache directory

	 * @return	bool

	 */

	function check_path($path = '')

	{

		if ($path == '')

		{

			if ($this->db->cachedir == '')

			{

				return $this->db->cache_off();

			}



			$path = $this->db->cachedir;

		}



		// Add a trailing slash to the path if needed

		$path = preg_replace("/(.+?)\/*$/", "\\1/",  $path);



		if ( ! is_dir($path) OR ! is_really_writable($path))

		{

			// If the path is wrong we'll turn off caching

			return $this->db->cache_off();

		}



		$this->db->cachedir = $path;

		return TRUE;

	}



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



	/**

	 * Retrieve a cached query

	 *

	 * The URI being requested will become the name of the cache sub-folder.

	 * An MD5 hash of the SQL statement will become the cache file name

	 *

	 * @access	public

	 * @return	string

	 */

	function read($sql)

	{

		if ( ! $this->check_path())

		{

			return $this->db->cache_off();

		}



		$segment_one = ($this->CI->uri->segment(1) == FALSE) ? 'default' : $this->CI->uri->segment(1);



		$segment_two = ($this->CI->uri->segment(2) == FALSE) ? 'index' : $this->CI->uri->segment(2);



		$filepath = $this->db->cachedir.$segment_one.'+'.$segment_two.'/'.md5($sql);



		if (FALSE === ($cachedata = read_file($filepath)))

		{

			return FALSE;

		}



		return unserialize($cachedata);

	}



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



	/**

	 * Write a query to a cache file

	 *

	 * @access	public

	 * @return	bool

	 */

	function write($sql, $object)

	{

		if ( ! $this->check_path())

		{

			return $this->db->cache_off();

		}



		$segment_one = ($this->CI->uri->segment(1) == FALSE) ? 'default' : $this->CI->uri->segment(1);



		$segment_two = ($this->CI->uri->segment(2) == FALSE) ? 'index' : $this->CI->uri->segment(2);



		$dir_path = $this->db->cachedir.$segment_one.'+'.$segment_two.'/';



		$filename = md5($sql);



		if ( ! @is_dir($dir_path))

		{

			if ( ! @mkdir($dir_path, DIR_WRITE_MODE))

			{

				return FALSE;

			}



			@chmod($dir_path, DIR_WRITE_MODE);

		}



		if (write_file($dir_path.$filename, serialize($object)) === FALSE)

		{

			return FALSE;

		}



		@chmod($dir_path.$filename, FILE_WRITE_MODE);

		return TRUE;

	}



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



	/**

	 * Delete cache files within a particular directory

	 *

	 * @access	public

	 * @return	bool

	 */

	function delete($segment_one = '', $segment_two = '')

	{

		if ($segment_one == '')

		{

			$segment_one  = ($this->CI->uri->segment(1) == FALSE) ? 'default' : $this->CI->uri->segment(1);

		}



		if ($segment_two == '')

		{

			$segment_two = ($this->CI->uri->segment(2) == FALSE) ? 'index' : $this->CI->uri->segment(2);

		}



		$dir_path = $this->db->cachedir.$segment_one.'+'.$segment_two.'/';



		delete_files($dir_path, TRUE);

	}



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



	/**

	 * Delete all existing cache files

	 *

	 * @access	public

	 * @return	bool

	 */

	function delete_all()

	{

		delete_files($this->db->cachedir, TRUE);

	}



}





/* End of file DB_cache.php */

/* Location: ./system/database/DB_cache.php */