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<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2016, 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 - 2016, 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 File Caching Class
 *
 * @package             CodeIgniter
 * @subpackage  Libraries
 * @category    Core
 * @author              EllisLab Dev Team
 * @link
 */
class CI_Cache_file extends CI_Driver {

        /**
         * Directory in which to save cache files
         *
         * @var string
         */
        protected $_cache_path;

        /**
         * Initialize file-based cache
         *
         * @return      void
         */
        public function __construct()
        {
                $CI =& get_instance();
                $CI->load->helper('file');
                $path = $CI->config->item('cache_path');
                $this->_cache_path = ($path === '') ? APPPATH.'cache/' : $path;
        }

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

        /**
         * Fetch from cache
         *
         * @param       string  $id     Cache ID
         * @return      mixed   Data on success, FALSE on failure
         */
        public function get($id)
        {
                $data = $this->_get($id);
                return is_array($data) ? $data['data'] : FALSE;
        }

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

        /**
         * Save into cache
         *
         * @param       string  $id     Cache ID
         * @param       mixed   $data   Data to store
         * @param       int     $ttl    Time to live in seconds
         * @param       bool    $raw    Whether to store the raw value (unused)
         * @return      bool    TRUE on success, FALSE on failure
         */
        public function save($id, $data, $ttl = 60, $raw = FALSE)
        {
                $contents = array(
                        'time'          => time(),
                        'ttl'           => $ttl,
                        'data'          => $data
                );

                if (write_file($this->_cache_path.$id, serialize($contents)))
                {
                        chmod($this->_cache_path.$id, 0640);
                        return TRUE;
                }

                return FALSE;
        }

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

        /**
         * Delete from Cache
         *
         * @param       mixed   unique identifier of item in cache
         * @return      bool    true on success/false on failure
         */
        public function delete($id)
        {
                return is_file($this->_cache_path.$id) ? unlink($this->_cache_path.$id) : FALSE;
        }

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

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

                if ($data === FALSE)
                {
                        $data = array('data' => 0, 'ttl' => 60);
                }
                elseif ( ! is_int($data['data']))
                {
                        return FALSE;
                }

                $new_value = $data['data'] + $offset;
                return $this->save($id, $new_value, $data['ttl'])
                        ? $new_value
                        : FALSE;
        }

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

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

                if ($data === FALSE)
                {
                        $data = array('data' => 0, 'ttl' => 60);
                }
                elseif ( ! is_int($data['data']))
                {
                        return FALSE;
                }

                $new_value = $data['data'] - $offset;
                return $this->save($id, $new_value, $data['ttl'])
                        ? $new_value
                        : FALSE;
        }

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

        /**
         * Clean the Cache
         *
         * @return      bool    false on failure/true on success
         */
        public function clean()
        {
                return delete_files($this->_cache_path, FALSE, TRUE);
        }

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

        /**
         * Cache Info
         *
         * Not supported by file-based caching
         *
         * @param       string  user/filehits
         * @return      mixed   FALSE
         */
        public function cache_info($type = NULL)
        {
                return get_dir_file_info($this->_cache_path);
        }

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

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

                $data = unserialize(file_get_contents($this->_cache_path.$id));

                if (is_array($data))
                {
                        $mtime = filemtime($this->_cache_path.$id);

                        if ( ! isset($data['ttl'], $data['time']))
                        {
                                return FALSE;
                        }

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

                return FALSE;
        }

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

        /**
         * Is supported
         *
         * In the file driver, check to see that the cache directory is indeed writable
         *
         * @return      bool
         */
        public function is_supported()
        {
                return is_really_writable($this->_cache_path);
        }

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

        /**
         * Get all data
         *
         * Internal method to get all the relevant data about a cache item
         *
         * @param       string  $id     Cache ID
         * @return      mixed   Data array on success or FALSE on failure
         */
        protected function _get($id)
        {
                if ( ! is_file($this->_cache_path.$id))
                {
                        return FALSE;
                }

                $data = unserialize(file_get_contents($this->_cache_path.$id));

                if ($data['ttl'] > 0 && time() > $data['time'] + $data['ttl'])
                {
                        unlink($this->_cache_path.$id);
                        return FALSE;
                }

                return $data;
        }

}