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



class Cache
{
        private $_ci;
        private $_path;
        private $_contents;
        private $_filename;
        private $_expires;
        private $_default_expires;
        private $_created;
        private $_dependencies;

        /**
         * Constructor - Initializes and references CI
         */
        function __construct()
        {
                log_message('debug', "Cache Class Initialized.");

                $this->_ci =& get_instance();
                $this->_reset();

                $this->_ci->load->config('cache');

                $this->_path = $this->_ci->config->item('cache_dir');
                $this->_default_expires = $this->_ci->config->item('cache_default_expires');
                if ( ! is_dir($this->_path))
                {
                        show_error("Cache Path not found: $this->_path");
                }
        }

        /**
         * Initialize Cache object to empty
         *
         * @access      private
         * @return      void
         */
        private function _reset()
        {
                $this->_contents = NULL;
                $this->_filename = NULL;
                $this->_expires = NULL;
                $this->_created = NULL;
                $this->_dependencies = array();
        }

        /**
         * Call a library's cached result or create new cache
         *
         * @access      public
         * @param       string
         * @return      array
         */
        public function library($library, $method, $arguments = array(), $expires = NULL)
        {
                if ( ! class_exists(ucfirst($library)))
                {
                        $this->_ci->load->library($library);
                }

                return $this->_call($library, $method, $arguments, $expires);
        }

        /**
         * Call a model's cached result or create new cache
         *
         * @access      public
         * @return      array
         */
        public function model($model, $method, $arguments = array(), $expires = NULL)
        {
                if ( ! class_exists(ucfirst($model)))
                {
                        $this->_ci->load->model($model);
                }

                return $this->_call($model, $method, $arguments, $expires);
        }

        // Depreciated, use model() or library()
        private function _call($property, $method, $arguments = array(), $expires = NULL)
        {
                $this->_ci->load->helper('security');

                if ( !  is_array($arguments))
                {
                        $arguments = (array) $arguments;
                }

                // Clean given arguments to a 0-index array
                $arguments = array_values($arguments);

                $cache_file = $property.DIRECTORY_SEPARATOR.do_hash($method.serialize($arguments), 'sha1');

                // See if we have this cached or delete if $expires is negative
                if($expires >= 0)
                {
                        $cached_response = $this->get($cache_file);
                }
                else
                {
                        $this->delete($cache_file);
                        return;
                }

                // Not FALSE? Return it
                if($cached_response !== FALSE && $cached_response !== NULL)
                {
                        return $cached_response;
                }

                else
                {
                        // Call the model or library with the method provided and the same arguments
                        $new_response = call_user_func_array(array($this->_ci->$property, $method), $arguments);
                        $this->write($new_response, $cache_file, $expires);

                        return $new_response;
                }
        }

        /**
         * Helper functions for the dependencies property
         */
        function set_dependencies($dependencies)
        {
                if (is_array($dependencies))
                {
                        $this->_dependencies = $dependencies;
                }
                else
                {
                        $this->_dependencies = array($dependencies);
                }

                return $this;
        }

        function add_dependencies($dependencies)
        {
                if (is_array($dependencies))
                {
                        $this->_dependencies = array_merge($this->_dependencies, $dependencies);
                }
                else
                {
                        $this->_dependencies[] = $dependencies;
                }

                return $this;
        }

        function get_dependencies() { return $this->_dependencies; }

        /**
         * Helper function to get the cache creation date
         */
        function get_created($created) { return $this->_created; }


        /**
         * Retrieve Cache File
         *
         * @access      public
         * @param       string
         * @param       boolean
         * @return      mixed
         */
        function get($filename = NULL, $use_expires = true)
        {
                // Check if cache was requested with the function or uses this object
                //print_r($filename);
                if ($filename !== NULL)
                {
                        $this->_reset();
                        $this->_filename = $filename;
                }

                // Check directory permissions
                if ( ! is_dir($this->_path) OR ! is_really_writable($this->_path))
                {
                        return FALSE;
                }

                // Build the file path.
                $filepath = $this->_path.$this->_filename.'.cache';
                // Check if the cache exists, if not return FALSE
                if ( ! @file_exists($filepath))
                {
        
                        return FALSE;
                }
                // Check if the cache can be opened, if not return FALSE
                if ( ! $fp = @fopen($filepath, FOPEN_READ))
                {
                        return FALSE;
                }
                // Lock the cache
                flock($fp, LOCK_SH);

                // If the file contains data return it, otherwise return NULL
                if (filesize($filepath) > 0)
                {
                        //echo 'file size'.filesize($filepath);
                        $this->_contents = unserialize(fread($fp, filesize($filepath)));
                        //print_r($this->_contents);
                }
                else
                {
                        //echo 'inside else';
                        $this->_contents = NULL;
                }
                // Unlock the cache and close the file
                flock($fp, LOCK_UN);
                fclose($fp);

                // Check cache expiration, delete and return FALSE when expired
                if ($use_expires && ! empty($this->_contents['__cache_expires']) && $this->_contents['__cache_expires'] < time())
                {
                        //echo 'inside if';
                        //$this->delete($filename);
                        return FALSE;
                }
                // Check Cache dependencies
                if(isset($this->_contents['__cache_dependencies']))
                {
                        //echo 'inside if';
                        foreach ($this->_contents['__cache_dependencies'] as $dep)
                        {
                                $cache_created = filemtime($this->_path.$this->_filename.'.cache');

                                // If dependency doesn't exist or is newer than this cache, delete and return FALSE
                                if (! file_exists($this->_path.$dep.'.cache') or filemtime($this->_path.$dep.'.cache') > $cache_created)
                                {
                                        //echo 'file deleted';
                                        $this->delete($filename);
                                        return FALSE;
                                }
                        }
                }
                // Instantiate the object variables
                $this->_expires         = isset($this->_contents['__cache_expires']) ? $this->_contents['__cache_expires'] : NULL;
                $this->_dependencies = isset($this->_contents['__cache_dependencies']) ? $this->_contents['__cache_dependencies'] : NULL;
                $this->_created         = isset($this->_contents['__cache_created']) ? $this->_contents['__cache_created'] : NULL;

                // Cleanup the meta variables from the contents
                $this->_contents = @$this->_contents['__cache_contents'];
                log_message('debug', "Cache retrieved: ".$filename);
                //print_r($this->_contents);
                //echo "<br/>----------------------------------------cache file ends--------------------------------------<br/>";
                // Return the cache
                log_message('debug', "Cache retrieved: ".$filename);
                return $this->_contents;
        }

        /**
         * Write Cache File
         *
         * @access      public
         * @param       mixed
         * @param       string
         * @param       int
         * @param       array
         * @return      void
         */
        function write($contents = NULL, $filename = NULL, $expires = NULL, $dependencies = array())
        {
                // Check if cache was passed with the function or uses this object
                if ($contents !== NULL)
                {
                        $this->_reset();
                        $this->_contents = $contents;
                        $this->_filename = $filename;
                        $this->_expires = $expires;
                        $this->_dependencies = $dependencies;
                }

                // Put the contents in an array so additional meta variables
                // can be easily removed from the output
                $this->_contents = array('__cache_contents' => $this->_contents);

                // Check directory permissions
                if ( ! is_dir($this->_path) OR ! is_really_writable($this->_path))
                {
                        return;
                }

                // check if filename contains dirs
                $subdirs = explode(DIRECTORY_SEPARATOR, $this->_filename);
                if (count($subdirs) > 1)
                {
                        array_pop($subdirs);
                        $test_path = $this->_path.implode(DIRECTORY_SEPARATOR, $subdirs);

                        // check if specified subdir exists
                        if ( ! @file_exists($test_path))
                        {
                                // create non existing dirs, asumes PHP5
                                if ( ! @mkdir($test_path, DIR_WRITE_MODE, TRUE)) return FALSE;
                        }
                }

                // Set the path to the cachefile which is to be created
                $cache_path = $this->_path.$this->_filename.'.cache';

                // Open the file and log if an error occures
                if ( ! $fp = @fopen($cache_path, FOPEN_WRITE_CREATE_DESTRUCTIVE))
                {
                        log_message('error', "Unable to write Cache file: ".$cache_path);
                        return;
                }

                // Meta variables
                $this->_contents['__cache_created'] = time();
                $this->_contents['__cache_dependencies'] = $this->_dependencies;

                // Add expires variable if its set...
                if (! empty($this->_expires))
                {
                        $this->_contents['__cache_expires'] = $this->_expires + time();
                }
                // ...or add default expiration if its set
                elseif (! empty($this->_default_expires) )
                {
                        $this->_contents['__cache_expires'] = $this->_default_expires + time();
                }

                // Lock the file before writing or log an error if it failes
                if (flock($fp, LOCK_EX))
                {
                        fwrite($fp, serialize($this->_contents));
                        flock($fp, LOCK_UN);
                }
                else
                {
                        log_message('error', "Cache was unable to secure a file lock for file at: ".$cache_path);
                        return;
                }
                fclose($fp);
                @chmod($cache_path, DIR_WRITE_MODE);

                // Log success
                log_message('debug', "Cache file written: ".$cache_path);

                // Reset values
                $this->_reset();
        }

        /**
         * Delete Cache File
         *
         * @access      public
         * @param       string
         * @return      void
         */
        function delete($filename = NULL)
        {
                if ($filename !== NULL) $this->_filename = $filename;

                $file_path = $this->_path.$this->_filename.'.cache';

                if (file_exists($file_path)) unlink($file_path);

                // Reset values
                $this->_reset();
        }

        /**
         * Delete a group of cached files
         *
         * Allows you to pass a group to delete cache. Example:
         *
         * <code>
         * $this->cache->write($data, 'nav_title');
         * $this->cache->write($links, 'nav_links');
         * $this->cache->delete_group('nav_');
         * </code>
         *
         * @param       string $group
         * @return      void
         */
        public function delete_group($group = null)
        {
                if ($group === null)
                {
                        return FALSE;
                }

                $this->_ci->load->helper('directory');
                $map = directory_map($this->_path, TRUE);

                foreach ($map AS $file)
                {
                        if (strpos($file, $group)  !== FALSE)
                        {
                                unlink($this->_path.$file);
                        }
                }

                // Reset values
                $this->_reset();
        }

        /**
         * Delete Full Cache or Cache subdir
         *
         * @access      public
         * @param       string
         * @return      void
         */
        function delete_all($dirname = '')
        {
                if (empty($this->_path))
                {
                        return FALSE;
                }

                $this->_ci->load->helper('file');
                if (file_exists($this->_path.$dirname)) delete_files($this->_path.$dirname, TRUE);

                // Reset values
                $this->_reset();
        }
}

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