<?php
/**
 * Caches manipulated variables into files for future use
 * @author		Charles Weiss < c w e i s s [ a t ] f t w m a r k e t i n g . c o m >
 * @copyright	Copyright (C) Fetch The Web 2006-2008
 * @version 0.1
 */
 
class ObjectCache {
	private $data;
	private $ext = '_ObjectCache.php';	// The group of the cache file ( appended to end of filename ) 
	private $path = '/tmp/';		// The FULL path to the cached file 

	function __construct() {
		$this->data = array();
	}
	
	 /**
	 * Fetches variable from the cache if cache exists and data has not expired
	 * @param  $id The id of that variable for use in the filename
	 * @param  $lock Optional parameter instructing the class to lock the file.
	 * @return the cache contents OR false on error
	 */
	 function get($id) {
		if (isset($this->data[$id])) return $this->data[$id]; // Already set, return to sender
		$path = $this->path.base64_encode($id).$this->ext;
		
		if (file_exists($path) && is_readable($path)) { // Check if the cache file exists
			include $path;
			if (isset($expires) && $expires <= time()) {
				$this->clear($id);
				return false;
			} else {
				$cache = file_get_contents($path);
			}
		} else {
			return false;
		}
	}

	 /**
	 * Sets variable into the cache
	 * @param  $id The id of that variable for use in the filename
	 * @param  $cache The data to be stored
	 * @param  $lifetime The expiration time  (in seconds) from file creation
	 * @return the cache contents OR false on error
	 */
	function put($id, $cache, $lifetime = 0) {
		$this->data[$id] = $cache;

		if (is_resource($cache)) return "Can't cache resource.";

		$path = $this->path.base64_encode($id).$this->ext;
		$fp = @fopen($path, 'w');
		if (!$fp) echo 'Unable to open file for writing.'.$path;
		@flock($fp, LOCK_EX);
		@fwrite($fp, '<?php $cache='.var_export($data, true).';');
		if ($lifetime > 0) @fwrite($fp, '$expires='.(time()+$lifetime).';');
		@fwrite($fp, ' ?>');
		@flock($fp, LOCK_UN);
		@fclose($fp);
	
		if (file_exists($path)) chmod($path, 666);
		else return false;
		
		return true;
	}

	 /**
	 * Deletes the cache file
	 * @param  $id The id of that variable for use in the filename
	 * @param  $lock Optional parameter instructing the class to lock the file.
	 * @return the true or descriptive string on error
	 */
	function clear($id) {
		if (isset($this->data[$id])) unset($this->data[$id]);
		$pretty_id = base64_encode($id);
		$path = $this->path.$pretty_id.$this->ext;
		if (file_exists($path) && unlink($path)) return true;
		else return 'Cache could not be cleared.';
	}
}

 /**
	* Example Usage
	include './ObjectCache.class.php';
	$data = array('a','b','c','d','e','f','g');
	$distinct_name = 'lala';
	$cache = new ObjectCache();
	// Cache will last 3600 seconds or 1 hr
	$cache->put($distinct_name, $data, 3600);
	$data2 = $cache->get($distinct_name);
	// Forcibly clear the cache (on data update via admin perhaps
	//$cache->clear($distinct_name);
	print_r($data2);
	unset($cache);

  */
?>