<?php
/*
** The settings in Settings.php should look like this:
// Select a system. Probably want to leave this up to the installer or admin panel.
$cache = array(
	// memcache, eaccelerator, mmcache, output_cache, xcache, apc, file, or false.
	'system' => '',
	// The level of caching. The higher the number, the more gets cached. An integer between 0 and 3 (0 turns caching off).
	'level' => 0,
	// This is generally only used for memcache. Should be a string of 'server:port, server:port'.
	'servers' => '',
	// Persistent connection (only of use to memcache).
	'persist' => false,
	// The directory where you want to store your cache files (if you are using the 'file' system).
	'dir' => '',
	// Boolean value. If true, it logs how many hits/misses and how long they took.
	'debug' => false,
);
*/
 
$cache = new cache($cache);
class cache
{
	public $hits = 0;
	public $count = 0;
	protected $settings = array();
 
	// Check all of the variables and setup what functions to use.
	function __construct ($settings = false)
	{
		$this->settings = $settings;
 
		if ($this->cache == false)
			return;
 
		$this->settings['level'] = !empty($this->settings['level']) ? (int) $this->settings['level'] : false;
		$this->settings['system'] = !empty($this->settings['system']) ? $this->settings['system'] : false;
		$this->settings['dir'] = !empty($this->settings['dir']) && file_exists($this->settings['dir']) ? $this->settings['dir'] : false;
 
		if (!$this->settings['system'] || !$this->settings['level'])
			$this->settings = false;
 
		// Define the Get, Set, and sometimes Remove functions.
		// Just added: remove, increment, decrement, status.
		switch ($this->settings['system'])
		{
			case 'apc':
				$this->get = 'apc_fetch';
				$this->set = 'apc_store';
				$this->rm = 'apc_delete';
				$this->clear = 'apc_clear_cache';
				break;
			case 'memcache':
				$this->get = 'memcache_get';
				$this->set = 'memcache_set';
				$this->rm = 'memcache_delete';
				$this->clear = 'memcache_flush';
				break;
			case 'eaccelerator':
				$this->get = 'eaccelerator_get';
				$this->set = 'eaccelerator_put';
				$this->rm = 'eaccelerator_rm';
				$this->gc = 'eaccelerator_gc';
				// Might have to use eaccelerator_list_keys() and rm all of them.
				//$this->clear = 'eaccelerator_gc';
				break;
			case 'mmcache':
				$this->get = 'mmcache_get';
				$this->set = 'mmcache_put';
				$this->rm = 'mmcache_rm';
				$this->gc = 'mmcache_gc';
				break;
			case 'output_cache':
				$this->get = 'output_cache_get';
				$this->set = 'output_cache_put';
				// Always one that has to be different. We must find those that check for TTL in get.
				$this->settings['req_ttl'] = true;
				$this->rm = 'output_cache_remove_key';
				// No idea how to implement clear() in this one.
				break;
			case 'xcache':
				$this->get = 'xcache_get';
				$this->set = 'xcache_set';
				$this->rm = 'xcache_unset';
				$this->clear = 'xcache_clear_cache';
				break;
			case: 'file':
				$this->get = array($this, 'get');
				$this->set = array($this, 'set');
				$this->rm = array($this, 'rm');
				$this->clear = array($this, 'clear');
				//$this->version = array($this, 'version'),
			default:
				$this->settings = false;
		}
 
		// Do we need to connect to the memcached server?
		if ($this->settings['system'] == 'memcache')
		{
			if (!empty($this->settings['servers']))
			{	
				// Not connected yet?
				if (empty($this->res))
				{
					$this->settings['servers'] = explode(',', $this->settings['servers']);
					get_memcached_server();
				}
				if (!$this->res)
					$this->settings = false;
			}
			else
				$this->settings = false;
		}
 
		// Do we need to do garbage collection?
		if (isset($this->gc) && mt_rand(0, 10) == 1)
			call_user_func($this->gc);
 
		// Let someone know that caching isn't working.
		if ($this->settings === false)
			trigger_error('Invalid cache type: ' . $this->settings['system'], E_USER_NOTICE);
 
		if (!is_callable($this->get) || !is_callable($this->set))
			trigger_error($this->get .' or ' . $this->set . ' functions not found', E_USER_NOTICE);
	}
 
	// Connect to a memcached server.
	private function get_memcached_server($level = 3)
	{	
		$server = explode(':', trim($this->settings['servers'][array_rand($this->settings['servers'])]));
 
		// Don't try more times than we have servers!
		$level = min(count($this->settings['servers']), $level);
 
		// Don't wait too long. It might be faster to just run without caching.
		if ($this->settings['persist'])
			$this->res = memcache_connect($server[0], empty($server[1]) ? 11211 : $server[1]);
		else
			$this->res = memcache_pconnect($server[0], empty($server[1]) ? 11211 : $server[1]);
 
		if (!$this->res && $level > 0)
			get_memcached_server($level - 1);
	}
 
	// Put an item in the cache.
	function put($key, $value, $ttl = 120, $level = 0)
	{	
		if (!$this->settings)
			return;
 
		if ($this->settings['debug'])
		{
			$this->count++;
			$this->hits[$this->count] = array('k' => $key, 'd' => 'put', 's' => $value === null ? 0 : strlen(serialize($value)));
			$st = microtime();
		}
 
		$key = $this->get_key($key);
		$value = $value === null ? null : serialize($value);
 
		if ($value === null)
			$this->rm($key);
 
		if ($this->settings['system'] == 'file')
		{
			// Create a PHP file with the info.
			if ($value !== null)
				file_put_contents($this->settings['dir'] . '/data_' . $key . '.php', '<?php if (' . (time() + $ttl) . ' < time()) $expired = true; else{$expired = false; $value = \'' . addcslashes($value, '\\\'') . '\';}?>', LOCK_EX);
			else
				$this->rm($this->settings['dir'] . '/data_' . $key . '.php');
		}
		// Some caches are accessed through a resource.
		elseif (isset($this->res))
			$cache['put']($this->res, $key, $value, 0, $ttl);
		else
			$cache['put']($key, $value, $ttl);
 
		if ($this->settings['debug'])
			$this->hits[$this->count]['t'] = array_sum(explode(' ', microtime())) - array_sum(explode(' ', $st));
	}
 
	// Return a cached item.
	function get($key, $ttl = 120, $level = 0)
	{	
		if (!$this->settings)
			return;
 
		if ($this->settings['debug'])
		{
			$this->count++;
			$this->hits[$this->count] = array('k' => $key, 'd' => 'get');
			$st = microtime();
		}
 
		$key = $this->get_key($key);
 
		if ($this->settings['system'] == 'file' && file_exists($this->settings['dir'] . '/data_' . $key . '.php') && filesize($this->settings['dir'] . '/data_' . $key . '.php') > 10)
		{
			require($this->settings['dir'] . '/data_' . $key . '.php');
			if (!empty($expired) && isset($value))
			{
				$this->rm($this->settings['dir'] . '/data_' . $key . '.php');
				unset($value);
			}
		}
		elseif (isset($this->res))
			$value = $this->get($this->res, $key);
		elseif ($this->settings['req_ttl'])
			$value = $this->get($key, $ttl);
		else
			$value = $this->get($key);
 
		if ($this->settings['debug'])
		{
			$this->hits[$this->count]['t'] = array_sum(explode(' ', microtime())) - array_sum(explode(' ', $st));
			$this->hits[$this->count]['s'] = isset($value) ? strlen($value) : 0;
		}
 
		if (!empty($value))
			return unserialize($value);
	}
 
	// Increment.
	function increment($key, $value = 1, $ttl = 120)
	{
		if (!$this->settings)
			return;
 
		if (!isset($this->inc))
		{
			$cached_value = call_user_func(array($this, 'get'), $key);
			if (is_int($cached_value))
			{
				call_user_func(array($this, 'put'), $cached_value + $value);
				return $cached_value + $value;
			}
		}
		elseif ($this->settings['req_ttl'])
			return call_user_func($this->inc, $value, $ttl);
		else
			return call_user_func($this->inc, $value);
	}
 
	// Decrement.
	function decrement($key, $value = 1, $ttl = 120)
	{
		if (!$this->settings)
			return;
 
		if (!isset($this->dec))
		{
			$cached_value = call_user_func(array($this, 'get'), $key);
			if (is_int($cached_value))
			{
				call_user_func(array($this, 'put'), $cached_value - $value);
				return $cached_value + $value;
			}
		}
		elseif ($this->settings['req_ttl'])
			return call_user_func($this->dec, $value, $ttl);
		else
			return call_user_func($this->dec, $value);
	}
 
	// Remove a cached item.
	function rm($key)
	{
		if (!$this->settings)
			return;
 
		if ($this->settings['system'] == 'file' && file_exists($this->settings['dir'] . '/data_' . $key . '.php'))
			unlink($this->settings['dir'] . '/data_' . $key . '.php');
		else
			call_user_func($this->rm);
	}
 
	// Clears the entire cache. Nothing will be left!
	function clear()
	{
		if (!$this->settings)
			return;
 
		if ($this->settings['system'] == 'file')
		{
			$files = scandir($this->settings['dir']);
			foreach ($files as $file)
				unlink($this->settings . '/' . $file);
		}
 
		// If there is no clear function defined, try to find all of the keys and delete those?
		// If we can't delete all of them, try dropping everything and then restarting?
	}
 
	// Return the version of the current cache.
	function version()
	{
		if (!$this->settings)
			return;
 
		switch($this->settings['system'])
		{
			case 'apc':
				$version = array('title' => 'Alternative PHP Cache', 'version' => phpversion('apc'));
				break;
			case 'memcache':
				$version = array('title' => 'Memcached', 'version' => memcache_get_version($this->resource));
				break;
			case 'eaccelerator':
				$version = array('title' => 'eAccelerator', 'version' => EACCELERATOR_VERSION);
				break;
			case 'mmcache':
				$version = array('title' => 'Turck MMCache', 'version' => MMCACHE_VERSION);
				break;
			case 'output_cache':
				global $_PHPA;
				$version = array('title' => 'Zend', 'version' => $_PHPA['VERSION']);
				break;
			case 'xcache':
				$version = array('title' => 'XCache', 'version' => XCACHE_VERSION);
				break;
			default:
				$version = array('title' => 'file', 'version' => 1);
		}
		return $version;
	}
 
	// One function to get the key so we can change how the keys are formatted easily.
	private function get_key($key)
	{
		//return md5(__DIR__ . filemtime(__FILE__) . __FILE__ . strtr($key, ':', '-'));
		return strtr($key, ':', '-');
	}
}
 
/*	Development Notes:
	*	I removed the @ operator from unlink because if we can't remove a file, we don't want to fill up our filesystem with cached files.
		I'd rather have it fill up an error log and let someone know about it.
	*	Webpages for support:
			MMCache:		http://turck-mmcache.sourceforge.net/index_old.html#api
			Xcache:			http://xcache.lighttpd.net/wiki/XcacheApi
			memcache:		http://www.php.net/memcache
			APC:			http://www.php.net/apc
			eAccelerator:	http://bart.eaccelerator.net/doc/phpdoc/
			Zend:			http://files.zend.com/help/Zend-Platform/partial_and_preemptive_page_caching.htm
*/
?>