<?php
/* @description     A very simple filesystem cache class that stores one entry per file        *
 * @author          Tom Butler tom@r.je                                                        *
 * @copyright       2015 Tom Butler                                                            *
 * @license         http://www.opensource.org/licenses/bsd-license.php  BSD License            *
 * @version         1.0                                                                        */
namespace SimpleCache;
class SimpleCache implements \ArrayAccess {
	private $dir;

	public function __construct($dir, $maxAge = null, $gcInterval = 86400) {
		$this->dir = rtrim(realpath($dir), \DIRECTORY_SEPARATOR);
		$this->gc($maxAge, $gcInterval);
	}

	public function offsetSet($key, $value) {
		file_put_contents($this->dir . \DIRECTORY_SEPARATOR . $key, serialize($value));
	}

	public function offsetGet($key) {
		touch($this->dir . \DIRECTORY_SEPARATOR . $key);
		if ($this->offsetExists($key)) return unserialize(file_get_contents($this->dir . \DIRECTORY_SEPARATOR . $key));
		else return null;
	}

	public function offsetExists($key) {
		return is_file($this->dir . \DIRECTORY_SEPARATOR . $key);
	}

	public function offsetUnset($key) {
		unlink($this->dir . \DIRECTORY_SEPARATOR . $key);
	}

	private function gc($maxAge, $gcInterval) {
		if ($maxAge && rand(1,100) == 1) {
			$lastRun = $this['___cacheGC'];
			if ($lastRun+$gcInterval < time()) {
				foreach (new \DirectoryIterator($this->dir) as $file) {
					if  (filemtime($this->dir . DIRECTORY_SEPARATOR . $file->getFileName()) + $maxAge < time()) {
						unlink($this->dir . DIRECTORY_SEPARATOR . $file->getFileName());
					}
				}
				$this['___cacheGC'] = time();
			}
		}
	}
}