<?php
//PHP page cache by Simon Chorley, 2007/08/07
//Feel free to modify and redistribute.

	//do hit counting session starting etc here

	if (!$_POST)	//don't cache files with POST variables
	{
		//Generate has name from script name so that we are using the actual served script file
		$uri = $_SERVER['SCRIPT_NAME'].((strlen($_SERVER['QUERY_STRING']) != 0) ? "?".$_SERVER['QUERY_STRING'] : "");
		$hash = $diskroot.$cachedir.md5($uri).".cache";	//generate cache file name
		if (file_exists($hash))	//check that this file exists
		{
			$dtime = 4440;	//time difference between server and my computer
			$ct = filemtime($hash)-$dtime;	//cache modification time
			$st = filemtime($_SERVER['SCRIPT_FILENAME']);	//script modification time
			if ($ct < $st)	//is it stale?
			{	//then regenerate
				ignore_user_abort(true);	//don't want to stop if the user closes their browser window
				$caching = true;	//tell then closing script that we are generating a cache page
				ob_start();	//start output buffering to record the page
			}
			else
			{
				readfile($hash);	//we have a good cache page so print the file
				echo "<!-- Cache: ".$ct.", Source: ".$st." -->\n<!-- Used cached file. -->\n";
				exit;	//exit processing
			}
		}
		else	//no cache page. start one
		{
			ignore_user_abort(true);
			$caching = true;
			ob_start();
		}
	}
	//If we are here then the page is processed as normal
?>