<?php

error_reporting(0);

define('RSS_ITEMS', 5);
define('RSS_TTL', 180);

define('RSS_FILE', './slug2.xml');
define('RSS_SOURCE', './slug.xml');
define('RSS_GENERATOR', 'http://www.usrtriton.nl/slug/rss.php');
define('RSS_HEADER', 'Content-type: application/xml; charset=UTF-8');

define('RSS_HEADERSIZE', 14);
define('RSS_FOOTERSIZE', 2);

clearstatcache();
if ( file_exists(RSS_FILE) && file_exists(RSS_SOURCE) && filemtime(RSS_FILE) >= filemtime(RSS_SOURCE) )
{
    header(RSS_HEADER);
    readfile(RSS_FILE);
    exit();
}

if ( file_exists(RSS_SOURCE) && time() - filemtime(RSS_SOURCE) < RSS_TTL * 60 )
    $rss = file(RSS_SOURCE);
else
    $rss = file(RSS_GENERATOR);

$header = array_splice($rss, 0, RSS_HEADERSIZE);
$footer = array_splice($rss, -RSS_FOOTERSIZE);
$body = array_values($rss);

$deleteheaderlines = array(5, 6, 8, 10, 11, 12, 13);
foreach ( $deleteheaderlines as $linenumber )
    unset($header[$linenumber]);

$items = 0;
$lines = count($body);
for ( $i = 0; $i < $lines; ++$i )
{
    if ( $items < RSS_ITEMS )
    {
        $s = trim($body[$i]);
        if ( strpos($s, '</item>') !== FALSE )
            ++$items;
        elseif ( strpos($s, '<item>') === FALSE
            && strpos($s, '<title>') === FALSE
            && strpos($s, '<link>') === FALSE )
            unset($body[$i]);
    }
    else
        unset($body[$i]);
}

$rss = implode('', $header).implode('', $body).implode('', $footer);

if ( $fp = fopen(RSS_FILE, 'wb') )
{
    fwrite($fp, $rss);
    fclose($fp);
    chmod(RSS_FILE, 0666);
}

header(RSS_HEADER);
echo $rss;

?>