recursive sitemap generator

<?php

    header("Content-type: text/xml");
    header("Cache-Control: private, max-age=10800, pre-check=10800");
    header("Pragma: private");
    header("Expires: " . date(DATE_RFC822, strtotime("2 day")));

    if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) {

        header('Last-Modified: ' . $_SERVER['HTTP_IF_MODIFIED_SINCE'], true, 304);
        exit;
    }

    $config = array(
        'startDir' => '.',
        'includeDir' => true,
        'include' => array(
            "hourly" => array(''),
            "daily" => array('pdf'),
            "weekly" => array('php'),
            "monthly" => array('')
        ),
        'exclude' => array(
            '/includes',
            '/xml',
            '/images',
            '/javascript',
            '/css',
            '/sitemap.php'
        )
    );

    //begin

    echo '<?xml version="1.0" encoding="UTF-8"?><urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">';

    scanDirectory($config['startDir'], $config);

    echo '</urlset>';

    function scanDirectory($path, $config) {

        if (substr($path, 0, 1) == '.') {

            $path = substr($path, 1);
        }

        if (is_readable('.' . $path)) {

            if (is_dir('.' . $path)) {

                if ($config['includeDir']) {

                    $time = date("c", filemtime($path));

                    echo '<url><loc>http://' . $_SERVER["SERVER_NAME"] . $path . '</loc><lastmod>' . $time . '</lastmod><changefreq>weekly</changefreq><priority>0.5</priority></url>';
                }

                readFiles('.' . $path, $config);
            }
        }
    }

    function readFiles($dir, $config) {

        $directory_list = opendir($dir);

        while($file = readdir($directory_list)) {

            if ($file != '.' && $file != '..') {

                $path = $dir . "/" . $file;

                if (is_readable($path)) {

                    if (substr($path, 0, 1) == '.') {

                        $path = substr($path, 1);
                    }

                    if (!in_array($path, $config['exclude'])) {

                        if (is_dir('.' . $path)) {

                            scanDirectory('.' . $path, $config);
                        }
                        else if (is_file('.' . $path)) {

                            $extension = end(explode('.', $path));

                            foreach($config['include'] as $change => $files) {

                                if (in_array($extension, $files)) {

                                    $time = date("c", filemtime('.' . $path));

                                    echo '<url><loc>http://' . $_SERVER["SERVER_NAME"] . $path . '</loc><lastmod>' . $time . '</lastmod><changefreq>' . $change . '</changefreq><priority>0.5</priority></url>';
                                }
                            }
                        }
                    }
                }
            }
        }
    }

?>