Simple router file for serving legacy PHP projects like Wordpress with `php -S host:port router.php`

router.php

<?php

$path = rtrim(parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH), '/');

// If that doesn't correspond to an existing path, assume a route...
$path = realpath(__DIR__ . $path) ?: __DIR__ . '/index.php';

extract(pathinfo_safe($path)); // $dirname, $basename, $extension, and $filename

if ( !$extension ) extract(pathinfo_safe($path .= '/index.php'));
// Use `index.php` (as Apache would) and re-parse...

// Execute PHP files...
if ( $extension == 'php' ) require_once $path;

// Pass through everything else...
else readfile($path);

/**
 * If a $path doesn't contain a part (and $options is not passed), pathinfo()
 * won't even return a _key_ for that part, which is kind of a pain,
 * particularly when using extract(). It would be nicer if we _always_ got keys
 * for every part.
 *
 * @param string $path to expand
 * @param integer $options bitmask of PATHINFO_* constants
 * @return mixed string|array hash of parts
 * @see pathinfo()
 */
function pathinfo_safe($path, $options = false) {
    if ( !$options ) return pathinfo($path) + array(
        'dirname' => null,
        'basename' => null,
        'extension' => null,
        'filename' => null,
    );

    return pathinfo($path, $options);
}