Как сделать простой php-роутер?

# .htaccess

Options +FollowSymlinks -Indexes
DirectoryIndex public/index.html public/index.php

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-l
RewriteRule ^(.*)$ /public/index.php?_url=/$1 [L,QSA]

<?php
// app.php

define('__ROOT__', __DIR__);
define('__APP__', realpath(__ROOT__ . '/app'));

$routes = require_once __APP__ . '/routes.php';

foreach ($routes as $pattern => $action) {
  if (! preg_match($pattern, $_SERVER['REQUEST_URI'], $matches)) continue;

  $action = array_filter(explode('/', $action));
  $file = basename(array_pop($action), '.php');

  array_push($action, $file);

  require __APP__ . '/controllers/' . implode('/', $action) . '.php';
  break;
}

<?php
// public/index.php

// strict
register_shutdown_function(function () {
  $error = error_get_last();
  if (! $error) return;
  if (! ($error['line'] ?? null)) return;

  $errno    = $error['type'];
  $errmsg   = $error['message'];
  $errfile  = $error['file'];
  $errline  = $error['line'];

  handle(new \ErrorException($errmsg, $errcode = -1, $errno, $errfile, $errline));
});

// error
set_error_handler(function ($errno, $errmsg, $errfile, $errline) {
  if (! $errline) return;

  throw new \ErrorException($errmsg, $errcode = -1, $errno, $errfile, $errline);
}, E_ALL);

// handle
function handle(\Throwable $e)
{
  echo '<pre>';
  die(var_dump($e));
}

// index.php
try {
  // run application
  require_once __DIR__ . '/../app.php';

} catch (\Throwable $e) { handle($e); }

<?php
// app/routes.php

$routes = [];

foreach ([
  '/' => 'index',
  '/foo/bar' => 'index',
  '/hello/world' => 'hello/world',
] as $pattern => $action) {
  $routes[ '/^' . preg_quote($pattern, '/') . '$/' ] = $action;
}

return $routes;

<?php
// app/controllers/index.php

echo 'Index';

<?php
// app/controllers/hello/world.php

echo 'Hello/World';