Challenge 1 — Solution

Task: Add a second route to the Router example: GET /about, mapped to a
new AboutController with a show() method that requires a simple
views/about.php containing static "About us" text (no model needed).
Trace through, in writing, exactly what happens from the request
hitting index.php to the final HTML being produced.

---- src/Controllers/AboutController.php ----

<?php
namespace App\Controllers;

class AboutController {
    public function show() {
        require __DIR__ . '/../../views/about.php';
    }
}

---- views/about.php ----

<h1>About Us</h1>
<p>This is a small demonstration application built to learn MVC.</p>

---- public/index.php (updated) ----

<?php
require __DIR__ . '/../vendor/autoload.php';

use App\Router;
use App\Controllers\PostController;
use App\Controllers\AboutController;

$router = new Router();
$router->get('/posts', [PostController::class, 'index']);
$router->get('/about', [AboutController::class, 'show']);

$uri = strtok($_SERVER['REQUEST_URI'], '?');
$router->dispatch($uri);
?>

---- Trace: a request to GET /about ----

1. The web server routes every request to public/index.php (the front
   controller), regardless of the actual URL path requested.
2. index.php loads Composer's autoloader, then registers two routes on
   a new Router instance: '/posts' and '/about', each mapped to a
   [ControllerClass, 'method'] pair.
3. strtok($_SERVER['REQUEST_URI'], '?') extracts just the path portion
   of the URL ("/about"), stripping away any query string like
   "?foo=bar" that might follow it.
4. $router->dispatch('/about') is called. Inside dispatch(), isset()
   checks whether '/about' exists as a registered route key - it does,
   so the 404 branch is skipped.
5. [$controllerClass, $method] destructures the stored handler into
   "App\Controllers\AboutController" and "show".
6. new $controllerClass() dynamically instantiates a real
   AboutController object, using the class name stored in a variable
   rather than written literally.
7. $controller->$method() dynamically calls show() on that object.
8. Inside show(), a plain require pulls in views/about.php directly -
   since this route needs no data at all, there's no Model step this
   time, just Controller -> View.
9. views/about.php's own static HTML (<h1>About Us</h1> etc.) is
   echoed directly as it's required, becoming the final response body
   sent back to the browser.

Notes:
- This route deliberately has no Model at all, showing that MVC's
  three roles are the available structure, not a mandatory checklist -
  a route with no real data needs no Model step.
- The dynamic new $controllerClass() / $controller->$method() pattern
  from Router.php works identically for AboutController as it did for
  PostController, without the Router class itself needing any changes
  to support a second, unrelated controller.