router.php

<?php

class Router {
  private $routes = [];

  public function get($pattern, $controller_method) {
    $this->route('get', $pattern, $controller_method);
  }

  public function post($pattern, $controller_method) {
    $this->route('post', $pattern, $controller_method);
  }

  public function patch($pattern, $controller_method) {
    $this->route('patch', $pattern, $controller_method);
  }

  public function puts($pattern, $controller_method) {
    $this->route('puts', $pattern, $controller_method);
  }

  public function delete($pattern, $controller_method) {
    $this->route('delete', $pattern, $controller_method);
  }

  public function route($http_method, $pattern, $controller_method) {
    $pattern = $this->route_to_regex($pattern);

    $this->routes[$http_method.$pattern] = [
      'http_method' => $http_method, 
      'url_pattern' => $pattern, 
      'controller_method' => $controller_method
    ];
  }

  public function execute($request_data) {
    foreach ($this->routes as $pattern => $actions) {
      if ($request_data['REQUEST_METHOD'] === strtoupper($actions['http_method'])) {
        if(preg_match($actions['url_pattern'], $request_data['REQUEST_URI'], $params) === 1) {
          $callables = $this->call_controller_class($actions['controller_method']);
          $controller = new $callables['controller'];

          array_shift($params);

          $format = array_key_exists('CONTENT_TYPE', $request_data) ? $request_data['CONTENT_TYPE'] : 'text/html';
          $params['format'] = explode('/', $format)[1];
          $params['method'] = $request_data['REQUEST_METHOD'];

          $controller->{$callables['action']}($params);

          break;
        }
      }
    }
  }

  private function route_to_regex($path) {
    $slashes_escaped = str_replace('/', '\/', $path);
    $route = preg_replace_callback('/({:.+?})/', function($matches) {
      $param_name = preg_replace("/[^A-Za-z0-9 ]/", '', $matches[0]);

      return "(?<{$param_name}>.*)";
    }, $slashes_escaped);

    return '/^'.$route.'$/';
  }

  private function call_controller_class($str) {
    $callables = explode('#', $str);
    $controller = [];

    foreach(explode('/', $callables[0]) as $controller_part) {
      array_push($controller, ucfirst($controller_part));
    }

    $controller = implode('\\', $controller).'Controller';

    return ['controller' => $controller, 'action' => $callables[1]];
  }
}