Auth.php

/*
Building a Middleware for Authentication

Components:
1) AuthFactory
- Responsible for creating the the session and loading it with data
*/
interface IAuthFactory {
  public function setData($data = []);
}
/*
2) Authenticator
- Responsbile for checking to see if its a valid user
*/
interface IAuthenticator {
  public function authorize($username, $password);
}
/*
3) AuthMiddleware
- Responsible for checking to make sure the user is authenticated
*/
interface IAuthMiddleware {
  public function __invoke(Request $req, Response $resp , $next);
}

//Usuage...

$securityMiddleware = new AuthMiddleware();

$app->get('/protect', 'Callable)->addMiddleware($securityMiddleware);

$app->post('/login', function ($req, $res, $args) {
  $result = $this->authenticator($req->getParsedBody()['username'], $req->getParsedBody()['password']);
  if ($result) {
    $this->authFactory->setData([]);
    //..
  } else {
    //..
  }
});