ApiMiddleware

This middleware is here to demonstrate how you can implement a simple authentication middleware in Borsch Framework.
It assumes that you have an API available at the /api path of your application.

Let say to access the API, your users need an access key.
It would not be really efficient to check the API Key in every route call, example:

$app->match(['GET', 'POST', 'PUT', 'DELETE'], '/api/cart[/{id:\d+}]', CartHandler::class); // Check in this handler
$app->match(['GET', 'POST', 'PUT', 'DELETE'], '/api/order[/{id:\d+}]', OrderHandler::class); // In this handler too
$app->match(['GET', 'POST', 'PUT', 'DELETE'], '/api/customer[/{id:\d+}]', CustomerHandler::class); // Here too

Instead, we can use a segregated path in your pipeline to validate the API Key for every route that match the path /api.

The bundled ApiMiddleware is really simple, and actually let every request pass through it. This middleware is simply a proof of concept.
If you do not need it, just remove it from the pipeline.

Here is a more realistic ApiMiddleware that will check API Key in a database:

class ApiMiddleware implements MiddlewareInterface
{

    /** @var \PDO */
    protected $pdo;

    /**
     * @param \PDO $pdo
     */
    public function __construct(\PDO $pdo)
    {
        $this->pdo = $pdo;
    }

    /**
     * @param ServerRequestInterface $request
     * @param RequestHandlerInterface $handler
     * @return ResponseInterface
     */
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        $api_key = $request->getHeaderLine('X-Api-Key');
        
        $statement = $this->pdo->prepare('SELECT `user_id` FROM `user` WHERE `apikey` = ?');
        if (!$statement->execute([$api_key]) || !$statement->columnCount()) {
            return new Response('php://memory', 403);
        }

        $request = $request->withAttribute('user_id', $statement->fetchColumn());

        $statement->closeCursor();

        return $handler->handle($request);
    }
}