CORS support (#23)

src/DependencyInjection/services.php

@@ -13,6 +13,7 @@
 use Freddie\Hub\Hub;
 use Freddie\Hub\HubControllerInterface;
 use Freddie\Hub\HubInterface;
+use Freddie\Hub\Middleware\CorsMiddleware;
 use Freddie\Hub\Middleware\HttpExceptionConverterMiddleware;
 use Freddie\Hub\Middleware\TokenExtractorMiddleware;
 use Freddie\Hub\Transport\TransportFactory;
@@ -111,6 +112,7 @@
     $services
         ->set(App::class)
         ->args([
+            service(CorsMiddleware::class),
             service(HttpExceptionConverterMiddleware::class),
             service(TokenExtractorMiddleware::class),
         ]);
@@ -124,6 +126,12 @@
     $services
         ->set(Factory::class);
 
+    $services
+        ->set(CorsMiddleware::class)
+        ->args([
+            param('env(string:default::CORS_ORIGINS)')
+        ]);
+
     $services
         ->set(Configuration::class)
         ->factory(service(ConfigurationFactory::class))

src/Hub/Middleware/CorsMiddleware.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace Freddie\Hub\Middleware;
+
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use React\Http\Message\Response;
+
+final class CorsMiddleware
+{
+    public function __construct(
+        private readonly ?string $corsOrigin = '*',
+    ) {
+    }
+
+    public function __invoke(
+        ServerRequestInterface $request,
+        callable $next
+    ): ResponseInterface {
+        $response = $next($request);
+
+        $corsOrigin = $this->corsOrigin ?? $this->getOrigin($request);
+
+        return $response->withAddedHeader('Access-Control-Allow-Origin', $corsOrigin)
+            ->withAddedHeader('Access-Control-Allow-Headers', '*')
+            ->withAddedHeader('Access-Control-Allow-Methods', '*')
+            ->withAddedHeader('Access-Control-Allow-Credentials', 'true')
+            ->withStatus(Response::STATUS_OK);
+    }
+
+    private function getOrigin(ServerRequestInterface $request): string
+    {
+        return $request->getHeaderLine('Origin') ?: 'null';
+    }
+}

tests/Unit/Hub/Middleware/CorsMiddlewareTest.php

@@ -0,0 +1,48 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Freddie\Tests\Unit\Hub\Middleware;
+
+use FrameworkX\App;
+use Freddie\Hub\Middleware\CorsMiddleware;
+use React\Http\Message\Response;
+use React\Http\Message\ServerRequest;
+
+use function expect;
+use function Freddie\Tests\handle;
+use function it;
+
+it('decorates response with CORS mechanism', function () {
+    // Given
+    $corsOrigins = 'http://testdomain.local';
+    $expectedResponse = new Response(200);
+    $app = new App(new CorsMiddleware($corsOrigins), fn () => $expectedResponse);
+    $request = new ServerRequest('POST', './well-known/mercure');
+
+    // When
+    $response = handle($app, $request);
+
+    // Then
+    expect($response->getHeaderLine('Access-Control-Allow-Origin'))->toBe($corsOrigins)
+        ->and($response->getHeaderLine('Access-Control-Allow-Methods'))->toBe('*')
+        ->and($response->getHeaderLine('Access-Control-Allow-Headers'))->toBe('*')
+        ->and($response->getHeaderLine('Access-Control-Allow-Credentials'))->toBe('true');
+});
+
+it('decorates response with CORS mechanism with default corsOrigin setup', function () {
+    // Given
+    $corsOrigins = null;
+    $expectedResponse = new Response(400);
+    $app = new App(new CorsMiddleware($corsOrigins), fn () => $expectedResponse);
+    $request = new ServerRequest('POST', './well-known/mercure');
+
+    // When
+    $response = handle($app, $request);
+
+    // Then
+    expect($response->getHeaderLine('Access-Control-Allow-Origin'))->toBe('null')
+        ->and($response->getHeaderLine('Access-Control-Allow-Methods'))->toBe('*')
+        ->and($response->getHeaderLine('Access-Control-Allow-Headers'))->toBe('*')
+        ->and($response->getHeaderLine('Access-Control-Allow-Credentials'))->toBe('true');
+});