Add ETag to FeedController

config/app.php

@@ -48,6 +48,7 @@ return [
 
         // Changes of request/response parameters
         \Engelsystem\Middleware\SetLocale::class,
+        \Engelsystem\Middleware\ETagHandler::class,
         \Engelsystem\Middleware\AddHeaders::class,
 
         // The application code

src/Controllers/FeedController.php

@@ -33,7 +33,7 @@ class FeedController extends BaseController
     {
         $news = $this->getNews();
 
-        return $this->response
+        return $this->withEtag($news)
             ->withHeader('content-type', 'application/atom+xml; charset=utf-8')
             ->withView('api/atom', ['news' => $news]);
     }
@@ -42,7 +42,7 @@ class FeedController extends BaseController
     {
         $news = $this->getNews();
 
-        return $this->response
+        return $this->withEtag($news)
             ->withHeader('content-type', 'application/rss+xml; charset=utf-8')
             ->withView('api/rss', ['news' => $news]);
     }
@@ -51,7 +51,7 @@ class FeedController extends BaseController
     {
         $shifts = $this->getShifts();
 
-        return $this->response
+        return $this->withEtag($shifts)
             ->withHeader('content-type', 'text/calendar; charset=utf-8')
             ->withHeader('content-disposition', 'attachment; filename=shifts.ics')
             ->withView('api/ical', ['shiftEntries' => $shifts]);
@@ -121,11 +121,18 @@ class FeedController extends BaseController
             ];
         }
 
-        return $this->response
+        return $this->withEtag($response)
             ->withAddedHeader('content-type', 'application/json; charset=utf-8')
             ->withContent(json_encode($response));
     }
 
+    protected function withEtag(mixed $value): Response
+    {
+        $hash = md5(json_encode($value));
+
+        return $this->response->setEtag($hash);
+    }
+
     protected function getNews(): Collection
     {
         $news = $this->request->has('meetings')

src/Middleware/ETagHandler.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Engelsystem\Middleware;
+
+use Illuminate\Support\Str;
+use Nyholm\Psr7\Stream;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\MiddlewareInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Symfony\Component\HttpFoundation\Response;
+
+class ETagHandler implements MiddlewareInterface
+{
+    /**
+     * Compare the response ETag to a requested If-None-Match header and send a 304 "not modified" if they match
+     */
+    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
+    {
+        $response = $handler->handle($request);
+
+        $etagMatch = $request->getHeader('If-None-Match');
+        $etag = $response->getHeader('ETag');
+
+        if (
+            !$etagMatch
+            || !$etag
+            || !Str::contains(implode(', ', $etagMatch), trim($etag[0], '"'))
+        ) {
+            return $response;
+        }
+
+        return $response
+            ->withStatus(Response::HTTP_NOT_MODIFIED)
+            ->withBody(Stream::create());
+    }
+}

tests/Unit/Controllers/FeedControllerTest.php

@@ -22,6 +22,7 @@ class FeedControllerTest extends ControllerTest
     /**
      * @covers \Engelsystem\Controllers\FeedController::__construct
      * @covers \Engelsystem\Controllers\FeedController::atom
+     * @covers \Engelsystem\Controllers\FeedController::withEtag
      */
     public function testAtom(): void
     {
@@ -33,6 +34,12 @@ class FeedControllerTest extends ControllerTest
             ['content-type', 'application/atom+xml; charset=utf-8'],
             $this->response
         );
+        $this->response->expects($this->once())
+            ->method('setEtag')
+            ->willReturnCallback(function ($etag) {
+                $this->assertNotEmpty($etag);
+                return $this->response;
+            });
         $this->response->expects($this->once())
             ->method('withView')
             ->willReturnCallback(function ($view, $data) {
@@ -58,6 +65,7 @@ class FeedControllerTest extends ControllerTest
             ['content-type', 'application/rss+xml; charset=utf-8'],
             $this->response
         );
+        $this->setExpects($this->response, 'setEtag', null, $this->response);
         $this->response->expects($this->once())
             ->method('withView')
             ->willReturnCallback(function ($view, $data) {
@@ -66,6 +74,7 @@ class FeedControllerTest extends ControllerTest
 
                 return $this->response;
             });
+
         $controller->rss();
     }
 
@@ -95,6 +104,8 @@ class FeedControllerTest extends ControllerTest
             )
             ->willReturn($this->response);
 
+        $this->setExpects($this->response, 'setEtag', null, $this->response);
+
         $this->response->expects($this->once())
             ->method('withView')
             ->willReturnCallback(function ($view, $data) {
@@ -109,6 +120,7 @@ class FeedControllerTest extends ControllerTest
 
                 return $this->response;
             });
+
         $controller->ical();
     }
 
@@ -137,6 +149,8 @@ class FeedControllerTest extends ControllerTest
             $this->response
         );
 
+        $this->setExpects($this->response, 'setEtag', null, $this->response);
+
         $this->response->expects($this->once())
             ->method('withContent')
             ->willReturnCallback(function ($jsonData) {
@@ -162,6 +176,7 @@ class FeedControllerTest extends ControllerTest
 
                 return $this->response;
             });
+
         $controller->shifts();
     }
 
@@ -184,6 +199,7 @@ class FeedControllerTest extends ControllerTest
 
         $this->request->attributes->set('meetings', $isMeeting);
         $this->setExpects($this->response, 'withHeader', null, $this->response);
+        $this->setExpects($this->response, 'setEtag', null, $this->response);
         $this->response->expects($this->once())
             ->method('withView')
             ->willReturnCallback(function ($view, $data) use ($isMeeting) {
@@ -210,6 +226,7 @@ class FeedControllerTest extends ControllerTest
         $controller = new FeedController($this->auth, $this->request, $this->response);
 
         $this->setExpects($this->response, 'withHeader', null, $this->response);
+        $this->setExpects($this->response, 'setEtag', null, $this->response);
         $this->response->expects($this->once())
             ->method('withView')
             ->willReturnCallback(function ($view, $data) {

tests/Unit/Middleware/ETagHandlerTest.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Engelsystem\Test\Unit\Middleware;
+
+use Engelsystem\Http\Request;
+use Engelsystem\Http\Response;
+use Engelsystem\Middleware\ETagHandler;
+use Engelsystem\Test\Unit\TestCase;
+use PHPUnit\Framework\MockObject\MockObject;
+use Psr\Http\Server\RequestHandlerInterface;
+
+class ETagHandlerTest extends TestCase
+{
+    /**
+     * @covers \Engelsystem\Middleware\ETagHandler::process
+     */
+    public function testRegister(): void
+    {
+        /** @var RequestHandlerInterface|MockObject $handler */
+        $handler = $this->getMockForAbstractClass(RequestHandlerInterface::class);
+        $request = Request::create('https://localhost')
+            ->withHeader('If-None-Match', 'FooBarBaz');
+        $originalResponse = (new Response())
+            ->withHeader('ETag', '"FooBarBaz"')
+            ->withHeader('original-header', 'value')
+            ->withContent('Foo bar!');
+        $this->setExpects($handler, 'handle', [$request], $originalResponse);
+
+        $middleware = new ETagHandler();
+        $response = $middleware->process($request, $handler);
+
+        $this->assertTrue($response->hasHeader('original-header'));
+        $this->assertEquals('value', $response->getHeader('original-header')[0]);
+
+        $this->assertEquals(304, $response->getStatusCode());
+        $this->assertEquals('', (string) $response->getBody());
+    }
+
+    /**
+     * @covers \Engelsystem\Middleware\ETagHandler::process
+     */
+    public function testRegisterNoChange(): void
+    {
+        /** @var RequestHandlerInterface|MockObject $handler */
+        $handler = $this->getMockForAbstractClass(RequestHandlerInterface::class);
+        $request = Request::create('https://localhost');
+        $originalResponse = new Response();
+        $this->setExpects($handler, 'handle', [$request], $originalResponse);
+
+        $middleware = new ETagHandler();
+        $response = $middleware->process($request, $handler);
+
+        $this->assertEquals($originalResponse, $response);
+    }
+}