Support to handle Options request using middleware stack

.gitignore

@@ -4,4 +4,6 @@ build
 composer.lock
 phpunit.xml
 vendor
-composer-require-checker.phar
+composer-require-checker.phar
+.php-cs-fixer.php
+tests/coverage

src/Router.php

@@ -17,6 +17,7 @@ final class Router implements RequestHandler
     use ForbidCloning;
     use ForbidSerialization;
 
+    public const OPTIONS_METHOD = 'OPTIONS';
     private const DEFAULT_CACHE_SIZE = 512;
 
     private bool $running = false;
@@ -80,6 +81,13 @@ public function handleRequest(Request $request): Response
 
         if (null === $match = $this->cache->get($toMatch)) {
             $match = $this->routeDispatcher->dispatch($method, $path);
+
+            if ($this->isNotAllowedOptionsMethod($match, $method)) {
+                $toMatch = self::OPTIONS_METHOD . "\0{$path}";
+
+                $match = $this->optionsRequests($match[1], $request);
+            }
+
             $this->cache->set($toMatch, $match);
         }
 
@@ -300,4 +308,24 @@ private function onStop(): void
         $this->routeDispatcher = null;
         $this->running = false;
     }
+
+    private function isNotAllowedOptionsMethod(array $match, string $method): bool
+    {
+        return $match[0] === Dispatcher::METHOD_NOT_ALLOWED
+            && \count($match[1]) > 0
+            && $method === self::OPTIONS_METHOD;
+    }
+
+    private function optionsRequests(array $methods, Request $request): array
+    {
+        $handler = new ClosureRequestHandler(fn () => $this->methodNotAllowed($methods, $request));
+
+        $requestHandler = Middleware\stackMiddleware($handler, ...$this->middlewares);
+
+        return [
+            Dispatcher::FOUND,
+            $requestHandler,
+            [],
+        ];
+    }
 }

test/RouterTest.php

@@ -42,7 +42,7 @@ public function testThrowsOnInvalidCacheSize(): void
     {
         $this->expectException(\Error::class);
 
-        new Router($this->server, $this->testLogger, $this->errorHandler, 0);
+        (new Router($this->server, $this->testLogger, $this->errorHandler, 0));
     }
 
     public function testRouteThrowsOnEmptyMethodString(): void
@@ -52,6 +52,7 @@ public function testRouteThrowsOnEmptyMethodString(): void
 
         $router = new Router($this->server, $this->testLogger, $this->errorHandler);
         $router->addRoute("", "/uri", new ClosureRequestHandler(function () {
+            // empty handler
         }));
     }
 
@@ -345,4 +346,65 @@ public function testSetFallbackAfterStart(): void
         $this->expectExceptionMessage('Cannot add fallback');
         $router->setFallback($requestHandler);
     }
+
+    public function testHandleOptionsRequestWhenRouteIsNotMatched(): void
+    {
+        $router = new Router($this->server, $this->testLogger, $this->errorHandler);
+
+        $this->server->start($router, $this->errorHandler);
+
+        $request = new Request($this->createMock(Client::class), Router::OPTIONS_METHOD, Uri\Http::createFromString("/foo/bar"));
+        $response = $router->handleRequest($request);
+        $this->assertEquals(HttpStatus::NOT_FOUND, $response->getStatus());
+        $this->assertNull($response->getHeader('allow'));
+    }
+
+    public function testHandleOptionsRequestWithoutMiddlewares(): void
+    {
+        $requestHandler = new ClosureRequestHandler(function () {
+            return new Response(HttpStatus::OK);
+        });
+
+        $router = new Router($this->server, $this->testLogger, $this->errorHandler);
+        $router->addRoute("GET", "/foo/{name}", $requestHandler);
+
+        $this->server->start($router, $this->errorHandler);
+
+        $request = new Request($this->createMock(Client::class), Router::OPTIONS_METHOD, Uri\Http::createFromString("/foo/bar"));
+        $response = $router->handleRequest($request);
+        $this->assertEquals(HttpStatus::METHOD_NOT_ALLOWED, $response->getStatus());
+        $this->assertSame('GET', $response->getHeader('allow'));
+    }
+
+    public function testHandleOptionsRequestWithCorsMiddleware(): void
+    {
+        $requestHandler = new ClosureRequestHandler(function () {
+            return new Response(HttpStatus::OK);
+        });
+
+        $router = new Router($this->server, $this->testLogger, $this->errorHandler);
+        $router->addRoute("GET", "/foo/{name}", $requestHandler);
+
+        $router->addMiddleware(new class implements Middleware {
+            public function handleRequest(Request $request, RequestHandler $requestHandler): Response
+            {
+                if ($request->getMethod() === 'OPTIONS') {
+                    $response = new Response();
+                    $response->setHeader('Access-Control-Allow-Origin', '*');
+                    $response->setStatus(HttpStatus::OK);
+
+                    return $response;
+                }
+
+                return $requestHandler->handleRequest($request);
+            }
+        });
+
+        $this->server->start($router, $this->errorHandler);
+
+        $request = new Request($this->createMock(Client::class), Router::OPTIONS_METHOD, Uri\Http::createFromString("/foo/bar"));
+        $response = $router->handleRequest($request);
+        $this->assertEquals(HttpStatus::OK, $response->getStatus());
+        $this->assertSame('*', $response->getHeader('access-control-allow-origin'));
+    }
 }