Code cleanup, return value fix, comments

src/WebSocketMiddleware.php

@@ -18,6 +18,8 @@ class WebSocketMiddleware implements EventEmitterInterface
 
     const MAGIC = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11';
 
+    const VERSION = 13;
+
     use EventEmitterTrait;
 
     private GroupManager $groupManager;
@@ -32,7 +34,7 @@ class WebSocketMiddleware implements EventEmitterInterface
 
     public function addRoute(string $path, callable $handler, array $allowedOrigins=[]): void
     {
-
+        // TODO implement or remove
     }
 
     public function __invoke(ServerRequestInterface $request, callable $next)
@@ -62,12 +64,14 @@ class WebSocketMiddleware implements EventEmitterInterface
             $this->emit(self::EVENT_CONNECTION, [ $websocket ]);
         //});
 
+        // TODO would it be possible or rather useful for the 'connection' event to set additional response headers to be sent here?
         return new Response(
             Response::STATUS_SWITCHING_PROTOCOLS,
             array(
                 'Upgrade' => 'websocket',
                 'Connection' => 'upgrade',
-                'Sec-WebSocket-Accept' => $handshakeResponse
+                'Sec-WebSocket-Accept' => $handshakeResponse,
+                'Sec-WebSocket-Version' => self::VERSION
             ),
             $stream
         );