public class HomeController extends Controller {

    private final Flow userFlow;

    @Inject
    public HomeController(ActorSystem actorSystem,
                          Materializer mat) {
        org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(this.getClass());
        LoggingAdapter logging = Logging.getLogger(actorSystem.eventStream(), logger.getName());

        //noinspection unchecked
        Source<String, Sink<String, NotUsed>> source = MergeHub.of(String.class)
                .log("source", logging)
                .recoverWithRetries(-1, new PFBuilder().match(Throwable.class, e -> Source.empty()).build());
        Sink<String, Source<String, NotUsed>> sink = BroadcastHub.of(String.class);

        Pair<Sink<String, NotUsed>, Source<String, NotUsed>> sinkSourcePair = source.toMat(sink, Keep.both()).run(mat);
        Sink<String, NotUsed> chatSink = sinkSourcePair.first();
        Source<String, NotUsed> chatSource = sinkSourcePair.second();
        this.userFlow = Flow.fromSinkAndSource(chatSink, chatSource).log("userFlow", logging);
    }

    public Result index() {
        Http.Request request = request();
        String url = routes.HomeController.chat().webSocketURL(request);
        return Results.ok(views.html.index.render(url));
    }

    public WebSocket chat() {
        return WebSocket.Text.acceptOrResult(request -> {
            if (sameOriginCheck(request)) {
                return CompletableFuture.completedFuture(F.Either.Right(userFlow));
            } else {
                return CompletableFuture.completedFuture(F.Either.Left(forbidden()));
            }
        });
    }
}