instance HasSpiderTimeline x => Reflex.Host.Class.MonadSubscribeEvent (SpiderTimeline x) (SpiderHostFrame x) where
  {-# INLINABLE subscribeEvent #-}
  subscribeEvent e = SpiderHostFrame $ do
    --TODO: Unsubscribe eventually (manually and/or with weak ref)
    val <- liftIO $ newIORef Nothing
    subscription <- subscribe (unSpiderEvent e) $ Subscriber
      { subscriberPropagate = \a -> do
          liftIO $ writeIORef val $ Just a
          scheduleClear val
      , subscriberInvalidateHeight = \_ -> return ()
      , subscriberRecalculateHeight = \_ -> return ()
      }
    return $ SpiderEventHandle
      { spiderEventHandleSubscription = subscription
      , spiderEventHandleValue = val
      }

instance HasSpiderTimeline x => Reflex.Host.Class.ReflexHost (SpiderTimeline x) where
  type EventTrigger (SpiderTimeline x) = RootTrigger x
  type EventHandle (SpiderTimeline x) = SpiderEventHandle x
  type HostFrame (SpiderTimeline x) = SpiderHostFrame x

instance HasSpiderTimeline x => Reflex.Host.Class.MonadReadEvent (SpiderTimeline x) (Reflex.Spider.Internal.ReadPhase x) where
  {-# NOINLINE readEvent #-}
  readEvent h = Reflex.Spider.Internal.ReadPhase $ fmap (fmap return) $ liftIO $ do
    result <- readIORef $ spiderEventHandleValue h
    touch h
    return result

instance (
#ifdef SPECIALIZE_TO_SPIDERTIMELINE_GLOBAL
           x ~ Global
#endif
         ) => Reflex.Host.Class.MonadReflexCreateTrigger (SpiderTimeline x) (SpiderHost x) where
  newEventWithTrigger = SpiderHost . lift . fmap SpiderEvent . newEventWithTriggerIO
  newFanEventWithTrigger f = SpiderHost $ lift $ do
    es <- newFanEventWithTriggerIO f
    return $ Reflex.Class.EventSelector $ SpiderEvent . Reflex.Spider.Internal.select es

instance (
#ifdef SPECIALIZE_TO_SPIDERTIMELINE_GLOBAL
           x ~ Global
#endif
         ) => Reflex.Host.Class.MonadReflexCreateTrigger (SpiderTimeline x) (SpiderHostFrame x) where
  newEventWithTrigger = SpiderHostFrame . EventM . liftIO . fmap SpiderEvent . newEventWithTriggerIO
  newFanEventWithTrigger f = SpiderHostFrame $ EventM $ liftIO $ do
    es <- newFanEventWithTriggerIO f
    return $ Reflex.Class.EventSelector $ SpiderEvent . Reflex.Spider.Internal.select es

instance HasSpiderTimeline x => Reflex.Host.Class.MonadSubscribeEvent (SpiderTimeline x) (SpiderHost x) where
  {-# INLINABLE subscribeEvent #-}
  subscribeEvent = runFrame . runSpiderHostFrame . Reflex.Host.Class.subscribeEvent

instance HasSpiderTimeline x => Reflex.Host.Class.MonadReflexHost (SpiderTimeline x) (SpiderHost x) where
  type ReadPhase (SpiderHost x) = Reflex.Spider.Internal.ReadPhase x
  fireEventsAndRead es (Reflex.Spider.Internal.ReadPhase a) = run es a
  runHostFrame = runFrame . runSpiderHostFrame