stateful night vision rework

pi/roverd/nightvision.go

@@ -81,6 +81,12 @@ func (n *NightVisionLight) HandleAction(action string) error {
 	}
 }
 
+func (n *NightVisionLight) NightVisionOn() bool {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+	return !n.on
+}
+
 func (n *NightVisionLight) setLocked(on bool) error {
 	if err := n.line.SetValue(boolToGPIO(on)); err != nil {
 		return err

pi/roverd/nightvision_dummy.go

@@ -18,3 +18,7 @@ func (n *NightVisionLight) Close() {}
 func (n *NightVisionLight) HandleAction(action string) error {
 	return fmt.Errorf("night vision not supported in dummy build")
 }
+
+func (n *NightVisionLight) NightVisionOn() bool {
+	return false
+}

pi/roverd/wsclient.go

@@ -184,7 +184,13 @@ func (c *WSClient) dispatch(ctx context.Context, msg *inboundMessage) error {
 		if c.nightVision == nil {
 			return fmt.Errorf("night vision disabled")
 		}
-		return c.nightVision.HandleAction(msg.NightVision.Action)
+		if err := c.nightVision.HandleAction(msg.NightVision.Action); err != nil {
+			return err
+		}
+		c.emitEvent("nightVision.state", map[string]any{
+			"nightVisionOn": c.nightVision.NightVisionOn(),
+		})
+		return nil
 	case msg.Song != nil:
 		slot := 0
 		if msg.Song.Slot != nil {