Reset handout when new presenter is connecting

Author: knutwalker

backend/src/main/scala/de/knutwalker/wdcm/HandoutSystem.scala

@@ -59,7 +59,10 @@ object HandoutSystem {
       case m@BespokeMessage.Deactivate(n) ⇒
         sequence :+= m
         viewers.foreach(_ ! m)
-      case BespokeMessage.Disconnect ⇒
+      case BespokeMessage.Connect         ⇒
+        sequence = Vector(BespokeMessage.Connect)
+        viewers.foreach(_ ! BespokeMessage.Connect)
+      case BespokeMessage.Disconnect      ⇒
         sequence = Vector()
         viewers.foreach(_ ! BespokeMessage.Disconnect)
     }

common/src/main/scala/de/knutwalker/wdcm/BespokeMessage.scala

@@ -9,13 +9,15 @@ object BespokeMessage {
   def slide(slide: Int): BespokeMessage = Slide(slide)
   def next(slide: Int): BespokeMessage = Next(slide)
   def prev(slide: Int): BespokeMessage = Prev(slide)
+  def connect: BespokeMessage = Connect
   def disconnect: BespokeMessage = Disconnect
 
   case class Deactivate(slide: Int) extends BespokeMessage
   case class Activate(slide: Int) extends BespokeMessage
   case class Slide(slide: Int) extends BespokeMessage
   case class Next(slide: Int) extends BespokeMessage
   case class Prev(slide: Int) extends BespokeMessage
+  case object Connect extends BespokeMessage
   case object Disconnect extends BespokeMessage
 
   implicit val picklerBespokeMessage: Pickler[BespokeMessage] =

frontend/src/main/scala/de/knutwalker/wdcm/Handout.scala

@@ -38,6 +38,10 @@ case object Handout extends Plugin with Websockets {
         case BespokeMessage.Activate(n) if n != active ⇒
           max = js.Math.max(n, max)
           deck.slide(n)
+        case BespokeMessage.Connect                    ⇒
+          max = 0
+          active = 0
+          deck.slide(0)
         case otherwise                                 ⇒
       }
     }

frontend/src/main/scala/de/knutwalker/wdcm/Presenter.scala

@@ -7,10 +7,17 @@ import boopickle.Default.Pickle
 
 case object Presenter extends Plugin with Websockets {
 
+  override protected def onOpen(ws: WebSocket, event: Event): Unit =
+    sendEvent(BespokeMessage.connect)
+
   override protected def onClose(ws: WebSocket, event: Event): Unit =
     sendEvent(BespokeMessage.disconnect)
 
   override def apply(deck: Deck): Unit = {
+    // Need to register before opening, otherwise we lose the race for handling
+    // 'next' and 'prev' against the bullet plugin, which swallows next events
+    // in order to open its bullets, but we could not inform the handout clients
+    // to jump to their next bullet item as well.
     registerUnbind(deck.on("activate", (e: BespokeEvent) ⇒ {
       sendEvent(BespokeMessage.activate(e.index))
     }))