Add detection of end for auto scrolling

src/main/java/com/faforever/client/chat/ChatMessage.java

@@ -2,6 +2,8 @@
 
 import com.faforever.client.chat.emoticons.Emoticon;
 import com.faforever.client.chat.emoticons.Reaction;
+import javafx.beans.property.BooleanProperty;
+import javafx.beans.property.SimpleBooleanProperty;
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableMap;
 import lombok.EqualsAndHashCode;
@@ -28,6 +30,7 @@ public class ChatMessage {
   @Getter
   private final ChatMessage targetMessage;
 
+  private final BooleanProperty open = new SimpleBooleanProperty();
   private final ObservableMap<Emoticon, ObservableMap<String, String>> reactions = FXCollections.synchronizedObservableMap(
       FXCollections.observableHashMap());
   private final ObservableMap<Emoticon, ObservableMap<String, String>> unmodifiableReactions = FXCollections.unmodifiableObservableMap(
@@ -52,6 +55,18 @@ public void removeReaction(Reaction reaction) {
     }
   }
 
+  public boolean isOpen() {
+    return open.get();
+  }
+
+  public BooleanProperty openProperty() {
+    return open;
+  }
+
+  public void setOpen(boolean open) {
+    this.open.set(open);
+  }
+
   public enum Type {
     MESSAGE, ACTION, PENDING
   }

src/main/java/com/faforever/client/chat/ChatMessageController.java

@@ -162,9 +162,11 @@ protected void onInitialize() {
     avatarTooltip.setShowDuration(Duration.seconds(30));
     Tooltip.install(avatarImageView, avatarTooltip);
 
-    chatMessage.subscribe((oldValue, newValue) -> {
+    chatMessage.when(attached).subscribe((oldValue, newValue) -> {
       if (oldValue != null) {
         oldValue.getReactions().removeListener(reactionChangeListener);
+        oldValue.openProperty().unbind();
+        oldValue.setOpen(false);
       }
 
       reactionNodeMap.clear();
@@ -173,6 +175,7 @@ protected void onInitialize() {
       if (newValue != null) {
         newValue.getReactions().forEach(this::addReaction);
         newValue.getReactions().addListener(reactionChangeListener);
+        newValue.openProperty().bind(showing);
       }
     });
 
@@ -195,6 +198,15 @@ protected void onInitialize() {
                                        .when(showing));
   }
 
+  @Override
+  protected void onDetached() {
+    ChatMessage chatMessage = getChatMessage();
+    if (chatMessage != null) {
+      chatMessage.openProperty().unbind();
+      chatMessage.setOpen(false);
+    }
+  }
+
   private void onReactionChange(
       MapChangeListener.Change<? extends Emoticon, ? extends ObservableMap<String, String>> change) {
     Emoticon reaction = change.getKey();

src/main/java/com/faforever/client/chat/ChatMessageViewController.java

@@ -12,6 +12,7 @@
 import com.faforever.client.util.PopupUtil;
 import javafx.beans.Observable;
 import javafx.beans.binding.Bindings;
+import javafx.beans.binding.BooleanExpression;
 import javafx.beans.property.ObjectProperty;
 import javafx.beans.property.SimpleObjectProperty;
 import javafx.beans.value.ObservableValue;
@@ -87,6 +88,9 @@ public class ChatMessageViewController extends NodeController<VBox> {
   private final ObservableList<ChatMessage> rawMessages = FXCollections.synchronizedObservableList(
       FXCollections.observableArrayList(chatMessage -> new Observable[]{chatMessage.getSender().categoryProperty()}));
   private final FilteredList<ChatMessage> filteredMessages = new FilteredList<>(rawMessages);
+  private final BooleanExpression atEnd = BooleanExpression.booleanExpression(
+      Bindings.valueAt(filteredMessages, Bindings.size(filteredMessages).subtract(1))
+              .flatMap(ChatMessage::openProperty));
 
   private Popup emoticonsPopup;
 
@@ -136,6 +140,7 @@ protected void onInitialize() {
         ObservableList<ChatChannelUser> typingUsers = newValue.getTypingUsers();
         setTypingLabel(typingUsers);
         typingUsers.addListener(typingUserListChangeListener);
+        scrollToEnd();
       }
     }));
 
@@ -158,12 +163,16 @@ protected void onInitialize() {
                                        .when(showing));
 
     filteredMessages.subscribe(() -> {
-      if (showing.get()) {
-        fxApplicationThreadExecutor.execute(() -> messagesListView.scrollTo(filteredMessages.size()));
+      if (atEnd.get()) {
+        scrollToEnd();
       }
     });
   }
 
+  private void scrollToEnd() {
+    fxApplicationThreadExecutor.execute(() -> messagesListView.scrollTo(filteredMessages.size()));
+  }
+
   private AutoCompletionHelper createAutoCompletionHelper() {
     return new AutoCompletionHelper(currentWord -> {
       ObservableList<ChatChannelUser> users = this.users.getValue();

src/main/java/com/faforever/client/fx/Controller.java

@@ -35,8 +35,8 @@ public final void initialize() {
         onDetached();
       }
     });
-    showing.subscribe(isSelected -> {
-      if (isSelected) {
+    showing.subscribe(isShowing -> {
+      if (isShowing) {
         onShow();
       } else {
         shownSubscriptions.forEach(Subscription::unsubscribe);

src/test/java/com/faforever/client/chat/KittehChatServiceTest.java

@@ -719,7 +719,7 @@ public void testJoinChannel() {
     instance.joinChannel(channelToJoin);
 
     verify(spyClient).addChannel(channelToJoin);
-    verify(spyClient).sendRawLine("CHATHISTORY LATEST " + channelToJoin + " * " + (chatPrefs.getMaxMessages() + 50));
+    verify(spyClient).sendRawLine("CHATHISTORY LATEST " + channelToJoin + " * " + (chatPrefs.getMaxMessages() * 2));
     verify(spyClient).sendRawLine("WHO " + channelToJoin);
   }