feat: plan viewer/editor tab switch and queue item events

Author: JMit-dev

app/queue-server/src/main/java/org/phoebus/applications/queueserver/view/QueueItemSelectionEvent.java

@@ -0,0 +1,42 @@
+package org.phoebus.applications.queueserver.util;
+
+import org.phoebus.applications.queueserver.api.QueueItem;
+import org.phoebus.applications.queueserver.view.TabSwitchEvent;
+
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.function.Consumer;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class QueueItemSelectionEvent {
+
+    private static final QueueItemSelectionEvent INSTANCE = new QueueItemSelectionEvent();
+
+    private final List<Consumer<QueueItem>> listeners = new CopyOnWriteArrayList<>();
+    private static final Logger LOG = Logger.getLogger(TabSwitchEvent.class.getName());
+
+    private QueueItemSelectionEvent() {}
+
+    public static QueueItemSelectionEvent getInstance() {
+        return INSTANCE;
+    }
+
+    public void addListener(Consumer<QueueItem> listener) {
+        listeners.add(listener);
+    }
+
+    public void removeListener(Consumer<QueueItem> listener) {
+        listeners.remove(listener);
+    }
+
+    public void notifySelectionChanged(QueueItem selectedItem) {
+        for (Consumer<QueueItem> listener : listeners) {
+            try {
+                listener.accept(selectedItem);
+            } catch (Exception e) {
+                LOG.log(Level.WARNING, "Error in queue selection listener", e);
+            }
+        }
+    }
+}

app/queue-server/src/main/java/org/phoebus/applications/queueserver/view/TabSwitchEvent.java

@@ -0,0 +1,33 @@
+package org.phoebus.applications.queueserver.view;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Consumer;
+import java.util.logging.Logger;
+import java.util.logging.Level;
+
+public class TabSwitchEvent {
+    private static final TabSwitchEvent instance = new TabSwitchEvent();
+    private final List<Consumer<String>> listeners = new ArrayList<>();
+    private static final Logger LOG = Logger.getLogger(TabSwitchEvent.class.getName());
+
+    private TabSwitchEvent() {}
+
+    public static TabSwitchEvent getInstance() {
+        return instance;
+    }
+
+    public void addListener(Consumer<String> listener) {
+        listeners.add(listener);
+    }
+
+    public void switchToTab(String tabName) {
+        for (Consumer<String> listener : listeners) {
+            try {
+                listener.accept(tabName);
+            } catch (Exception e) {
+                LOG.log(Level.WARNING, "Tab switch listener error", e);
+            }
+        }
+    }
+}