@Override
public void treeWillExpand(TreeExpansionEvent event) throws ExpandVetoException {

    TreePath selPath = event.getPath();
    DefaultMutableTreeNode node = (DefaultMutableTreeNode) selPath.getLastPathComponent();
    Question question = (Question) node.getUserObject();
    if (!isOneOpen(node)) {
        return;
    } else if ("lock".equals(question.getStatus())) {
        MessageUtils.showMsg(toolWindow.getContentManager().getComponent(), MessageType.INFO, "info", "no permissions");
        throw new ExpandVetoException(event);
    }
    ProgressManager.getInstance().run(new Task.Backgroundable(project,"leetcode.editor.tree",false) {
        @Override
        public void run(@NotNull ProgressIndicator progressIndicator) {
            loadData(question,node,selPath,tree,toolWindow);
        }
    });
    throw new ExpandVetoException(event);
}
 

/** Messaged if the tree expansion event (for which we will have already
 * constructed a TableModelEvent) was vetoed;  disposes of the constructed
 * TableModelEvent in that circumstance. */
@Override
public void treeExpansionVetoed(TreeExpansionEvent event, ExpandVetoException exception) {
    assert SwingUtilities.isEventDispatchThread();
    
    log ("treeExpansionVetoed", exception);
    
    //Make sure the event that was vetoed is the one we're interested in
    if (event == inProgressEvent) {
        //If so, delete the expansion event we thought we were going
        //to use in treeExpanded/treeCollapsed, so that it doesn't
        //stick around forever holding references to objects from the
        //model
        pendingExpansionEvent = null;
        inProgressEvent = null;
    }
}
 

@Override
public void treeWillExpand(TreeExpansionEvent event) throws ExpandVetoException {
  final InspectionTreeNode node = (InspectionTreeNode)event.getPath().getLastPathComponent();
  final Object userObject = node.getUserObject();
  //TODO: never re-sort
  if (node.isValid() && !myExpandedUserObjects.contains(userObject)) {
    sortChildren(node);
    nodeStructureChanged(node);
  }
  myExpandedUserObjects.add(userObject);
  // Smart expand
  if (node.getChildCount() == 1) {
    ApplicationManager.getApplication().invokeLater(new Runnable() {
      @Override
      public void run() {
        expandPath(new TreePath(node.getPath()));
      }
    });
  }
}
 

@Override
public void treeWillExpand(TreeExpansionEvent event)
throws ExpandVetoException {
    // prepare wait cursor and optionally show it
    TreePath path = event.getPath();
    prepareWaitCursor(DragDropUtilities.secureFindNode(path.getLastPathComponent()));
}
 

/** Receives a TreeWillCollapse event and constructs a TableModelEvent
 * based on the pending changes while the model still reflects the unchanged
 * state */
@Override
public void treeWillCollapse(TreeExpansionEvent event) throws ExpandVetoException {
    assert SwingUtilities.isEventDispatchThread();
    
    log ("treeWillCollapse", event);
    
    //Construct the TableModelEvent here, before data structures have
    //changed.  We will fire it from TreeCollapsed if the change is 
    //not vetoed.
    pendingExpansionEvent = translateEvent (event, false);
    log ("treeWillCollapse generated ", pendingExpansionEvent);
    inProgressEvent = event;
}
 

/** Receives a TreeWillExpand event and constructs a TableModelEvent
 * based on the pending changes while the model still reflects the unchanged
 * state */
@Override
public void treeWillExpand(TreeExpansionEvent event) throws ExpandVetoException {
    assert SwingUtilities.isEventDispatchThread();

    log ("treeWillExpand", event);
    
    //Construct the TableModelEvent here, before data structures have
    //changed.  We will fire it from TreeExpanded if the change is not
    //vetoed
    pendingExpansionEvent = translateEvent (event, true);
    
    log ("treeWillExpand generated", pendingExpansionEvent);
    inProgressEvent = event;
}
 

private void fireTreeWillExpand (TreeExpansionEvent e, boolean expanded) throws ExpandVetoException {
    int size = weListeners.size();
    
    TreeWillExpandListener[] listeners = new TreeWillExpandListener[size];
    synchronized (this) {
        listeners = weListeners.toArray(listeners);
    }
    for (int i=0; i < listeners.length; i++) {
        if (expanded) {
            listeners[i].treeWillExpand(e);
        } else {
            listeners[i].treeWillCollapse(e);
        }
    }
}
 

private void fireTreeExpansionVetoed (TreeExpansionEvent e, ExpandVetoException ex) {
    int size = weListeners.size();
    
    TreeWillExpandListener[] listeners = new TreeWillExpandListener[size];
    synchronized (this) {
        listeners = weListeners.toArray(listeners);
    }
    for (int i=0; i < listeners.length; i++) {
        if (listeners[i] instanceof ExtTreeWillExpandListener) {
            ((ExtTreeWillExpandListener) listeners[i]).treeExpansionVetoed(e,
                ex);
        }
    }
}
 

/**
 * Maps {@code JTree.fireTreeWillCollapse(TreePath)} through queue
 */
public void fireTreeWillCollapse(final TreePath treePath) {
    runMapping(new MapVoidAction("fireTreeWillCollapse") {
        @Override
        public void map() throws ExpandVetoException {
            ((JTree) getSource()).fireTreeWillCollapse(treePath);
        }
    });
}
 

/**
 * Maps {@code JTree.fireTreeWillExpand(TreePath)} through queue
 */
public void fireTreeWillExpand(final TreePath treePath) {
    runMapping(new MapVoidAction("fireTreeWillExpand") {
        @Override
        public void map() throws ExpandVetoException {
            ((JTree) getSource()).fireTreeWillExpand(treePath);
        }
    });
}
 

/**
 * Invoked whenever a node in the tree is about to be expanded.
 */
public void treeWillExpand(TreeExpansionEvent event) throws ExpandVetoException {
    if (classificationViewer.isLocked()) {
        throw new ExpandVetoException(event);
    }
    jTree.addChildren((ViewerJTree.MyJTreeNode) event.getPath().getLastPathComponent());
}
 

/**
 * Invoked whenever a node in the tree is about to be collapsed.
 */
public void treeWillCollapse(TreeExpansionEvent event) throws ExpandVetoException {
    if (inspectorWindow.isLocked()) {
        if (dir.getDocument().getProgressListener() != null)
            dir.getDocument().getProgressListener().setUserCancelled(true);
        throw new ExpandVetoException(event);
    }
}
 

/**
 * Invoked whenever a node in the tree is about to be expanded.
 */
public void treeWillExpand(TreeExpansionEvent event) throws ExpandVetoException {
    if (inspectorWindow.isLocked()) {
        if (dir.getDocument().getProgressListener() != null)
            dir.getDocument().getProgressListener().setUserCancelled(true);
        throw new ExpandVetoException(event);
    }

    final TreePath path = event.getPath();
    final NodeBase node = (NodeBase) path.getLastPathComponent();
    if (node.getChildCount() > 0) { // has already been expanded
        if (node.isCompleted())
            return;
        else {
            int result = JOptionPane.showConfirmDialog(inspectorWindow.getFrame(), "List of children incomplete, re-fetch?", "Re-fetch", JOptionPane.YES_NO_CANCEL_OPTION);
            if (result == JOptionPane.NO_OPTION)
                return;
            else if (result == JOptionPane.CANCEL_OPTION)
                throw new ExpandVetoException(event);
            else // remove all children to trigger re-download
                node.removeAllChildren();
        }
    }

    if (node instanceof TopLevelNode) {
        inspectorWindow.addChildren((TopLevelNode) node);
    } else if (node instanceof ReadHeadLineNode) {
        inspectorWindow.addChildren((ReadHeadLineNode) node, path.getPathComponent(1).toString());
    }
    if (node instanceof ReadDataHeadLineNode) {
        inspectorWindow.addChildren((ReadDataHeadLineNode) node);
    } else if (node instanceof MatchHeadLineNode) {
        inspectorWindow.addChildren((MatchHeadLineNode) node);
    }
}
 

@Override
 	public void treeWillCollapse(TreeExpansionEvent e) throws ExpandVetoException {
// Prevent root key from being collapsed
 		if (e.getPath().getPathCount() == 1) {
 			throw new ExpandVetoException(e);        			
 		}
 	}
 

@Override public void treeWillExpand(TreeExpansionEvent e) throws ExpandVetoException {
  TreePath path = e.getPath();
  Object o = path.getLastPathComponent();
  if (o instanceof DefaultMutableTreeNode) {
    DefaultMutableTreeNode node = (DefaultMutableTreeNode) o;
    File file = (File) node.getUserObject();
    if (file.isFile()) {
      throw new ExpandVetoException(e, "Tree expansion cancelled");
    }
  }
}
 

@Override public void treeWillExpand(TreeExpansionEvent e) throws ExpandVetoException {
  TreePath path = e.getPath();
  Object o = path.getLastPathComponent();
  if (o instanceof DefaultMutableTreeNode) {
    DefaultMutableTreeNode node = (DefaultMutableTreeNode) o;
    File file = (File) node.getUserObject();
    String name = file.getName();
    // System.out.println(name);
    if (!name.isEmpty() && name.codePointAt(0) == '.') {
      throw new ExpandVetoException(e, "Tree expansion cancelled");
    }
  }
}
 

@Override
public void treeWillExpand(TreeExpansionEvent event) throws ExpandVetoException {
  final TreePath path = event.getPath();
  if (path == null) return;
  final PackageDependenciesNode node = (PackageDependenciesNode)path.getLastPathComponent();
  node.sortChildren();
  ((DefaultTreeModel)myTree.getModel()).reload(node);
}
 

@Override
public void treeWillCollapse(TreeExpansionEvent event)
throws ExpandVetoException {
}
 

public void treeWillExpand(TreeExpansionEvent event) throws ExpandVetoException {
    Object expanding = event.getPath().getLastPathComponent();
    if (expanding instanceof TreeNode) nodeExpanding((TreeNode)expanding);
}
 

public void treeWillCollapse(TreeExpansionEvent event) throws ExpandVetoException {
    Object collapsing = event.getPath().getLastPathComponent();
    if (collapsing instanceof TreeNode) nodeCollapsing((TreeNode)collapsing);
}
 

public void treeWillExpand(TreeExpansionEvent event) throws ExpandVetoException {
    Object expanding = event.getPath().getLastPathComponent();
    if (expanding instanceof TreeNode) nodeExpanding((TreeNode)expanding);
}
 

public void treeWillCollapse(TreeExpansionEvent event) throws ExpandVetoException {
    Object collapsing = event.getPath().getLastPathComponent();
    if (collapsing instanceof TreeNode) nodeCollapsing((TreeNode)collapsing);
}
 

@Override
public void treeWillExpand(TreeExpansionEvent e) throws ExpandVetoException {}
 

/**
 * {@inheritDoc}
 */
public void treeWillCollapse(final TreeExpansionEvent event)
        throws ExpandVetoException {

}
 

public void treeWillExpand( final TreeExpansionEvent event ) throws ExpandVetoException {
  addExpandedNode( getRowForPath( event.getPath() ) );
}
 

public void treeWillCollapse( final TreeExpansionEvent event ) throws ExpandVetoException {
  removeExpandedNode( getRowForPath( event.getPath() ) );
}
 

@Override
public void treeWillCollapse(TreeExpansionEvent event) throws ExpandVetoException {
  InspectionTreeNode node = (InspectionTreeNode)event.getPath().getLastPathComponent();
  myExpandedUserObjects.remove(node.getUserObject());
}
 

@Override
public void treeWillCollapse(TreeExpansionEvent event) throws ExpandVetoException {
}
 

/**
 * Invoked whenever a node in the tree is about to be expanded.
 */
public void treeWillExpand(TreeExpansionEvent event) throws ExpandVetoException;
 

/**
 * Invoked whenever a node in the tree is about to be collapsed.
 */
public void treeWillCollapse(TreeExpansionEvent event) throws ExpandVetoException;