package org.greenstone.gatherer.util;
/**
 *#########################################################################
 *
 * A component of the Gatherer application, part of the Greenstone digital
 * library suite from the New Zealand Digital Library Project at the
 * University of Waikato, New Zealand.
 *
 * Author: John Thompson, Greenstone Digital Library, University of Waikato
 *
 * Copyright (C) 1999 New Zealand Digital Library Project
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *########################################################################
 */
import java.util.Vector;
import javax.swing.JTree;
import javax.swing.event.TreeExpansionEvent;
import javax.swing.event.TreeExpansionListener;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.TreeModel;
import javax.swing.tree.TreePath;
import org.greenstone.gatherer.gui.tree.DragTree;
/** My latest diabolical class synchronizes the expansion state of two or more JTrees. Muh-hahahaha. Note that these tree should be based on the same model. 
 * @author John Thompson, Greenstone Digital Library, University of Waikato
 * @version 2.1
 */
final public class TreeSynchronizer 
	 extends Vector 
	 implements TreeExpansionListener, TreeSelectionListener {
	 /** <i>true</i> if we should temporarily ignore further events, most likely because we know our actions are causing them. */ 
	 private boolean ignore;
	 /** A list of tree selection listeners. */
	 private Vector selection_listeners = new Vector();
	 /** Add a new tree to the synchronization list of trees to be synchronized.
	  * @param tree The lastest victim, a <strong>JTree</strong>.
	  */
	 public void add(JTree tree) {
		  super.add(tree);
		  tree.addTreeExpansionListener(this);
		  //tree.addTreeSelectionListener(this);
	 }

	 /** We allow the Gatherer to add tree listeners to this class, as it persists between collection changes transparently. Thus there is no need to reattach listeners everytime the collection changes. */
	 public void addTreeSelectionListener(TreeSelectionListener listener) {
		  if(!selection_listeners.contains(listener)) {
				selection_listeners.add(listener);
		  }
	 }

	 /** Called whenever an item in the tree has been collapsed.
	  * @param event A <strong>TreeExpansionEvent</strong> containing information about the event.
	  */
	 public void treeCollapsed(TreeExpansionEvent event) {
		  if(!ignore) {
				ignore = true;
				// Collapse that path in all registered trees.
				JTree tree = (JTree)event.getSource();
				TreePath path = event.getPath();
				for(int i = size(); i != 0; i--) {
					 JTree sibling = (JTree) get(i - 1);
					 if(!sibling.equals(tree)) {
						  sibling.collapsePath(path);
					 }
				}
				ignore = false;
		  }
	 }
	 /** Called whenever an item in the tree has been expanded.
	  * @param event A <strong>TreeExpansionEvent</strong> containing information about the event.
	  */
	 public void treeExpanded(TreeExpansionEvent event) {
		  if(!ignore) {
				ignore = true;
				// Expand that path in all registered trees.
				JTree tree = (JTree)event.getSource();
				TreePath path = event.getPath();
				for(int i = size(); i != 0; i--) {
					 JTree sibling = (JTree) get(i - 1);
					 if(!sibling.equals(tree)) {
						  sibling.expandPath(path);
					 }
				}
				ignore = false;
		  }
	 }
	 /** Called whenever the one of the trees selection changes.
	  * @param event A <strong>TreeSelectionEvent</strong> containing information about the event.
	  */
	 public void valueChanged(TreeSelectionEvent event) {
		  if(!ignore) {
				ignore = true;
				// Recover the tree that is the source.
				JTree tree = (JTree) event.getSource();
				// Brute Force approach.
				// Extract the currently selected paths.
				TreePath paths[] = tree.getSelectionPaths();
				// Then for every registered tree, that isn't this one, ensure those paths are selected.
				for(int i = size(); paths != null && i != 0; i--) {
					 JTree sibling = (JTree) get(i - 1);
					 if(!sibling.equals(tree)) {
						  // One last thing to do. If this is actually a DragTree we are dealing with we have to tell it to set the selection values immediately, not wait for the clear until it is sure it is no the pre-cursor to a drag.
						  if(sibling instanceof DragTree) {
								DragTree gtree = (DragTree)sibling;
								gtree.setImmediate(true);
								gtree.setSelectionPaths(paths);
								// I'm going to ensure that the last selected path is visible.
								gtree.scrollPathToVisible(paths[paths.length - 1]);
								gtree.setImmediate(false);
						  }
						  else {
								sibling.setSelectionPaths(paths);
								sibling.scrollPathToVisible(paths[paths.length - 1]);
						  }
					 }
				}
				// Pass on message to all listeners.
				for(int i = 0; i < selection_listeners.size(); i++) {
					 ((TreeSelectionListener) selection_listeners.get(i)).valueChanged(event);
				}
				ignore = false;
		  }
	 }
}