/*
    *  XNap - A P2P framework and client.
    *
    *  See the file AUTHORS for copyright information.
    *
    *  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.
    *
   *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  package org.xnap.gui.util;
  
  import java.awt.Color;
  import java.awt.Component;
  import java.awt.Container;
  import java.awt.Window;
  import java.awt.event.ActionEvent;
  import java.awt.event.ActionListener;
  import java.awt.event.KeyEvent;
  import java.net.URL;
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.List;
  import javax.help.CSH;
  import javax.help.HelpBroker;
  import javax.help.HelpSet;
  import javax.swing.AbstractButton;
  import javax.swing.JComponent;
  import javax.swing.JMenu;
  import javax.swing.JPopupMenu;
  import javax.swing.KeyStroke;
  import javax.swing.MenuElement;
  import javax.swing.border.Border;
  import javax.swing.border.LineBorder;
  import javax.swing.plaf.BorderUIResource;
  import javax.swing.plaf.basic.BasicBorders;
  import org.apache.log4j.Logger;
  import org.xnap.loader.XNapClassLoader;
  
  /***
   * A helper class providing the main helpset and helpbroker and some
   * convenience functions for registering help keys in components.
   */
  public class HelpManager
  {
      
      //--- Constant(s) ---
  
      public static final String XNAP_MANUAL = "xnap-manual";
  
      //--- Data field(s) ---
  
      private static HelpSet mainHelpSet = null;
      private static XNapHelpBroker mainHelpBroker = null;
  
      private static ActionListener tracker = null;
  
      private static Logger logger = Logger.getLogger(HelpManager.class);
      
      //--- Constructor(s) ---
  
      private HelpManager()
      {
      }
  
      //--- Method(s) ---
  
      /***
       * Returns the main helpset.
       *
       * If helpset isn't loaded yet, it will be loaded on demand.
       *
       * @return returns null if helpset couldn't be loaded.
       */
      public static HelpSet getMainHelpSet()
      {
  		if (mainHelpSet == null) {
  			mainHelpSet = loadHelpSet(XNAP_MANUAL);
  		}
  		return mainHelpSet;
      }
  
      /***
       * Returns the main helpbroker.
       */
      public static XNapHelpBroker getMainHelpBroker()
      {
  		if (mainHelpBroker == null) {
  			if (getMainHelpSet() != null) {
  				mainHelpBroker = new XNapHelpBroker(getMainHelpSet());
 			}
 		}
 		return mainHelpBroker;
     }
 
     /***
      * Adds helpset to the main helpset hierarchy.
      */
     public static void add(HelpSet hs)
     {
 		getMainHelpSet().add(hs);
     }
 
     /***
      * Removes helpset from the main helpset hierarchy.
      */
     public static void remove(HelpSet hs)
     {
 		getMainHelpSet().remove(hs);
     }
 
     /***
      * Helper method to load helpsets.
      *
      * @param helpset name of the helpset file without the ending, e.g.
      * "xnap-manual" from "xnap-manual.hs".
      */
     public static HelpSet loadHelpSet(String helpset)
     {
 		URL url = HelpSet.findHelpSet(XNapClassLoader.getInstance(), helpset);
 		if (url != null) {
 			try {
 				return new HelpSet(XNapClassLoader.getInstance(), url);
 			}
 			catch (Exception e) {
 				logger.debug("Could not load helpset" + helpset, e);
 			}
 		}
 		else {
 			logger.debug("Could not find helpset");
 		}
 		return null;
     }
 
     /***
      * Convenience method enabling the help keys and the context help key for
      * a JComponent.
      */
     public static void enableHelpKeys(JComponent comp, String id, HelpSet hs)
     {
 		HelpBroker hb = getMainHelpBroker();
 		if (hb != null) {
 			hb.enableHelpKey(comp, id, hs);
 			enableContextHelpKey(comp);
 		}
     }
 
     /***
      * Enables the context help key for a JComponent.
      */
     public static void enableContextHelpKey(JComponent jc)
     {
 		if (getMainHelpBroker() != null) {
 			jc.registerKeyboardAction
 				(getTracker(), KeyStroke.getKeyStroke(KeyEvent.VK_F1,
 													  KeyEvent.SHIFT_MASK),
 				 JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
 		}
     }
 
     public static ActionListener getTracker()
     {
 		if (tracker == null) {
 			tracker = new Tracker();
 		}
 		return tracker;
     }
 
 	private static class Tracker implements ActionListener
 	{
 		private ActionListener tracker = 
 			new CSH.DisplayHelpAfterTracking(getMainHelpBroker());
 
 		private class CBPair
 		{
 			public JComponent c;
 			public Border b;
 			public boolean p;
 
 			public CBPair(JComponent c, Border b, boolean p)
 			{
 				this.c = c;
 				this.b = b;
 				this.p = p;
 			}
 
 			public CBPair(JComponent c, Border b)
 			{
 				this(c, b, false);
 			}
 		}
 
 		public void actionPerformed(ActionEvent event)
 		{
 			List borders = new LinkedList();
 			if (event.getSource() instanceof Component) {
 				Component c = (Component)event.getSource();
 				c = getTopComponent(c);
 				setBorders(c, borders);
 			}
 			tracker.actionPerformed(event);
 			resetBorders(borders);
 		}
 
 		private Component getTopComponent(Component c)
 		{
 			for (Component parent = c; parent != null;) {
 				c = parent;
 				if (parent instanceof Window) {
 					break;
 				}
 				if (parent instanceof MenuElement) {
 					if (parent instanceof JPopupMenu) {
 						parent = ((JPopupMenu)parent).getInvoker();
 					}
 					else {
 						parent = ((MenuElement)parent).getComponent();
 					}
 				}
 				parent = parent.getParent();
 			}
 			return c;
 		}
 
 		private void setBorders(Component c, List borders)
 		{
 			if (c instanceof JComponent) {
 				JComponent jc = (JComponent)c;
 				String helpID = (String)jc.getClientProperty("HelpID");
 				if (helpID != null) {
 					try {
 						BorderUIResource.CompoundBorderUIResource b =
 							new BorderUIResource.CompoundBorderUIResource
 								(new LineBorder(Color.RED), 
 								 jc.getBorder());
 						if (jc instanceof AbstractButton) {
 							AbstractButton ab = (AbstractButton)jc;
 							borders.add(new CBPair(jc, jc.getBorder(),
 												   ab.isBorderPainted()));
 							ab.setBorderPainted(true);
 							ab.setBorder(b);
 						}
 						else {
 							borders.add(new CBPair(jc, jc.getBorder()));
 							jc.setBorder(b);
 						}
 					}
 					catch (IllegalArgumentException iae) {
 					}
 				}
 			}
 			if (c instanceof Container) {
 				Container cont = (Container)c;
 				for (int i = 0; i < cont.getComponentCount(); i++) {
 					setBorders(cont.getComponent(i), borders);
 				}
 			}
 			else if (c instanceof JMenu) {
 				setBorders(((JMenu)c).getPopupMenu(), borders);
 			}
 		}
 
 		private void resetBorders(List borders)
 		{
 			for (Iterator it = borders.iterator(); it.hasNext();) {
 				CBPair pair = (CBPair)it.next();
 				if (pair.c instanceof AbstractButton) {
 					((AbstractButton)pair.c).setBorderPainted(pair.p);
 				}
 				pair.c.setBorder(pair.b);
 			}
 		}
 	}
 }