/*
 * HelpViewer.java - HTML Help viewer
 * :tabSize=8:indentSize=8:noTabs=false:
 * :folding=explicit:collapseFolds=1:
 *
 * Copyright (C) 1999, 2002 Slava Pestov
 *
 * 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 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

package org.gjt.sp.jedit.help;

//{{{ Imports
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.event.*;
import javax.swing.text.html.*;
import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import java.io.*;
import java.net.*;
import org.gjt.sp.jedit.gui.RolloverButton;
import org.gjt.sp.jedit.msg.PluginUpdate;
import org.gjt.sp.jedit.*;
import org.gjt.sp.util.Log;
//}}}

/**
 * jEdit's searchable help viewer. It uses a Swing JEditorPane to display the HTML,
 * and implements a URL history.
 * @author Slava Pestov
 * @version $Id: HelpViewer.java,v 1.14 2004/06/28 06:45:27 spestov Exp $
 */
public class HelpViewer extends JFrame implements EBComponent
{
	//{{{ HelpViewer constructor
	/**
	 * Creates a new help viewer with the default help page.
	 * @since jEdit 4.0pre4
	 */
	public HelpViewer()
	{
		this("welcome.html");
	} //}}}

	//{{{ HelpViewer constructor
	/**
	 * Creates a new help viewer for the specified URL.
	 * @param url The URL
	 */
	public HelpViewer(URL url)
	{
		this(url.toString());
	} //}}}

	//{{{ HelpViewer constructor
	/**
	 * Creates a new help viewer for the specified URL.
	 * @param url The URL
	 */
	public HelpViewer(String url)
	{
		super(jEdit.getProperty("helpviewer.title"));

		setIconImage(GUIUtilities.getEditorIcon());

		try
		{
			baseURL = new File(MiscUtilities.constructPath(
				jEdit.getJEditHome(),"doc")).toURL().toString();
		}
		catch(MalformedURLException mu)
		{
			Log.log(Log.ERROR,this,mu);
			// what to do?
		}

		history = new String[25];

		ActionHandler actionListener = new ActionHandler();

		JTabbedPane tabs = new JTabbedPane();
		tabs.addTab(jEdit.getProperty("helpviewer.toc.label"),
			toc = new HelpTOCPanel(this));
		tabs.addTab(jEdit.getProperty("helpviewer.search.label"),
			new HelpSearchPanel(this));
		tabs.setMinimumSize(new Dimension(0,0));

		JPanel rightPanel = new JPanel(new BorderLayout());

		JToolBar toolBar = new JToolBar();
		toolBar.setFloatable(false);

		toolBar.add(title = new JLabel());
		toolBar.add(Box.createGlue());

		JPanel buttons = new JPanel();
		buttons.setLayout(new BoxLayout(buttons,BoxLayout.X_AXIS));
		buttons.setBorder(new EmptyBorder(0,12,0,0));
		back = new RolloverButton(GUIUtilities.loadIcon(
			jEdit.getProperty("helpviewer.back.icon")));
		back.setToolTipText(jEdit.getProperty("helpviewer.back.label"));
		back.addActionListener(actionListener);
		toolBar.add(back);
		forward = new RolloverButton(GUIUtilities.loadIcon(
			jEdit.getProperty("helpviewer.forward.icon")));
		forward.addActionListener(actionListener);
		forward.setToolTipText(jEdit.getProperty("helpviewer.forward.label"));
		toolBar.add(forward);
		back.setPreferredSize(forward.getPreferredSize());

		rightPanel.add(BorderLayout.NORTH,toolBar);

		viewer = new JEditorPane();
		viewer.setEditable(false);
		viewer.addHyperlinkListener(new LinkHandler());
		viewer.setFont(new Font("Monospaced",Font.PLAIN,12));
		viewer.addPropertyChangeListener(new PropertyChangeHandler());

		rightPanel.add(BorderLayout.CENTER,new JScrollPane(viewer));

		splitter = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
			tabs,rightPanel);
		splitter.setBorder(null);

		getContentPane().add(BorderLayout.CENTER,splitter);

		gotoURL(url,true);

		setDefaultCloseOperation(DISPOSE_ON_CLOSE);

		getRootPane().setPreferredSize(new Dimension(750,500));

		pack();
		GUIUtilities.loadGeometry(this,"helpviewer");

		EditBus.addToBus(this);

		setVisible(true);

		SwingUtilities.invokeLater(new Runnable()
		{
			public void run()
			{
				splitter.setDividerLocation(jEdit.getIntegerProperty(
					"helpviewer.splitter",250));
				viewer.requestFocus();
			}
		});
	} //}}}

	//{{{ gotoURL() method
	/**
	 * Displays the specified URL in the HTML component.
	 * @param url The URL
	 * @param addToHistory Should the URL be added to the back/forward
	 * history?
	 */
	public void gotoURL(String url, boolean addToHistory)
	{
		// the TOC pane looks up user's guide URLs relative to the
		// doc directory...
		String shortURL;
		if(MiscUtilities.isURL(url))
		{
			if(url.startsWith(baseURL))
			{
				shortURL = url.substring(baseURL.length());
				if(shortURL.startsWith("/"))
					shortURL = shortURL.substring(1);
			}
			else
			{
				shortURL = url;
			}
		}
		else
		{
			shortURL = url;
			if(baseURL.endsWith("/"))
				url = baseURL + url;
			else
				url = baseURL + '/' + url;
		}

		// reset default cursor so that the hand cursor doesn't
		// stick around
		viewer.setCursor(Cursor.getDefaultCursor());

		URL _url = null;
		try
		{
			_url = new URL(url);

			if(!_url.equals(viewer.getPage()))
				title.setText(jEdit.getProperty("helpviewer.loading"));
			else
			{
				/* don't show loading msg because we won't
				   receive a propertyChanged */
			}

			viewer.setPage(_url);
			if(addToHistory)
			{
				history[historyPos] = url;
				if(historyPos + 1 == history.length)
				{
					System.arraycopy(history,1,history,
						0,history.length - 1);
					history[historyPos] = null;
				}
				else
					historyPos++;
			}
		}
		catch(MalformedURLException mf)
		{
			Log.log(Log.ERROR,this,mf);
			String[] args = { url, mf.getMessage() };
			GUIUtilities.error(this,"badurl",args);
			return;
		}
		catch(IOException io)
		{
			Log.log(Log.ERROR,this,io);
			String[] args = { url, io.toString() };
			GUIUtilities.error(this,"read-error",args);
			return;
		}

		this.shortURL = shortURL;

		// select the appropriate tree node.
		if(shortURL != null)
			toc.selectNode(shortURL);
	} //}}}

	//{{{ dispose() method
	public void dispose()
	{
		EditBus.removeFromBus(this);
		jEdit.setIntegerProperty("helpviewer.splitter",
			splitter.getDividerLocation());
		GUIUtilities.saveGeometry(this,"helpviewer");
		super.dispose();
	} //}}}

	//{{{ handleMessage() method
	public void handleMessage(EBMessage msg)
	{
		if(msg instanceof PluginUpdate)
		{
			PluginUpdate pmsg = (PluginUpdate)msg;
			if(pmsg.getWhat() == PluginUpdate.LOADED
				|| pmsg.getWhat() == PluginUpdate.UNLOADED)
			{
				if(!pmsg.isExiting())
				{
					if(!queuedTOCReload)
						queueTOCReload();
					queuedTOCReload = true;
				}
			}
		}
	} //}}}

	//{{{ getBaseURL() method
	public String getBaseURL()
	{
		return baseURL;
	} //}}}

	//{{{ getShortURL() method
	String getShortURL()
	{
		return shortURL;
	} //}}}

	//{{{ Private members

	//{{{ Instance members
	private String baseURL;
	private String shortURL;
	private JButton back;
	private JButton forward;
	private JEditorPane viewer;
	private JLabel title;
	private JSplitPane splitter;
	private String[] history;
	private int historyPos;
	private HelpTOCPanel toc;
	private boolean queuedTOCReload;
	//}}}

	//{{{ queueTOCReload() method
	public void queueTOCReload()
	{
		SwingUtilities.invokeLater(new Runnable()
		{
			public void run()
			{
				queuedTOCReload = false;
				toc.load();
			}
		});
	} //}}}

	//}}}

	//{{{ Inner classes

	//{{{ ActionHandler class
	class ActionHandler implements ActionListener
	{
		//{{{ actionPerformed() class
		public void actionPerformed(ActionEvent evt)
		{
			Object source = evt.getSource();
			if(source == back)
			{
				if(historyPos <= 1)
					getToolkit().beep();
				else
				{
					String url = history[--historyPos - 1];
					gotoURL(url,false);
				}
			}
			else if(source == forward)
			{
				if(history.length - historyPos <= 1)
					getToolkit().beep();
				else
				{
					String url = history[historyPos];
					if(url == null)
						getToolkit().beep();
					else
					{
						historyPos++;
						gotoURL(url,false);
					}
				}
			}
		} //}}}
	} //}}}

	//{{{ LinkHandler class
	class LinkHandler implements HyperlinkListener
	{
		//{{{ hyperlinkUpdate() method
		public void hyperlinkUpdate(HyperlinkEvent evt)
		{
			if(evt.getEventType() == HyperlinkEvent.EventType.ACTIVATED)
			{
				if(evt instanceof HTMLFrameHyperlinkEvent)
				{
					((HTMLDocument)viewer.getDocument())
						.processHTMLFrameHyperlinkEvent(
						(HTMLFrameHyperlinkEvent)evt);
				}
				else
				{
					URL url = evt.getURL();
					if(url != null)
						gotoURL(url.toString(),true);
				}
			}
			else if (evt.getEventType() == HyperlinkEvent.EventType.ENTERED) {
				viewer.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
			}
			else if (evt.getEventType() == HyperlinkEvent.EventType.EXITED) {
				viewer.setCursor(Cursor.getDefaultCursor());
			}
		} //}}}
	} //}}}

	//{{{ PropertyChangeHandler class
	class PropertyChangeHandler implements PropertyChangeListener
	{
		public void propertyChange(PropertyChangeEvent evt)
		{
			if("page".equals(evt.getPropertyName()))
			{
				String titleStr = (String)viewer.getDocument()
					.getProperty("title");
				if(titleStr == null)
				{
					titleStr = MiscUtilities.getFileName(
						viewer.getPage().toString());
				}
				title.setText(titleStr);
			}
		}
	} //}}}

	//}}}
}