/*
 * Copyright 1999,2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j.chainsaw;

import org.apache.log4j.chainsaw.icons.ChainsawIcons;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;

import java.io.IOException;

import java.net.URL;

import java.util.Stack;

import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JEditorPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JToolBar;
import javax.swing.SwingUtilities;
import javax.swing.event.HyperlinkEvent;
import javax.swing.event.HyperlinkListener;


/**
 * An initial Welcome Panel that is used when Chainsaw starts up, can displays
 * a HTML pages based on URLs.
 *
 * @author Paul Smith
 * @author Scott Deboy <sdeboy@apache.org>
 */
public class WelcomePanel extends JPanel {
  private Stack urlStack = new Stack();
  private final JEditorPane textInfo = new JEditorPane();
  private final URLToolbar urlToolbar = new URLToolbar();

  public WelcomePanel() {
    super(new BorderLayout());
    setBackground(Color.white);
    add(urlToolbar, BorderLayout.NORTH);

	URL helpURL = ChainsawConstants.WELCOME_URL;

    if (helpURL != null) {
      textInfo.setBorder(BorderFactory.createEmptyBorder(0, 5, 0, 5));
      textInfo.setEditable(false);
      textInfo.setPreferredSize(new Dimension(320, 240));

      JScrollPane pane = new JScrollPane(textInfo);
      pane.setBorder(null);
      add(pane, BorderLayout.CENTER);

      try {
        textInfo.setPage(helpURL);
        textInfo.addHyperlinkListener(
          new HyperlinkListener() {
            public void hyperlinkUpdate(HyperlinkEvent e) {
              if (e.getEventType() == HyperlinkEvent.EventType.ACTIVATED) {
                urlStack.add(textInfo.getPage());

                try {
                  textInfo.setPage(e.getURL());
                  urlToolbar.updateToolbar();
                } catch (IOException e1) {
                  e1.printStackTrace();
                }
              }
            }
          });
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
  }

  void setURL(final URL url) {
    SwingUtilities.invokeLater(
      new Runnable() {
        public void run() {
          try {
            urlStack.push(textInfo.getPage());
            textInfo.setPage(url);
            urlToolbar.updateToolbar();
          } catch (IOException e) {
            e.printStackTrace();
          }
        }
      });
  }

  private class URLToolbar extends JToolBar {
    private final Action previousAction =
      new AbstractAction(null, new ImageIcon(ChainsawIcons.ICON_BACK)) {
        public void actionPerformed(ActionEvent e) {
          if (urlStack.isEmpty()) {
            return;
          }

          setURL((URL) urlStack.pop());
        }
      };

    private final Action homeAction =
      new AbstractAction(null, new ImageIcon(ChainsawIcons.ICON_HOME)) {
        public void actionPerformed(ActionEvent e) {
          setURL(ChainsawConstants.WELCOME_URL);
          urlStack.clear();
        }
      };

    private URLToolbar() {
      setFloatable(false);
      updateToolbar();
      previousAction.putValue(Action.SHORT_DESCRIPTION, "Back");
      homeAction.putValue(Action.SHORT_DESCRIPTION, "Home");

      JButton home = new SmallButton(homeAction);
      add(home);

      addSeparator();

      JButton previous = new SmallButton(previousAction);
      previous.setEnabled(false);
      add(previous);

      addSeparator();
    }

    void updateToolbar() {
      previousAction.setEnabled(!urlStack.isEmpty());
    }
  }

  /**
   * @return tooolbar
   */
  public JToolBar getToolbar() {
    return urlToolbar;
  }
}