/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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 javax.swing.*;
  import javax.swing.event.HyperlinkEvent;
  import java.awt.*;
  import java.awt.event.ActionEvent;
  import java.io.IOException;
  import java.net.URL;
  import java.util.Stack;
  
  
  /**
   * 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<URL> 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));
  
              JScrollPane pane = new JScrollPane(textInfo);
              pane.setBorder(null);
              add(pane, BorderLayout.CENTER);
  
              try {
                  textInfo.setEditable(false);
                  textInfo.setPreferredSize(new Dimension(320, 240));
                  textInfo.setPage(helpURL);
                  JTextComponentFormatter.applySystemFontAndSize(textInfo);
                  textInfo.addHyperlinkListener(
                      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(
              () -> {
                  try {
                      urlStack.push(textInfo.getPage());
                      textInfo.setPage(url);
                      //not all pages displayed in the Welcome Panel are html-based (example receiver config is an xml file)..
                      JTextComponentFormatter.applySystemFontAndSize(textInfo);
                      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(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;
     }
 }