/**
 * Copyright (c) 2002-2005, Simone Bordet
 * All rights reserved.
 *
 * This software is distributable under the BSD license.
 * See the terms of the BSD license in the documentation provided with this software.
 */

package foxtrot.examples;

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;

import javax.swing.DefaultComboBoxModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.SwingUtilities;
import javax.swing.border.EmptyBorder;

import foxtrot.Job;
import foxtrot.Worker;

/**
 * An example of how to use progress indication with Foxtrot.
 * The main advantage is that there is no more need to create a separate thread
 * for the progressive operation, but just use the Foxtrot API.
 * And, of course, with Foxtrot the GUI can be interrupted in any moment.
 *
 * @version $Revision: 1.6 $
 */
public class ProgressExample extends JFrame
{
   private JButton button;
   private JProgressBar bar;
   private boolean running;
   private boolean taskInterrupted;

   public static void main(String[] args)
   {
      ProgressExample example = new ProgressExample();
      example.setVisible(true);
   }

   public ProgressExample()
   {
      super("Foxtrot Example");

      button = new JButton("Run Task !");
      button.addActionListener(new ActionListener()
      {
         public void actionPerformed(ActionEvent e)
         {
            if (running)
               onCancelClicked();
            else
               onRunClicked();
         }
      });

      bar = new JProgressBar();
      bar.setStringPainted(true);

      setDefaultCloseOperation(EXIT_ON_CLOSE);

      Container c = getContentPane();
      c.setLayout(new BorderLayout(0, 0));

      JPanel main = new JPanel(new BorderLayout(0, 0));
      main.setBorder(new EmptyBorder(35, 35, 35, 35));
      c.add(main, BorderLayout.CENTER);

      JPanel p = new JPanel(new BorderLayout(20, 20));
      p.add(bar, BorderLayout.NORTH);
      p.add(button, BorderLayout.SOUTH);

      main.add(p);

      setSize(300, 200);

      Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
      Dimension size = getSize();
      int x = (screen.width - size.width) >> 1;
      int y = (screen.height - size.height) >> 1;
      setLocation(x, y);
   }

   private void onRunClicked()
   {
      // We are running
      running = true;

      // We just started, set the task as not interrupted, to
      // clear any eventual previous status
      setTaskInterrupted(false);

      // We will execute a long operation, change the text signaling
      // that the user can interrupt the operation
      button.setText("Cancel");

      // getData() will block until the heavy operation is finished
      // and the AWT-Swing events will be dequeued and processed
      ArrayList list = getData();

      // Restore the button's text
      button.setText("Run Task !");

      // We're not running anymore
      running = false;

      // getData() finished or was interrupted ?
      // If was interrupted we get back a null list
      if (list != null)
      {
         // Task completed successfully, do whatever useful with the list
         // For example, populate a JComboBox
         // The reader will finish this part :)
         DefaultComboBoxModel model = new DefaultComboBoxModel(list.toArray());
      }
   }

   private void onCancelClicked()
   {
      // Here if we want to interrupt the Task

      setTaskInterrupted(true);
   }

   private ArrayList getData()
   {
      return (ArrayList)Worker.post(new Job()
      {
         public Object run()
         {
            ArrayList list = new ArrayList();
            StringBuffer buffer = new StringBuffer();

            // A repetitive operation that updates a progress bar.
            int max = 20;
            for (int i = 1; i <= max; ++i)
            {
               // Simulate a heavy operation to retrieve data
               try
               {
                  Thread.sleep(250);
               }
               catch (InterruptedException ignored)
               {
               }

               // Populate the data structure
               Object data = new Object();
               list.add(data);

               // Prepare the progress bar string
               buffer.setLength(0);
               buffer.append("Step ").append(i).append(" of ").append(max);

               if (isTaskInterrupted())
               {
                  buffer.append(" - Interrupted !");
                  update(i, max, buffer.toString());
                  break;
               }
               else
               {
                  // Update the progress bar
                  update(i, max, buffer.toString());
               }
            }

            if (isTaskInterrupted())
            {
               // Task is interrupted, clean the half-populated data structure
               // and return from the Task
               list.clear();
               return null;
            }
            else
            {
               return list;
            }
         }
      });
   }

   private void update(final int index, final int max, final String string)
   {
      // This method is called by the Foxtrot Worker thread, but I want to
      // update the GUI, so I use SwingUtilities.invokeLater, as the Task
      // is not finished yet.

      SwingUtilities.invokeLater(new Runnable()
      {
         public void run()
         {
            bar.setMaximum(max);
            bar.setValue(index);
            bar.setString(string);
         }
      });
   }

   private synchronized boolean isTaskInterrupted()
   {
      // Called from the Foxtrot Worker Thread.
      // Must be synchronized, since the variable taskInterrupted is accessed from 2 threads.
      // While it is easier just to change the variable value without synchronizing, it is possible
      // that the Foxtrot worker thread doesn't see the change (it may cache the value of the variable
      // in a registry).
      return taskInterrupted;
   }

   private synchronized void setTaskInterrupted(boolean value)
   {
      // Called from the AWT Event Dispatch Thread.
      // See comments above on why it must be synchronized.
      taskInterrupted = value;
   }
}