/* ProgressMonitor.java --
   Copyright (C) 2002, 2004, 2005, 2006, Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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General Public License for more details.

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02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package javax.swing;

import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.accessibility.AccessibleContext;

/**
 * <p>Using this class you can easily monitor tasks where you cannot
 * estimate the duration exactly.</p>
 *
 * <p>A ProgressMonitor instance waits until the first time setProgress
 * is called. When <code>millisToDecideToPopup</code> time elapsed the
 * instance estimates the duration until the whole operation is completed.
 * If this duration exceeds <code>millisToPopup</code> a non-modal dialog
 * with a message and a progress bar is shown.</p>
 *
 * <p>The value of <code>millisToDecideToPopup</code> defaults to
 * <code>500</code> and <code>millisToPopup</code> to
 * <code>2000</code>.</p>
 *
 * @author Andrew Selkirk
 * @author Robert Schuster (robertschuster@fsfe.org)
 * @since 1.2
 * @status updated to 1.2
 */
public class ProgressMonitor
{
  
  /**
   * The accessible content for this component
   */
  protected AccessibleContext accessibleContext;
  
  /**
   * parentComponent
   */
  Component component;

  /**
   * note
   */
  String note;

  /**
   * message
   */
  Object message;

  /**
   * millisToDecideToPopup
   */
  int millisToDecideToPopup = 500;

  /**
   * millisToPopup
   */
  int millisToPopup = 2000;

  int min, max, progress;

  JProgressBar progressBar;

  JLabel noteLabel;

  JDialog progressDialog;

  Timer timer;

  boolean canceled;

  /**
   * Creates a new <code>ProgressMonitor</code> instance.  This is used to 
   * monitor a task and pops up a dialog if the task is taking a long time to 
   * run.
   * 
   * @param component The parent component of the progress dialog or 
   *                  <code>null</code>.
   * @param message A constant message object which works in the way it does 
   *                in {@link JOptionPane}.
   * @param note A string message which can be changed while the operation goes
   *             on.
   * @param minimum The minimum value for the operation (start value).
   * @param maximum The maximum value for the operation (end value).
   */
  public ProgressMonitor(Component component, Object message,
                         String note, int minimum, int maximum)
  {

    // Set data.
    this.component = component;
    this.message = message;
    this.note = note;

    min = minimum;
    max = maximum;
  }

  /**
   * <p>Hides the dialog and stops any measurements.</p>
   *
   * <p>Has no effect when <code>setProgress</code> is not at least
   * called once.</p>
   */
  public void close()
  {
    if (progressDialog != null)
      {
        progressDialog.setVisible(false);
      }

    if (timer != null)
      {
        timer.stop();
        timer = null;
      }
  }

  /**
   * <p>Updates the progress value.</p>
   *
   * <p>When called for the first time this initializes a timer
   * which decides after <code>millisToDecideToPopup</code> time
   * whether to show a progress dialog or not.</p>
   *
   * <p>If the progress value equals or exceeds the maximum
   * value the progress dialog is closed automatically.</p>
   *
   * @param progress New progress value.
   */
  public void setProgress(int progress)
  {
    this.progress = progress;

    // Initializes and starts a timer with a task
    // which measures the duration and displays
    // a progress dialog if neccessary.
    if (timer == null && progressDialog == null)
      {
        timer = new Timer(25, null);
        timer.addActionListener(new TimerListener());
        timer.start();
      }

    // Cancels timer and hides progress dialog if the
    // maximum value is reached.
    if (progressBar != null && this.progress >= progressBar.getMaximum())
      {
        // The reason for using progressBar.getMaximum() instead of max is that
        // we want to prevent that changes to the value have any effect after the
        // progress dialog is visible (This is how the JDK behaves.).
        close();
      }

  }

  /** 
   * Returns the minimum or start value of the operation.
   *
   * @return Minimum or start value of the operation.
   */
  public int getMinimum()
  {
    return min;
  }

  /**
   * <p>Use this method to set the minimum or start value of
   * your operation.</p>
   *
   * <p>For typical application like copy operation this will be
   * zero.</p>
   *
   * <p>Keep in mind that changing this value after the progress
   * dialog is made visible has no effect upon the progress bar.</p>
   *
   * @param minimum The new minimum value.
   */
  public void setMinimum(int minimum)
  {
    min = minimum;
  }

  /**
   * Return the maximum or end value of your operation.
   *
   * @return Maximum or end value.
   */
  public int getMaximum()
  {
    return max;
  }

  /**
   * <p>Sets the maximum or end value of the operation to the
   * given integer.</p>
   *
   * @param maximum
   */
  public void setMaximum(int maximum)
  {
    max = maximum;
  }

  /**
   * Returns whether the user canceled the operation.
   *
   * @return Whether the operation was canceled.
   */
  public boolean isCanceled()
  {
    // The value is predefined to false
    // and changes only when the user clicks
    // the cancel button in the progress dialog.
    return canceled;
  }

  /**
   * Returns the amount of milliseconds to wait
   * until the ProgressMonitor should decide whether
   * a progress dialog is to be shown or not.
   *
   * @return The duration in milliseconds.
   */
  public int getMillisToDecideToPopup()
  {
    return millisToDecideToPopup;
  }

  /**
   * Sets the amount of milliseconds to wait until the
   * ProgressMonitor should decide whether a progress dialog
   * is to be shown or not.
   *
   * <p>This method has no effect when the progress dialog
   * is already visible.</p>
   *
   * @param time The duration in milliseconds.
   */
  public void setMillisToDecideToPopup(int time)
  {
    millisToDecideToPopup = time;
  }

  /**
   * Returns the number of milliseconds to wait before displaying the progress
   * dialog.  The default value is 2000.
   * 
   * @return The number of milliseconds.
   * 
   * @see #setMillisToPopup(int)
   */
  public int getMillisToPopup()
  {
    return millisToPopup;
  }

  /**
   * Sets the number of milliseconds to wait before displaying the progress
   * dialog.
   * 
   * @param time  the number of milliseconds.
   * 
   * @see #getMillisToPopup()
   */
  public void setMillisToPopup(int time)
  {
    millisToPopup = time;
  }

  /**
   * Returns a message which is shown in the progress dialog.
   *
   * @return The changeable message visible in the progress dialog.
   */
  public String getNote()
  {
    return note;
  }

  /**
   * <p>Set the message shown in the progess dialog.</p>
   *
   * <p>Changing the note while the progress dialog is visible
   * is possible.</p>
   *
   * @param note A message shown in the progress dialog.
   */
  public void setNote(String note)
  {
    if (noteLabel != null)
      {
        noteLabel.setText(note);
      }
    else
      {
        this.note = note;
      }
  }

  /** 
   * Internal method that creates the progress dialog.
   */
  void createDialog()
  {
    // If there is no note we suppress the generation of the
    // label.
    Object[] tmp = (note == null) ?
      new Object[]
        {
          message,
          progressBar = new JProgressBar(min, max)
        }
      :
      new Object[]
        {
          message,
          noteLabel = new JLabel(note),
          progressBar = new JProgressBar(min, max)
        };

    JOptionPane pane = new JOptionPane(tmp, JOptionPane.INFORMATION_MESSAGE);

    // FIXME: Internationalize the button
    JButton cancelButton = new JButton("Cancel");
    cancelButton.addActionListener(new ActionListener()
    {
      public void actionPerformed(ActionEvent ae)
      {
        canceled = true;
      }
    });

    pane.setOptions(new Object[] { cancelButton });

    // FIXME: Internationalize the title
    progressDialog = pane.createDialog(component, "Progress ...");
    progressDialog.setModal(false);
    progressDialog.setResizable(true);

    progressDialog.pack();
    progressDialog.setVisible(true);

  }

  /** An ActionListener implementation which does the measurements
   * and estimations of the ProgressMonitor.
   */
  class TimerListener implements ActionListener
  {
    long timestamp;

    int lastProgress;

    boolean first = true;

    TimerListener()
    {
       timestamp = System.currentTimeMillis();
    }

    public void actionPerformed(ActionEvent ae)
    {
       long now = System.currentTimeMillis();

       if (first)
       {
         if ((now - timestamp) > millisToDecideToPopup)
         {
           first = false;


           long expected = (progress - min == 0) ? 
	     (now - timestamp) * (max - min) : 
	     (now - timestamp) * (max - min) / (progress - min);

           if (expected > millisToPopup)
           {
             createDialog();
           }
         }
         else
         {
           // We have not waited long enough to make a decision,
           // so return and try again when the timer is invoked.
           return;
         }
       }
       else if (progressDialog != null)
       {
         // The progress dialog is being displayed. We now calculate
         // whether setting the progress bar to the current progress
         // value would result in a visual difference. 
         int delta = progress - progressBar.getValue();

         if ((delta * progressBar.getWidth() / (max - min)) > 0)
         {
           // At least one pixel would change.
           progressBar.setValue(progress);
         }
       }
       else
       {
         // No dialog necessary
         timer.stop();
         timer = null;
       }

      timestamp = now;
    }
  }
  
  /**
   * Gets the accessible context.
   * 
   * @return the accessible context.
   */
  public AccessibleContext getAccessibleContext()
  {
    return accessibleContext;
  }
}