/**
 *#########################################################################
 *
 * A component of the Gatherer application, part of the Greenstone digital
 * library suite from the New Zealand Digital Library Project at the
 * University of Waikato, New Zealand.
 *
 * Author: John Thompson, Greenstone Digital Library, University of Waikato
 *
 * Copyright (C) New Zealand Digital Library Project
 *
 * 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
 * (at your option) 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *########################################################################
 */
package org.greenstone.gatherer.gui;


import javax.swing.*;


/** A progress bar that doesn't pack a sad when you feed it longs (such as the sizes of files) which get mangled into negative numbers. I know how it feels, as I often have negative progress. Also tries to be efficent when updating the JProgressBar, so only updates when the value actually changes, which become necessary when you move a large number of files with millions of bytes (where upon shifting a file of a thousand bytes would be pretty insignificant, maybe not even a percent, but would fire several progress updates). 
 * @author John Thompson, Greenstone Digital Library, University of Waikato
 */
public class GProgressBar
    extends JProgressBar
{
    private long cur_value = 0L;
    private long max_value = 0L;

    /** The previous percentage value. */
    private int previous = -1;


    public GProgressBar()
    {
	super(0, 100);
    }


    public void addMaximum(long amount)
    {
	if (amount > 0) {
	    max_value = max_value + amount;
	    update();
	}
    }


    public void addValue(long amount)
    {
	if (amount > 0) {
	    cur_value = cur_value + amount;
	    update();
	}
    }


    public void clear()
    {
 	previous = -1;
 	update();
    }


    public void reset()
    {
 	cur_value = 0L;
 	max_value = 0L;
 	previous = -1;
 	update();
    }


    public void setIndeterminate(boolean indeterminate)
    {
	SwingUtilities.invokeLater(new SafeSetIndeterminateTask(indeterminate));		  
    }


    public void setString(String label)
    {
	SwingUtilities.invokeLater(new SafeSetStringTask(label));
    }


    public void setMaximum(int value)
    {
	max_value = value;
	update();
    }

	 
    public void setValue(int value)
    {
	cur_value = value;
	update();
    }


    /** Only bother updating the progress bar if the percentage has changed. */
    private void update()
    {
	int percentage = -1;
	if (cur_value == 0L || max_value == 0L) {
	    percentage = 0;
	}
	else {
	    long per_value = (cur_value * 100) / max_value;
	    percentage = (int) per_value;
	    if (percentage > 100) {
		percentage = 100;
	    }
	}

	if (percentage != previous) {
	    previous = percentage;
	    setString(percentage + "%");
	    SwingUtilities.invokeLater(new SafeSetValueTask(percentage));
	}
    }


    /** Internal class to call JProgressBar.setIndeterminate safely. */
    private class SafeSetIndeterminateTask
	implements Runnable
    {
	private boolean indeterminate;

	public SafeSetIndeterminateTask(boolean indeterminate)
	{
	    this.indeterminate = indeterminate;
	}

	public void run()
	{
	    unsafeSetIndeterminate(indeterminate);
	}
    }

    /** This method is unsafe, -unless- it is called from the Event Queue (eg. from SafeSetIndeterminateTask). */
    private void unsafeSetIndeterminate(boolean indeterminate)
    {
	super.setIndeterminate(indeterminate);
    }


    /** Internal class to call JProgressBar.setString safely. */
    private class SafeSetStringTask
	implements Runnable
    {
	private String label;

	public SafeSetStringTask(String label)
	{
	    this.label = label;
	}

	public void run()
	{
	    unsafeSetString(label);
	}
    }

    /** This method is unsafe, -unless- it is called from the Event Queue (eg. from SafeSetStringTask). */
    private void unsafeSetString(String label)
    {
	super.setString(label);
    }


    /** Internal class to call JProgressBar.setValue safely. */
    private class SafeSetValueTask
	implements Runnable
    {
	private int value;

	public SafeSetValueTask(int value)
	{
	    this.value = value;
	}

	public void run()
	{
	    unsafeSetValue(value);
	}
    }

    /** This method is unsafe, -unless- it is called from the Event Queue (eg. from SafeSetValueTask). */
    private void unsafeSetValue(int value)
    {
	super.setValue(value);
    }
}