/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.dialogs;

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.StackLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.ProgressBar;

/**
 * A control for showing progress feedback for a long running operation. This
 * control supports both determinate and indeterminate SWT progress bars. For
 * indeterminate progress, we don't have to know the total amount of work in
 * advance and no <code>worked</code> method needs to be called.
 */
public class ProgressIndicator extends Composite {
    private final static int PROGRESS_MAX = 1000; // value to use for max in

    // progress bar
    private boolean animated = true;

    private StackLayout layout;

    private ProgressBar determinateProgressBar;

    private ProgressBar indeterminateProgressBar;

    private double totalWork;

    private double sumWorked;

    /**
     * Create a ProgressIndicator as a child under the given parent.
     * 
     * @param parent
     *            The widgets parent
     */
    public ProgressIndicator(Composite parent) {
        super(parent, SWT.NULL);
        determinateProgressBar = new ProgressBar(this, SWT.HORIZONTAL);
        indeterminateProgressBar = new ProgressBar(this, SWT.HORIZONTAL
                | SWT.INDETERMINATE);
        layout = new StackLayout();
        setLayout(layout);
    }

    /**
     * Initialize the progress bar to be animated.
     */
    public void beginAnimatedTask() {
        done();
        layout.topControl = indeterminateProgressBar;
        layout();
        animated = true;
    }

    /**
     * Initialize the progress bar.
     * 
     * @param max
     *            The maximum value.
     */
    public void beginTask(int max) {
        done();
        this.totalWork = max;
        this.sumWorked = 0;
        determinateProgressBar.setMinimum(0);
        determinateProgressBar.setMaximum(PROGRESS_MAX);
        determinateProgressBar.setSelection(0);
        layout.topControl = determinateProgressBar;
        layout();
        animated = false;
    }

    /**
     * Progress is done.
     */
    public void done() {
        if (!animated) {
            determinateProgressBar.setMinimum(0);
            determinateProgressBar.setMaximum(0);
            determinateProgressBar.setSelection(0);
        }
        layout.topControl = null;
        layout();
    }

    /**
     * Moves the progress indicator to the end.
     */
    public void sendRemainingWork() {
        worked(totalWork - sumWorked);
    }

    /**
     * Moves the progress indicator by the given amount of work units
     * @param work the amount of work to increment by.
     */
    public void worked(double work) {
        if (work == 0 || animated) {
            return;
        }
        sumWorked += work;
        if (sumWorked > totalWork) {
            sumWorked = totalWork;
        }
        if (sumWorked < 0) {
            sumWorked = 0;
        }
        int value = (int) (sumWorked / totalWork * PROGRESS_MAX);
        if (determinateProgressBar.getSelection() < value) {
            determinateProgressBar.setSelection(value);
        }
    }
}