/*******************************************************************************
 * Copyright (c) 2000, 2006 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
 *     
 * Port to the D programming language:
 *     Jacob Carlborg <jacob.carlborg@gmail.com>
 *******************************************************************************/
module dwt.custom.BusyIndicator;

import dwt.DWT;
import dwt.graphics.Cursor;
import dwt.widgets.Display;
import dwt.widgets.Shell;

import dwt.dwthelper.Runnable;
import dwt.dwthelper.string;
import dwt.dwthelper.utils : Integer;

/**
 * Support for showing a Busy Cursor during a long running process.
 */
public class BusyIndicator {

    static int nextBusyId = 1;
    static final String BUSYID_NAME = "DWT BusyIndicator"; //$NON-NLS-1$
    static final String BUSY_CURSOR = "DWT BusyIndicator Cursor"; //$NON-NLS-1$

    /**
     * Runs the given <code>Runnable</code> while providing
     * busy feedback using this busy indicator.
     * 
     * @param display the display on which the busy feedback should be
     *        displayed.  If the display is null, the Display for the current
     *        thread will be used.  If there is no Display for the current thread,
     *        the runnable code will be executed and no busy feedback will be displayed.
     * @param runnable the runnable for which busy feedback is to be shown.
     *        Must not be null.
     * 
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the runnable is null</li>
     * </ul>
     */

    public static void showWhile (Display display, Runnable runnable) {
        if (runnable is null)
            DWT.error(DWT.ERROR_NULL_ARGUMENT);
        if (display is null) {
            display = Display.getCurrent();
            if (display is null) {
                runnable.run();
                return;
            }
        }

        Integer busyId = new Integer(nextBusyId);
        nextBusyId++;
        Cursor cursor = display.getSystemCursor(DWT.CURSOR_WAIT);
        Shell[] shells = display.getShells();
        for (int i = 0; i < shells.length; i++) {
            Integer id = cast(Integer) shells[i].getData(BUSYID_NAME);
            if (id is null) {
                shells[i].setCursor(cursor);
                shells[i].setData(BUSYID_NAME, busyId);
            }
        }

        try {
            runnable.run();
        }
        finally {
            shells = display.getShells();
            for (int i = 0; i < shells.length; i++) {
                Integer id = cast(Integer) shells[i].getData(BUSYID_NAME);
                if (id is busyId) {
                    shells[i].setCursor(null);
                    shells[i].setData(BUSYID_NAME, null);
                }
            }
        }
    }
}