/*******************************************************************************
 * Copyright (c) 2006, 2007 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:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwtx.jface.fieldassist.FieldAssistColors;


import dwt.DWT;
import dwt.graphics.Color;
import dwt.graphics.RGB;
import dwt.widgets.Control;
import dwt.widgets.Display;
import dwtx.jface.resource.JFaceColors;

import dwt.dwthelper.utils;
import dwtx.dwtxhelper.Collection;
import dwt.dwthelper.Runnable;
import tango.io.Stdout;

/**
 * FieldAssistColors defines protocol for retrieving colors that can be used to
 * provide visual cues with fields. For consistency with JFace dialogs and
 * wizards, it is recommended that FieldAssistColors is used when colors are
 * used to annotate fields.
 * <p>
 * Color resources that are returned using methods in this class are maintained
 * in the JFace color registries, or by DWT. Users of any color resources
 * provided by this class are not responsible for the lifecycle of the color.
 * Colors provided by this class should never be disposed by clients. In some
 * cases, clients are provided information, such as RGB values, in order to
 * create their own color resources. In these cases, the client should manage
 * the lifecycle of any created resource.
 *
 * @since 3.2
 * @deprecated As of 3.3, this class is no longer necessary.
 */
public class FieldAssistColors {

    private static bool DEBUG = false;

    /*
     * Keys are background colors, values are the color with the alpha value
     * applied
     */
    private static Map requiredFieldColorMap;

    /*
     * Keys are colors we have created, values are the displays on which they
     * were created.
     */
    private static Map displays;

    static this(){
        requiredFieldColorMap = new HashMap();
        displays = new HashMap();
    }

    /**
     * Compute the RGB of the color that should be used for the background of a
     * control to indicate that the control has an error. Because the color
     * suitable for indicating an error depends on the colors set into the
     * control, this color is always computed dynamically and provided as an RGB
     * value. Clients who use this RGB to create a Color resource are
     * responsible for managing the life cycle of the color.
     * <p>
     * This color is computed dynamically each time that it is queried. Clients
     * should typically call this method once, create a color from the RGB
     * provided, and dispose of the color when finished using it.
     *
     * @param control
     *            the control for which the background color should be computed.
     * @return the RGB value indicating a background color appropriate for
     *         indicating an error in the control.
     */
    public static RGB computeErrorFieldBackgroundRGB(Control control) {
        /*
         * Use a 10% alpha of the error color applied on top of the widget
         * background color.
         */
        Color dest = control.getBackground();
        Color src = JFaceColors.getErrorText(control.getDisplay());
        int destRed = dest.getRed();
        int destGreen = dest.getGreen();
        int destBlue = dest.getBlue();

        // 10% alpha
        int alpha = cast(int) (0xFF * 0.10f);
        // Alpha blending math
        destRed += (src.getRed() - destRed) * alpha / 0xFF;
        destGreen += (src.getGreen() - destGreen) * alpha / 0xFF;
        destBlue += (src.getBlue() - destBlue) * alpha / 0xFF;

        return new RGB(destRed, destGreen, destBlue);
    }

    /**
     * Return the color that should be used for the background of a control to
     * indicate that the control is a required field and does not have content.
     * <p>
     * This color is managed by FieldAssistResources and should never be
     * disposed by clients.
     *
     * @param control
     *            the control on which the background color will be used.
     * @return the color used to indicate that a field is required.
     */
    public static Color getRequiredFieldBackgroundColor(Control control) {
        final Display display = control.getDisplay();

        // If we are in high contrast mode, then don't apply an alpha
        if (display.getHighContrast()) {
            return control.getBackground();
        }

        // See if a color has already been computed
        Object storedColor = requiredFieldColorMap.get(control.getBackground());
        if (storedColor !is null) {
            return cast(Color) storedColor;
        }

        // There is no color already created, so we must create one.
        // Use a 15% alpha of yellow on top of the widget background.
        Color dest = control.getBackground();
        Color src = display.getSystemColor(DWT.COLOR_YELLOW);
        int destRed = dest.getRed();
        int destGreen = dest.getGreen();
        int destBlue = dest.getBlue();

        // 15% alpha
        int alpha = cast(int) (0xFF * 0.15f);
        // Alpha blending math
        destRed += (src.getRed() - destRed) * alpha / 0xFF;
        destGreen += (src.getGreen() - destGreen) * alpha / 0xFF;
        destBlue += (src.getBlue() - destBlue) * alpha / 0xFF;

        // create the color
        Color color = new Color(display, destRed, destGreen, destBlue);
        // record the color in a map using the original color as the key
        requiredFieldColorMap.put(dest, color);
        // If we have never created a color on this display before, install
        // a dispose exec on the display.
        if (!displays.containsKey(display)) {
            display.disposeExec(new class Runnable {
                public void run() {
                    disposeColors(display);
                }
            });
        }
        // Record the color and its display in a map for later disposal.
        displays.put(color, display);
        return color;
    }

    /*
     * Dispose any colors that were allocated for the given display.
     */
    private static void disposeColors(Display display) {
        List toBeRemoved = new ArrayList(1);

        if (DEBUG) {
            Stdout.formatln("Display map is {}", (cast(Object)displays).toString()); //$NON-NLS-1$
            Stdout.formatln("Color map is {}", (cast(Object)requiredFieldColorMap).toString()); //$NON-NLS-1$
        }

        // Look for any stored colors that were created on this display
        for (Iterator i = displays.keySet().iterator(); i.hasNext();) {
            Color color = cast(Color) i.next();
            if ((cast(Display) displays.get(color)).opEquals(display)) {
                // The color is on this display. Mark it for removal.
                toBeRemoved.add(color);

                // Now look for any references to it in the required field color
                // map
                List toBeRemovedFromRequiredMap = new ArrayList(1);
                for (Iterator iter = requiredFieldColorMap.keySet().iterator(); iter
                        .hasNext();) {
                    Color bgColor = cast(Color) iter.next();
                    if ((cast(Color) requiredFieldColorMap.get(bgColor))
                            .opEquals(color)) {
                        // mark it for removal from the required field color map
                        toBeRemovedFromRequiredMap.add(bgColor);
                    }
                }
                // Remove references in the required field map now that
                // we are done iterating.
                for (int j = 0; j < toBeRemovedFromRequiredMap.size(); j++) {
                    requiredFieldColorMap.remove(toBeRemovedFromRequiredMap
                            .get(j));
                }
            }
        }
        // Remove references in the display map now that we are
        // done iterating
        for (int i = 0; i < toBeRemoved.size(); i++) {
            Color color = cast(Color) toBeRemoved.get(i);
            // Removing from the display map must be done before disposing the
            // color or else the comparison between this color and the one
            // in the map will fail.
            displays.remove(color);
            // Dispose it
            if (DEBUG) {
                Stdout.formatln("Disposing color {}", color.toString()); //$NON-NLS-1$
            }
            color.dispose();
        }
        if (DEBUG) {
            Stdout.formatln("Display map is {}", (cast(Object)displays).toString()); //$NON-NLS-1$
            Stdout.formatln("Color map is {}", (cast(Object)requiredFieldColorMap).toString()); //$NON-NLS-1$
        }
    }

}