/*******************************************************************************

 * Copyright (c) 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

 ******************************************************************************/

package org.eclipse.ui.internal.themes;

import java.util.Hashtable;

import org.eclipse.core.runtime.IConfigurationElement;

import org.eclipse.core.runtime.IExecutableExtension;

import org.eclipse.swt.graphics.RGB;

import org.eclipse.ui.themes.ColorUtil;

import org.eclipse.ui.themes.IColorFactory;

/**

 * ColorSelectionFactory is the abstract superclass of factories that compare

 * two colors.

 * 

 * @since 3.3

 * 

 */

public class KelvinColorFactory implements IColorFactory,

		IExecutableExtension {

	protected static final RGB white = new RGB(255, 255, 255);

	String base;

	String definitionId; 

	/**

	 * This executable extension requires parameters to be explicitly declared

	 * via the second method described in the <code>IExecutableExtension</code>

	 * documentation. The following parameters are parsed:

	 * <code>base</code>, describes the base color to produce all other colours from.

	 * This value may either be an RGB triple or an SWT constant.

	 * <code>definitionId</code>, describes the id of color we are looking for, one of

	 * "org.eclipse.ui.workbench.ACTIVE_TAB_BG_START"

	 * "org.eclipse.ui.workbench.ACTIVE_TAB_BG_END"

	 * @see org.eclipse.core.runtime.IExecutableExtension#setInitializationData(org.eclipse.core.runtime.IConfigurationElement,

	 *      java.lang.String, java.lang.Object)

	 */

	public void setInitializationData(IConfigurationElement config,

			String propertyName, Object data) {

		if (data instanceof Hashtable) {

			Hashtable table = (Hashtable) data;

			base = (String) table.get("base"); //$NON-NLS-1$

			definitionId = (String) table.get("definitionId"); //$NON-NLS-1$

		}

	}

	/* 

	 * Return the number of RGB values in test that are

	 * equal to or between lower and upper.

	 */

	protected int valuesInRange(RGB test, int lower, int upper) {

		int hits = 0;

		if(test.red >= lower && test.red <= upper) hits++;

		if(test.blue >= lower && test.blue <= upper) hits++;

		if(test.green >= lower && test.green <= upper) hits++;

		return hits;

	}

	/*

	 * Return the RGB value for the bottom tab color

	 * based on a blend of white and sample color

	 */

	private RGB getLightenedColor(RGB sample) {

		//Group 1

		if(valuesInRange(sample, 180, 255) >= 2)

			return sample;

		//Group 2

		if(valuesInRange(sample, 100, 179) >= 2)

			return ColorUtil.blend(white, sample, 30);

		//Group 3

		if(valuesInRange(sample, 0, 99) >= 2)

			return ColorUtil.blend(white, sample, 60);

		//Group 4

		return ColorUtil.blend(white, sample, 30);

	}

	/*

	 * Return the Start (top of tab) color as an RGB

	 */

	private RGB createStartColor() {

		if (base == null) 

			return new RGB(0, 0, 0);

		RGB base = createEndColor();

		return ColorUtil.blend(white, base, 75);

	}

	/*

	 * Return the End (top of tab) color as an RGB

	 */

	public RGB createEndColor() {

		if (base == null) 

			return new RGB(0, 0, 0);

		return getLightenedColor(

				ColorUtil.getColorValue(base));

	}	

	/*

	 * (non-Javadoc)

	 * 

	 * @see org.eclipse.ui.themes.IColorFactory#createColor()

	 */

	public RGB createColor() {

		//should have base, otherwise error in the xml

		if (base == null) 

			return white;

		if (definitionId.equals("org.eclipse.ui.workbench.ACTIVE_TAB_BG_START")) //$NON-NLS-1$

			return createStartColor();

		if (definitionId.equals("org.eclipse.ui.workbench.ACTIVE_TAB_BG_END")) //$NON-NLS-1$

			return createEndColor();

		//should be one of start or end, otherwise error in the xml

		return white;

	}

}