/*******************************************************************************
 * Copyright (c) 2000, 2013 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.graphics;

import java.io.*;

import org.eclipse.swt.*;

/**
 * Instances of this class are descriptions of colors in
 * terms of the primary additive color model (red, green and
 * blue). A color may be described in terms of the relative
 * intensities of these three primary colors. The brightness
 * of each color is specified by a value in the range 0 to 255,
 * where 0 indicates no color (blackness) and 255 indicates
 * maximum intensity.
 * <p>
 * The hashCode() method in this class uses the values of the public
 * fields to compute the hash value. When storing instances of the
 * class in hashed collections, do not modify these fields after the
 * object has been inserted.
 * </p>
 * <p>
 * Application code does <em>not</em> need to explicitly release the
 * resources managed by each instance when those instances are no longer
 * required, and thus no <code>dispose()</code> method is provided.
 * </p>
 *
 * @see Color
 * @see <a href="https://eclipse.dev/eclipse/swt/snippets/#color">Color and RGB snippets</a>
 * @see <a href="https://eclipse.dev/eclipse/swt/">Sample code and further information</a>
 */

public final class RGB implements Serializable {

	/**
	 * the red component of the RGB
	 */
	public int red;

	/**
	 * the green component of the RGB
	 */
	public int green;

	/**
	 * the blue component of the RGB
	 */
	public int blue;

	static final long serialVersionUID = 3258415023461249074L;

/**
 * Constructs an instance of this class with the given
 * red, green and blue values.
 *
 * @param red the red component of the new instance
 * @param green the green component of the new instance
 * @param blue the blue component of the new instance
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the red, green or blue argument is not between 0 and 255</li>
 * </ul>
 */
public RGB(int red, int green, int blue) {
	if ((red > 255) || (red < 0) ||
		(green > 255) || (green < 0) ||
		(blue > 255) || (blue < 0))
			SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	this.red = red;
	this.green = green;
	this.blue = blue;
}

/**
* Constructs an instance of this class with the given
* hue, saturation, and brightness.
*
* @param hue the hue value for the HSB color (from 0 to 360)
* @param saturation the saturation value for the HSB color (from 0 to 1)
* @param brightness the brightness value for the HSB color (from 0 to 1)
*
* @exception IllegalArgumentException <ul>
*    <li>ERROR_INVALID_ARGUMENT - if the hue is not between 0 and 360 or
*    the saturation or brightness is not between 0 and 1</li>
* </ul>
*
* @since 3.2
*/
public RGB(float hue, float saturation, float brightness) {
	if (hue < 0 || hue > 360 || saturation < 0 || saturation > 1 ||
		brightness < 0 || brightness > 1) {
		SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
	float r, g, b;
	if (saturation == 0) {
		r = g = b = brightness;
	} else {
		if (hue == 360) hue = 0;
		hue /= 60;
		int i = (int)hue;
		float f = hue - i;
		float p = brightness * (1 - saturation);
		float q = brightness * (1 - saturation * f);
		float t = brightness * (1 - saturation * (1 - f));
		b = switch (i) {
		case 0 -> {
			r = brightness;
			g = t;
			yield p;
		}
		case 1 -> {
			r = q;
			g = brightness;
			yield p;
		}
		case 2 -> {
			r = p;
			g = brightness;
			yield t;
		}
		case 3 -> {
			r = p;
			g = q;
			yield brightness;
		}
		case 4 -> {
			r = t;
			g = p;
			yield brightness;
		}
		case 5 -> {
			r = brightness;
			g = p;
			yield q;
		}
		default -> {
			r = brightness;
			g = p;
			yield q;
		}
		};
	}
	red = (int)(r * 255 + 0.5);
	green = (int)(g * 255 + 0.5);
	blue = (int)(b * 255 + 0.5);
}

/**
 * Returns the hue, saturation, and brightness of the color.
 *
 * @return color space values in float format:<ul>
 *             <li>hue (from 0 to 360)</li>
 *             <li>saturation (from 0 to 1)</li>
 *             <li>brightness (from 0 to 1)</li>
 *             </ul>
 * @see #RGB(float, float, float)
 *
 * @since 3.2
 */
public float[] getHSB() {
	float r = red / 255f;
	float g = green / 255f;
	float b = blue / 255f;
	float max = Math.max(Math.max(r, g), b);
	float min = Math.min(Math.min(r, g), b);
	float delta = max - min;
	float hue = 0;
	float brightness = max;
	float saturation = max == 0 ? 0 : (max - min) / max;
	if (delta != 0) {
		if (r == max) {
			hue = (g  - b) / delta;
		} else {
			if (g == max) {
				hue = 2 + (b - r) / delta;
			} else {
				hue = 4 + (r - g) / delta;
			}
		}
		hue *= 60;
		if (hue < 0) hue += 360;
	}
	return new float[] {hue, saturation, brightness};
}

/**
 * Compares the argument to the receiver, and returns true
 * if they represent the <em>same</em> object using a class
 * specific comparison.
 *
 * @param object the object to compare with this object
 * @return <code>true</code> if the object is the same as this object and <code>false</code> otherwise
 *
 * @see #hashCode()
 */
@Override
public boolean equals(Object object) {
	if (object == this) return true;
	if (!(object instanceof RGB rgb)) return false;
	return (rgb.red == this.red) && (rgb.green == this.green) && (rgb.blue == this.blue);
}

/**
 * Returns an integer hash code for the receiver. Any two
 * objects that return <code>true</code> when passed to
 * <code>equals</code> must return the same value for this
 * method.
 *
 * @return the receiver's hash
 *
 * @see #equals(Object)
 */
@Override
public int hashCode() {
	return (blue << 16) | (green << 8) | red;
}

/**
 * Returns a string containing a concise, human-readable
 * description of the receiver.
 *
 * @return a string representation of the <code>RGB</code>
 */
@Override
public String toString() {
	return "RGB {" + red + ", " + green + ", " + blue + "}"; //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
}

}
