/*
 * From http://tips4java.wordpress.com/2009/07/05/hsl-color/
 *
 * License note on http://tips4java.wordpress.com/about/
 *   "You are free to use and/or modify any or all code posted on the
 *    Java Tips Weblog without restriction. A credit in the code comments
 *    would be nice, but not in any way mandatory."
 */

package com.formdev.flatlaf.util;

import java.awt.Color;

/**
 *  The HSLColor class provides methods to manipulate HSL (Hue, Saturation
 *  Luminance) values to create a corresponding Color object using the RGB
 *  ColorSpace.
 *
 *  The HUE is the color, the Saturation is the purity of the color (with
 *  respect to grey) and Luminance is the brightness of the color (with respect
 *  to black and white)
 *
 *  The Hue is specified as an angel between 0 - 360 degrees where red is 0,
 *  green is 120 and blue is 240. In between you have the colors of the rainbow.
 *  Saturation is specified as a percentage between 0 - 100 where 100 is fully
 *  saturated and 0 approaches gray. Luminance is specified as a percentage
 *  between 0 - 100 where 0 is black and 100 is white.
 *
 *  In particular the HSL color space makes it easier change the Tone or Shade
 *  of a color by adjusting the luminance value.
 */
public class HSLColor
{
	private final Color rgb;
	private final float[] hsl;
	private final float alpha;

	/**
	 *  Create a HSLColor object using an RGB Color object.
	 *
	 *  @param rgb the RGB Color object
	 */
	public HSLColor(Color rgb)
	{
		this.rgb = rgb;
		hsl = fromRGB( rgb );
		alpha = rgb.getAlpha() / 255.0f;
	}

	/**
	 *  Create a HSLColor object using individual HSL values and a default
	 * alpha value of 1.0.
	 *
	 *  @param h is the Hue value in degrees between 0 - 360
	 *  @param s is the Saturation percentage between 0 - 100
	 *  @param l is the Lumanance percentage between 0 - 100
	 */
	public HSLColor(float h, float s, float l)
	{
		this(h, s, l, 1.0f);
	}

	/**
	 *  Create a HSLColor object using individual HSL values.
	 *
	 *  @param h     the Hue value in degrees between 0 - 360
	 *  @param s     the Saturation percentage between 0 - 100
	 *  @param l     the Lumanance percentage between 0 - 100
	 *  @param alpha the alpha value between 0 - 1
	 */
	public HSLColor(float h, float s, float l, float alpha)
	{
		hsl = new float[] {h, s, l};
		this.alpha = alpha;
		rgb = toRGB(hsl, alpha);
	}

	/**
	 *  Create a HSLColor object using an an array containing the
	 *  individual HSL values and with a default alpha value of 1.
	 *
	 *  @param hsl  array containing HSL values
	 */
	public HSLColor(float[] hsl)
	{
		this(hsl, 1.0f);
	}

	/**
	 *  Create a HSLColor object using an an array containing the
	 *  individual HSL values.
	 *
	 *  @param hsl  array containing HSL values
	 *  @param alpha the alpha value between 0 - 1
	 */
	public HSLColor(float[] hsl, float alpha)
	{
		this.hsl = hsl;
		this.alpha = alpha;
		rgb = toRGB(hsl, alpha);
	}

	/**
	 *  Create a RGB Color object based on this HSLColor with a different
	 *  Hue value. The degrees specified is an absolute value.
	 *
	 *  @param degrees - the Hue value between 0 - 360
	 *  @return the RGB Color object
	 */
	public Color adjustHue(float degrees)
	{
		return toRGB(degrees, hsl[1], hsl[2], alpha);
	}

	/**
	 *  Create a RGB Color object based on this HSLColor with a different
	 *  Luminance value. The percent specified is an absolute value.
	 *
	 *  @param percent - the Luminance value between 0 - 100
	 *  @return the RGB Color object
	 */
	public Color adjustLuminance(float percent)
	{
		return toRGB(hsl[0], hsl[1], percent, alpha);
	}

	/**
	 *  Create a RGB Color object based on this HSLColor with a different
	 *  Saturation value. The percent specified is an absolute value.
	 *
	 *  @param percent - the Saturation value between 0 - 100
	 *  @return the RGB Color object
	 */
	public Color adjustSaturation(float percent)
	{
		return toRGB(hsl[0], percent, hsl[2], alpha);
	}

	/**
	 *  Create a RGB Color object based on this HSLColor with a different
	 *  Shade. Changing the shade will return a darker color. The percent
	 *  specified is a relative value.
	 *
	 *  @param percent - the value between 0 - 100
	 *  @return the RGB Color object
	 */
	public Color adjustShade(float percent)
	{
		float multiplier = (100.0f - percent) / 100.0f;
		float l = Math.max(0.0f, hsl[2] * multiplier);

		return toRGB(hsl[0], hsl[1], l, alpha);
	}

	/**
	 *  Create a RGB Color object based on this HSLColor with a different
	 *  Tone. Changing the tone will return a lighter color. The percent
	 *  specified is a relative value.
	 *
	 *  @param percent - the value between 0 - 100
	 *  @return the RGB Color object
	 */
	public Color adjustTone(float percent)
	{
		float multiplier = (100.0f + percent) / 100.0f;
		float l = Math.min(100.0f, hsl[2] * multiplier);

		return toRGB(hsl[0], hsl[1], l, alpha);
	}

	/**
	 *  Get the Alpha value.
	 *
	 *  @return the Alpha value.
	 */
	public float getAlpha()
	{
		return alpha;
	}

	/**
	 *  Create a RGB Color object that is the complementary color of this
	 *  HSLColor. This is a convenience method. The complementary color is
	 *  determined by adding 180 degrees to the Hue value.
	 *  @return the RGB Color object
	 */
	public Color getComplementary()
	{
		float hue = (hsl[0] + 180.0f) % 360.0f;
		return toRGB(hue, hsl[1], hsl[2]);
	}

	/**
	 *  Get the Hue value.
	 *
	 *  @return the Hue value.
	 */
	public float getHue()
	{
		return hsl[0];
	}

	/**
	 *  Get the HSL values.
	 *
	 *  @return the HSL values.
	 */
	public float[] getHSL()
	{
		return hsl;
	}

	/**
	 *  Get the Luminance value.
	 *
	 *  @return the Luminance value.
	 */
	public float getLuminance()
	{
		return hsl[2];
	}

	/**
	 *  Get the RGB Color object represented by this HDLColor.
	 *
	 *  @return the RGB Color object.
	 */
	public Color getRGB()
	{
		return rgb;
	}

	/**
	 *  Get the Saturation value.
	 *
	 *  @return the Saturation value.
	 */
	public float getSaturation()
	{
		return hsl[1];
	}

	@Override
	public String toString()
	{
		String toString =
			"HSLColor[h=" + hsl[0] +
			",s=" + hsl[1] +
			",l=" + hsl[2] +
			",alpha=" + alpha + "]";

		return toString;
	}

	/**
	 *  Convert a RGB Color to it corresponding HSL values.
	 *
	 *  @return an array containing the 3 HSL values.
	 */
	public static float[] fromRGB(Color color)
	{
		//  Get RGB values in the range 0 - 1

		float[] rgb = color.getRGBColorComponents( null );
		float r = rgb[0];
		float g = rgb[1];
		float b = rgb[2];

		//	Minimum and Maximum RGB values are used in the HSL calculations

		float min = Math.min(r, Math.min(g, b));
		float max = Math.max(r, Math.max(g, b));

		//  Calculate the Hue

		float h = 0;

		if (max == min)
			h = 0;
		else if (max == r)
			h = ((60 * (g - b) / (max - min)) + 360) % 360;
		else if (max == g)
			h = (60 * (b - r) / (max - min)) + 120;
		else if (max == b)
			h = (60 * (r - g) / (max - min)) + 240;

		//  Calculate the Luminance

		float l = (max + min) / 2;
//		System.out.println(max + " : " + min + " : " + l);

		//  Calculate the Saturation

		float s = 0;

		if (max == min)
			s = 0;
		else if (l <= .5f)
			s = (max - min) / (max + min);
		else
			s = (max - min) / (2 - max - min);

//		System.out.println(new HSLColor( new float[] {h, s * 100, l * 100} ));
		return new float[] {h, s * 100, l * 100};
	}

	/**
	 *  Convert HSL values to a RGB Color with a default alpha value of 1.
	 *  H (Hue) is specified as degrees in the range 0 - 360.
	 *  S (Saturation) is specified as a percentage in the range 1 - 100.
	 *  L (Lumanance) is specified as a percentage in the range 1 - 100.
	 *
	 *  @param hsl an array containing the 3 HSL values
	 *
	 *  @return the RGB Color object
	 */
	public static Color toRGB(float[] hsl)
	{
		return toRGB(hsl, 1.0f);
	}

	/**
	 *  Convert HSL values to a RGB Color.
	 *  H (Hue) is specified as degrees in the range 0 - 360.
	 *  S (Saturation) is specified as a percentage in the range 1 - 100.
	 *  L (Lumanance) is specified as a percentage in the range 1 - 100.
	 *
	 *  @param hsl    an array containing the 3 HSL values
	 *  @param alpha  the alpha value between 0 - 1
	 *
	 *  @return the RGB Color object
	 */
	public static Color toRGB(float[] hsl, float alpha)
	{
		return toRGB(hsl[0], hsl[1], hsl[2], alpha);
	}

	/**
	 *  Convert HSL values to a RGB Color with a default alpha value of 1.
	 *
	 *  @param h Hue is specified as degrees in the range 0 - 360.
	 *  @param s Saturation is specified as a percentage in the range 1 - 100.
	 *  @param l Lumanance is specified as a percentage in the range 1 - 100.
	 *
	 *  @return the RGB Color object
	 */
	public static Color toRGB(float h, float s, float l)
	{
		return toRGB(h, s, l, 1.0f);
	}

	/**
	 *  Convert HSL values to a RGB Color.
	 *
	 *  @param h Hue is specified as degrees in the range 0 - 360.
	 *  @param s Saturation is specified as a percentage in the range 1 - 100.
	 *  @param l Lumanance is specified as a percentage in the range 1 - 100.
	 *  @param alpha  the alpha value between 0 - 1
	 *
	 *  @return the RGB Color object
	 */
	public static Color toRGB(float h, float s, float l, float alpha)
	{
		if (s <0.0f || s > 100.0f)
		{
			String message = "Color parameter outside of expected range - Saturation";
			throw new IllegalArgumentException( message );
		}

		if (l <0.0f || l > 100.0f)
		{
			String message = "Color parameter outside of expected range - Luminance";
			throw new IllegalArgumentException( message );
		}

		if (alpha <0.0f || alpha > 1.0f)
		{
			String message = "Color parameter outside of expected range - Alpha";
			throw new IllegalArgumentException( message );
		}

		//  Formula needs all values between 0 - 1.

		h = h % 360.0f;
		h /= 360f;
		s /= 100f;
		l /= 100f;

		float q = 0;

		if (l < 0.5)
			q = l * (1 + s);
		else
			q = (l + s) - (s * l);

		float p = 2 * l - q;

		float r = Math.max(0, HueToRGB(p, q, h + (1.0f / 3.0f)));
		float g = Math.max(0, HueToRGB(p, q, h));
		float b = Math.max(0, HueToRGB(p, q, h - (1.0f / 3.0f)));

		r = Math.min(r, 1.0f);
		g = Math.min(g, 1.0f);
		b = Math.min(b, 1.0f);

		return new Color(r, g, b, alpha);
	}

	private static float HueToRGB(float p, float q, float h)
	{
		if (h < 0) h += 1;

		if (h > 1 ) h -= 1;

		if (6 * h < 1)
		{
			return p + ((q - p) * 6 * h);
		}

		if (2 * h < 1 )
		{
			return  q;
		}

		if (3 * h < 2)
		{
			return p + ( (q - p) * 6 * ((2.0f / 3.0f) - h) );
		}

   		return p;
	}
}
