using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Media;

namespace BuzzGUI.Common
{
	public class HSPA
	{
		const double Pr = 0.299;
		const double Pg = 0.587;
		const double Pb = 0.114;

		public double H { get; set; }
		public double S { get; set; }
		public double P { get; set; }
		public double A { get; set; }

		public HSPA(double h, double s, double p)
		{
			H = h;
			S = s;
			P = p;
			A = 1.0;
		}

		public HSPA(double h, double s, double p, double a)
		{
			H = h;
			S = s;
			P = p;
			A = a;
		}

		public Color ToColor()
		{
			double r, g, b;
			HSPtoRGB(out r, out g, out b);
			return Color.FromArgb((byte)Math.Min(255, A * 255), (byte)Math.Min(255, r * 255), (byte)Math.Min(255, g * 255), (byte)Math.Min(255, b * 255));
		}

		public static HSPA Blend(HSPA x, HSPA y, double alpha)
		{
			return new HSPA(
				x.H + alpha * (y.H - x.H),
				x.S + alpha * (y.S - x.S),
				x.P + alpha * (y.P - x.P),
				x.A + alpha * (y.A - x.A));
		}

		public double MaxRGBValue
		{
			get
			{
				double r, g, b;
				HSPtoRGB(out r, out g, out b);
				return Math.Max(Math.Max(r, g), b);
			}
		}

		void HSPtoRGB(out double R, out double G, out double B)
		{
			var h = H;
			var s = S;
			var p = P;
			double part, minOverMax = 1.0 - s;

			if (minOverMax > 0.0)
			{
				if (h < 1.0 / 6.0)
				{   //  R>G>B
					h = 6.0 * (h - 0.0 / 6.0); part = 1.0 + h * (1.0 / minOverMax - 1.0);
					B = p / Math.Sqrt(Pr / minOverMax / minOverMax + Pg * part * part + Pb);
					R = (B) / minOverMax; G = (B) + h * ((R) - (B));
				}
				else if (h < 2.0 / 6.0)
				{   //  G>R>B
					h = 6.0 * (-h + 2.0 / 6.0); part = 1.0 + h * (1.0 / minOverMax - 1.0);
					B = p / Math.Sqrt(Pg / minOverMax / minOverMax + Pr * part * part + Pb);
					G = (B) / minOverMax; R = (B) + h * ((G) - (B));
				}
				else if (h < 3.0 / 6.0)
				{   //  G>B>R
					h = 6.0 * (h - 2.0 / 6.0); part = 1.0 + h * (1.0 / minOverMax - 1.0);
					R = p / Math.Sqrt(Pg / minOverMax / minOverMax + Pb * part * part + Pr);
					G = (R) / minOverMax; B = (R) + h * ((G) - (R));
				}
				else if (h < 4.0 / 6.0)
				{   //  B>G>R
					h = 6.0 * (-h + 4.0 / 6.0); part = 1.0 + h * (1.0 / minOverMax - 1.0);
					R = p / Math.Sqrt(Pb / minOverMax / minOverMax + Pg * part * part + Pr);
					B = (R) / minOverMax; G = (R) + h * ((B) - (R));
				}
				else if (h < 5.0 / 6.0)
				{   //  B>R>G
					h = 6.0 * (h - 4.0 / 6.0); part = 1.0 + h * (1.0 / minOverMax - 1.0);
					G = p / Math.Sqrt(Pb / minOverMax / minOverMax + Pr * part * part + Pg);
					B = (G) / minOverMax; R = (G) + h * ((B) - (G));
				}
				else
				{   //  R>B>G
					h = 6.0 * (-h + 6.0 / 6.0); part = 1.0 + h * (1.0 / minOverMax - 1.0);
					G = p / Math.Sqrt(Pr / minOverMax / minOverMax + Pb * part * part + Pg);
					R = (G) / minOverMax; B = (G) + h * ((R) - (G));
				}
			}
			else
			{
				if (h < 1.0 / 6.0)
				{   //  R>G>B
					h = 6.0 * (h - 0.0 / 6.0); R = Math.Sqrt(p * p / (Pr + Pg * h * h)); G = (R) * h; B = 0.0;
				}
				else if (h < 2.0 / 6.0)
				{   //  G>R>B
					h = 6.0 * (-h + 2.0 / 6.0); G = Math.Sqrt(p * p / (Pg + Pr * h * h)); R = (G) * h; B = 0.0;
				}
				else if (h < 3.0 / 6.0)
				{   //  G>B>R
					h = 6.0 * (h - 2.0 / 6.0); G = Math.Sqrt(p * p / (Pg + Pb * h * h)); B = (G) * h; R = 0.0;
				}
				else if (h < 4.0 / 6.0)
				{   //  B>G>R
					h = 6.0 * (-h + 4.0 / 6.0); B = Math.Sqrt(p * p / (Pb + Pg * h * h)); G = (B) * h; R = 0.0;
				}
				else if (h < 5.0 / 6.0)
				{   //  B>R>G
					h = 6.0 * (h - 4.0 / 6.0); B = Math.Sqrt(p * p / (Pb + Pr * h * h)); R = (B) * h; G = 0.0;
				}
				else
				{   //  R>B>G
					h = 6.0 * (-h + 6.0 / 6.0); R = Math.Sqrt(p * p / (Pr + Pb * h * h)); B = (R) * h; G = 0.0;
				}
			}
		}

	}
}