#ifndef COLOR_H

#define COLOR_H

#include "real.h"

typedef Real ColorReal;

class Color {

public:

	union {

		struct { ColorReal channels[4]; };

		struct { ColorReal r, g, b, a; };

	};

	Color(): r(), g(), b(), a() { }

	explicit Color(

		const ColorReal r,

		const ColorReal g,

		const ColorReal b,

		const ColorReal a = 1

	):

		r(r), g(g), b(b), a(a) { }

	const Real& operator[] (int i) const { return channels[i]; }

	Real& operator[] (int i) { return channels[i]; }

	bool operator< (const Color &c) const {

		return less(r, c.r) ? true : less(c.r, r) ? false

			 : less(g, c.g) ? true : less(c.g, g) ? false

			 : less(b, c.b) ? true : less(c.b, b) ? false

			 : less(a, c.a);

	}

	bool operator== (const Color &c) const { return equal(r, c.r) && equal(g, c.g) && equal(b, c.b) && equal(a, c.a); }

	bool operator!= (const Color &c) const { return !(*this == c); }

	bool istransparent() const { return *this == Color(); }

	void reset() { *this = Color(); }

	Color withalpha(const ColorReal &a) const { return Color(r, g, b, a); }

	Color mulalpha(const ColorReal &a = 0.5) const { return Color(r, g, b, this->a*a); }

	Color blend(const Color &c, const ColorReal &value = 1) const {

		ColorReal asrc = c.a*value;

		ColorReal adst = a*(1 - asrc);

		ColorReal ares = asrc + adst;

		if (lesseq(ares, 0))

			return Color();

		ColorReal k = 1/ares;

		return Color(

			(r*asrc + c.r*adst)*k,

			(g*asrc + c.g*adst)*k,

			(b*asrc + c.b*adst)*k,

			ares );

	}

	Color mergecolor(const Color &c, const ColorReal &value = 0.5) const {

		ColorReal v = 1 - value;

		return Color(

			r*v + c.r*value,

			g*v + c.g*value,

			b*v + c.b*value,

			a );

	}

	Color merge(const Color &c, const ColorReal &value = 0.5) const

		{ return mergecolor(c, value).withalpha(a*(1 - value) + c.a*value); }

	static Color transparent() { return Color(); }

	static Color black()       { return Color(0, 0, 0); }

	static Color white()       { return Color(1, 1, 1); }

	static Color red()         { return Color(1, 0, 0); }

	static Color green()       { return Color(0, 1, 0); }

	static Color blue()        { return Color(0, 0, 1); }

	static Color yellow()      { return Color(1, 1, 0); }

	static Color cyan()        { return Color(0, 1, 1); }

	static Color magenta()     { return Color(1, 0, 1); }

	static Color gray(const ColorReal &value = 0.5) { return Color(value, value, value); }

};

#endif