function fillPartialHSL(newcolor, oldcolor) {
	//console.log(newcolor, oldcolor);
	let color = {};
	color.hue = (newcolor.hue != null) ? newcolor.hue : oldcolor.hue;
	color.sat = (newcolor.sat != null) ? newcolor.sat : oldcolor.sat;
	color.l = (newcolor.l != null) ? newcolor.l : oldcolor.l;
	return color;
}

function clamp(value, min, max) {
	return Math.min(max, Math.max(min, value));
}

function hue2rgb(p, q, t) {
	if (t < 0) t += 1;
	if (t > 1) t -= 1;
	if (t < 1/6) return p + (q - p) * 6 * t;
	if (t < 1/2) return q;
	if (t < 2/3) return p + (q - p) * (2/3 - t) * 6;
	return p;
}

function HSL_to_RGB(hsl) {
	let h = hsl.hue / 360;
	let s = hsl.sat / 100;
	let l = hsl.l / 100;

	let r, g, b;

	if (s == 0) {
	  	r = g = b = l; // achromatic
	} else {
		let q = l < 0.5 ? l * (1 + s) : l + s - l * s;
		let p = 2 * l - q;

		r = hue2rgb(p, q, h + 1/3);
		g = hue2rgb(p, q, h);
		b = hue2rgb(p, q, h - 1/3);
	}

	return {
		red: Math.round(r * 255),
		green: Math.round(g * 255),
		blue: Math.round(b * 255)
	};
}

function RGB_to_HSL(rgb) {
	let r = rgb.red / 255;
	let g = rgb.green / 255;
	let b = rgb.blue / 255;

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

	let h = 0;
	let s = 0;

	if (max == min || max - min < 0.01) {
		h = 0; // achromatic
		s = 0;
	} else {
		let d = max - min;
		s = d / (2 - max - min);

		switch (max) {
			case r: h = (g - b) / d + (g < b ? 6 : 0); break;
			case g: h = (b - r) / d + 2; break;
			case b: h = (r - g) / d + 4; break;
		}

		h /= 6;
	}

	let l = 1 - 0.5 * s;

	return {
		hue: Math.round(h * 360),
		sat: Math.round(s * 100),
		l: Math.round(l * 100)
	};
}

module.exports = {
    fillPartialHSL,
    clamp,
    HSL_to_RGB,
	RGB_to_HSL,
	hue2rgb,
};