/**
 * CIE LAB space model
 *
 * @module color-space/lab
 */

import xyz from './xyz.js';

var lab = {
	name: 'lab',
	min: [0, -100, -100],
	max: [100, 100, 100],
	channel: ['lightness', 'a', 'b'],
	alias: ['LAB', 'cielab'],
}

lab.xyz = ([l, a, b]) => {
	var x, y, z, y2;

	if (l <= 8) {
		y = (l * 100) / 903.3;
		y2 = (7.787 * (y / 100)) + (16 / 116);
	} else {
		y = 100 * Math.pow((l + 16) / 116, 3);
		y2 = Math.pow(y / 100, 1 / 3);
	}

	x = x / 95.047 <= 0.008856 ? x = (95.047 * ((a / 500) + y2 - (16 / 116))) / 7.787 : 95.047 * Math.pow((a / 500) + y2, 3);

	z = z / 108.883 <= 0.008859 ? z = (108.883 * (y2 - (b / 200) - (16 / 116))) / 7.787 : 108.883 * Math.pow(y2 - (b / 200), 3);

	return [x, y, z];
}


export default (lab);


xyz.lab = ([x, y, z]) => {
	var l, a, b;

	x /= 95.047;
	y /= 100;
	z /= 108.883;

	x = x > 0.008856 ? Math.pow(x, 1 / 3) : (7.787 * x) + (16 / 116);
	y = y > 0.008856 ? Math.pow(y, 1 / 3) : (7.787 * y) + (16 / 116);
	z = z > 0.008856 ? Math.pow(z, 1 / 3) : (7.787 * z) + (16 / 116);

	l = (116 * y) - 16;
	a = 500 * (x - y);
	b = 200 * (y - z);

	return [l, a, b];
};