import { desaturate } from './render_geo.mjs';

function t_from_ratio(ratio) {
	return Math.min(Math.max((ratio - 1) / 0.4, 0), 1);
}

// Hue-wheel position (0-1) → RGB at full saturation and value.
function hue_to_rgb(h) {
	const s = 6 * (h % 1);
	const i = Math.floor(s);
	const f = s - i;
	const q = 1 - f;
	if (i === 0) { return [1, f, 0]; }
	if (i === 1) { return [q, 1, 0]; }
	if (i === 2) { return [0, 1, f]; }
	if (i === 3) { return [0, q, 1]; }
	if (i === 4) { return [f, 0, 1]; }
	return [1, 0, q];
}

export const PALETTES = [
	{
		id:   'classic',
		name: 'Classic',
		face_color(ratio, is_pentagon) {
			if (is_pentagon) { return desaturate([1.0, 0.85, 0.23], 0.45); }
			const t = t_from_ratio(ratio);
			return desaturate([Math.min(1, 2*t), t < 0.5 ? t*1.4 : 0.7-(t-0.5)*1.4, Math.max(0, 1-2*t)], 0.45);
		},
	},
	{
		id:   'vibrant',
		name: 'Vibrant',
		face_color(ratio, is_pentagon) {
			if (is_pentagon) { return [1.0, 0.82, 0.10]; }
			const t = t_from_ratio(ratio);
			return [Math.min(1, 2*t), t < 0.5 ? t*1.4 : 0.7-(t-0.5)*1.4, Math.max(0, 1-2*t)];
		},
	},
	{
		id:   'arctic',
		name: 'Arctic',
		// Low distortion = pale ice blue, high = deep indigo.
		face_color(ratio, is_pentagon) {
			if (is_pentagon) { return [0.95, 0.75, 0.20]; }
			const t = t_from_ratio(ratio);
			return desaturate([
				0.55 - t * 0.45,
				0.80 - t * 0.50,
				1.0  - t * 0.15,
			], 0.7 + t * 0.3);
		},
	},
	{
		id:   'ember',
		name: 'Ember',
		// Low distortion = dark red, high = bright yellow-white.
		face_color(ratio, is_pentagon) {
			if (is_pentagon) { return desaturate([0.25, 0.55, 0.85], 0.6); }
			const t = t_from_ratio(ratio);
			return [
				0.35 + t * 0.65,
				t * t * 0.85,
				t * t * t * 0.25,
			];
		},
	},
	{
		id:   'rainbow',
		name: 'Rainbow',
		// Full hue sweep: low distortion = blue (240°), high = red (0°).
		face_color(ratio, is_pentagon) {
			if (is_pentagon) { return [1.0, 1.0, 1.0]; }
			const t = t_from_ratio(ratio);
			return desaturate(hue_to_rgb(0.67 - t * 0.67), 0.85);
		},
	},
];

export const DEFAULT_PALETTE = PALETTES[0];