import tokens from "@wealthledger/tokens/tokens.json";
import { describe, expect, it } from "vitest";

function luminance(color: string) {
	const channels = [1, 3, 5]
		.map((index) => Number.parseInt(color.slice(index, index + 2), 16) / 255)
		.map((value) =>
			value <= 0.04045 ? value / 12.92 : ((value + 0.055) / 1.055) ** 2.4,
		);
	return channels[0] * 0.2126 + channels[1] * 0.7152 + channels[2] * 0.0722;
}
describe("semantic text contrast", () => {
	it.each(["positive", "negative", "muted"] as const)(
		"keeps %s readable on canvas, white, subtle and tinted surfaces",
		(tone) => {
			const role = tokens.color.roles[tone];
			const palettes = tokens.color.palettes;
			const foreground =
				palettes[role.color as keyof typeof palettes][role.shade];
			const surfaces = [
				"#ffffff",
				palettes.gray[0],
				palettes.gray[2],
				...Object.entries(palettes)
					.filter(([name]) => name !== "dark")
					.map(([, palette]) => palette[0]),
				...Object.entries(palettes)
					.filter(([name]) => name !== "dark")
					.map(
						([, palette]) =>
							`#${[1, 3, 5]
								.map((index) =>
									Math.round(
										Number.parseInt(palette[0].slice(index, index + 2), 16) *
											0.45 +
											255 * 0.55,
									)
										.toString(16)
										.padStart(2, "0"),
								)
								.join("")}`,
					),
			];
			for (const background of surfaces)
				expect(
					(luminance(background) + 0.05) / (luminance(foreground) + 0.05),
				).toBeGreaterThanOrEqual(4.5);
		},
	);
});