import { describe, expect, it } from "vitest";

import { colorDistance, parseOpaqueColor } from "./color-math.js";

describe("parseOpaqueColor", () => {
  it("parses hex in 3, 6, and opaque 4/8 digit forms", () => {
    expect(parseOpaqueColor("#25f")).toEqual({ r: 0x22, g: 0x55, b: 0xff });
    expect(parseOpaqueColor("#2563eb")).toEqual({ r: 0x25, g: 0x63, b: 0xeb });
    expect(parseOpaqueColor("#2563ebff")).toEqual({ r: 0x25, g: 0x63, b: 0xeb });
    expect(parseOpaqueColor("#25ff")).toEqual({ r: 0x22, g: 0x55, b: 0xff });
  });

  it("rejects translucent values in every notation", () => {
    expect(parseOpaqueColor("#2563eb80")).toBeNull();
    expect(parseOpaqueColor("rgba(37, 99, 235, 0.5)")).toBeNull();
    expect(parseOpaqueColor("rgb(37 99 235 / 0.5)")).toBeNull();
    expect(parseOpaqueColor("hsl(217 91% 60% / 50%)")).toBeNull();
    expect(parseOpaqueColor("oklch(0.55 0.24 263 / 0.8)")).toBeNull();
  });

  it("parses rgb()/rgba() in comma and space syntax, with percentages", () => {
    expect(parseOpaqueColor("rgb(37, 99, 235)")).toEqual({ r: 37, g: 99, b: 235 });
    expect(parseOpaqueColor("rgba(37, 99, 235, 1)")).toEqual({ r: 37, g: 99, b: 235 });
    expect(parseOpaqueColor("rgb(37 99 235)")).toEqual({ r: 37, g: 99, b: 235 });
    expect(parseOpaqueColor("rgb(37 99 235 / 100%)")).toEqual({ r: 37, g: 99, b: 235 });
    expect(parseOpaqueColor("rgb(100% 0% 50%)")).toEqual({ r: 255, g: 0, b: 128 });
  });

  it("parses hsl()/hsla() to the same color as its hex equivalent", () => {
    // Tailwind blue-500: #3b82f6 ≈ hsl(217, 91%, 60%)
    const fromHsl = parseOpaqueColor("hsl(217, 91%, 60%)");
    const fromHex = parseOpaqueColor("#3b82f6");
    expect(fromHsl).not.toBeNull();
    expect(colorDistance(fromHsl!, fromHex!)).toBeLessThan(10);
    expect(parseOpaqueColor("hsla(217, 91%, 60%, 1)")).toEqual(fromHsl);
    expect(parseOpaqueColor("hsl(217deg 91% 60%)")).toEqual(fromHsl);
  });

  it("parses oklch() to the same color as its hex equivalent", () => {
    // #2563eb = oklch(0.54615 0.215208 262.881) (exact sRGB→OKLCH conversion)
    const fromOklch = parseOpaqueColor("oklch(0.54615 0.215208 262.881)");
    const fromHex = parseOpaqueColor("#2563eb");
    expect(fromOklch).not.toBeNull();
    expect(colorDistance(fromOklch!, fromHex!)).toBeLessThan(5);
    // Percentage lightness form.
    expect(parseOpaqueColor("oklch(54.615% 0.215208 262.881)")).toEqual(fromOklch);
    // Published reference: sRGB red is oklch(0.62796 0.25768 29.234).
    const red = parseOpaqueColor("oklch(0.62796 0.25768 29.234)");
    expect(colorDistance(red!, parseOpaqueColor("#ff0000")!)).toBeLessThan(5);
  });

  it("returns null for unsupported notations", () => {
    expect(parseOpaqueColor("rebeccapurple")).toBeNull();
    expect(parseOpaqueColor("lab(52% 40 59)")).toBeNull();
    expect(parseOpaqueColor("color(display-p3 1 0 0)")).toBeNull();
    expect(parseOpaqueColor("var(--fui-color-accent)")).toBeNull();
  });
});

describe("colorDistance", () => {
  it("is zero for identical colors and small for same-family shades", () => {
    const accent = parseOpaqueColor("#7c3aed")!;
    expect(colorDistance(accent, accent)).toBe(0);
    expect(colorDistance(accent, parseOpaqueColor("#7c3acc")!)).toBeLessThan(60);
  });

  it("is large across hue families", () => {
    const blue = parseOpaqueColor("#2563eb")!;
    const red = parseOpaqueColor("#dc2626")!;
    expect(colorDistance(blue, red)).toBeGreaterThan(200);
  });
});