import { describe, expect, it } from "vitest";
import {
  isPreviewSurfaceColor,
  mostCommonOpaqueColor,
  randomPreviewSurfaceColor,
  readableCardFill,
} from "../../lib/create/previewSurfaceColor";

function pixel(r: number, g: number, b: number, a = 255): number[] {
  return [r, g, b, a];
}

describe("mostCommonOpaqueColor", () => {
  it("returns the average of the largest quantized bucket", () => {
    const data = new Uint8ClampedArray([
      ...pixel(200, 10, 10),
      ...pixel(201, 11, 9),
      ...pixel(202, 9, 11),
      ...pixel(10, 10, 220),
    ]);

    expect(mostCommonOpaqueColor(data)).toBe("rgb(201, 10, 10)");
  });

  it("ignores transparent pixels", () => {
    const data = new Uint8ClampedArray([
      ...pixel(255, 255, 255, 0),
      ...pixel(255, 255, 255, 0),
      ...pixel(20, 40, 60),
    ]);

    expect(mostCommonOpaqueColor(data)).toBe("rgb(20, 40, 60)");
  });

  it("returns null when nothing is opaque", () => {
    const data = new Uint8ClampedArray([...pixel(1, 2, 3, 0)]);
    expect(mostCommonOpaqueColor(data)).toBeNull();
  });

  it("counts a translucent fill", () => {
    const data = new Uint8ClampedArray([...pixel(255, 0, 0, 127)]);
    expect(mostCommonOpaqueColor(data)).toBe("rgb(255, 0, 0)");
  });
});

describe("readableCardFill", () => {
  it("keeps a light logo color", () => {
    expect(readableCardFill(201, 254, 249)).toBe("rgb(201, 254, 249)");
  });

  it("lifts a dark logo color into a pale tint of the same hue", () => {
    const fill = readableCardFill(255, 0, 0);
    const channels = fill
      .split(/[^\d]+/)
      .filter(Boolean)
      .map(Number);
    const lightness =
      (Math.max(...channels) + Math.min(...channels)) / 2 / 255;
    expect(lightness).toBeGreaterThanOrEqual(0.8);
    expect(channels[0]).toBeGreaterThan(channels[2]);
  });
});

describe("randomPreviewSurfaceColor", () => {
  it("stays in a light range so black type can sit on it", () => {
    let call = 0;
    const sequence = [0, 0, 0];
    expect(randomPreviewSurfaceColor(() => sequence[call++] ?? 0)).toBe(
      "hsl(0, 50%, 76%)",
    );

    call = 0;
    const high = [0.999, 0.999, 0.999];
    expect(randomPreviewSurfaceColor(() => high[call++] ?? 0)).toBe(
      "hsl(359, 84%, 87%)",
    );
  });
});

describe("isPreviewSurfaceColor", () => {
  it("accepts the hsl strings this module writes", () => {
    expect(isPreviewSurfaceColor("hsl(12, 50%, 80%)")).toBe(true);
    expect(isPreviewSurfaceColor("hsl(359, 84%, 87%)")).toBe(true);
  });

  it("rejects other CSS colors", () => {
    expect(isPreviewSurfaceColor("rgb(12, 80, 40)")).toBe(false);
    expect(isPreviewSurfaceColor("red")).toBe(false);
  });
});