import { describe, expect, it } from 'vitest';
import { rgb, wavePalette, WAVE_COLORS } from './wave-anim';

function hsl(color: string) {
  const [r, g, b] = rgb(color).map((v) => v / 255) as [number, number, number];
  const max = Math.max(r, g, b);
  const min = Math.min(r, g, b);
  const c = max - min;
  const l = (max + min) / 2;
  const h = c === 0 ? 0 : max === r ? (g - b) / c : max === g ? (b - r) / c + 2 : (r - g) / c + 4;
  return { h: (h * 60 + 360) % 360, s: c === 0 ? 0 : c / (1 - Math.abs(2 * l - 1)), l };
}

describe('wave cover palette', () => {
  it.each([
    undefined, [], ['#fff'], ['#000', '#888', '#fff'],
    ['#010203', '#fefdfc', '#808182'], ['#ff0000', 'invalid', '#0000ff'],
  ])('uses the default palette for missing, neutral or malformed colors: %j', (colors) => {
    expect(wavePalette(colors)).toEqual(WAVE_COLORS);
  });

  it('ignores neutral colors and preserves the strongest cover hue', () => {
    const colors = ['#ffffff', '#007733', '#222222'];
    const before = [...colors];
    expect(hsl(wavePalette(colors)[0]).h).toBeCloseTo(hsl('#007733').h, 0);
    expect(wavePalette(colors)).toEqual(wavePalette(['#007733', '#222222', '#ffffff']));
    expect(colors).toEqual(before);
    expect(wavePalette(['#fff', '#073', '#222'])).toEqual(wavePalette(colors));
  });

  it.each([
    ['#040e08', '#18281d', '#374450'], // dark, muted cover like the reported case
    ['#ff0000', '#00ff00', '#0000ff'], // opposing hues must not mix to gray
    ['#ffff00', '#ffffff', '#000000'],
    ['#ff0080', '#540029', '#fefefe'], // hue offsets wrap around red
  ])('keeps a visible, saturated, harmonious palette for %j', (...colors) => {
    const palette = wavePalette(colors);
    const base = hsl(palette[0]);
    for (const color of palette) {
      expect(color).toMatch(/^#[\da-f]{6}$/i);
      const { h, s, l } = hsl(color);
      expect(s).toBeGreaterThanOrEqual(0.70);
      expect(s).toBeLessThanOrEqual(0.84);
      expect(l).toBeGreaterThanOrEqual(0.45);
      expect(l).toBeLessThanOrEqual(0.59);
      const distance = Math.abs(h - base.h);
      expect(Math.min(distance, 360 - distance)).toBeLessThan(29);
    }
  });
});