import { describe, expect, it } from 'vitest';
import { MAX_SCALE, MIN_SCALE, scaleToSlider, sliderToScale } from './timeScale';

describe('sliderToScale', () => {
  it('is exact at the endpoints (0 → 1×, 1 → 60×)', () => {
    expect(sliderToScale(0)).toBe(MIN_SCALE);
    expect(sliderToScale(1)).toBe(MAX_SCALE);
  });

  it('maps mid-slider to ~8× (√60 rounds to 8)', () => {
    expect(sliderToScale(0.5)).toBe(8);
  });

  it('is monotonic non-decreasing across the whole range', () => {
    let prev = sliderToScale(0);
    for (let i = 1; i <= 2000; i++) {
      const t = i / 2000;
      const s = sliderToScale(t);
      expect(s).toBeGreaterThanOrEqual(prev);
      prev = s;
    }
  });

  it('covers every integer scale 1..60 somewhere on the slider', () => {
    const seen = new Set<number>();
    for (let i = 0; i <= 2000; i++) seen.add(sliderToScale(i / 2000));
    for (let s = MIN_SCALE; s <= MAX_SCALE; s++) expect(seen.has(s)).toBe(true);
  });

  it('clamps out-of-range and non-finite input', () => {
    expect(sliderToScale(-0.5)).toBe(MIN_SCALE);
    expect(sliderToScale(1.5)).toBe(MAX_SCALE);
    expect(sliderToScale(NaN)).toBe(MIN_SCALE);
  });
});

describe('scaleToSlider', () => {
  it('is exact at the endpoints (1× → 0, 60× → 1)', () => {
    expect(scaleToSlider(1)).toBe(0);
    expect(scaleToSlider(60)).toBe(1);
  });

  it('stays within [0, 1] for in-range scales', () => {
    for (let s = MIN_SCALE; s <= MAX_SCALE; s++) {
      const t = scaleToSlider(s);
      expect(t).toBeGreaterThanOrEqual(0);
      expect(t).toBeLessThanOrEqual(1);
    }
  });

  it('clamps out-of-range and non-finite input', () => {
    expect(scaleToSlider(0)).toBe(0);
    expect(scaleToSlider(-3)).toBe(0);
    expect(scaleToSlider(61)).toBe(1);
    expect(scaleToSlider(NaN)).toBe(0);
  });
});

describe('round-trip', () => {
  it('sliderToScale(scaleToSlider(s)) === s for every integer scale 1..60', () => {
    for (let s = MIN_SCALE; s <= MAX_SCALE; s++) {
      expect(sliderToScale(scaleToSlider(s))).toBe(s);
    }
  });
});