import { describe, it, expect } from 'vitest';
import { timeToX, xToTime, type TimelineState } from '$lib/timeline/renderer';

function makeState(overrides: Partial<TimelineState> = {}): TimelineState {
  return {
    visibleStart: 0,
    visibleEnd: 60,
    zoom: 1,
    width: 600,
    height: 160,
    ...overrides,
  };
}

describe('timeToX', () => {
  it('maps start of visible range to 0', () => {
    const state = makeState();
    expect(timeToX(0, state)).toBe(0);
  });

  it('maps end of visible range to width', () => {
    const state = makeState();
    expect(timeToX(60, state)).toBe(600);
  });

  it('maps midpoint correctly', () => {
    const state = makeState();
    expect(timeToX(30, state)).toBe(300);
  });

  it('handles zoomed-in view', () => {
    const state = makeState({ visibleStart: 10, visibleEnd: 20 });
    expect(timeToX(15, state)).toBe(300);
  });
});

describe('xToTime', () => {
  it('maps 0 to visible start', () => {
    const state = makeState();
    expect(xToTime(0, state)).toBe(0);
  });

  it('maps width to visible end', () => {
    const state = makeState();
    expect(xToTime(600, state)).toBe(60);
  });

  it('maps midpoint correctly', () => {
    const state = makeState();
    expect(xToTime(300, state)).toBe(30);
  });

  it('inverse of timeToX', () => {
    const state = makeState({ visibleStart: 10, visibleEnd: 20 });
    expect(xToTime(timeToX(15, state), state)).toBeCloseTo(15);
  });
});