import { describe, it, expect } from 'vitest';
import { clampZoom, computeZoom, type TimelineState } from '$lib/timeline/interactions';

describe('clampZoom', () => {
  it('clamps zoom above minimum', () => {
    expect(clampZoom(0.5, 60)).toBeGreaterThanOrEqual(1);
  });

  it('clamps zoom below maximum', () => {
    expect(clampZoom(10000, 60)).toBeLessThanOrEqual(600);
  });
});

describe('computeZoom', () => {
  it('zooming in narrows the visible range', () => {
    const state: TimelineState = {
      visibleStart: 0,
      visibleEnd: 60,
      zoom: 1,
      width: 600,
      height: 160,
    };
    const result = computeZoom(state, 30, 1.1, 60);
    const newRange = result.visibleEnd - result.visibleStart;
    expect(newRange).toBeLessThan(60);
  });

  it('zooming out widens the visible range', () => {
    const state: TimelineState = {
      visibleStart: 10,
      visibleEnd: 20,
      zoom: 6,
      width: 600,
      height: 160,
    };
    const result = computeZoom(state, 15, 0.9, 60);
    const newRange = result.visibleEnd - result.visibleStart;
    expect(newRange).toBeGreaterThan(10);
  });
});