import { describe, expect, it } from 'vitest';
import {
  gapAt,
  maxScroll,
  moveTarget,
  STRIP_PAD,
  TILE,
  TILE_GAP,
  tileIndexAt,
} from '../../src/editor/animation/strip';

const STEP = TILE + TILE_GAP;

describe('the frame strip', () => {
  it('finds the tile under the pointer, and none in the gaps or past the last', () => {
    const at = (x: number) => tileIndexAt(x, 3, 0);
    expect([at(STRIP_PAD), at(STRIP_PAD + TILE), at(STRIP_PAD + STEP + 1)]).toEqual([0, 0, 1]);
    expect([at(STRIP_PAD - 1), at(STRIP_PAD + TILE + 2), at(STRIP_PAD + 3 * STEP + 1)]).toEqual([-1, -1, -1]);
    expect(tileIndexAt(STRIP_PAD + 1, 3, STEP)).toBe(1);
  });

  it('drops into the gap nearest to the pointer', () => {
    const gap = (x: number) => gapAt(x, 3, 0);
    expect([gap(0), gap(STRIP_PAD + TILE / 2 - 1), gap(STRIP_PAD + TILE / 2 + 1), gap(9999)]).toEqual([
      0, 0, 1, 3,
    ]);
  });

  it('turns a gap into the index the frame ends up at, and a drop beside itself into nothing', () => {
    expect([moveTarget(0, 0), moveTarget(0, 1)]).toEqual([null, null]);
    expect([moveTarget(0, 3), moveTarget(2, 0), moveTarget(1, 3)]).toEqual([2, 0, 2]);
  });

  it('scrolls only as far as the last tile needs', () => {
    expect(maxScroll(2, 500)).toBe(0);
    expect(maxScroll(10, 300)).toBe(STRIP_PAD * 2 + 10 * TILE + 9 * TILE_GAP - 300);
  });
});