import { describe, expect, it } from 'vitest';
import { type LabelBox, stackLabels, type WantedLabel } from '../../src/viewport/labelRows';

const H = 12;
const STEP = 13;

function label(id: string, x: number, y: number, w = 40): WantedLabel {
  return { id, x, y, w, h: H };
}

function overlap(a: LabelBox, b: LabelBox): boolean {
  return a.x < b.x + b.w && b.x < a.x + a.w && a.y < b.y + b.h && b.y < a.y + a.h;
}

describe('stackLabels', () => {
  it('leaves names that do not touch on their own row', () => {
    const tops = stackLabels([label('a', 0, 0), label('b', 100, 0), label('c', 0, 20)], [], STEP);
    expect([...tops]).toEqual([
      ['a', 0],
      ['b', 0],
      ['c', 20],
    ]);
  });

  it('moves the lower of two colliding names a row down', () => {
    const tops = stackLabels([label('low', 10, 4), label('high', 0, 0)], [], STEP);
    expect(tops.get('high')).toBe(0);
    expect(tops.get('low')).toBe(4 + STEP);
  });

  it('stacks names on one spot row by row: down, up, two down, two up', () => {
    const names = ['a', 'b', 'c', 'd', 'e'].map((id) => label(id, 0, 0));
    const tops = stackLabels(names, [], STEP);
    expect(names.map((n) => tops.get(n.id))).toEqual([0, STEP, -STEP, 2 * STEP, -2 * STEP]);
  });

  it('keeps names off icons they would cover', () => {
    // Covers the row above, the name's own and the next one down: two rows down is the first free.
    const icon = { x: 20, y: -6, w: 18, h: 30 };
    const tops = stackLabels([label('a', 0, 0)], [icon], STEP);
    const box = { ...label('a', 0, 0), y: tops.get('a')! };
    expect(overlap(box, icon)).toBe(false);
    expect(tops.get('a')).toBe(2 * STEP);
  });

  it('leaves no two names overlapping in a crowd', () => {
    const names = Array.from({ length: 30 }, (_, k) =>
      label(`n${k}`, (k * 7) % 50, (k * 5) % 30, 30 + (k % 4) * 10),
    );
    const tops = stackLabels(names, [], STEP);
    const boxes = names.map((n) => ({ ...n, y: tops.get(n.id)! }));
    for (let i = 0; i < boxes.length; i++)
      for (let j = i + 1; j < boxes.length; j++) expect(overlap(boxes[i]!, boxes[j]!)).toBe(false);
    // Only up or down: every name stays where its icon wants it across.
    for (const box of boxes) expect(box.x).toBe(names.find((n) => n.id === box.id)!.x);
  });
});