import { test, expect } from '@playwright/test';
import path from 'node:path';
import { scrollThrough } from '../lib/scroll';
import { PROBE_SCRIPT, startProbe, perStep } from '../lib/probe';

const fx = (n: string) => 'file://' + path.resolve(__dirname, '../fixtures', n);

test('scrollThrough: длинный список y проходится до конца', async ({ page }) => {
  await page.goto(fx('long-list.html'));
  const r = await scrollThrough(page, '#box', 'y');
  expect(r.complete).toBe(true);
  expect(r.steps).toBeGreaterThanOrEqual(100);
  // вернулись к началу
  expect(await page.evaluate(() => document.querySelector('#box')!.scrollTop)).toBeLessThanOrEqual(2);
});

test('scrollThrough: ось x', async ({ page }) => {
  await page.goto(fx('long-list.html'));
  const r = await scrollThrough(page, '#box', 'x');
  expect(r.complete).toBe(true);
});

test('scrollThrough: при исчерпании maxSteps complete === false', async ({ page }) => {
  await page.goto(fx('clipped-list.html'));
  const r = await scrollThrough(page, '#box', 'y', 200, 10);
  expect(r.complete).toBe(false);
  expect(r.steps).toBeLessThanOrEqual(10);
});

test('scrollThrough: контейнер без переполнения - complete === false, reason no_overflow, 0 шагов', async ({ page }) => {
  await page.goto(fx('no-overflow.html'));
  for (const axis of ['y', 'x'] as const) {
    const r = await scrollThrough(page, '#box', axis);
    expect(r.complete).toBe(false);
    expect(r.steps).toBe(0);
    expect(r.reason).toBe('no_overflow');
  }
});

test('scrollThrough: ось x на длинном по высоте, но не по ширине контейнере - no_overflow', async ({ page }) => {
  await page.goto(fx('clipped-list.html'));
  const r = await scrollThrough(page, '#box', 'x');
  expect(r.complete).toBe(false);
  expect(r.reason).toBe('no_overflow');
});

test('scroll + probe: main_thread_ms_per_step = main_thread_ms / steps', async ({ page }) => {
  await page.addInitScript(PROBE_SCRIPT);
  await page.goto(fx('long-list.html'));
  const p = await startProbe(page);
  const r = await scrollThrough(page, '#box', 'y');
  const m = await p.stop();
  expect(r.steps).toBeGreaterThan(0);
  expect(m.main_thread_ms).toBeGreaterThan(0);
  const ps = perStep(m, r.steps);
  expect(ps.main_thread_ms_per_step).toBeCloseTo(m.main_thread_ms / r.steps, 6);
  expect(perStep(m, 0)).toEqual({}); // нет шагов (фильтр, no_overflow) - метрики на шаг нет
});