/**
 * #24 — the queue stops being a column when it cannot afford to be one.
 *
 * In flow the panel is `flex-shrink: 0`, so it takes its width *from
 * the main panel* rather than covering it. Measured against the running
 * app on the Playlists page, that left 379px of content at 900×600 —
 * with all three of the page header's actions clipped — 69px at 390px
 * wide, and **0px** at 320px, where the content was not degraded but
 * gone.
 *
 * The rule is `available - panelWidth >= MAIN_PANEL_FLOOR`, and the
 * reason it is a computed property rather than a `@media` block is the
 * third test here: the panel's width is user state, drag-resizable
 * between 200 and 500px and persisted, so a breakpoint on the viewport
 * alone is wrong by up to 180px for a user who has widened it — in the
 * direction that hurts, since a wider queue is exactly when the content
 * can least afford it.
 *
 * The parent is `.content-area`, i.e. the viewport minus the sidebar,
 * which is why these mount into a sized wrapper rather than into
 * `document.body`: the width that decides this is the *parent's*, and
 * `fixture()` would hand the panel the whole test window.
 */
import { describe, expect, it, afterEach } from 'vitest';

import '@components/queue-panel/queue-panel';
import type { QueuePanel } from '@components/queue-panel/queue-panel';
import { shadow } from '@test/support/render';

const wrappers: HTMLElement[] = [];

afterEach(() => {
  for (const w of wrappers.splice(0)) w.remove();
});

/**
 * Mount a panel inside a parent of a stated width.
 *
 * The wrapper is `position: relative` and `display: flex` because that
 * is what `.content-area` is; the mode is measured from
 * `parentElement.clientWidth`, so a wrapper that collapses to its
 * content would measure the panel rather than the space around it.
 */
async function panelIn(parentWidth: number): Promise<QueuePanel> {
  const wrapper = document.createElement('div');

  wrapper.style.cssText = `position: relative; display: flex; width: ${parentWidth}px;`;
  document.body.append(wrapper);
  wrappers.push(wrapper);

  const el = document.createElement('queue-panel') as QueuePanel;

  el.open = true;
  wrapper.append(el);

  await el.updateComplete;
  await settle(el);

  return el;
}

/**
 * A ResizeObserver delivers on a frame, not a microtask, so the mode
 * lands a frame after the width that decides it.
 */
async function settle(el: QueuePanel): Promise<void> {
  for (let frame = 0; frame < 4; frame += 1) {
    await new Promise((r) => {
      requestAnimationFrame(() => r(null));
    });
    await el.updateComplete;
  }
}

/** Drag the resize handle by `dx`, the way a user widens the panel. */
async function dragHandleBy(el: QueuePanel, dx: number): Promise<void> {
  const handle = shadow<HTMLElement>(el, '.resize-handle');
  const startX = el.getBoundingClientRect().left;

  if (!handle) throw new Error('no resize handle to drag');

  handle.dispatchEvent(
    new MouseEvent('mousedown', { clientX: startX, bubbles: true }),
  );
  document.dispatchEvent(
    new MouseEvent('mousemove', { clientX: startX - dx, bubbles: true }),
  );
  document.dispatchEvent(new MouseEvent('mouseup', { bubbles: true }));

  await settle(el);
}

describe('the queue panel decides whether it can be a column', () => {
  it('stays inline while the content can spare the width', async () => {
    const el = await panelIn(1080);

    expect(el.overlay).toBe(false);
    expect(el.hasAttribute('overlay')).toBe(false);
  });

  it('becomes an overlay when it cannot', async () => {
    const el = await panelIn(700);

    expect(el.overlay).toBe(true);
    expect(el.hasAttribute('overlay')).toBe(true);
  });

  /**
   * The test the media query could not have passed. The parent does not
   * move; only the user's own panel width does.
   */
  it('flips to overlay when the user widens the panel, at a fixed width', async () => {
    const el = await panelIn(880);

    expect(el.overlay).toBe(false);

    await dragHandleBy(el, 180);

    expect(el.overlay).toBe(true);
  });

  it('gives an overlay a scrim and a named way out, and an inline panel neither', async () => {
    const overlaid = await panelIn(700);

    expect(shadow(overlaid, '.scrim')).toBeTruthy();

    const close = shadow(overlaid, '[data-testid="queue-close"]');

    expect(close?.getAttribute('aria-label')).toBe('Close queue');

    const inline = await panelIn(1080);

    expect(inline.shadowRoot?.querySelector('.scrim')).toBeNull();
    expect(
      inline.shadowRoot?.querySelector('[data-testid="queue-close"]'),
    ).toBeNull();
  });

  it('closes on the scrim, on the close button and on Escape', async () => {
    for (const close of [
      (el: QueuePanel) => shadow<HTMLElement>(el, '.scrim')?.click(),
      (el: QueuePanel) =>
        shadow<HTMLElement>(el, '[data-testid="queue-close"]')?.click(),
      () =>
        document.dispatchEvent(
          new KeyboardEvent('keydown', { key: 'Escape', bubbles: true }),
        ),
    ]) {
      const el = await panelIn(700);

      expect(el.open).toBe(true);

      close(el);
      await el.updateComplete;

      expect(el.open).toBe(false);
    }
  });

  /**
   * Escape belongs to the overlay, not to the queue. An inline panel is
   * beside the content rather than over it, so there is nothing to
   * dismiss and the key has to reach whatever else wants it.
   */
  it('leaves Escape alone while inline', async () => {
    const el = await panelIn(1080);

    document.dispatchEvent(
      new KeyboardEvent('keydown', { key: 'Escape', bubbles: true }),
    );
    await el.updateComplete;

    expect(el.open).toBe(true);
  });
});