import { colourDistance } from '../lib/harness.mjs';
import { openTab } from './lib/scaffold.mjs';

const RED = '#ff0000';
const SIZE = 40;

/**
 * Animations (#97, #98, #99, #110, #102): a row is added through the dialog, keys are set, moved,
 * banded, deleted, copied, pasted and duplicated on the timeline with real gestures, frames are
 * inserted, and the preview above it is read at the playhead – as a model value, as a screen rectangle and as pixels. The subject is a container whose child
 * is animated, since a row aiming inside the root is the case a single sprite cannot show. It
 * removes everything it made.
 */
export async function animation(t) {
  const { check, json, evaluate, mutate, shot, click, doubleClick, drag, press, typeText, wheel } = t;
  const { undo, settle, sleep, waitUntil, find } = t;

  await press('Escape');
  await evaluate('document.activeElement instanceof HTMLElement && document.activeElement.blur()');
  await mutate(`
    const p = __gm.state.project;
    const scene = __gm.state.activeScene;
    const sprite = structuredClone(p.assets.find((a) => a.id === 'crate'));
    Object.assign(sprite, { id: 'an-sprite', name: 'Arm sprite' });
    sprite.props = { ...sprite.props, width: ${SIZE}, height: ${SIZE}, color: 0xff0000, texture: '', shader: '' };
    const arm = structuredClone(scene.objects[0]);
    Object.assign(arm, {
      id: 'an-arm', assetId: 'an-sprite', name: 'Arm', parentId: '',
      position: { x: 0, y: 0, z: 0 }, overrides: {}, instanceEdits: {},
    });
    p.assets.push(
      sprite,
      { id: 'an-box', type: 'container', name: 'Dancer', props: { enabled: true }, objects: [arm] },
      { id: 'an-walk', type: 'animation', name: 'Walk', props: { fps: 10, playback: 'loop' }, root: 'an-box', tracks: [] },
    );
    __gm.state.select({ kind: 'asset', assetId: 'an-walk' });
  `);
  await openTab(t, 'animation');
  await sleep(300);
  check('the animation tab shows the animation', (await json('__gm.animation.current()')) === 'an-walk');

  const walk = () => json("__gm.state.project.assets.find((a) => a.id === 'an-walk')");
  const template = () =>
    json("JSON.stringify(__gm.state.project.assets.find((a) => a.id === 'an-box').objects)");
  const keysOf = async () => (await walk()).tracks[0]?.keys ?? [];
  const templateBefore = await template();

  // 25a. The dialog offers the root and what is placed inside it; a row aims at the child.
  const add = await json('__gm.animation.addRowAt()');
  await click(add.x, add.y);
  const offered = await json('__gm.animation.rowDialog()');
  check(
    'the row dialog offers the root itself and the object placed inside it',
    JSON.stringify(offered?.targets) === JSON.stringify(['Dancer (itself)', 'Arm']),
    JSON.stringify(offered),
  );
  await evaluate("__gm.animation.rowDialogPick('an-arm', 'x')");
  await settle();
  const armOffered = (await json('__gm.animation.rowDialog()')).properties;
  const armProperties = armOffered.length;
  check(
    'the position rows come first, Z (the draw order) after X and Y',
    JSON.stringify(armOffered.slice(0, 3)) === JSON.stringify(['X', 'Y', 'Z']),
    JSON.stringify(armOffered),
  );
  const addButton = await find('Add row', true);
  await click(addButton.x, addButton.y);
  const row = (await walk()).tracks;
  check(
    'confirming adds one row aimed at the child, with no keys yet',
    row.length === 1 && row[0].target === 'an-arm' && row[0].property === 'x' && row[0].keys.length === 0,
    JSON.stringify(row),
  );
  const trackId = row[0]?.id;

  await click(add.x, add.y);
  await evaluate("__gm.animation.rowDialogPick('an-arm', 'x')");
  await settle();
  const again = await json('__gm.animation.rowDialog()');
  check(
    'the same object and property is not offered a second time and cannot be confirmed',
    again.properties.length === armProperties - 1 && again.ok === false,
    JSON.stringify({ armProperties, again }),
  );
  const cancel = await find('Cancel', true);
  await click(cancel.x, cancel.y);
  check('cancelling adds nothing', (await walk()).tracks.length === 1);

  // 25b. A double click sets a key with the value the row has there; the inspector edits the key.
  const cell = (frame) => json(`__gm.animation.cellAt(${JSON.stringify(trackId)}, ${frame})`);
  const c0 = await cell(0);
  await doubleClick(c0.x, c0.y);
  const c10 = await cell(10);
  await doubleClick(c10.x, c10.y);
  const doubled = await keysOf();
  check(
    'a double click sets a key holding the value in force there – the child stands at 0',
    JSON.stringify(doubled) ===
      JSON.stringify([
        { frame: 0, value: 0 },
        { frame: 10, value: 0 },
      ]),
    JSON.stringify(doubled),
  );

  const selection = (await t.state()).selection;
  const valueField = await json("__gm.inspectorField('Value')");
  check(
    'the key just set is picked and the inspector shows its value',
    selection?.kind === 'track' && selection.keys?.[0]?.frame === 10 && Boolean(valueField),
    JSON.stringify({ selection, valueField }),
  );
  await click(valueField.x, valueField.y);
  await press('a', { ctrl: true });
  await typeText('100');
  await press('Enter');
  await settle();
  const edited = await keysOf();
  check(
    'typing a value writes the key, and the container template stays as it was',
    edited.find((k) => k.frame === 10)?.value === 100 && (await template()) === templateBefore,
    JSON.stringify(edited),
  );
  const info = await json('__gm.animation.info()');
  check(
    'the readout counts to the last key: 11 frames, 1.1 s',
    info === '1 row · 11 frames · 10 fps · 1.1 s',
    info,
  );

  // 25b-ii. Easing is two fields: the curve, and for a curve its direction. Each pick is a step,
  //         all three are undone here so 25h counts only its own.
  const easingOf = async () => (await keysOf()).find((k) => k.frame === 10)?.interpolation ?? 'linear';
  const pick = async (field, label) => {
    const row = await json(`__gm.inspectorField(${JSON.stringify(field)})`);
    await click(row.x, row.y);
    await sleep(100);
    const rows = await json('__gm.menuRows()');
    const entry = await t.locate(label, true);
    await click(entry.x, entry.y);
    await settle();
    return rows;
  };
  const shapes = await pick('Easing', 'Cubic');
  const cubicDirection = await json("__gm.inspectorField('Direction')");
  check(
    'the Easing field lists every curve, and a curve brings the Direction field, eased both ways',
    JSON.stringify(shapes) ===
      JSON.stringify([
        'Linear',
        'Step',
        'Sine',
        'Quad',
        'Cubic',
        'Quart',
        'Quint',
        'Expo',
        'Circ',
        'Back',
        'Elastic',
        'Bounce',
        'Curve',
      ]) &&
      (await easingOf()) === 'cubic-in-out' &&
      Boolean(cubicDirection),
    JSON.stringify({ shapes, easing: await easingOf(), cubicDirection }),
  );
  const directions = await pick('Direction', 'Out');
  await shot('25-animation-easing');
  const outward = await easingOf();
  await pick('Easing', 'Back');
  const back = await easingOf();
  check(
    'Direction offers In, Out and In-out, and a new curve keeps the direction picked',
    JSON.stringify(directions) === JSON.stringify(['In', 'Out', 'In-out']) &&
      outward === 'cubic-out' &&
      back === 'back-out',
    JSON.stringify({ directions, outward, back }),
  );
  await pick('Easing', 'Linear');
  const linearDirection = await json("__gm.inspectorField('Direction')");
  const linear = await easingOf();
  await focusTimeline();
  await undo();
  const backAgain = await easingOf();
  for (let i = 0; i < 3; i++) await undo();
  const easingUndone = await easingOf();
  const keptValue = (await keysOf()).find((k) => k.frame === 10)?.value;
  check(
    'linear drops the Direction field and the stored easing, and undo takes the four picks back one by one',
    !linearDirection &&
      linear === 'linear' &&
      backAgain === 'back-out' &&
      easingUndone === 'linear' &&
      keptValue === 100,
    JSON.stringify({ linearDirection, linear, backAgain, easingUndone, keptValue }),
  );

  // 25c. The ruler scrubs, and the preview draws the child at the playhead. Framed at the far end,
  //      so both ends and the middle are on screen together.
  const scrubTo = async (frame) => {
    const p = await json(`__gm.animation.rulerAt(${frame})`);
    await click(p.x, p.y);
    await sleep(100);
  };
  const armId = await json("__gm.animation.preview.objectId('an-arm')");
  const rectAt = async (frame) => {
    await scrubTo(frame);
    return json(`__gm.animation.preview.rect(${JSON.stringify(armId)})`);
  };
  await scrubTo(10);
  const fit = await json('__gm.animation.preview.fitAt()');
  await click(fit.x, fit.y);
  await sleep(200);
  const start = await rectAt(0);
  const end = await rectAt(10);
  const middle = await rectAt(5);
  const playhead = (await json('__gm.animation.view()')).playhead;
  const drawn = await json(`__gm.animation.preview.item(${JSON.stringify(armId)})`);
  const expectedX = start && end ? (start.x + end.x) / 2 : NaN;
  check(
    'clicking the ruler at 5 puts the playhead there, and the child is drawn half way at x 50',
    playhead === 5 && drawn?.x === 50 && Math.abs(middle?.x - expectedX) <= 1 && end?.x - start?.x > SIZE,
    JSON.stringify({ playhead, drawn: drawn?.x, start, middle, end }),
  );
  await shot('25-animation-preview');
  if (!start || !middle || !end) return;

  // Pixels: red all over the child where it is drawn, and nothing red where it stood at frame 0.
  const grid = [];
  for (const fx of [-0.3, 0, 0.3]) for (const fy of [-0.3, 0, 0.3]) grid.push([fx, fy]);
  const samples = await json(
    `[${grid.map(([fx, fy]) => `__gm.pixelAt(${Math.round(middle.x + fx * middle.w)}, ${Math.round(middle.y + fy * middle.h)})`).join(',')}]`,
  );
  const left = await json(`__gm.pixelAt(${Math.round(start.x)}, ${Math.round(start.y)})`);
  check(
    'the preview paints the child red at frame 5, and the spot it held at frame 0 is empty',
    samples.every((c) => colourDistance(c, RED) < 30) && colourDistance(left, RED) > 150,
    JSON.stringify({ samples, left }),
  );

  // 25d. Drag moves a key, landing on another replaces it; undo brings the replaced one back.
  const c5 = await cell(5);
  await doubleClick(c5.x, c5.y);
  const withMiddle = await keysOf();
  const from = await cell(5);
  const to = await cell(10);
  await drag(from.x, from.y, to.x, to.y);
  const landed = await keysOf();
  check(
    'a key dragged onto another replaces it and keeps its own value',
    withMiddle.find((k) => k.frame === 5)?.value === 50 &&
      JSON.stringify(landed) ===
        JSON.stringify([
          { frame: 0, value: 0 },
          { frame: 10, value: 50 },
        ]),
    JSON.stringify({ withMiddle, landed }),
  );
  await undo();
  check(
    'undo takes the drag back, the replaced key included',
    JSON.stringify(await keysOf()) === JSON.stringify(withMiddle),
    JSON.stringify(await keysOf()),
  );

  // 25e. A band from the empty space below the row over all three keys, then Delete.
  const bandFrom = { x: (await cell(14)).x, y: c0.y + 40 };
  const bandTo = { x: c0.x - 12, y: c0.y - 11 };
  await drag(bandFrom.x, bandFrom.y, bandTo.x, bandTo.y);
  const banded = (await json('__gm.animation.keys()')).filter((k) => k.selected).map((k) => k.frame);
  await press('Delete');
  const deleted = await keysOf();
  check(
    'the band picks every key it spans, and Delete removes them all but keeps the row',
    banded.join() === '0,5,10' && deleted.length === 0 && (await walk()).tracks.length === 1,
    JSON.stringify({ banded, deleted }),
  );
  await undo();
  check(
    'one undo brings all three keys back',
    JSON.stringify(await keysOf()) === JSON.stringify(withMiddle),
    JSON.stringify(await keysOf()),
  );

  // 25f. Once (hold) keeps the last value; once (reset) puts the starting value back at the end.
  const playThrough = async (playback) => {
    await mutate(`__gm.state.project.assets.find((a) => a.id === 'an-walk').props.playback = '${playback}'`);
    await scrubTo(0);
    const play = await json('__gm.animation.playAt()');
    await click(play.x, play.y);
    await waitUntil('!__gm.animation.view().playing', { timeout: 5000, label: `the ${playback} pass ended` });
    await sleep(100);
    return {
      playhead: (await json('__gm.animation.view()')).playhead,
      x: (await json(`__gm.animation.preview.item(${JSON.stringify(armId)})`))?.x,
      button: (await json('__gm.animation.playAt()')).text,
    };
  };
  const held = await playThrough('once');
  const reset = await playThrough('once-reset');
  check(
    'a once pass ends holding the last key, a once-reset pass ends showing the starting value',
    held.x === 100 && reset.x === 0 && reset.playhead >= 10 && reset.button === 'Play',
    JSON.stringify({ held, reset }),
  );

  // 25g. Copy and paste (#102): two keys banded, Ctrl+C, the playhead to 12, Ctrl+V – they land
  //      relative to the playhead, keeping their distance, and come back picked. Each step undone.
  await mutate(`__gm.state.project.assets.find((a) => a.id === 'an-walk').props.playback = 'loop'`);
  const three = JSON.stringify(withMiddle);
  const pickedFrames = async () =>
    (await json('__gm.animation.keys()')).filter((k) => k.selected).map((k) => k.frame);
  const c3 = await cell(3);
  await drag((await cell(14)).x, c0.y + 40, c3.x, c0.y - 11);
  const copied = await pickedFrames();
  await press('c', { ctrl: true });
  const clip = await json('__gm.animation.clipboard()');
  await scrubTo(12);
  await press('v', { ctrl: true });
  const pasted = await keysOf();
  const pastedPick = await pickedFrames();
  check(
    'Ctrl+C and Ctrl+V paste the banded keys relative to the playhead and pick them',
    copied.join() === '5,10' &&
      JSON.stringify(clip?.rows?.[0]?.keys?.map((k) => k.offset)) === '[0,5]' &&
      JSON.stringify(pasted) ===
        JSON.stringify([...withMiddle, { frame: 12, value: 50 }, { frame: 17, value: 100 }]) &&
      pastedPick.join() === '12,17',
    JSON.stringify({ copied, clip, pasted, pastedPick }),
  );
  await undo();
  check(
    'one undo takes the paste back',
    JSON.stringify(await keysOf()) === three,
    JSON.stringify(await keysOf()),
  );

  // Ctrl+drag duplicates: the key at 5 stays, a copy lands on 7.
  const k5 = await cell(5);
  const k7 = await cell(7);
  await click(k5.x, k5.y);
  await drag(k5.x, k5.y, k7.x, k7.y, { modifiers: { ctrl: true } });
  const duplicated = await keysOf();
  check(
    'Ctrl+drag leaves the key where it was and drops a copy where the pointer lets go',
    JSON.stringify(duplicated) ===
      JSON.stringify([withMiddle[0], withMiddle[1], { frame: 7, value: 50 }, withMiddle[2]]),
    JSON.stringify(duplicated),
  );
  await undo();

  // Right-click → Insert frames… at the playhead: every key from there on moves by the count.
  await scrubTo(5);
  const inCells = await cell(2);
  await click(inCells.x, inCells.y + 40, 'right');
  const insertItem = await find('Insert frames at 5…', true);
  await click(insertItem.x, insertItem.y);
  await evaluate('__gm.animation.framesDialogCount(3)');
  await settle();
  const dialog = await json('__gm.animation.framesDialog()');
  const confirm = await json('__gm.animation.framesDialogConfirm()');
  await click(confirm.x, confirm.y);
  const inserted = await keysOf();
  check(
    'the menu inserts 3 frames at the playhead: the keys on 5 and 10 move to 8 and 13, the one on 0 stays',
    dialog?.summary === 'Moves 2 keys 3 frames later.' &&
      JSON.stringify(inserted.map((k) => k.frame)) === '[0,8,13]' &&
      (await json('__gm.animation.framesDialog()')) === null,
    JSON.stringify({ dialog, inserted }),
  );
  await undo();
  check(
    'undo takes the inserted frames back',
    JSON.stringify(await keysOf()) === three,
    JSON.stringify(await keysOf()),
  );

  // Right-click on the row's header → Delete row: the row goes, the animation stays picked; undo.
  const rowHeader = await json(`__gm.animation.headerAt(${JSON.stringify(trackId)})`);
  await click(rowHeader.x, rowHeader.y, 'right');
  const deleteItem = await find('Delete row', true);
  // A destructive entry is red text on the plain menu, not a filled red row.
  const menuRows = await json('__gm.menuRows()');
  const looks = await json('__gm.menuLooks()');
  const danger = await json(`__gm.themeColor('danger')`);
  const plain = await json(`__gm.themeColor('text')`);
  const deleteLook = looks[menuRows.indexOf('Delete row')];
  const insertLook = looks[menuRows.findIndex((row) => row?.startsWith('Insert frames'))];
  check(
    'Delete row is drawn in red text without a red fill, a plain entry in the normal text colour',
    deleteLook?.text === danger && deleteLook.fill !== danger && insertLook?.text === plain,
    JSON.stringify({ deleteLook, insertLook, danger, plain }),
  );
  await click(deleteItem.x, deleteItem.y);
  const rowsGone = (await walk()).tracks.length;
  const afterDelete = await json('__gm.state.selection');
  await undo();
  check(
    'the menu on a row header deletes that row, and undo brings it back with its keys',
    rowsGone === 0 &&
      afterDelete?.kind === 'asset' &&
      (await walk()).tracks.length === 1 &&
      JSON.stringify(await keysOf()) === three,
    JSON.stringify({ rowsGone, afterDelete, keys: await keysOf() }),
  );

  // 25h. Undo all the way: the key at 5, the value edit, the keys at 10 and 0, then the row. Exactly
  //      that many – one more would take back a command of an earlier step, so the count is checked
  //      on the way: after four the row is still there, empty.
  await focusTimeline();
  for (let i = 0; i < 4; i++) await undo();
  const emptied = await walk();
  await undo();
  const undone = await walk();
  check(
    'undo takes back the keys and the value edit one by one, and the row last',
    emptied.tracks.length === 1 &&
      emptied.tracks[0].keys.length === 0 &&
      undone.tracks.length === 0 &&
      (await template()) === templateBefore,
    JSON.stringify({ emptied: emptied.tracks, undone: undone.tracks }),
  );

  // 25i. The header (#408): rows grouped under their object in the order of the hierarchy, each
  //      object's rows in the order of its properties, the value at the playhead in the row, and
  //      a value typed there keys it at the playhead.
  await mutate(`
    __gm.state.project.assets.find((a) => a.id === 'an-walk').tracks = [
      { id: 'an-r1', target: 'an-arm', property: 'color', keys: [] },
      { id: 'an-r2', target: '', property: 'enabled', keys: [] },
      { id: 'an-r3', target: 'an-arm', property: 'x', keys: [{ frame: 0, value: 0 }, { frame: 10, value: 100 }] },
    ];
  `);
  await evaluate('__gm.animation.scrub(4)');
  await sleep(150);
  const lines = await json('__gm.animation.lines()');
  const shape = lines.map((l) => (l.kind === 'group' ? l.text : `  ${l.text}=${JSON.stringify(l.value)}`));
  check(
    'the header groups the rows under Dancer and Arm, X before Color, each with its value at frame 4',
    JSON.stringify(shape) ===
      JSON.stringify(['Dancer', '  Enabled=true', 'Arm', '  X=40', `  Color=${0xff0000}`]) &&
      lines[1].indent > lines[0].indent,
    JSON.stringify(lines),
  );
  await shot('20-grouped-header');
  const xField = await json("__gm.animation.valueAt('an-r3')");
  await click(xField.x, xField.y);
  await typeText('55');
  await press('Enter');
  await sleep(150);
  const typed = (await walk()).tracks.find((r) => r.id === 'an-r3').keys;
  const typedPick = await json('__gm.state.selectedKeys');
  check(
    'a value typed into the row keys it at the playhead and picks that key',
    JSON.stringify(typed) ===
      JSON.stringify([
        { frame: 0, value: 0 },
        { frame: 4, value: 55 },
        { frame: 10, value: 100 },
      ]) && JSON.stringify(typedPick) === JSON.stringify([{ trackId: 'an-r3', frame: 4 }]),
    JSON.stringify({ typed, typedPick }),
  );

  // Pressing the ruler while playing pauses – and the button says Play again.
  const playButton = await json('__gm.animation.playAt()');
  await click(playButton.x, playButton.y);
  const whilePlaying = (await json('__gm.animation.playAt()')).text;
  const ruler = await json('__gm.animation.rulerAt(2)');
  await click(ruler.x, ruler.y);
  const scrubbed = {
    text: (await json('__gm.animation.playAt()')).text,
    ...(await json('__gm.animation.view()')),
  };
  check(
    'scrubbing on the ruler while playing pauses, and the button turns back to Play',
    whilePlaying === 'Pause' && scrubbed.text === 'Play' && scrubbed.playing === false,
    JSON.stringify({ whilePlaying, scrubbed }),
  );

  // 25i-ii. A double click into a row without keys keys what its header showed (#412): the Arm
  //         stands at x 40, not at the property's default 0.
  await mutate(`
    const p = __gm.state.project;
    p.assets.find((a) => a.id === 'an-box').objects[0].position.x = 40;
    p.assets.find((a) => a.id === 'an-walk').tracks = [{ id: 'an-r4', target: 'an-arm', property: 'x', keys: [] }];
  `);
  await sleep(150);
  const shownX = (await json('__gm.animation.lines()')).find((l) => l.kind !== 'group')?.value;
  const emptyCell = await json("__gm.animation.cellAt('an-r4', 3)");
  await doubleClick(emptyCell.x, emptyCell.y);
  const keyedX = (await walk()).tracks[0].keys;
  check(
    'a double click into an empty row keys the value its header showed – 40, not the default 0',
    shownX === 40 && JSON.stringify(keyedX) === JSON.stringify([{ frame: 3, value: 40 }]),
    JSON.stringify({ shownX, keyedX }),
  );

  // 25j. More rows than room (#413): 16 objects with a row each. The wheel over the header column
  //      scrolls the rows, the last one comes into view and its field keys a typed value; the
  //      scrollbar's thumb dragged up takes them back to the top.
  await mutate(`
    const p = __gm.state.project;
    const box = p.assets.find((a) => a.id === 'an-box');
    const arm = box.objects[0];
    for (let i = 2; i <= 16; i++)
      box.objects.push({ ...structuredClone(arm), id: 'an-arm' + i, name: 'Arm ' + i });
    p.assets.find((a) => a.id === 'an-walk').tracks = box.objects.map((o, i) => (
      { id: i === 15 ? 'an-last' : 'an-s' + i, target: o.id, property: 'x', keys: [] }
    ));
  `);
  await evaluate('__gm.animation.scrub(2)');
  await sleep(150);
  const before = { view: await json('__gm.animation.view()'), thumb: await json('__gm.animation.thumb()') };
  const lastHidden = await json("__gm.animation.valueAt('an-last')");
  const header = await json("__gm.animation.headerAt('an-s0')");
  await wheel(header.x, header.y, 5000);
  const scrolled = await json('__gm.animation.view()');
  const lastField = await json("__gm.animation.valueAt('an-last')");
  if (lastField) {
    await click(lastField.x, lastField.y);
    await typeText('77');
    await press('Enter');
    await sleep(150);
  }
  const lastKeys = (await walk()).tracks.find((r) => r.id === 'an-last').keys;
  check(
    'the wheel over the headers scrolls to the last row, and its field keys a typed value',
    before.view.scrollY === 0 &&
      before.thumb !== null &&
      lastHidden === null &&
      scrolled.scrollY === before.thumb.max &&
      scrolled.cellWidth === before.view.cellWidth &&
      lastField !== null &&
      JSON.stringify(lastKeys) === JSON.stringify([{ frame: 2, value: 77 }]),
    JSON.stringify({ before, lastHidden, scrolled, lastField, lastKeys }),
  );
  await shot('21-scrolled-rows');
  const thumb = await json('__gm.animation.thumb()');
  await drag(thumb.x, thumb.y, thumb.x, 5);
  const toTop = await json('__gm.animation.view()');
  check(
    'the scrollbar thumb dragged up takes the rows back to the top',
    toTop.scrollY === 0 && (await json("__gm.animation.valueAt('an-last')")) === null,
    JSON.stringify({ thumb, toTop }),
  );

  // 25k. Folding a group (#414): the Arm with a Hand under it. Folded, the Arm's rows and the Hand's
  //      group are gone and the head shows a diamond on every keyed frame; dragging the one on 6 to 8
  //      moves both keys there in one undo step, and Delete on the one on 4 takes the Hand's key.
  //      Open again, the head keeps its diamonds.
  await mutate(`
    const p = __gm.state.project;
    const box = p.assets.find((a) => a.id === 'an-box');
    const arm = box.objects[0];
    box.objects = [arm, { ...structuredClone(arm), id: 'an-hand', name: 'Hand', parentId: arm.id }];
    p.assets.find((a) => a.id === 'an-walk').tracks = [
      { id: 'an-k1', target: arm.id, property: 'x', keys: [{ frame: 0, value: 0 }, { frame: 6, value: 60 }] },
      { id: 'an-k2', target: arm.id, property: 'y', keys: [{ frame: 2, value: 0 }, { frame: 6, value: 10 }] },
      { id: 'an-k3', target: 'an-hand', property: 'rotation', keys: [{ frame: 4, value: 90 }] },
    ];
  `);
  await sleep(150);
  const tracksNow = async () =>
    JSON.stringify((await walk()).tracks.map((r) => [r.id, r.keys.map((k) => k.frame)]));
  const tracksBefore = await tracksNow();
  const fold = await json("__gm.animation.foldAt('an-arm')");
  await click(fold.x, fold.y);
  const folded = await json('__gm.animation.lines()');
  check(
    'a click on the triangle folds the Arm: its rows and the Hand go, the head shows diamonds on 0, 2, 4 and 6',
    folded.length === 1 &&
      folded[0].text === 'Arm' &&
      folded[0].folded === true &&
      JSON.stringify(folded[0].summary) === '[0,2,4,6]',
    JSON.stringify(folded),
  );
  await shot('22-folded-group');
  const six = await json("__gm.animation.summaryAt('an-arm', 6)");
  const eight = await json("__gm.animation.summaryAt('an-arm', 8)");
  await drag(six.x, six.y, eight.x, eight.y);
  const movedTo = await tracksNow();
  await undo();
  const movedBack = await tracksNow();
  check(
    "dragging the diamond on 6 to 8 moves both of the Arm's keys there, the Hand's stays, one undo takes it back",
    movedTo ===
      JSON.stringify([
        ['an-k1', [0, 8]],
        ['an-k2', [2, 8]],
        ['an-k3', [4]],
      ]) && movedBack === tracksBefore,
    JSON.stringify({ movedTo, movedBack }),
  );
  const four = await json("__gm.animation.summaryAt('an-arm', 4)");
  await click(four.x, four.y);
  const pickedFour = await json('__gm.state.selectedKeys');
  await press('Delete');
  const foldedDelete = await tracksNow();
  await undo();
  check(
    "the diamond on 4 picks the folded Hand's key, Delete removes it, undo brings it back, the group stays folded",
    JSON.stringify(pickedFour) === JSON.stringify([{ trackId: 'an-k3', frame: 4 }]) &&
      foldedDelete ===
        JSON.stringify([
          ['an-k1', [0, 6]],
          ['an-k2', [2, 6]],
          ['an-k3', []],
        ]) &&
      (await tracksNow()) === tracksBefore &&
      (await json('__gm.animation.lines()')).length === 1,
    JSON.stringify({ pickedFour, foldedDelete }),
  );
  await click(fold.x, fold.y);
  const opened = await json('__gm.animation.lines()');
  check(
    'a second click opens it again, and the open head still shows its diamonds',
    JSON.stringify(opened.map((l) => l.text)) === JSON.stringify(['Arm', 'X', 'Y', 'Hand', 'Rotation']) &&
      opened[0].folded === false &&
      JSON.stringify(opened[0].summary) === '[0,2,4,6]' &&
      JSON.stringify(opened[3].summary) === '[4]',
    JSON.stringify(opened),
  );

  await mutate(`
    const p = __gm.state.project;
    p.assets = p.assets.filter((a) => !['an-walk', 'an-box', 'an-sprite'].includes(a.id));
    __gm.state.select(null);
  `);
  const leftOver = await json(
    "__gm.state.project.assets.filter((a) => ['an-walk', 'an-box', 'an-sprite'].includes(a.id)).length",
  );
  check('the step leaves the fixture as it found it', leftOver === 0, String(leftOver));

  /** Puts the keyboard on the timeline, so Ctrl+Z is not taken by a text field. */
  async function focusTimeline() {
    const header = await json(`__gm.animation.headerAt(${JSON.stringify(trackId)})`);
    await click(header.x, header.y);
  }
}