import { colourDistance } from '../lib/harness.mjs';
import { LANES, MAKE_OBJECT } from './lib/scaffold.mjs';

/**
 * Pixel art (#130): a picture painted pixel by pixel, in layers and frames, with a palette. Every
 * block goes the way a user goes – the asset comes out of the + menu, the tools are picked in the
 * side panel and dragged across the canvas – and reads back what only a running editor can show:
 * the indices in the cels, the colours on screen, and that the picture reaches a sprite and survives
 * a reload. Runs last: the reload at its end starts the page afresh.
 */

/** Colours of the default palette (PICO-8), by index. */
const RED = 9; // #ff004d
const GREEN = 12; // #00e436
const BLUE = 13; // #29adff
const HEX = { [RED]: '#ff004d', [GREEN]: '#00e436', [BLUE]: '#29adff' };

export async function pixelArt(t) {
  const {
    api,
    check,
    click,
    drag,
    evaluate,
    json,
    mutate,
    navigate,
    press,
    projectId,
    saved,
    settle,
    shot,
    showTab,
    sleep,
    typeText,
    undo,
  } = t;
  const Y = LANES.pixelArt;

  const control = async (name) => {
    const found = await json(`__gm.pixelArt.control(${JSON.stringify(name)})`);
    await settle();
    // Revealing may have scrolled the panel; ask again for where it is now.
    return (await json(`__gm.pixelArt.control(${JSON.stringify(name)})`)) ?? found;
  };
  const press_ = async (name) => {
    const at = await control(name);
    await click(at.x, at.y);
    await settle();
  };
  const swatch = async (index) => {
    await json(`__gm.pixelArt.swatch(${index})`);
    await settle();
    const at = await json(`__gm.pixelArt.swatch(${index})`);
    await click(at.x, at.y);
    await settle();
  };
  /** A row of the layer or frame list, scrolled into view: its centre, and for a layer its eye. */
  const listRow = async (list, rowId) => {
    const hook = `__gm.pixelArt.${list}Row(${JSON.stringify(rowId)})`;
    await json(hook);
    await settle();
    return json(hook);
  };
  const at = (x, y) => json(`__gm.pixelArt.pixelAt(${x}, ${y})`);
  const paint = async (from, to, modifiers = {}) => {
    const a = await at(from[0], from[1]);
    const b = await at(to[0], to[1]);
    await drag(a.x, a.y, b.x, b.y, { steps: 8, modifiers });
    await settle();
  };
  const asset = (id) => json(`__gm.pixelArt.asset(${JSON.stringify(id)})`);
  /** The indices of a layer on a frame, as a flat array; all zero for an empty cel. */
  const cel = async (id, frameIndex, layerIndex) => {
    const a = await asset(id);
    const file = a.frames[frameIndex]?.cels[a.layers[layerIndex]?.id] ?? '';
    const read = file ? await json(`__gm.pixelArt.cel(${JSON.stringify(file)})`) : null;
    return read && read !== 'loading' ? read.data : new Array(a.width * a.height).fill(0);
  };
  const count = (data, index) => data.filter((i) => i === index).length;
  const screen = async (x, y) => {
    const p = await at(x, y);
    return json(`__gm.pixelAt(${Math.round(p.x)}, ${Math.round(p.y)})`);
  };

  // 48a. The + menu makes the asset, and a palette with it, and opens it in its tab.
  const inOverlay = async (text) => {
    const box = await json('__gm.overlayRect()');
    const hits = (await json(`__gm.locateAll(${JSON.stringify(text)})`)) ?? [];
    return (
      hits.find((h) => h.x >= box.x && h.x <= box.x + box.w && h.y >= box.y && h.y <= box.y + box.h) ?? null
    );
  };
  const palettesBefore = await json("__gm.state.project.assets.filter((a) => a.type === 'palette').length");
  await showTab('scene');
  await t.clickText('+');
  const entry = await inOverlay('Pixel art');
  check('the + menu offers Pixel art', Boolean(entry), JSON.stringify(await json('__gm.menuRows()')));
  await click(entry.x, entry.y);
  await settle();
  const id = (
    await json("__gm.state.project.assets.filter((a) => a.type === 'pixelart').map((a) => a.id)")
  ).at(-1);
  const made = await asset(id);
  const palettes = await json(
    "__gm.state.project.assets.filter((a) => a.type === 'palette').map((a) => a.id)",
  );
  check(
    'it makes a 32 x 32 pixel art asset with one layer and one frame, painted in a new palette',
    made?.width === 32 &&
      made.height === 32 &&
      made.layers.length === 1 &&
      made.frames.length === 1 &&
      palettes.length === palettesBefore + 1 &&
      made.props.palette === palettes.at(-1),
    JSON.stringify({ made, palettes, palettesBefore }),
  );
  check(
    'and opens it in the Pixel art tab',
    (await json('__gm.pixelArt.current()')) === id &&
      (await json('__gm.pixelArt.info()')) ===
        `32 × 32 px · 1 frame · ${await json('__gm.pixelArt.zoom()')}x` &&
      (await json('__gm.pixelArt.zoom()')) > 1,
    JSON.stringify({
      current: await json('__gm.pixelArt.current()'),
      info: await json('__gm.pixelArt.info()'),
    }),
  );

  // A middle drag pans by what the pointer moved; the way back leaves the view as the steps below expect it.
  const origin = await json('__gm.pixelArt.pixelAt(0, 0)');
  const middle = await json('__gm.pixelArt.pixelAt(16, 16)');
  await drag(middle.x, middle.y, middle.x + 30, middle.y + 20, { steps: 6, button: 'middle' });
  const panned = await json('__gm.pixelArt.pixelAt(0, 0)');
  await drag(middle.x + 30, middle.y + 20, middle.x, middle.y, { steps: 6, button: 'middle' });
  check(
    'a middle drag pans the canvas by as much as the pointer moved, and back',
    panned.x - origin.x === 30 &&
      panned.y - origin.y === 20 &&
      JSON.stringify(await json('__gm.pixelArt.pixelAt(0, 0)')) === JSON.stringify(origin),
    JSON.stringify({ origin, panned, back: await json('__gm.pixelArt.pixelAt(0, 0)') }),
  );

  // 48b. The pencil: a swatch picks the colour, a drag paints a row, and one undo takes the stroke back.
  await swatch(RED);
  await press_('pencil');
  await paint([2, 2], [9, 2]);
  let data = await cel(id, 0, 0);
  const row = data.slice(2 * 32, 3 * 32);
  check(
    'a drag with the pencil paints the pixels it crosses in the picked colour',
    (await json('__gm.pixelArt.color()')) === RED &&
      row.slice(2, 10).every((i) => i === RED) &&
      count(data, RED) === 8,
    JSON.stringify({ color: await json('__gm.pixelArt.color()'), row, painted: count(data, RED) }),
  );
  const onScreen = await screen(5, 2);
  check('the canvas shows them in the palette colour', colourDistance(onScreen, HEX[RED]) < 10, onScreen);
  await undo();
  data = await cel(id, 0, 0);
  const undone = count(data, RED);
  await t.redo();
  data = await cel(id, 0, 0);
  check(
    'the stroke is one undo step',
    undone === 0 && count(data, RED) === 8,
    JSON.stringify({ afterUndo: undone, afterRedo: count(data, RED) }),
  );

  // 48c. Fill pours into the area it is poured into; the painted row keeps its colour.
  await swatch(GREEN);
  await press_('fill');
  await paint([0, 20], [0, 20]);
  data = await cel(id, 0, 0);
  check(
    'fill turns every transparent pixel joined to the one clicked green, and leaves the row',
    count(data, GREEN) === 32 * 32 - 8 && count(data, RED) === 8,
    JSON.stringify({ green: count(data, GREEN), red: count(data, RED) }),
  );

  // 48d. The picker, and Alt with any tool.
  await press_('pencil');
  const redAt = await at(5, 2);
  await click(redAt.x, redAt.y, 'left', { alt: true });
  await settle();
  const altPicked = await json('__gm.pixelArt.color()');
  await press_('picker');
  const greenAt = await at(20, 20);
  await click(greenAt.x, greenAt.y);
  await settle();
  check(
    'Alt+click picks the colour under the pointer, and so does the picker',
    altPicked === RED && (await json('__gm.pixelArt.color()')) === GREEN,
    JSON.stringify({ altPicked, picked: await json('__gm.pixelArt.color()') }),
  );

  // 48e. A second layer, and the shape tools on it.
  const layersBefore = (await asset(id)).layers.length;
  await press_('layer:add');
  let art = await asset(id);
  const top = art.layers.at(-1).id;
  check(
    'Add puts a new layer on top and paints on it',
    art.layers.length === layersBefore + 1 && (await json('__gm.pixelArt.layerId()')) === top,
    JSON.stringify({ layers: art.layers.map((l) => l.name), current: await json('__gm.pixelArt.layerId()') }),
  );
  await swatch(BLUE);
  await press_('rect');
  await paint([10, 10], [15, 14]);
  data = await cel(id, 0, 1);
  const rectCount = count(data, BLUE);
  await press_('line');
  await paint([0, 31], [31, 0]);
  data = await cel(id, 0, 1);
  const lineCount = count(data, BLUE) - rectCount;
  check(
    'a rectangle outline is its border, and a diagonal line one pixel per column',
    rectCount === 2 * (6 + 5) - 4 && lineCount >= 31 && lineCount <= 32 && data[31 * 32 + 0] === BLUE,
    JSON.stringify({ rectCount, lineCount }),
  );
  await undo();
  // Filled shapes stands beside the shape tools only.
  await press_('ellipse');
  const filledBox = await control('filled');
  await click(filledBox.x, filledBox.y);
  await settle();
  await paint([20, 20], [27, 27]);
  data = await cel(id, 0, 1);
  check(
    'a filled ellipse covers its middle and leaves the corners of its box',
    data[23 * 32 + 23] === BLUE &&
      data[20 * 32 + 20] === 0 &&
      data[27 * 32 + 27] === 0 &&
      count(data, BLUE) - rectCount > 30,
    JSON.stringify({
      middle: data[23 * 32 + 23],
      corner: data[20 * 32 + 20],
      ellipse: count(data, BLUE) - rectCount,
    }),
  );
  await click(filledBox.x, filledBox.y);

  // 48f. The eye in the layer's row and the opacity change what the canvas shows, not the pixels.
  const blueShown = await screen(10, 10);
  const eyeAt = (await listRow('layer', top)).eye;
  await click(eyeAt.x, eyeAt.y);
  await settle();
  const hidden = await screen(10, 10);
  const hiddenFlag = (await asset(id)).layers.at(-1).hidden;
  await click(eyeAt.x, eyeAt.y);
  await settle();
  // The opacity stands in the layer's row, in percent.
  const opacity = (await listRow('layer', top)).opacity;
  await click(opacity.x, opacity.y);
  await press('a', { ctrl: true });
  await typeText('50');
  await press('Enter');
  await settle();
  const half = await screen(10, 10);
  art = await asset(id);
  // Half blue over green, as the composer mixes straight colours.
  const mixed =
    '#' +
    [
      [0x29, 0x00],
      [0xad, 0xe4],
      [0xff, 0x36],
    ]
      .map(([a, b]) =>
        Math.round(a * 0.5 + b * 0.5)
          .toString(16)
          .padStart(2, '0'),
      )
      .join('');
  check(
    'the eye hides a layer, which is then not drawn, and a layer at 50 % in its row is mixed with the one below',
    colourDistance(blueShown, HEX[BLUE]) < 10 &&
      hiddenFlag === true &&
      colourDistance(hidden, HEX[GREEN]) < 10 &&
      !art.layers.at(-1).hidden &&
      art.layers.at(-1).opacity === 0.5 &&
      colourDistance(half, mixed) < 12,
    JSON.stringify({ blueShown, hiddenFlag, hidden, half, mixed, opacity: art.layers.at(-1).opacity }),
  );

  // 48f-i. Scrubbing the opacity drags the number, not the row: the order stays, the canvas follows
  //        while the pointer moves, and the whole scrub is one undo step back to 50 %.
  const orderBeforeScrub = await json('__gm.pixelArt.layerRows()');
  const scrubFrom = (await listRow('layer', top)).opacity;
  await drag(scrubFrom.x, scrubFrom.y, scrubFrom.x + 30, scrubFrom.y + 12, { steps: 10 });
  await settle();
  const scrubbed = (await asset(id)).layers.at(-1).opacity;
  const orderAfterScrub = await json('__gm.pixelArt.layerRows()');
  const scrubText = (await listRow('layer', top)).opacity?.value;
  await undo();
  await settle();
  const scrubUndone = (await asset(id)).layers.at(-1).opacity;
  check(
    'scrubbing the opacity in a row changes it without moving the row, and one undo takes it back',
    scrubbed === 0.8 &&
      scrubText === '80' &&
      orderAfterScrub.join() === orderBeforeScrub.join() &&
      scrubUndone === 0.5,
    JSON.stringify({ scrubbed, scrubText, orderBeforeScrub, orderAfterScrub, scrubUndone }),
  );

  // 48f-ii-a. The duplicate mark copies the layer right above it and paints on the copy; a
  //           double-click on its name edits it in the row. Both are undone again.
  const layersBeforeCopy = (await asset(id)).layers;
  const copyMark = (await listRow('layer', top)).duplicate;
  if (copyMark) await click(copyMark.x, copyMark.y);
  await settle();
  const withLayerCopy = await asset(id);
  const layerCopy = withLayerCopy.layers.at(-1);
  check(
    'the duplicate mark on a layer row puts a copy above it, with the same pixels, and paints on it',
    copyMark != null &&
      withLayerCopy.layers.length === layersBeforeCopy.length + 1 &&
      layerCopy.name === `${layersBeforeCopy.at(-1).name} copy` &&
      layerCopy.opacity === 0.5 &&
      withLayerCopy.frames[0].cels[layerCopy.id] === withLayerCopy.frames[0].cels[top] &&
      (await json('__gm.pixelArt.layerId()')) === layerCopy.id,
    JSON.stringify({ copyMark, layers: withLayerCopy.layers, cels: withLayerCopy.frames[0].cels }),
  );
  await undo();
  await settle();

  const nameSpot = (await listRow('layer', top)).name;
  await t.doubleClick(nameSpot.x, nameSpot.y);
  await settle();
  const editing = (await listRow('layer', top)).renaming;
  await press('a', { ctrl: true });
  await typeText('Ink');
  await press('Enter');
  await settle();
  const renamedLayer = (await asset(id)).layers.find((l) => l.id === top);
  check(
    'a double-click on a layer name edits it in the row, and Enter keeps the new name',
    editing?.value === layersBeforeCopy.at(-1).name &&
      renamedLayer?.name === 'Ink' &&
      (await listRow('layer', top)).renaming === null,
    JSON.stringify({ editing, renamed: renamedLayer?.name }),
  );
  await undo();
  await settle();

  // 48f-ii. Each layer row shows that layer alone, on the frame painted, and the list is dragged into
  //         another order. The picture's centre is canvas pixel (16, 16): green below, empty above.
  const bottom = art.layers[0].id;
  const topRow = await listRow('layer', top);
  const bottomRow = await listRow('layer', bottom);
  const topThumb = await json(`__gm.pixelAt(${topRow.thumb.x}, ${topRow.thumb.y})`);
  const bottomThumb = await json(`__gm.pixelAt(${bottomRow.thumb.x}, ${bottomRow.thumb.y})`);
  check(
    'a layer row pictures that layer alone: green below, nothing painted there above',
    colourDistance(bottomThumb, HEX[GREEN]) < 12 &&
      colourDistance(topThumb, HEX[GREEN]) > 60 &&
      colourDistance(topThumb, HEX[BLUE]) > 60,
    JSON.stringify({ topThumb, bottomThumb }),
  );
  const rowsBefore = await json('__gm.pixelArt.layerRows()');
  await drag(topRow.x, topRow.y, bottomRow.x, bottomRow.y + 20, { steps: 8 });
  await settle();
  const movedLayers = (await asset(id)).layers.map((l) => l.id);
  const rowsAfter = await json('__gm.pixelArt.layerRows()');
  check(
    'dragging the top layer row below the other puts that layer first in the drawing order',
    rowsBefore.join() === [top, bottom].join() &&
      movedLayers.join() === [top, bottom].join() &&
      rowsAfter.join() === [bottom, top].join(),
    JSON.stringify({ rowsBefore, movedLayers, rowsAfter }),
  );
  await undo();
  await settle();

  // 48g. Merge down: one layer left, holding both; the upper layer's opacity is not kept.
  await press_('layer:merge');
  art = await asset(id);
  data = await cel(id, 0, 0);
  check(
    'merging lays the upper layer onto the lower one and takes it out',
    art.layers.length === 1 && data[10 * 32 + 10] === BLUE && data[2 * 32 + 5] === RED && data[0] === GREEN,
    JSON.stringify({
      layers: art.layers.length,
      rect: data[10 * 32 + 10],
      row: data[2 * 32 + 5],
      ground: data[0],
    }),
  );

  // 48h. Frames: a copy, a painted difference, onion skin and the playing preview.
  const frameMark = (await listRow('frame', await json('__gm.pixelArt.frameId()'))).duplicate;
  await click(frameMark.x, frameMark.y);
  await settle();
  art = await asset(id);
  const second = await json('__gm.pixelArt.frameId()');
  check(
    'the duplicate mark on a frame row adds a copy of the frame after it and paints on the copy',
    art.frames.length === 2 &&
      art.frames[1].id === second &&
      JSON.stringify(art.frames[1].cels) === JSON.stringify(art.frames[0].cels) &&
      /· 2 frames ·/.test(await json('__gm.pixelArt.info()')),
    JSON.stringify({ frames: art.frames, info: await json('__gm.pixelArt.info()') }),
  );
  await press_('frame:add');
  await swatch(RED);
  await press_('pencil');
  await paint([16, 16], [16, 16]);
  art = await asset(id);
  data = await cel(id, 2, 0);
  const emptyThird = count(data, 0);
  const onionOff = await screen(10, 10);
  const onion = await control('onion');
  await click(onion.x, onion.y);
  await settle();
  const onionOn = await screen(10, 10);
  await click(onion.x, onion.y);
  check(
    'an empty frame shows the one before it faintly while onion skin is on',
    art.frames.length === 3 &&
      emptyThird === 32 * 32 - 1 &&
      colourDistance(onionOn, onionOff) > 20 &&
      colourDistance(onionOn, HEX[BLUE]) > 60,
    JSON.stringify({ frames: art.frames.length, emptyThird, onionOff, onionOn }),
  );
  const seen = new Set();
  for (let i = 0; i < 8; i++) {
    seen.add(await json('__gm.pixelArt.previewIndex()'));
    await sleep(70);
  }
  check('the preview plays through the frames', seen.size >= 2, JSON.stringify([...seen]));

  // 48h-ii. The frame rows picture their frames and are dragged into another order, first on top.
  const framesBefore = (await asset(id)).frames.map((f) => f.id);
  const firstFrameRow = await listRow('frame', framesBefore[0]);
  const lastFrameRow = await listRow('frame', framesBefore[2]);
  const firstThumb = await json(`__gm.pixelAt(${firstFrameRow.thumb.x}, ${firstFrameRow.thumb.y})`);
  const lastThumb = await json(`__gm.pixelAt(${lastFrameRow.thumb.x}, ${lastFrameRow.thumb.y})`);
  await drag(firstFrameRow.x, firstFrameRow.y, lastFrameRow.x, lastFrameRow.y + 20, { steps: 8 });
  await settle();
  const framesAfter = (await asset(id)).frames.map((f) => f.id);
  const frameRowsAfter = await json('__gm.pixelArt.frameRows()');
  check(
    'a frame row pictures its frame, and dragging the first row to the bottom makes it the last frame',
    colourDistance(firstThumb, HEX[GREEN]) < 12 &&
      colourDistance(lastThumb, HEX[GREEN]) > 60 &&
      framesAfter.join() === [framesBefore[1], framesBefore[2], framesBefore[0]].join() &&
      frameRowsAfter.join() === framesAfter.join(),
    JSON.stringify({ firstThumb, lastThumb, framesBefore, framesAfter, frameRowsAfter }),
  );
  await undo();
  await settle();

  // 48h-iii. The cross on a frame row takes that frame out; undo brings it back.
  const lastFrameAgain = await listRow('frame', framesBefore[2]);
  if (lastFrameAgain?.remove) await click(lastFrameAgain.remove.x, lastFrameAgain.remove.y);
  await settle();
  const framesCrossed = (await asset(id)).frames.map((f) => f.id);
  check(
    'the cross on a frame row removes that frame',
    lastFrameAgain?.remove != null && framesCrossed.join() === framesBefore.slice(0, 2).join(),
    JSON.stringify({ remove: lastFrameAgain?.remove, framesBefore, framesCrossed }),
  );
  await undo();
  await settle();

  // 48i. Tile preview: the picture repeats around the canvas. Shown on the first frame, which is painted all over.
  const first = (await asset(id)).frames[0].id;
  const firstRowAt = await json(`__gm.pixelArt.frameRow(${JSON.stringify(first)})`);
  await click(firstRowAt.x, firstRowAt.y);
  await settle();
  const tiles = await control('tiles');
  await click(tiles.x, tiles.y);
  await settle();
  // Two pixels left of the canvas: the frame's pixel 30 in the tile beside it, painted green.
  const left = await screen(-2, 2);
  await shot('48-pixel-art');
  await click(tiles.x, tiles.y);
  await settle();
  const leftOff = await screen(-2, 2);
  check(
    'the tile preview repeats the frame beside the canvas',
    colourDistance(left, HEX[GREEN]) < 10 && colourDistance(leftOff, HEX[GREEN]) > 60,
    JSON.stringify({ left, leftOff }),
  );

  // 48j. Resize with the anchor in the middle: the picture keeps its place relative to it.
  await press_('resize');
  let dialog = await json('__gm.pixelArt.resizeDialog()');
  await click(dialog.width.x, dialog.width.y);
  await press('a', { ctrl: true });
  await typeText('40');
  await press('Enter');
  const centre = dialog.anchors['0.5,0.5'];
  await click(centre.x, centre.y);
  dialog = await json('__gm.pixelArt.resizeDialog()');
  await click(dialog.confirm.x, dialog.confirm.y);
  await settle();
  art = await asset(id);
  data = await cel(id, 0, 0);
  const wide = data.slice(2 * 40, 3 * 40);
  check(
    'resizing to 40 wide from the middle moves every pixel 4 to the right and keeps the frames',
    art.width === 40 &&
      art.height === 32 &&
      art.frames[0].id === first &&
      wide[6] === RED &&
      wide[13] === RED &&
      wide[14] !== RED &&
      wide[0] === 0,
    JSON.stringify({ width: art.width, row: wide }),
  );
  await undo();
  art = await asset(id);
  check(
    'one undo gives the canvas its old size back',
    art.width === 32,
    JSON.stringify({ width: art.width }),
  );

  // 48k. The palette: a colour changed there recolours the picture, as one undo step.
  await swatch(RED);
  // The field's middle is its hex text; a click there puts a caret in it, so the old value goes first.
  const colorField = await control('color');
  await click(colorField.x, colorField.y);
  await press('a', { ctrl: true });
  await typeText('123456');
  await press('Enter');
  await settle();
  const paletteColor = () =>
    json(
      `(() => { const p = __gm.state.project; const a = p.assets.find((x) => x.id === ${JSON.stringify(id)});` +
        ` return p.assets.find((x) => x.id === a.props.palette).colors[${RED - 1}]; })()`,
    );
  const recolouredColor = await paletteColor();
  const recoloured = await screen(5, 2);
  await undo();
  const restored = await paletteColor();
  check(
    'changing a palette colour recolours every pixel painted with it, and undo takes it back',
    recolouredColor === 0x123456 && colourDistance(recoloured, '#123456') < 10 && restored === 0xff004d,
    JSON.stringify({ recolouredColor, recoloured, restored }),
  );

  // 48k-ii. Remove takes the picked colour out of the middle (#201): its pixels turn transparent,
  // the later colours move down one index, and every other pixel keeps the colour it had.
  const paletteOf = () =>
    json(
      `(() => { const p = __gm.state.project; const a = p.assets.find((x) => x.id === ${JSON.stringify(id)});` +
        ` return p.assets.find((x) => x.id === a.props.palette).colors; })()`,
    );
  const colorsBefore = await paletteOf();
  const allCels = async () => {
    const a = await asset(id);
    const out = [];
    for (let f = 0; f < a.frames.length; f++)
      for (let l = 0; l < a.layers.length; l++) out.push(await cel(id, f, l));
    return out;
  };
  const celsBefore = await allCels();
  await swatch(GREEN);
  const removeButton = await control('removeColor');
  await click(removeButton.x, removeButton.y);
  await settle();
  const colorsAfter = await paletteOf();
  const celsAfter = await allCels();
  const shifted = celsBefore.every((before, c) =>
    before.every((i, p) => celsAfter[c][p] === (i === GREEN ? 0 : i > GREEN ? i - 1 : i)),
  );
  // The colour after it moves into its index, so an index that moved down still names its colour.
  check(
    'Remove takes the picked colour out: its pixels go transparent, every other pixel keeps its colour',
    removeButton.text === 'Remove' &&
      colorsAfter.length === colorsBefore.length - 1 &&
      colorsAfter[GREEN - 1] === colorsBefore[GREEN] &&
      celsBefore.some((before) => before.includes(GREEN)) &&
      shifted,
    JSON.stringify({
      text: removeButton.text,
      before: colorsBefore.length,
      after: colorsAfter.length,
      shifted,
    }),
  );
  await undo();
  const celsUndone = await allCels();
  check(
    'and one undo gives back the colour and every pixel',
    JSON.stringify(await paletteOf()) === JSON.stringify(colorsBefore) &&
      JSON.stringify(celsUndone) === JSON.stringify(celsBefore),
    JSON.stringify({ colors: (await paletteOf()).length }),
  );

  // 48k-iii. The palette runs across the whole width of the panel (#201).
  await control('palette');
  const span = await json('__gm.pixelArt.sideSpan()');
  const firstSwatch = await json(`__gm.pixelArt.swatch(0)`);
  const cell = (await json(`__gm.pixelArt.swatch(1)`)).x - firstSwatch.x - 2;
  let perRow = 1;
  while (perRow < 32 && (await json(`__gm.pixelArt.swatch(${perRow})`)).y === firstSwatch.y) perRow++;
  const lastInRow = await json(`__gm.pixelArt.swatch(${perRow - 1})`);
  // Swatches are whole pixels wide, so the row may stop up to a pixel per swatch short.
  const reach = { left: firstSwatch.x - cell / 2, right: lastInRow.x + cell / 2 };
  const removeRight = removeButton.x + removeButton.w / 2;
  check(
    'the palette fills the width of the panel, more than eight swatches to a row, and Remove ends inside it',
    perRow > 8 &&
      Math.abs(reach.left - span.left) <= 1 &&
      span.right - reach.right <= perRow &&
      removeRight <= span.right + 0.5,
    JSON.stringify({ span, reach, perRow, cell, removeRight }),
  );

  // 48k-iv. Each tool shows only the options that change what it paints (#201).
  const options = async () => ({
    brush: (await json(`__gm.pixelArt.control('brush')`)) !== null,
    filled: (await json(`__gm.pixelArt.control('filled')`)) !== null,
    contiguous: (await json(`__gm.pixelArt.control('contiguous')`)) !== null,
  });
  const shownFor = {};
  for (const tool of ['pencil', 'fill', 'picker', 'rect']) {
    await press_(tool);
    shownFor[tool] = await options();
  }
  const filledToggle = await control('filled');
  await click(filledToggle.x, filledToggle.y);
  await settle();
  shownFor.filledRect = await options();
  // The box stays where it was while the brush beside it goes, so the same spot switches it off.
  await click(filledToggle.x, filledToggle.y);
  await settle();
  shownFor.outlinedAgain = (await json(`__gm.pixelArt.control('brush')`)) !== null;
  const want = {
    pencil: { brush: true, filled: false, contiguous: false },
    fill: { brush: false, filled: false, contiguous: true },
    picker: { brush: false, filled: false, contiguous: false },
    rect: { brush: true, filled: true, contiguous: false },
    filledRect: { brush: false, filled: true, contiguous: false },
    outlinedAgain: true,
  };
  check(
    'brush, Filled shapes and Contiguous show only with the tools they change',
    JSON.stringify(shownFor) === JSON.stringify(want),
    JSON.stringify(shownFor),
  );
  await press_('pencil');
  await shot('48-pixel-tools');

  // 48l. A sprite wears the second frame; the picker offers every frame by name.
  await mutate(`
    const project = __gm.state.project;
    const scene = __gm.state.activeScene;
    ${MAKE_OBJECT}
    const sprite = structuredClone(project.assets.find((a) => a.id === 'crate'));
    sprite.id = 'pa-sprite';
    sprite.name = 'Pixel sprite';
    sprite.props = { ...sprite.props, width: 128, height: 128, color: 0xffffff, texture: ${JSON.stringify(second)}, shader: '' };
    project.assets.push(sprite);
    scene.objects.push(make('pa-object', 'pa-sprite', '', ${Y}, 'Pixel object'));
    __gm.state.select({ kind: 'asset', assetId: 'pa-sprite' })`);
  await showTab('scene');
  await evaluate(`__gm.lookAt(0, ${Y})`);
  await settle();
  await sleep(300);
  const box = await json("__gm.objectRect('pa-object')");
  const spriteAt = (px, py) =>
    json(
      `__gm.pixelAt(${Math.round(box.x - box.w / 2 + ((px + 0.5) / 32) * box.w)}, ${Math.round(box.y - box.h / 2 + ((py + 0.5) / 32) * box.h)})`,
    );
  const spriteRed = await spriteAt(5, 2);
  const spriteBlue = await spriteAt(10, 10);
  check(
    'a sprite wearing the second frame shows that frame in the scene',
    colourDistance(spriteRed, HEX[RED]) < 12 && colourDistance(spriteBlue, HEX[BLUE]) < 12,
    JSON.stringify({ spriteRed, spriteBlue }),
  );
  const textureRow = await json("__gm.inspectorField('Texture', true)");
  await click(textureRow.x, textureRow.y);
  await settle();
  const offers = (await json('__gm.menuRows()')) ?? [];
  await press('Escape');
  const name =
    (await asset(id)) &&
    (await json(`__gm.state.project.assets.find((a) => a.id === ${JSON.stringify(id)}).name`));
  check(
    'the Texture row offers the asset and each of its frames',
    [name, `${name} / Frame 1`, `${name} / Frame 2`, `${name} / Frame 3`].every((label) =>
      offers.some((row) => row.endsWith(label)),
    ),
    JSON.stringify({ name, offers }),
  );

  // The asset's menu makes a sprite and an animation that keys every frame in order.
  const artRow = await json(`__gm.assetRow(${JSON.stringify(id)})`);
  await click(artRow.x, artRow.y, 'right');
  const animationEntry = await json("__gm.locate('Create animation from frames', false)");
  if (animationEntry) await click(animationEntry.x, animationEntry.y);
  await settle();
  const keyed = await json(`(() => {
    const p = __gm.state.project;
    const s = __gm.state.selection;
    const anim = s && s.kind === 'asset' ? p.assets.find((a) => a.id === s.assetId) : null;
    const root = anim && p.assets.find((a) => a.id === anim.root);
    return anim && anim.type === 'animation'
      ? { keys: anim.tracks[0].keys.map((k) => [k.frame, k.value]), rootTexture: root && root.props.texture }
      : null;
  })()`);
  const frameIds = (await asset(id)).frames.map((f) => f.id);
  check(
    'Create animation from frames keys every frame in order on a sprite wearing the first',
    animationEntry !== null &&
      JSON.stringify(keyed?.keys) === JSON.stringify(frameIds.map((f, i) => [i, f])) &&
      keyed.rootTexture === frameIds[0],
    JSON.stringify({ entry: animationEntry !== null, keyed, frameIds }),
  );

  // 48m. Saved: the cels reach the server before the project does, and a reload paints them again.
  await saved();
  const pending = await json('__gm.pixelArt.pending()');
  const doc = await api(`projects/${projectId}`);
  const stored = doc.project.assets.find((a) => a.id === id);
  const files = [...new Set(stored.frames.flatMap((f) => Object.values(f.cels)))];
  const statuses = JSON.parse(
    await evaluate(
      `Promise.all(${JSON.stringify(files)}.map((f) => fetch('/game-maker/data/pixels/' + f).then((r) => r.status))).then((s) => JSON.stringify(s))`,
    ),
  );
  check(
    'saving uploads every cel the project names, and the file names them',
    pending === 0 && files.length >= 2 && statuses.every((s) => s === 200),
    JSON.stringify({ pending, files: files.length, statuses }),
  );
  await navigate();
  await sleep(500);
  await evaluate(`__gm.openDocument('asset:' + ${JSON.stringify(id)})`);
  await settle();
  await sleep(500);
  const back = await screen(5, 2);
  check(
    'after a reload the tab paints the saved pixels again',
    (await json('__gm.pixelArt.current()')) === id && colourDistance(back, HEX[RED]) < 10,
    JSON.stringify({ current: await json('__gm.pixelArt.current()'), back }),
  );
  await showTab('scene');
}