feuerwerk/src/editor/inspector/trackSection.ts

import {
  RemoveAnimationKeysCommand,
  SetAnimationKeyCommand,
  SetKeyInterpolationCommand,
  SetTrackRelativeCommand,
} from '../../core/commands/animationCommands';
import {
  blends,
  EASING_DIRECTIONS,
  EASING_SHAPES,
  easingOf,
  type EasingShape,
  easingValue,
  findKey,
  findTrack,
  interpolationOf,
  type KeyRef,
  trackDef,
  trackLabel,
} from '../../core/model/animation';
import type {
  AnimationAsset,
  AnimationKey,
  AnimationTrack,
  EasingDirection,
  KeyInterpolation,
} from '../../core/model/Asset';
import { findAssetOf, type Project } from '../../core/model/Project';
import { textOf } from '../../core/model/Properties';
import type { PropertyDef } from '../../core/properties/PropertySchema';
import { Button } from '../../ui';
import { openRowDialog, RowDialog } from '../animation/RowDialog';
import { createFieldRow } from './fieldFactory';
import { addGap, addNote, addTitle, type InspectorHost } from './host';

/**
 * Structure-defining facts of a track selection: which row, how many keys and of what kind – a
 * key's value field is built for its kind, and a colour key needs another widget than a number.
 */
export function trackSignature(
  project: Project,
  assetId: string,
  trackId: string,
  keys: readonly KeyRef[],
): string {
  const { asset, track } = rowOf(project, assetId, trackId);
  if (!asset || !track) return 'missing';
  const kind = kindOf(project, asset, track) ?? 'missing';
  const key = keys.length === 1 ? `${keys[0]!.trackId}@${keys[0]!.frame}` : String(keys.length);
  return `${track.id}|${track.target}|${track.property}|${kind}|${track.relative ? 'rel' : 'abs'}|${key}|${curveState(
    project,
    asset,
    keys,
  )}`;
}

/**
 * Which curve the shown easing picks and whether it is there (#247): the Curve row and its warning
 * come and go with it, so a change here has to rebuild the section.
 */
function curveState(project: Project, asset: AnimationAsset, keys: readonly KeyRef[]): string {
  const key = easingKey(project, asset, keys);
  const easing = key && easingOf(interpolationOf(key));
  if (easing?.shape !== 'curve') return '';
  const found = findAssetOf(project, easing.curve ?? '', 'curve');
  return `curve:${easing.curve ?? ''}:${found ? 'here' : 'gone'}`;
}

const CURVE_ROW: PropertyDef = {
  key: 'curve',
  label: 'Curve',
  kind: 'asset',
  default: '',
  assetTypes: ['curve'],
};

/**
 * A row of the timeline: what it aims at, whether it is relative, and – with one key picked – the
 * key's value. Several keys show their count and the way to delete them at once.
 */
export function buildTrackSection(
  host: InspectorHost,
  assetId: string,
  trackId: string,
  keys: readonly KeyRef[],
): void {
  const { asset, track } = rowOf(host.state.project, assetId, trackId);
  if (!asset || !track) return;
  const kind = kindOf(host.state.project, asset, track);

  addTitle(host, 'TIMELINE ROW');
  const label = createFieldRow(
    host,
    { key: 'row', label: 'Row', kind: 'text', default: '' },
    trackLabel(host.state.project, asset, track),
    { onInput: () => {}, onChange: () => {} },
  );
  host.body.add(label.row);
  if (!kind)
    addNote(host, 'The object or property this row aims at is gone; it is skipped when played.', 'warning');
  else addNote(host, `A ${kind} row of "${asset.name}".`);

  host.body.add(
    new Button('Change target…', {
      onClick: () => {
        const now = rowOf(host.state.project, assetId, trackId);
        if (now.asset && now.track) openRowDialog(new RowDialog(host.state, now.asset, now.track));
      },
    }),
  );

  if (kind === 'number') {
    const relative = createFieldRow(
      host,
      { key: 'relative', label: 'Relative', kind: 'boolean', default: false },
      Boolean(track.relative),
      {
        onInput: () => {},
        onChange: (value) =>
          host.state.execute(new SetTrackRelativeCommand(assetId, trackId, Boolean(value))),
      },
    );
    host.fields.set('relative', relative);
    host.body.add(relative.row);
    addNote(host, 'Relative: the keys add to where the target stood when the animation started.', 'small');
  }

  if (keys.length === 1) buildKey(host, asset, keys[0]!);
  else if (keys.length > 1) {
    addGap(host);
    addTitle(host, `${keys.length} KEYS`);
    buildEasing(host, asset, keys);
    host.body.add(
      new Button('Delete keys', {
        variant: 'danger',
        onClick: () => host.state.execute(new RemoveAnimationKeysCommand(assetId, [...keys])),
      }),
    );
  }
}

/** The value of the one picked key, editable in the widget its kind calls for. */
function buildKey(host: InspectorHost, asset: AnimationAsset, ref: KeyRef): void {
  const track = findTrack(asset, ref.trackId);
  const key = findKey(asset, ref);
  const def = track && trackDef(host.state.project, asset, track);
  if (!track || !key || !def) return;
  addGap(host);
  addTitle(host, `KEY AT FRAME ${ref.frame}`);
  const row = createFieldRow(host, { ...def, key: 'value', label: 'Value' }, key.value, {
    onInput: () => {},
    onChange: (value) =>
      host.state.execute(new SetAnimationKeyCommand(asset.id, ref.trackId, ref.frame, value)),
  });
  host.fields.set('value', row);
  host.body.add(row.row);
  if (track.relative) addNote(host, 'An offset, since the row is relative.', 'small');
  buildEasing(host, asset, [ref]);
}

/**
 * How the picked keys blend into their next key – for all of them at once: a curve and, for one that
 * is not linear or step, its direction. It shows the easing of the key picked last among those that
 * can blend; a row that cannot blend offers none, it always jumps.
 */
function buildEasing(host: InspectorHost, asset: AnimationAsset, keys: readonly KeyRef[]): void {
  const shown = easingKey(host.state.project, asset, keys);
  if (!shown) return;
  const easing = easingOf(interpolationOf(shown));
  // Read at the click, not now: the other field may have changed the key since this row was built.
  const current = () => {
    const key = easingKey(host.state.project, asset, keys);
    return easingOf(key ? interpolationOf(key) : 'linear');
  };
  const set = (value: KeyInterpolation) =>
    host.state.execute(new SetKeyInterpolationCommand(asset.id, [...keys], value));
  const shape = createFieldRow(
    host,
    {
      key: 'easing',
      label: 'Easing',
      kind: 'enum',
      default: 'linear',
      options: EASING_SHAPES.map((i) => ({ ...i })),
    },
    easing.shape,
    {
      onInput: () => {},
      onChange: (value) => {
        const now = current();
        // Switched to Curve, a key takes the curve it had, else the first one there is.
        const curve = now.curve || firstCurveId(host.state.project);
        set(easingValue(value as EasingShape, now.direction, curve));
      },
    },
  );
  host.fields.set('easing', shape);
  host.body.add(shape.row);
  if (easing.shape === 'curve') buildCurveRow(host, easing.curve ?? '', set);
  if (easing.direction) {
    const direction = createFieldRow(
      host,
      {
        key: 'direction',
        label: 'Direction',
        kind: 'enum',
        default: 'in-out',
        options: EASING_DIRECTIONS.map((i) => ({ ...i })),
      },
      easing.direction,
      {
        onInput: () => {},
        onChange: (value) => set(easingValue(current().shape, value as EasingDirection)),
      },
    );
    host.fields.set('direction', direction);
    host.body.add(direction.row);
  }
  addNote(host, 'Easing: the way from this key to the next one.', 'small');
}

/** The Curve asset the keys blend along, and why they blend linearly when there is none. */
function buildCurveRow(host: InspectorHost, curveId: string, set: (value: KeyInterpolation) => void): void {
  const row = createFieldRow(host, CURVE_ROW, curveId, {
    onInput: () => {},
    onChange: (value) => set(easingValue('curve', undefined, textOf(value))),
  });
  host.fields.set('curve', row);
  host.body.add(row.row);
  if (!curveId) addNote(host, 'No curve picked – the key blends linearly.', 'warning');
  else if (!findAssetOf(host.state.project, curveId, 'curve'))
    addNote(host, 'That curve is gone – the key blends linearly.', 'warning');
}

function firstCurveId(project: Project): string {
  return project.assets.find((a) => a.type === 'curve')?.id ?? '';
}

/** The last picked key on a row that blends; undefined when none of them can ease. */
function easingKey(
  project: Project,
  asset: AnimationAsset,
  keys: readonly KeyRef[],
): AnimationKey | undefined {
  for (const ref of [...keys].reverse()) {
    const track = findTrack(asset, ref.trackId);
    const kind = track && kindOf(project, asset, track);
    if (!kind || !blends(kind)) continue;
    const key = findKey(asset, ref);
    if (key) return key;
  }
  return undefined;
}

/** Pushes the current values into the rows. False when the row is gone (rebuild). */
export function refreshTrackSection(
  host: InspectorHost,
  assetId: string,
  trackId: string,
  keys: readonly KeyRef[],
): boolean {
  const { asset, track } = rowOf(host.state.project, assetId, trackId);
  if (!asset || !track) return false;
  host.fields.get('relative')?.setValue(Boolean(track.relative));
  const ref = keys.length === 1 ? keys[0] : undefined;
  if (ref) {
    const key = findKey(asset, ref);
    if (!key) return false;
    host.fields.get('value')?.setValue(key.value);
  }
  const eased = easingKey(host.state.project, asset, keys);
  if (Boolean(eased) !== host.fields.has('easing')) return false;
  if (!eased) return true;
  const easing = easingOf(interpolationOf(eased));
  if (Boolean(easing.direction) !== host.fields.has('direction')) return false;
  host.fields.get('easing')?.setValue(easing.shape);
  if (easing.direction) host.fields.get('direction')?.setValue(easing.direction);
  if (easing.shape === 'curve') host.fields.get('curve')?.setValue(easing.curve ?? '');
  return true;
}

function rowOf(
  project: Project,
  assetId: string,
  trackId: string,
): { asset?: AnimationAsset; track?: AnimationTrack } {
  const asset = findAssetOf(project, assetId, 'animation');
  return { asset, track: asset && findTrack(asset, trackId) };
}

function kindOf(project: Project, asset: AnimationAsset, track: AnimationTrack): string | undefined {
  return trackDef(project, asset, track)?.kind;
}