feuerwerk/src/core/commands/containerCommands.ts

import { newId } from '../ids';
import type { ContainerAsset } from '../model/Asset';
import { findObject, removeSubtrees, subtreeIds, subtreeRoots, treeOrder } from '../model/hierarchy';
import { type InstanceEdit, isLiveInstance, materializeInstance } from '../model/instance';
import { apply, invert, multiply, translation } from '../model/matrix';
import type { Position } from '../model/Properties';
import { findAsset, findObjectHolder, type Project } from '../model/Project';
import { createSceneObject, type SceneObject } from '../model/SceneObject';
import {
  carryTransform,
  localPositionFor,
  parentTransform,
  worldPosition,
  worldTransform,
} from '../properties/transform';
import { removeById, type Removed, restoreAt } from '../util/list';
import { buildAsset } from './assetCommands';
import { type Command, CommandError } from './Command';
import { nextAssetName } from './naming';
import { requireHolder, requireStructuralObject } from './require';

/**
 * Turns the selected objects and their descendants into a container asset placed in their stead, the
 * template centred on the selection's bounding box (z = 0).
 */
export class CreateContainerCommand implements Command {
  readonly label = 'Create container';
  readonly assetId = newId();
  readonly objectId = newId();
  private removed: Removed<SceneObject>[] = [];
  /** Kept across a redo: the ids of the resolved content are built from them. */
  private readonly templateIds = new Map<string, string>();

  constructor(
    private readonly holderId: string,
    private readonly objectIds: readonly string[],
  ) {}

  execute(project: Project): void {
    const holder = requireHolder(project, this.holderId);
    const ids = [...new Set(this.objectIds)];
    const selected = ids.map((id) => requireStructuralObject(project, holder, id));
    if (selected.length === 0) throw new CommandError('Select at least one object to create a container');

    const worlds = selected.map((o) => worldPosition(project, holder, o));
    const centre: Position = {
      x: Math.round((Math.min(...worlds.map((p) => p.x)) + Math.max(...worlds.map((p) => p.x))) / 2),
      y: Math.round((Math.min(...worlds.map((p) => p.y)) + Math.max(...worlds.map((p) => p.y))) / 2),
      z: 0,
    };

    // Members are collected in tree order, so a parent is always built before its children.
    const roots = new Set(
      subtreeRoots(
        holder,
        selected.map((o) => o.id),
      ),
    );
    const memberIds = subtreeIds(holder, roots);
    const members = treeOrder(holder)
      .map((e) => e.object)
      .filter((o) => memberIds.has(o.id));
    const rootParents = new Set([...roots].map((id) => findObject(holder, id)!.parentId));
    const containerParentId = rootParents.size === 1 ? [...rootParents][0]! : '';

    const asset = buildAsset(
      'container',
      nextAssetName(project, 'Container'),
      this.assetId,
    ) as ContainerAsset;
    const containerLocal = localPositionFor(project, holder, containerParentId, centre);
    // The template is the container's frame: a root keeps its place and look inside it, which
    // under a turned or sized parent means transform rows of its own (see `carryTransform`).
    const containerWorld = multiply(
      parentTransform(project, holder, containerParentId).m,
      translation(containerLocal.x, containerLocal.y),
    );
    const templateIds = this.templateIds;
    for (const object of members) if (!templateIds.has(object.id)) templateIds.set(object.id, newId());
    for (const object of members) {
      const isRoot = roots.has(object.id);
      const world = worldTransform(project, holder, object);
      const inside = apply(invert(containerWorld), { x: world.m.tx, y: world.m.ty });
      const template: SceneObject = {
        ...object,
        id: templateIds.get(object.id)!,
        position: isRoot ? { x: inside.x, y: inside.y, z: world.z } : { ...object.position },
        // A view-only offset belongs to the placed object, not to the template.
        editorOffset: { x: 0, y: 0 },
        overrides: { ...object.overrides },
        parentId: isRoot ? '' : (templateIds.get(object.parentId) ?? ''),
        instanceEdits: { ...object.instanceEdits },
      };
      const objectAsset = findAsset(project, object.assetId);
      if (isRoot && objectAsset)
        carryTransform(
          objectAsset,
          template,
          parentTransform(project, holder, object.parentId).m,
          containerWorld,
        );
      asset.objects.push(template);
    }

    const container = createSceneObject(this.objectId, this.assetId, containerLocal, containerParentId);
    this.removed = removeSubtrees(holder, [...roots]);
    project.assets.push(asset);
    holder.objects.push(container);
  }

  undo(project: Project): void {
    const holder = findObjectHolder(project, this.holderId);
    if (holder) {
      holder.objects = removeById(holder.objects, this.objectId);
      restoreAt(holder.objects, this.removed);
    }
    project.assets = removeById(project.assets, this.assetId);
  }
}

/**
 * Writes the content a placed container shows into the holder as ordinary objects. It stops
 * following the template from then on – which is what makes its structure editable, the one thing
 * an instance does not allow.
 */
export class UnpackContainerCommand implements Command {
  readonly label = 'Unpack container';
  private createdIds: string[] = [];
  private edits: Record<string, InstanceEdit> = {};

  constructor(
    private readonly holderId: string,
    private readonly objectId: string,
  ) {}

  execute(project: Project): void {
    const holder = requireHolder(project, this.holderId);
    const object = requireStructuralObject(project, holder, this.objectId);
    if (!isLiveInstance(project, holder, object))
      throw new CommandError(`${object.name || 'That object'} is not a placed container`);
    const created = materializeInstance(project, holder, object);
    if (created.length === 0) throw new CommandError('The container is empty, there is nothing to unpack');
    this.createdIds = created.map((o) => o.id);
    this.edits = object.instanceEdits;
    object.instanceEdits = {};
    holder.objects.push(...created);
  }

  undo(project: Project): void {
    const holder = findObjectHolder(project, this.holderId);
    if (!holder) return;
    const ids = new Set(this.createdIds);
    holder.objects = holder.objects.filter((o) => !ids.has(o.id));
    const object = findObject(holder, this.objectId);
    if (object) object.instanceEdits = this.edits;
  }
}