import { type Asset, type ContainerAsset, isSceneAsset, type SceneAsset } from './Asset';

/** 2: a placed container carries no copy of its template. */
export const PROJECT_FORMAT_VERSION = 2;

export interface Project {
  formatVersion: number;
  id: string;
  name: string;
  assets: Asset[];
  /** Empty string = none. */
  activeSceneId: string;
}

export function createEmptyProject(id: string, name: string): Project {
  return { formatVersion: PROJECT_FORMAT_VERSION, id, name, assets: [], activeSceneId: '' };
}

export function findAsset(project: Project, assetId: string): Asset | undefined {
  return project.assets.find((a) => a.id === assetId);
}

export function findAssetOf<T extends Asset['type']>(
  project: Project,
  assetId: string,
  type: T,
): Extract<Asset, { type: T }> | undefined {
  const asset = findAsset(project, assetId);
  return asset?.type === type ? (asset as Extract<Asset, { type: T }>) : undefined;
}

export function findScene(project: Project, sceneId: string): SceneAsset | undefined {
  const asset = findAsset(project, sceneId);
  return asset && isSceneAsset(asset) ? asset : undefined;
}

export function listScenes(project: Project): SceneAsset[] {
  return project.assets.filter(isSceneAsset);
}

/**
 * Everything that holds placed objects. A container's `objects` are a template, so anything
 * walking "all placed objects" must cover both or it silently skips the templates.
 */
export type ObjectHolder = SceneAsset | ContainerAsset;

export function isObjectHolder(asset: Asset): asset is ObjectHolder {
  return asset.type === 'scene' || asset.type === 'container';
}

export function objectHolders(project: Project): ObjectHolder[] {
  return project.assets.filter(isObjectHolder);
}

/**
 * The scene or container asset an object belongs to. Editing a container's template is the same
 * work as editing a scene, so the object commands resolve their target through this rather than
 * through `findScene`.
 */
export function findObjectHolder(project: Project, holderId: string): ObjectHolder | undefined {
  const asset = findAsset(project, holderId);
  return asset && isObjectHolder(asset) ? asset : undefined;
}