import { schemaForAsset } from '../properties/PropertySchema';
import { type Asset, type ContainerAsset, isSceneAsset, type SceneAsset } from './Asset';
import type { SceneObject } from './SceneObject';

/** Written into every document. Reserved for format migrations – the loader does not branch on it yet. */
export const PROJECT_FORMAT_VERSION = 1;

export interface Project {
  formatVersion: number;
  id: string;
  name: string;
  assets: Asset[];
  /** Scene shown in the viewport and instantiated on Play. 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);
}

/** The scene asset with that id – undefined for other asset types as well. */
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. Container assets do so just like scenes: their
 * `objects` are the template a placed container is instantiated from. Anything that walks
 * "all placed objects" has to cover both, or it silently skips the templates.
 */
export type ObjectHolder = SceneAsset | ContainerAsset;

export function objectHolders(project: Project): ObjectHolder[] {
  return project.assets.filter((a): a is ObjectHolder => a.type === 'scene' || a.type === 'container');
}

export interface SceneObjectRef {
  holder: ObjectHolder;
  object: SceneObject;
}

/** Objects of all scenes and container templates that satisfy `predicate`, each with its holder. */
export function objectsWhere(
  project: Project,
  predicate: (object: SceneObject) => boolean,
): SceneObjectRef[] {
  const result: SceneObjectRef[] = [];
  for (const holder of objectHolders(project)) {
    for (const object of holder.objects) if (predicate(object)) result.push({ holder, object });
  }
  return result;
}

/** Every placed instance of an asset, in scenes and in container templates alike. */
export function findUsages(project: Project, assetId: string): SceneObjectRef[] {
  return objectsWhere(project, (o) => o.assetId === assetId);
}

/** One place where an `asset`-kind property points at an asset. */
export type PropertyUsage =
  | { on: 'asset'; asset: Asset; key: string }
  | { on: 'object'; holder: ObjectHolder; object: SceneObject; key: string };

/**
 * Every property that references `assetId`, on assets and on the overrides of placed objects.
 *
 * This is the other half of "where is this asset used": `findUsages` finds assets that were
 * *placed*, which is meaningless for a texture – a texture is never placed, it is worn by
 * sprites through their `texture` property. Deleting one therefore has to count both, or it
 * reports "0 uses" for a picture that ten sprites are showing.
 *
 * A reference is deliberately left dangling rather than cleared when its asset goes: a
 * dangling one resolves to "no picture" everywhere it is read, and it comes back by itself
 * when the delete is undone.
 */
export function findPropertyUsages(project: Project, assetId: string): PropertyUsage[] {
  if (!assetId) return [];
  const result: PropertyUsage[] = [];
  const assetKeys = new Map<string, string[]>();
  for (const asset of project.assets) {
    const keys = schemaForAsset(asset)
      .filter((def) => def.kind === 'asset')
      .map((def) => def.key);
    assetKeys.set(asset.id, keys);
    for (const key of keys) if (asset.props[key] === assetId) result.push({ on: 'asset', asset, key });
  }
  for (const holder of objectHolders(project)) {
    for (const object of holder.objects) {
      for (const key of assetKeys.get(object.assetId) ?? [])
        if (object.overrides[key] === assetId) result.push({ on: 'object', holder, object, key });
    }
  }
  return result;
}