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import type {
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  CollectionDomainError,
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  DomainCollection,
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  DomainDescribeInput,
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  DomainObjectResources,
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} from "@/worker/objects/common/collection-types";
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export interface CollectionDescribeSpec<
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  TDb,
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  TCollection extends DomainCollection,
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  TObject,
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  TResource extends { href: string; syncToken?: string },
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  TError extends CollectionDomainError,
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> {
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  collectionKind: string;
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  ensureCollection(db: TDb, subjectId: string, nowMs: number, collectionName: string): TCollection | null;
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  homeResource(db: TDb): TResource;
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  listCollections(db: TDb, subjectId: string, nowMs: number): TCollection[];
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  collectionResource(db: TDb, collection: TCollection): TResource;
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  objectByName(db: TDb, collectionId: string, objectName: string): TObject | undefined;
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  objectResource(db: TDb, collection: TCollection, object: TObject): TResource;
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  objectResources(db: TDb, collection: TCollection, maxResults: number): DomainObjectResources<TResource>;
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  syncToken(seq: number): string;
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  collectionNotFound(): TError;
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  objectNotFound(): TError;
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}
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export function describeCollectionDomain<
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  TDb,
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  TCollection extends DomainCollection,
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  TObject,
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  TResource extends { href: string; syncToken?: string },
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  TError extends CollectionDomainError,
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>(
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  db: TDb,
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  input: DomainDescribeInput,
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  spec: CollectionDescribeSpec<TDb, TCollection, TObject, TResource, TError>,
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): { ok: true; resources: TResource[]; syncToken: string } | TError {
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  if (input.kind === "home") {
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    const collections = spec.listCollections(db, input.subjectId, input.nowMs);
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    return {
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      ok: true,
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      resources: [spec.homeResource(db), ...collections.map((collection) => spec.collectionResource(db, collection))],
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      syncToken: spec.syncToken(0),
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    };
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  }
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  const collection = spec.ensureCollection(db, input.subjectId, input.nowMs, input.collectionName ?? "");
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  if (!collection) return spec.collectionNotFound();
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  if (input.kind === spec.collectionKind) {
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    const resources = [spec.collectionResource(db, collection)];
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    if (input.depth === "1") resources.push(...spec.objectResources(db, collection, input.maxResults).resources);
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    return { ok: true, resources, syncToken: resources[0]!.syncToken ?? spec.syncToken(0) };
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  }
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  const object = spec.objectByName(db, collection.id, input.objectName ?? "");
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  if (!object) return spec.objectNotFound();
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  return { ok: true, resources: [spec.objectResource(db, collection, object)], syncToken: spec.syncToken(0) };
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}