import type { Nuri } from "./port";
import { isNuri } from "./nuri";

/**
 * What a depositor puts in an index document's inbox: **a bare reference, and
 * nothing else**.
 *
 * Not an instruction — not "add this row", not even "I published this". The
 * curator resolves the reference and looks; what it finds is what decides. This
 * is the shape NextGraph already uses upstream: a `SocialQueryRequest` carries
 * `definition_commit_body_ref` — a REFERENCE — and the recipient's
 * `inbox_processor` composes its own SPARQL. Since anyone may deposit into any
 * index, a payload that carried an operation would be a licence to rewrite
 * someone else's document.
 *
 * It carries no index reference either. The deposit is addressed to the index
 * document's inbox, and upstream an inbox belongs to exactly one repo — the
 * address IS the identification. The polyfill says the same of its own inbox:
 * "Tagging deposits with their document would be an invention consumers would
 * have to unlearn at migration."
 *
 * And it carries no indexed data. Indexing is limited to PUBLIC objects
 * precisely so that the curator can open the object itself; a value copied into
 * the deposit would let a depositor put something in the index that the object
 * does not say.
 *
 * What is left is the NURI. That is the whole payload.
 */
export type IndexDeposit = Nuri;

/**
 * Anyone may deposit anything into an index's inbox, so every payload is
 * untrusted input. Returns `null` for everything that is not a reference.
 */
export function decodeReference(payload: unknown): Nuri | null {
  return isNuri(payload) ? payload : null;
}