import sodium, { type StateAddress } from "libsodium-wrappers-sumo";
import { toBase64 } from "./encoding.js";

// The content hash an uploading client records in a file's metadata: unkeyed
// BLAKE2b with a 64-byte output over the original's bytes, fed in chunks, as
// standard base64 with padding. Named after the upstream client's functions.
// The output length is read at call time for the same reason as
// `streamTagFinal` in stream.ts: libsodium sets its constants only once ready.

export const chunkHashInit = (): StateAddress =>
    sodium.crypto_generichash_init(null, sodium.crypto_generichash_BYTES_MAX);

export const chunkHashUpdate = (state: StateAddress, chunk: Uint8Array): void =>
    sodium.crypto_generichash_update(state, chunk);

export const chunkHashFinal = (state: StateAddress): string =>
    toBase64(
        sodium.crypto_generichash_final(
            state,
            sodium.crypto_generichash_BYTES_MAX,
        ),
    );