import { tinyCbor } from '../../deps.ts';

/**
 * Whatever CBOR encoder is used should keep CBOR data the same length when data is re-encoded
 *
 * MOST CRITICALLY, this means the following needs to be true of whatever CBOR library we use:
 * - CBOR Map type values MUST decode to JavaScript Maps
 * - CBOR tag 64 (uint8 Typed Array) MUST NOT be used when encoding Uint8Arrays back to CBOR
 *
 * So long as these requirements are maintained, then CBOR sequences can be encoded and decoded
 * freely while maintaining their lengths for the most accurate pointer movement across them.
 */

/**
 * Decode and return the first item in a sequence of CBOR-encoded values
 *
 * @param input The CBOR data to decode
 * @param asObject (optional) Whether to convert any CBOR Maps into JavaScript Objects. Defaults to
 * `false`
 */
export function decodeFirst<Type>(input: Uint8Array): Type {
  // Make a copy so we don't mutate the original
  const _input = new Uint8Array(input);
  const decoded = tinyCbor.decodePartialCBOR(_input, 0) as [Type, number];

  const [first] = decoded;

  return first;
}

/**
 * Encode data to CBOR
 */
export function encode(input: tinyCbor.CBORType): Uint8Array {
  return tinyCbor.encodeCBOR(input);
}