import { TPKT_HEADER_LEN, TPKT_VERSION } from './constants.js';

export function encodeTPKT(payload: Buffer): Buffer {
  const len = TPKT_HEADER_LEN + payload.length;
  const buf = Buffer.alloc(len);
  buf[0] = TPKT_VERSION;
  buf[1] = 0x00;
  buf.writeUInt16BE(len, 2);
  payload.copy(buf, TPKT_HEADER_LEN);
  return buf;
}

export function parseTPKTHeader(header: Buffer): { version: number; length: number } {
  return {
    version: header[0],
    length: header.readUInt16BE(2),
  };
}

export function isValidTPKTHeader(header: Buffer): boolean {
  return header.length >= TPKT_HEADER_LEN && header[0] === TPKT_VERSION;
}