import { NIL } from 'uuid';

// custom implementation of stringify, as provided uuid's are not valid according to RFC4122
const stringify = (buffer: Buffer | null): string => {
  if (buffer === null) {
    return NIL;
  }
  if (buffer.length != 16) {
    throw new Error('Invalid buffer length for uuid: ' + buffer.length);
  }
  if (buffer.equals(Buffer.alloc(16))) {
    return NIL; // If buffer is all zeros, return zero'd uuid
  }

  const hex = buffer.toString('hex');
  return `${hex.slice(0, 8)}-${hex.slice(8, 12)}-${hex.slice(12, 16)}-${hex.slice(16, 20)}-${hex.slice(20)}`;
};

const parseUuid = (uuid: string): Buffer => {
  const uuidTester =
    /^[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}$/i;

  if (!uuidTester.test(uuid)) {
    throw new Error('Invalid UUID');
  }

  return Buffer.from(uuid.replaceAll('-', ''), 'hex');
};

export const uuidTransformer = {
  to(uuid: string): Buffer {
    return parseUuid(uuid);
  },
  from(bin: Buffer | null): string {
    return stringify(bin);
  },
};