import { isoCBOR } from './iso/index.ts';

/**
 * Convert authenticator extension data buffer to a proper object
 *
 * @param extensionData Authenticator Extension Data buffer
 */
export function decodeAuthenticatorExtensions(
  extensionData: Uint8Array,
): AuthenticationExtensionsAuthenticatorOutputs | undefined {
  let toCBOR: Map<string, unknown>;
  try {
    toCBOR = isoCBOR.decodeFirst(extensionData);
  } catch (err) {
    const _err = err as Error;
    throw new Error(`Error decoding authenticator extensions: ${_err.message}`);
  }

  return convertMapToObjectDeep(toCBOR);
}

export type AuthenticationExtensionsAuthenticatorOutputs = {
  devicePubKey?: DevicePublicKeyAuthenticatorOutput;
  uvm?: UVMAuthenticatorOutput;
};

export type DevicePublicKeyAuthenticatorOutput = {
  dpk?: Uint8Array;
  sig?: string;
  nonce?: Uint8Array;
  scope?: Uint8Array;
  aaguid?: Uint8Array;
};

// TODO: Need to verify this format
// https://w3c.github.io/webauthn/#sctn-uvm-extension.
export type UVMAuthenticatorOutput = {
  uvm?: Uint8Array[];
};

/**
 * CBOR-encoded extensions can be deeply-nested Maps, which are too deep for a simple
 * `Object.entries()`. This method will recursively make sure that all Maps are converted into
 * basic objects.
 */
function convertMapToObjectDeep(
  input: Map<string, unknown>,
): { [key: string]: unknown } {
  const mapped: { [key: string]: unknown } = {};

  for (const [key, value] of input) {
    if (value instanceof Map) {
      mapped[key] = convertMapToObjectDeep(value);
    } else {
      mapped[key] = value;
    }
  }

  return mapped;
}