/** Firebase Auth base URlLformat when using the auth emultor. */
const FIREBASE_AUTH_EMULATOR_BASE_URL_FORMAT =
  'http://{host}/identitytoolkit.googleapis.com/{version}/projects/{projectId}{api}';

/** Firebase Auth base URlLformat when using the auth emultor. */
const FIREBASE_AUTH_EMULATOR_BASE_URL_FORMAT =
  '{scheme}://{host}/identitytoolkit.googleapis.com/{version}/projects/{projectId}{api}';

class AuthResourceUrlBuilder {

  protected urlFormat: string;
  private projectId: string;

  /**
   * The resource URL builder constructor.
   *
   * @param projectId - The resource project ID.
   * @param version - The endpoint API version.
   * @constructor
   */
  constructor(protected app: App, protected version: string = 'v1') {
    if (useEmulator()) {
      this.urlFormat = utils.formatString(FIREBASE_AUTH_EMULATOR_BASE_URL_FORMAT, {
        host: emulatorHost(),
        scheme: emulatorScheme() || 'http'
      });
    } else {
      this.urlFormat = FIREBASE_AUTH_BASE_URL_FORMAT;
    }
  }

 // ......
}

function emulatorHost(): string | undefined {
  return process.env.FIREBASE_AUTH_EMULATOR_HOST
}

function emulatorScheme(): string | undefined {
  return process.env.FIREBASE_AUTH_EMULATOR_SCHEME
}