@react-native-firebase/app/lib/common/promise.ts

A well tested, feature rich Firebase implementation for React Native, supporting iOS & Android. Individual module support for Admob, Analytics, Auth, Crash Reporting, Cloud Firestore, Database, Dynamic Links, Functions, Messaging (FCM), Remote Config, Sto

/*
 * Copyright (c) 2016-present Invertase Limited & Contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this library except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

import { isFunction } from './validate';
import type { Deferred, Callback } from '../types/internal';

/**
 * Creates a deferred promise
 */
export function promiseDefer<T = void>(): Deferred<T> {
  const deferred: Deferred<T> = {
    promise: null as unknown as Promise<T>,
    resolve: null,
    reject: null,
  };

  deferred.promise = new Promise<T>((resolve, reject) => {
    deferred.resolve = resolve;
    deferred.reject = reject;
  });

  return deferred;
}

/**
 * Attaches an optional callback to a promise
 * @param promise
 * @param callback
 */
export function promiseWithOptionalCallback<T>(
  promise: Promise<T>,
  callback?: Callback<T>,
): Promise<T> {
  if (!isFunction(callback)) {
    return promise;
  }

  return promise
    .then(result => {
      if (callback && callback.length === 1) {
        (callback as (error: Error | null) => void)(null);
      } else if (callback) {
        (callback as (error: Error | null, result?: T) => void)(null, result);
      }

      return result;
    })
    .catch(error => {
      if (callback) {
        callback(error);
      }
      return Promise.reject(error);
    });
}