react-native-firebase/lib/modules/storage/task.js

/* @flow */
import { statics as StorageStatics } from './';
import { isObject, isFunction } from './../../utils';
import StorageReference from './reference';

export const UPLOAD_TASK = 'upload';
export const DOWNLOAD_TASK = 'download';

declare type UploadTaskSnapshotType = {
  bytesTransferred: number,
  downloadURL: string|null,
  metadata: Object, // TODO flow type def for https://firebase.google.com/docs/reference/js/firebase.storage.FullMetadata.html
  ref: StorageReference,
  state: StorageStatics.TaskState.RUNNING
    |StorageStatics.TaskState.PAUSED
    |StorageStatics.TaskState.SUCCESS
    |StorageStatics.TaskState.CANCELLED
    |StorageStatics.TaskState.ERROR,
  task: StorageTask,
  totalBytes: number,
};

declare type FuncSnapshotType = null|(snapshot: UploadTaskSnapshotType) => any;

declare type FuncErrorType = null|(error: Error) => any;

declare type NextOrObserverType = null
  |{ next?: FuncSnapshotType, error?: FuncErrorType, complete?:FuncSnapshotType }
  |FuncSnapshotType;

/**
 * @url https://firebase.google.com/docs/reference/js/firebase.storage.UploadTask
 */
export default class StorageTask {
  constructor(type: UPLOAD_TASK|DOWNLOAD_TASK, promise: Promise, storageRef: StorageReference) {
    this.type = type;
    this.ref = storageRef;
    this.storage = storageRef.storage;
    this.path = storageRef.path;

    // 'proxy' original promise
    this.then = promise.then(this._interceptSnapshotEvent);
    this.catch = promise.catch.bind(promise);
  }

  /**
   * Intercepts a native snapshot result object attaches ref / task instances
   * and calls the original function
   * @returns {Promise.<T>}
   * @private
   */
  _interceptSnapshotEvent(f: Function|null|undefined): null|() => any {
    if (!isFunction(f)) return null;
    return (snapshot) => {
      const _snapshot = Object.assign({}, snapshot);
      _snapshot.task = this;
      _snapshot.ref = this.ref;
      return f(_snapshot);
    };
  }

  /**
   * Intercepts a error object form native and converts to a JS Error
   * @param f
   * @returns {*}
   * @private
   */
  _interceptErrorEvent(f: Function|null|undefined): null|() => any {
    if (!isFunction(f)) return null;
    return (error) => {
      const _error = new Error(error.message);
      _error.code = error.code;
      return f(_error);
    };
  }

  /**
   *
   * @param nextOrObserver
   * @param error
   * @param complete
   * @returns {function()}
   * @private
   */
  _subscribe(nextOrObserver: NextOrObserverType, error: FuncErrorType, complete: FuncSnapshotType): Function {
    const observer = isObject(nextOrObserver);

    const _error = this._interceptErrorEvent(observer ? nextOrObserver.error : error);
    const _next = this._interceptSnapshotEvent(observer ? nextOrObserver.next : nextOrObserver);
    const _complete = this._interceptSnapshotEvent(observer ? nextOrObserver.complete : complete);

    if (_next) this.storage._addListener(this.path, StorageStatics.TaskEvent.STATE_CHANGED, _next);
    if (_error) this.storage._addListener(this.path, `${this.type}_failure`, _error);
    if (_complete) this.storage._addListener(this.path, `${this.type}_success`, _complete);

    return () => {
      if (_next) this.storage._removeListener(this.path, StorageStatics.TaskEvent.STATE_CHANGED, _next);
      if (_error) this.storage._removeListener(this.path, `${this.type}_failure`, _error);
      if (_complete) this.storage._removeListener(this.path, `${this.type}_success`, _complete);
    };
  }

  /**
   *
   * @param event
   * @param nextOrObserver
   * @param error
   * @param complete
   * @returns {function()}
   */
  on(event: string = StorageStatics.TaskEvent.STATE_CHANGED, nextOrObserver: NextOrObserverType, error: FuncErrorType, complete: FuncSnapshotType): Function {
    if (!event) {
      throw new Error('StorageTask.on listener is missing required string argument \'event\'.');
    }

    if (event !== StorageStatics.TaskEvent.STATE_CHANGED) {
      throw new Error(`StorageTask.on event argument must be a string with a value of '${StorageStatics.TaskEvent.STATE_CHANGED}'`);
    }

    // if only event provided return the subscriber function
    if (!nextOrObserver && !error && !complete) {
      return this._subscribe.bind(this);
    }

    return this._subscribe(nextOrObserver, error, complete);
  }

  pause() {
    throw new Error('.pause() is not currently supported by react-native-firebase');
  }

  resume() {
    // todo
    throw new Error('.resume() is not currently supported by react-native-firebase');
  }

  cancel() {
    // todo
    throw new Error('.cancel() is not currently supported by react-native-firebase');
  }
}