/**
 * @license
 * Copyright 2020 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file 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 { FirestoreError } from '../util/error';
/**
 * Represents the state of bundle loading tasks.
 *
 * Both 'Error' and 'Success' are sinking state: task will abort or complete and there will
 * be no more updates after they are reported.
 */
export type TaskState = 'Error' | 'Running' | 'Success';
/**
 * Represents a progress update or a final state from loading bundles.
 */
export interface LoadBundleTaskProgress {
    /** How many documents have been loaded. */
    documentsLoaded: number;
    /** How many documents are in the bundle being loaded. */
    totalDocuments: number;
    /** How many bytes have been loaded. */
    bytesLoaded: number;
    /** How many bytes are in the bundle being loaded. */
    totalBytes: number;
    /** Current task state. */
    taskState: TaskState;
}
/**
 * Represents the task of loading a Firestore bundle. It provides progress of bundle
 * loading, as well as task completion and error events.
 *
 * The API is compatible with `Promise<LoadBundleTaskProgress>`.
 */
export declare class LoadBundleTask implements PromiseLike<LoadBundleTaskProgress> {
    private _progressObserver;
    private _taskCompletionResolver;
    private _lastProgress;
    /**
     * Registers functions to listen to bundle loading progress events.
     * @param next - Called when there is a progress update from bundle loading. Typically `next` calls occur
     *   each time a Firestore document is loaded from the bundle.
     * @param error - Called when an error occurs during bundle loading. The task aborts after reporting the
     *   error, and there should be no more updates after this.
     * @param complete - Called when the loading task is complete.
     */
    onProgress(next?: (progress: LoadBundleTaskProgress) => unknown, error?: (err: Error) => unknown, complete?: () => void): void;
    /**
     * Implements the `Promise<LoadBundleTaskProgress>.catch` interface.
     *
     * @param onRejected - Called when an error occurs during bundle loading.
     */
    catch<R>(onRejected: (a: Error) => R | PromiseLike<R>): Promise<R | LoadBundleTaskProgress>;
    /**
     * Implements the `Promise<LoadBundleTaskProgress>.then` interface.
     *
     * @param onFulfilled - Called on the completion of the loading task with a final `LoadBundleTaskProgress` update.
     *   The update will always have its `taskState` set to `"Success"`.
     * @param onRejected - Called when an error occurs during bundle loading.
     */
    then<T, R>(onFulfilled?: (a: LoadBundleTaskProgress) => T | PromiseLike<T>, onRejected?: (a: Error) => R | PromiseLike<R>): Promise<T | R>;
    /**
     * Notifies all observers that bundle loading has completed, with a provided
     * `LoadBundleTaskProgress` object.
     *
     * @private
     */
    _completeWith(progress: LoadBundleTaskProgress): void;
    /**
     * Notifies all observers that bundle loading has failed, with a provided
     * `Error` as the reason.
     *
     * @private
     */
    _failWith(error: FirestoreError): void;
    /**
     * Notifies a progress update of loading a bundle.
     * @param progress - The new progress.
     *
     * @private
     */
    _updateProgress(progress: LoadBundleTaskProgress): void;
}