/**
 * @license
 * Copyright 2022 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 { AggregateField, AggregateQuerySnapshot, AggregateSpec } from './aggregate_types';
import { FieldPath } from './field_path';
import { DocumentData, Query } from './reference';
/**
 * Calculates the number of documents in the result set of the given query
 * without actually downloading the documents.
 *
 * Using this function to count the documents is efficient because only the
 * final count, not the documents' data, is downloaded. This function can
 * count the documents in cases where the result set is prohibitively large to
 * download entirely (thousands of documents).
 *
 * @param query - The query whose result set size is calculated.
 * @returns A Promise that will be resolved with the count; the count can be
 * retrieved from `snapshot.data().count`, where `snapshot` is the
 * `AggregateQuerySnapshot` to which the returned Promise resolves.
 */
export declare function getCount<AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>): Promise<AggregateQuerySnapshot<{
    count: AggregateField<number>;
}, AppModelType, DbModelType>>;
/**
 * Calculates the specified aggregations over the documents in the result
 * set of the given query without actually downloading the documents.
 *
 * Using this function to perform aggregations is efficient because only the
 * final aggregation values, not the documents' data, are downloaded. This
 * function can perform aggregations of the documents in cases where the result
 * set is prohibitively large to download entirely (thousands of documents).
 *
 * @param query - The query whose result set is aggregated over.
 * @param aggregateSpec - An `AggregateSpec` object that specifies the aggregates
 * to perform over the result set. The AggregateSpec specifies aliases for each
 * aggregate, which can be used to retrieve the aggregate result.
 * @example
 * ```typescript
 * const aggregateSnapshot = await getAggregate(query, {
 *   countOfDocs: count(),
 *   totalHours: sum('hours'),
 *   averageScore: average('score')
 * });
 *
 * const countOfDocs: number = aggregateSnapshot.data().countOfDocs;
 * const totalHours: number = aggregateSnapshot.data().totalHours;
 * const averageScore: number | null = aggregateSnapshot.data().averageScore;
 * ```
 */
export declare function getAggregate<AggregateSpecType extends AggregateSpec, AppModelType, DbModelType extends DocumentData>(query: Query<AppModelType, DbModelType>, aggregateSpec: AggregateSpecType): Promise<AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>>;
/**
 * Create an AggregateField object that can be used to compute the sum of
 * a specified field over a range of documents in the result set of a query.
 * @param field - Specifies the field to sum across the result set.
 */
export declare function sum(field: string | FieldPath): AggregateField<number>;
/**
 * Create an AggregateField object that can be used to compute the average of
 * a specified field over a range of documents in the result set of a query.
 * @param field - Specifies the field to average across the result set.
 */
export declare function average(field: string | FieldPath): AggregateField<number | null>;
/**
 * Create an AggregateField object that can be used to compute the count of
 * documents in the result set of a query.
 */
export declare function count(): AggregateField<number>;
/**
 * Compares two 'AggregateField` instances for equality.
 *
 * @param left - Compare this AggregateField to the `right`.
 * @param right - Compare this AggregateField to the `left`.
 */
export declare function aggregateFieldEqual(left: AggregateField<unknown>, right: AggregateField<unknown>): boolean;
/**
 * Compares two `AggregateQuerySnapshot` instances for equality.
 *
 * Two `AggregateQuerySnapshot` instances are considered "equal" if they have
 * underlying queries that compare equal, and the same data.
 *
 * @param left - The first `AggregateQuerySnapshot` to compare.
 * @param right - The second `AggregateQuerySnapshot` to compare.
 *
 * @returns `true` if the objects are "equal", as defined above, or `false`
 * otherwise.
 */
export declare function aggregateQuerySnapshotEqual<AggregateSpecType extends AggregateSpec, AppModelType, DbModelType extends DocumentData>(left: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>, right: AggregateQuerySnapshot<AggregateSpecType, AppModelType, DbModelType>): boolean;