/*!
 * Copyright 2017 Google Inc. All Rights Reserved.
 *
 * 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 { grpc, CallOptions, Operation as GaxOperation } from 'google-gax';
import { protos } from '@google-cloud/spanner-api';
import instanceAdmin = protos.google;
import databaseAdmin = protos.google;
export type IOperation = instanceAdmin.longrunning.IOperation;
export type Schema = string | string[] | databaseAdmin.spanner.admin.database.v1.IUpdateDatabaseDdlRequest;
export interface ResourceCallback<Resource, Response> {
    (err: grpc.ServiceError | null, resource?: Resource | null, response?: Response): void;
}
export type PagedResponse<Item, Response> = [Item[], {} | null, Response];
export type RequestCallback<T, R = void> = R extends void ? NormalCallback<T> : PagedCallback<T, R>;
export interface NormalCallback<TResponse> {
    (err: grpc.ServiceError | null, res?: TResponse | null): void;
}
export interface PagedCallback<Item, Response> {
    (err: grpc.ServiceError | null, results?: Item[] | null, nextQuery?: {} | null, response?: Response | null): void;
}
export interface LongRunningCallback<Resource> {
    (err: grpc.ServiceError | null, resource?: Resource | null, operation?: GaxOperation | null, apiResponse?: IOperation): void;
}
export interface PagedOptions {
    pageSize?: number;
    pageToken?: string;
    gaxOptions?: CallOptions;
}
export interface PagedOptionsWithFilter extends PagedOptions {
    filter?: string;
}
/*!
 * HTTP header for the resource prefix to improve routing
 * by the backend.
 */
export declare const CLOUD_RESOURCE_HEADER = "google-cloud-resource-prefix";
/*!
 * HTTP header to route the requests at Leader
 */
export declare const LEADER_AWARE_ROUTING_HEADER = "x-goog-spanner-route-to-leader";
export declare const END_TO_END_TRACING_HEADER = "x-goog-spanner-end-to-end-tracing";
export declare const AFE_SERVER_TIMING_HEADER = "x-goog-spanner-enable-afe-server-timing";
/**
 * Add Leader aware routing header to existing header list.
 * @param headers Existing header list.
 */
export declare function addLeaderAwareRoutingHeader(headers: {
    [k: string]: string;
}): void;
/**
 * Returns common headers to add.
 * @param headers Common header list.
 */
export declare function getCommonHeaders(resourceName: string, enableTracing?: boolean): {
    [k: string]: string;
};