import { ApolloLink } from '@apollo/client/core';
import { AuthOptions } from 'aws-appsync-auth-link';

/*!
 * Copyright 2017-2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */

declare const CONTROL_EVENTS_KEY = "@@controlEvents";

type UrlInfo = {
    url: string;
    auth: AuthOptions;
    region: string;
};
/**
 * Route connections through a proxy (e.g. CloudFront) instead of connecting
 * directly to AppSync. The library will send traffic to the proxy URL while
 * using the original AppSync host for authentication.
 *
 * @example
 * ```ts
 * {
 *   url: 'https://xxx.appsync-api.us-east-1.amazonaws.com/graphql',
 *   region: 'us-east-1',
 *   auth: { type: AUTH_TYPE.API_KEY, apiKey: 'da2-xxx' },
 *   proxy: { url: 'https://d111111abcdef8.cloudfront.net/graphql' }
 * }
 * ```
 */
type ProxyConfig = {
    /** The proxy endpoint that sits in front of AppSync (e.g. a CloudFront distribution URL). */
    url: string;
};
type AppSyncRealTimeSubscriptionConfig = UrlInfo & {
    keepAliveTimeoutMs?: number;
    /** Optional proxy configuration for routing through CloudFront or another CDN. */
    proxy?: ProxyConfig;
};

declare function createSubscriptionHandshakeLink(args: AppSyncRealTimeSubscriptionConfig, resultsFetcherLink?: ApolloLink): ApolloLink;
declare function createSubscriptionHandshakeLink(url: string, resultsFetcherLink?: ApolloLink): ApolloLink;

export { CONTROL_EVENTS_KEY, createSubscriptionHandshakeLink };