subscriber_client.ts

// Copyright 2021 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
//
//     https://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.
//
// ** This file is automatically generated by gapic-generator-typescript. **
// ** https://github.com/googleapis/gapic-generator-typescript **
// ** All changes to this file may be overwritten. **

/* global window */
import * as gax from 'google-gax';
import {
  Callback,
  CallOptions,
  Descriptors,
  ClientOptions,
  PaginationCallback,
  GaxCall,
  IamClient,
  IamProtos,
} from 'google-gax';

import {Transform} from 'stream';
import {RequestType} from 'google-gax/build/src/apitypes';
import * as protos from '../../protos/protos';
import jsonProtos = require('../../protos/protos.json');
/**
 * Client JSON configuration object, loaded from
 * `src/v1/subscriber_client_config.json`.
 * This file defines retry strategy and timeouts for all API methods in this library.
 */
import * as gapicConfig from './subscriber_client_config.json';

const version = require('../../../package.json').version;

/**
 *  The service that an application uses to manipulate subscriptions and to
 *  consume messages from a subscription via the `Pull` method or by
 *  establishing a bi-directional stream using the `StreamingPull` method.
 * @class
 * @memberof v1
 */
export class SubscriberClient {
  private _terminated = false;
  private _opts: ClientOptions;
  private _gaxModule: typeof gax | typeof gax.fallback;
  private _gaxGrpc: gax.GrpcClient | gax.fallback.GrpcClient;
  private _protos: {};
  private _defaults: {[method: string]: gax.CallSettings};
  auth: gax.GoogleAuth;
  descriptors: Descriptors = {
    page: {},
    stream: {},
    longrunning: {},
    batching: {},
  };
  innerApiCalls: {[name: string]: Function};
  iamClient: IamClient;
  pathTemplates: {[name: string]: gax.PathTemplate};
  subscriberStub?: Promise<{[name: string]: Function}>;

  /**
   * Construct an instance of SubscriberClient.
   *
   * @param {object} [options] - The configuration object.
   * The options accepted by the constructor are described in detail
   * in [this document](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#creating-the-client-instance).
   * The common options are:
   * @param {object} [options.credentials] - Credentials object.
   * @param {string} [options.credentials.client_email]
   * @param {string} [options.credentials.private_key]
   * @param {string} [options.email] - Account email address. Required when
   *     using a .pem or .p12 keyFilename.
   * @param {string} [options.keyFilename] - Full path to the a .json, .pem, or
   *     .p12 key downloaded from the Google Developers Console. If you provide
   *     a path to a JSON file, the projectId option below is not necessary.
   *     NOTE: .pem and .p12 require you to specify options.email as well.
   * @param {number} [options.port] - The port on which to connect to
   *     the remote host.
   * @param {string} [options.projectId] - The project ID from the Google
   *     Developer's Console, e.g. 'grape-spaceship-123'. We will also check
   *     the environment variable GCLOUD_PROJECT for your project ID. If your
   *     app is running in an environment which supports
   *     {@link https://developers.google.com/identity/protocols/application-default-credentials Application Default Credentials},
   *     your project ID will be detected automatically.
   * @param {string} [options.apiEndpoint] - The domain name of the
   *     API remote host.
   * @param {gax.ClientConfig} [options.clientConfig] - Client configuration override.
   *     Follows the structure of {@link gapicConfig}.
   * @param {boolean} [options.fallback] - Use HTTP fallback mode.
   *     In fallback mode, a special browser-compatible transport implementation is used
   *     instead of gRPC transport. In browser context (if the `window` object is defined)
   *     the fallback mode is enabled automatically; set `options.fallback` to `false`
   *     if you need to override this behavior.
   */
  constructor(opts?: ClientOptions) {
    // Ensure that options include all the required fields.
    const staticMembers = this.constructor as typeof SubscriberClient;
    const servicePath =
      opts?.servicePath || opts?.apiEndpoint || staticMembers.servicePath;
    const port = opts?.port || staticMembers.port;
    const clientConfig = opts?.clientConfig ?? {};
    const fallback =
      opts?.fallback ??
      (typeof window !== 'undefined' && typeof window?.fetch === 'function');
    opts = Object.assign({servicePath, port, clientConfig, fallback}, opts);

    // If scopes are unset in options and we're connecting to a non-default endpoint, set scopes just in case.
    if (servicePath !== staticMembers.servicePath && !('scopes' in opts)) {
      opts['scopes'] = staticMembers.scopes;
    }

    // Choose either gRPC or proto-over-HTTP implementation of google-gax.
    this._gaxModule = opts.fallback ? gax.fallback : gax;

    // Create a `gaxGrpc` object, with any grpc-specific options sent to the client.
    this._gaxGrpc = new this._gaxModule.GrpcClient(opts);

    // Save options to use in initialize() method.
    this._opts = opts;

    // Save the auth object to the client, for use by other methods.
    this.auth = this._gaxGrpc.auth as gax.GoogleAuth;

    // Set the default scopes in auth client if needed.
    if (servicePath === staticMembers.servicePath) {
      this.auth.defaultScopes = staticMembers.scopes;
    }
    this.iamClient = new IamClient(this._gaxGrpc, opts);

    // Determine the client header string.
    const clientHeader = [`gax/${this._gaxModule.version}`, `gapic/${version}`];
    if (typeof process !== 'undefined' && 'versions' in process) {
      clientHeader.push(`gl-node/${process.versions.node}`);
    } else {
      clientHeader.push(`gl-web/${this._gaxModule.version}`);
    }
    if (!opts.fallback) {
      clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
    }
    if (opts.libName && opts.libVersion) {
      clientHeader.push(`${opts.libName}/${opts.libVersion}`);
    }
    // Load the applicable protos.
    this._protos = this._gaxGrpc.loadProtoJSON(jsonProtos);

    // This API contains "path templates"; forward-slash-separated
    // identifiers to uniquely identify resources within the API.
    // Create useful helper objects for these.
    this.pathTemplates = {
      projectPathTemplate: new this._gaxModule.PathTemplate(
        'projects/{project}'
      ),
      projectTopicPathTemplate: new this._gaxModule.PathTemplate(
        'projects/{project}/topics/{topic}'
      ),
      schemaPathTemplate: new this._gaxModule.PathTemplate(
        'projects/{project}/schemas/{schema}'
      ),
      snapshotPathTemplate: new this._gaxModule.PathTemplate(
        'projects/{project}/snapshots/{snapshot}'
      ),
      subscriptionPathTemplate: new this._gaxModule.PathTemplate(
        'projects/{project}/subscriptions/{subscription}'
      ),
    };

    // Some of the methods on this service return "paged" results,
    // (e.g. 50 results at a time, with tokens to get subsequent
    // pages). Denote the keys used for pagination and results.
    this.descriptors.page = {
      listSubscriptions: new this._gaxModule.PageDescriptor(
        'pageToken',
        'nextPageToken',
        'subscriptions'
      ),
      listSnapshots: new this._gaxModule.PageDescriptor(
        'pageToken',
        'nextPageToken',
        'snapshots'
      ),
    };

    // Some of the methods on this service provide streaming responses.
    // Provide descriptors for these.
    this.descriptors.stream = {
      streamingPull: new this._gaxModule.StreamDescriptor(
        gax.StreamType.BIDI_STREAMING
      ),
    };

    // Put together the default options sent with requests.
    this._defaults = this._gaxGrpc.constructSettings(
      'google.pubsub.v1.Subscriber',
      gapicConfig as gax.ClientConfig,
      opts.clientConfig || {},
      {'x-goog-api-client': clientHeader.join(' ')}
    );

    // Set up a dictionary of "inner API calls"; the core implementation
    // of calling the API is handled in `google-gax`, with this code
    // merely providing the destination and request information.
    this.innerApiCalls = {};
  }

  /**
   * Initialize the client.
   * Performs asynchronous operations (such as authentication) and prepares the client.
   * This function will be called automatically when any class method is called for the
   * first time, but if you need to initialize it before calling an actual method,
   * feel free to call initialize() directly.
   *
   * You can await on this method if you want to make sure the client is initialized.
   *
   * @returns {Promise} A promise that resolves to an authenticated service stub.
   */
  initialize() {
    // If the client stub promise is already initialized, return immediately.
    if (this.subscriberStub) {
      return this.subscriberStub;
    }

    // Put together the "service stub" for
    // google.pubsub.v1.Subscriber.
    this.subscriberStub = this._gaxGrpc.createStub(
      this._opts.fallback
        ? (this._protos as protobuf.Root).lookupService(
            'google.pubsub.v1.Subscriber'
          )
        : // eslint-disable-next-line @typescript-eslint/no-explicit-any
          (this._protos as any).google.pubsub.v1.Subscriber,
      this._opts
    ) as Promise<{[method: string]: Function}>;

    // Iterate over each of the methods that the service provides
    // and create an API call method for each.
    const subscriberStubMethods = [
      'createSubscription',
      'getSubscription',
      'updateSubscription',
      'listSubscriptions',
      'deleteSubscription',
      'modifyAckDeadline',
      'acknowledge',
      'pull',
      'streamingPull',
      'modifyPushConfig',
      'getSnapshot',
      'listSnapshots',
      'createSnapshot',
      'updateSnapshot',
      'deleteSnapshot',
      'seek',
    ];
    for (const methodName of subscriberStubMethods) {
      const callPromise = this.subscriberStub.then(
        stub => (...args: Array<{}>) => {
          if (this._terminated) {
            return Promise.reject('The client has already been closed.');
          }
          const func = stub[methodName];
          return func.apply(stub, args);
        },
        (err: Error | null | undefined) => () => {
          throw err;
        }
      );

      const descriptor =
        this.descriptors.page[methodName] ||
        this.descriptors.stream[methodName] ||
        undefined;
      const apiCall = this._gaxModule.createApiCall(
        callPromise,
        this._defaults[methodName],
        descriptor
      );

      this.innerApiCalls[methodName] = apiCall;
    }

    return this.subscriberStub;
  }

  /**
   * The DNS address for this API service.
   * @returns {string} The DNS address for this service.
   */
  static get servicePath() {
    return 'pubsub.googleapis.com';
  }

  /**
   * The DNS address for this API service - same as servicePath(),
   * exists for compatibility reasons.
   * @returns {string} The DNS address for this service.
   */
  static get apiEndpoint() {
    return 'pubsub.googleapis.com';
  }

  /**
   * The port for this API service.
   * @returns {number} The default port for this service.
   */
  static get port() {
    return 443;
  }

  /**
   * The scopes needed to make gRPC calls for every method defined
   * in this service.
   * @returns {string[]} List of default scopes.
   */
  static get scopes() {
    return [
      'https://www.googleapis.com/auth/cloud-platform',
      'https://www.googleapis.com/auth/pubsub',
    ];
  }

  getProjectId(): Promise<string>;
  getProjectId(callback: Callback<string, undefined, undefined>): void;
  /**
   * Return the project ID used by this class.
   * @returns {Promise} A promise that resolves to string containing the project ID.
   */
  getProjectId(
    callback?: Callback<string, undefined, undefined>
  ): Promise<string> | void {
    if (callback) {
      this.auth.getProjectId(callback);
      return;
    }
    return this.auth.getProjectId();
  }

  // -------------------
  // -- Service calls --
  // -------------------
  createSubscription(
    request: protos.google.pubsub.v1.ISubscription,
    options?: CallOptions
  ): Promise<
    [
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.ISubscription | undefined,
      {} | undefined
    ]
  >;
  createSubscription(
    request: protos.google.pubsub.v1.ISubscription,
    options: CallOptions,
    callback: Callback<
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.ISubscription | null | undefined,
      {} | null | undefined
    >
  ): void;
  createSubscription(
    request: protos.google.pubsub.v1.ISubscription,
    callback: Callback<
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.ISubscription | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Creates a subscription to a given topic. See the [resource name rules]
   * (https://cloud.google.com/pubsub/docs/admin#resource_names).
   * If the subscription already exists, returns `ALREADY_EXISTS`.
   * If the corresponding topic doesn't exist, returns `NOT_FOUND`.
   *
   * If the name is not provided in the request, the server will assign a random
   * name for this subscription on the same project as the topic, conforming
   * to the [resource name format]
   * (https://cloud.google.com/pubsub/docs/admin#resource_names). The generated
   * name is populated in the returned Subscription object. Note that for REST
   * API requests, you must specify a name in the request.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.name
   *   Required. The name of the subscription. It must have the format
   *   `"projects/{project}/subscriptions/{subscription}"`. `{subscription}` must
   *   start with a letter, and contain only letters (`[A-Za-z]`), numbers
   *   (`[0-9]`), dashes (`-`), underscores (`_`), periods (`.`), tildes (`~`),
   *   plus (`+`) or percent signs (`%`). It must be between 3 and 255 characters
   *   in length, and it must not start with `"goog"`.
   * @param {string} request.topic
   *   Required. The name of the topic from which this subscription is receiving
   *   messages. Format is `projects/{project}/topics/{topic}`. The value of this
   *   field will be `_deleted-topic_` if the topic has been deleted.
   * @param {google.pubsub.v1.PushConfig} request.pushConfig
   *   If push delivery is used with this subscription, this field is
   *   used to configure it. An empty `pushConfig` signifies that the subscriber
   *   will pull and ack messages using API methods.
   * @param {number} request.ackDeadlineSeconds
   *   The approximate amount of time (on a best-effort basis) Pub/Sub waits for
   *   the subscriber to acknowledge receipt before resending the message. In the
   *   interval after the message is delivered and before it is acknowledged, it
   *   is considered to be <i>outstanding</i>. During that time period, the
   *   message will not be redelivered (on a best-effort basis).
   *
   *   For pull subscriptions, this value is used as the initial value for the ack
   *   deadline. To override this value for a given message, call
   *   `ModifyAckDeadline` with the corresponding `ack_id` if using
   *   non-streaming pull or send the `ack_id` in a
   *   `StreamingModifyAckDeadlineRequest` if using streaming pull.
   *   The minimum custom deadline you can specify is 10 seconds.
   *   The maximum custom deadline you can specify is 600 seconds (10 minutes).
   *   If this parameter is 0, a default value of 10 seconds is used.
   *
   *   For push delivery, this value is also used to set the request timeout for
   *   the call to the push endpoint.
   *
   *   If the subscriber never acknowledges the message, the Pub/Sub
   *   system will eventually redeliver the message.
   * @param {boolean} request.retainAckedMessages
   *   Indicates whether to retain acknowledged messages. If true, then
   *   messages are not expunged from the subscription's backlog, even if they are
   *   acknowledged, until they fall out of the `message_retention_duration`
   *   window. This must be true if you would like to [Seek to a timestamp]
   *   (https://cloud.google.com/pubsub/docs/replay-overview#seek_to_a_time).
   * @param {google.protobuf.Duration} request.messageRetentionDuration
   *   How long to retain unacknowledged messages in the subscription's backlog,
   *   from the moment a message is published.
   *   If `retain_acked_messages` is true, then this also configures the retention
   *   of acknowledged messages, and thus configures how far back in time a `Seek`
   *   can be done. Defaults to 7 days. Cannot be more than 7 days or less than 10
   *   minutes.
   * @param {number[]} request.labels
   *   See <a href="https://cloud.google.com/pubsub/docs/labels"> Creating and
   *   managing labels</a>.
   * @param {boolean} request.enableMessageOrdering
   *   If true, messages published with the same `ordering_key` in `PubsubMessage`
   *   will be delivered to the subscribers in the order in which they
   *   are received by the Pub/Sub system. Otherwise, they may be delivered in
   *   any order.
   * @param {google.pubsub.v1.ExpirationPolicy} request.expirationPolicy
   *   A policy that specifies the conditions for this subscription's expiration.
   *   A subscription is considered active as long as any connected subscriber is
   *   successfully consuming messages from the subscription or is issuing
   *   operations on the subscription. If `expiration_policy` is not set, a
   *   *default policy* with `ttl` of 31 days will be used. The minimum allowed
   *   value for `expiration_policy.ttl` is 1 day.
   * @param {string} request.filter
   *   An expression written in the Pub/Sub [filter
   *   language](https://cloud.google.com/pubsub/docs/filtering). If non-empty,
   *   then only `PubsubMessage`s whose `attributes` field matches the filter are
   *   delivered on this subscription. If empty, then no messages are filtered
   *   out.
   * @param {google.pubsub.v1.DeadLetterPolicy} request.deadLetterPolicy
   *   A policy that specifies the conditions for dead lettering messages in
   *   this subscription. If dead_letter_policy is not set, dead lettering
   *   is disabled.
   *
   *   The Cloud Pub/Sub service account associated with this subscriptions's
   *   parent project (i.e.,
   *   service-{project_number}@gcp-sa-pubsub.iam.gserviceaccount.com) must have
   *   permission to Acknowledge() messages on this subscription.
   * @param {google.pubsub.v1.RetryPolicy} request.retryPolicy
   *   A policy that specifies how Pub/Sub retries message delivery for this
   *   subscription.
   *
   *   If not set, the default retry policy is applied. This generally implies
   *   that messages will be retried as soon as possible for healthy subscribers.
   *   RetryPolicy will be triggered on NACKs or acknowledgement deadline
   *   exceeded events for a given message.
   * @param {boolean} request.detached
   *   Indicates whether the subscription is detached from its topic. Detached
   *   subscriptions don't receive messages from their topic and don't retain any
   *   backlog. `Pull` and `StreamingPull` requests will return
   *   FAILED_PRECONDITION. If the subscription is a push subscription, pushes to
   *   the endpoint will not be made.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Subscription]{@link google.pubsub.v1.Subscription}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.createSubscription(request);
   */
  createSubscription(
    request: protos.google.pubsub.v1.ISubscription,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.pubsub.v1.ISubscription,
          protos.google.pubsub.v1.ISubscription | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.ISubscription | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.ISubscription | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      name: request.name || '',
    });
    this.initialize();
    return this.innerApiCalls.createSubscription(request, options, callback);
  }
  getSubscription(
    request: protos.google.pubsub.v1.IGetSubscriptionRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.IGetSubscriptionRequest | undefined,
      {} | undefined
    ]
  >;
  getSubscription(
    request: protos.google.pubsub.v1.IGetSubscriptionRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.IGetSubscriptionRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  getSubscription(
    request: protos.google.pubsub.v1.IGetSubscriptionRequest,
    callback: Callback<
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.IGetSubscriptionRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Gets the configuration details of a subscription.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.subscription
   *   Required. The name of the subscription to get.
   *   Format is `projects/{project}/subscriptions/{sub}`.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Subscription]{@link google.pubsub.v1.Subscription}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.getSubscription(request);
   */
  getSubscription(
    request: protos.google.pubsub.v1.IGetSubscriptionRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.pubsub.v1.ISubscription,
          protos.google.pubsub.v1.IGetSubscriptionRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.IGetSubscriptionRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.IGetSubscriptionRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      subscription: request.subscription || '',
    });
    this.initialize();
    return this.innerApiCalls.getSubscription(request, options, callback);
  }
  updateSubscription(
    request: protos.google.pubsub.v1.IUpdateSubscriptionRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.IUpdateSubscriptionRequest | undefined,
      {} | undefined
    ]
  >;
  updateSubscription(
    request: protos.google.pubsub.v1.IUpdateSubscriptionRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.IUpdateSubscriptionRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  updateSubscription(
    request: protos.google.pubsub.v1.IUpdateSubscriptionRequest,
    callback: Callback<
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.IUpdateSubscriptionRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Updates an existing subscription. Note that certain properties of a
   * subscription, such as its topic, are not modifiable.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {google.pubsub.v1.Subscription} request.subscription
   *   Required. The updated subscription object.
   * @param {google.protobuf.FieldMask} request.updateMask
   *   Required. Indicates which fields in the provided subscription to update.
   *   Must be specified and non-empty.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Subscription]{@link google.pubsub.v1.Subscription}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.updateSubscription(request);
   */
  updateSubscription(
    request: protos.google.pubsub.v1.IUpdateSubscriptionRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.pubsub.v1.ISubscription,
          protos.google.pubsub.v1.IUpdateSubscriptionRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.IUpdateSubscriptionRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.pubsub.v1.ISubscription,
      protos.google.pubsub.v1.IUpdateSubscriptionRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      'subscription.name': request.subscription!.name || '',
    });
    this.initialize();
    return this.innerApiCalls.updateSubscription(request, options, callback);
  }
  deleteSubscription(
    request: protos.google.pubsub.v1.IDeleteSubscriptionRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IDeleteSubscriptionRequest | undefined,
      {} | undefined
    ]
  >;
  deleteSubscription(
    request: protos.google.pubsub.v1.IDeleteSubscriptionRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IDeleteSubscriptionRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  deleteSubscription(
    request: protos.google.pubsub.v1.IDeleteSubscriptionRequest,
    callback: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IDeleteSubscriptionRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Deletes an existing subscription. All messages retained in the subscription
   * are immediately dropped. Calls to `Pull` after deletion will return
   * `NOT_FOUND`. After a subscription is deleted, a new one may be created with
   * the same name, but the new one has no association with the old
   * subscription or its topic unless the same topic is specified.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.subscription
   *   Required. The subscription to delete.
   *   Format is `projects/{project}/subscriptions/{sub}`.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Empty]{@link google.protobuf.Empty}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.deleteSubscription(request);
   */
  deleteSubscription(
    request: protos.google.pubsub.v1.IDeleteSubscriptionRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.protobuf.IEmpty,
          protos.google.pubsub.v1.IDeleteSubscriptionRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IDeleteSubscriptionRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IDeleteSubscriptionRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      subscription: request.subscription || '',
    });
    this.initialize();
    return this.innerApiCalls.deleteSubscription(request, options, callback);
  }
  modifyAckDeadline(
    request: protos.google.pubsub.v1.IModifyAckDeadlineRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IModifyAckDeadlineRequest | undefined,
      {} | undefined
    ]
  >;
  modifyAckDeadline(
    request: protos.google.pubsub.v1.IModifyAckDeadlineRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IModifyAckDeadlineRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  modifyAckDeadline(
    request: protos.google.pubsub.v1.IModifyAckDeadlineRequest,
    callback: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IModifyAckDeadlineRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Modifies the ack deadline for a specific message. This method is useful
   * to indicate that more time is needed to process a message by the
   * subscriber, or to make the message available for redelivery if the
   * processing was interrupted. Note that this does not modify the
   * subscription-level `ackDeadlineSeconds` used for subsequent messages.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.subscription
   *   Required. The name of the subscription.
   *   Format is `projects/{project}/subscriptions/{sub}`.
   * @param {string[]} request.ackIds
   *   Required. List of acknowledgment IDs.
   * @param {number} request.ackDeadlineSeconds
   *   Required. The new ack deadline with respect to the time this request was
   *   sent to the Pub/Sub system. For example, if the value is 10, the new ack
   *   deadline will expire 10 seconds after the `ModifyAckDeadline` call was
   *   made. Specifying zero might immediately make the message available for
   *   delivery to another subscriber client. This typically results in an
   *   increase in the rate of message redeliveries (that is, duplicates).
   *   The minimum deadline you can specify is 0 seconds.
   *   The maximum deadline you can specify is 600 seconds (10 minutes).
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Empty]{@link google.protobuf.Empty}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.modifyAckDeadline(request);
   */
  modifyAckDeadline(
    request: protos.google.pubsub.v1.IModifyAckDeadlineRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.protobuf.IEmpty,
          protos.google.pubsub.v1.IModifyAckDeadlineRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IModifyAckDeadlineRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IModifyAckDeadlineRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      subscription: request.subscription || '',
    });
    this.initialize();
    return this.innerApiCalls.modifyAckDeadline(request, options, callback);
  }
  acknowledge(
    request: protos.google.pubsub.v1.IAcknowledgeRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IAcknowledgeRequest | undefined,
      {} | undefined
    ]
  >;
  acknowledge(
    request: protos.google.pubsub.v1.IAcknowledgeRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IAcknowledgeRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  acknowledge(
    request: protos.google.pubsub.v1.IAcknowledgeRequest,
    callback: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IAcknowledgeRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Acknowledges the messages associated with the `ack_ids` in the
   * `AcknowledgeRequest`. The Pub/Sub system can remove the relevant messages
   * from the subscription.
   *
   * Acknowledging a message whose ack deadline has expired may succeed,
   * but such a message may be redelivered later. Acknowledging a message more
   * than once will not result in an error.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.subscription
   *   Required. The subscription whose message is being acknowledged.
   *   Format is `projects/{project}/subscriptions/{sub}`.
   * @param {string[]} request.ackIds
   *   Required. The acknowledgment ID for the messages being acknowledged that
   *   was returned by the Pub/Sub system in the `Pull` response. Must not be
   *   empty.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Empty]{@link google.protobuf.Empty}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.acknowledge(request);
   */
  acknowledge(
    request: protos.google.pubsub.v1.IAcknowledgeRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.protobuf.IEmpty,
          protos.google.pubsub.v1.IAcknowledgeRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IAcknowledgeRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IAcknowledgeRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      subscription: request.subscription || '',
    });
    this.initialize();
    return this.innerApiCalls.acknowledge(request, options, callback);
  }
  pull(
    request: protos.google.pubsub.v1.IPullRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.pubsub.v1.IPullResponse,
      protos.google.pubsub.v1.IPullRequest | undefined,
      {} | undefined
    ]
  >;
  pull(
    request: protos.google.pubsub.v1.IPullRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.pubsub.v1.IPullResponse,
      protos.google.pubsub.v1.IPullRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  pull(
    request: protos.google.pubsub.v1.IPullRequest,
    callback: Callback<
      protos.google.pubsub.v1.IPullResponse,
      protos.google.pubsub.v1.IPullRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Pulls messages from the server. The server may return `UNAVAILABLE` if
   * there are too many concurrent pull requests pending for the given
   * subscription.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.subscription
   *   Required. The subscription from which messages should be pulled.
   *   Format is `projects/{project}/subscriptions/{sub}`.
   * @param {boolean} [request.returnImmediately]
   *   Optional. If this field set to true, the system will respond immediately
   *   even if it there are no messages available to return in the `Pull`
   *   response. Otherwise, the system may wait (for a bounded amount of time)
   *   until at least one message is available, rather than returning no messages.
   *   Warning: setting this field to `true` is discouraged because it adversely
   *   impacts the performance of `Pull` operations. We recommend that users do
   *   not set this field.
   * @param {number} request.maxMessages
   *   Required. The maximum number of messages to return for this request. Must
   *   be a positive integer. The Pub/Sub system may return fewer than the number
   *   specified.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [PullResponse]{@link google.pubsub.v1.PullResponse}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.pull(request);
   */
  pull(
    request: protos.google.pubsub.v1.IPullRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.pubsub.v1.IPullResponse,
          protos.google.pubsub.v1.IPullRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.pubsub.v1.IPullResponse,
      protos.google.pubsub.v1.IPullRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.pubsub.v1.IPullResponse,
      protos.google.pubsub.v1.IPullRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      subscription: request.subscription || '',
    });
    this.initialize();
    return this.innerApiCalls.pull(request, options, callback);
  }
  modifyPushConfig(
    request: protos.google.pubsub.v1.IModifyPushConfigRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IModifyPushConfigRequest | undefined,
      {} | undefined
    ]
  >;
  modifyPushConfig(
    request: protos.google.pubsub.v1.IModifyPushConfigRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IModifyPushConfigRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  modifyPushConfig(
    request: protos.google.pubsub.v1.IModifyPushConfigRequest,
    callback: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IModifyPushConfigRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Modifies the `PushConfig` for a specified subscription.
   *
   * This may be used to change a push subscription to a pull one (signified by
   * an empty `PushConfig`) or vice versa, or change the endpoint URL and other
   * attributes of a push subscription. Messages will accumulate for delivery
   * continuously through the call regardless of changes to the `PushConfig`.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.subscription
   *   Required. The name of the subscription.
   *   Format is `projects/{project}/subscriptions/{sub}`.
   * @param {google.pubsub.v1.PushConfig} request.pushConfig
   *   Required. The push configuration for future deliveries.
   *
   *   An empty `pushConfig` indicates that the Pub/Sub system should
   *   stop pushing messages from the given subscription and allow
   *   messages to be pulled and acknowledged - effectively pausing
   *   the subscription if `Pull` or `StreamingPull` is not called.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Empty]{@link google.protobuf.Empty}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.modifyPushConfig(request);
   */
  modifyPushConfig(
    request: protos.google.pubsub.v1.IModifyPushConfigRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.protobuf.IEmpty,
          protos.google.pubsub.v1.IModifyPushConfigRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IModifyPushConfigRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IModifyPushConfigRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      subscription: request.subscription || '',
    });
    this.initialize();
    return this.innerApiCalls.modifyPushConfig(request, options, callback);
  }
  getSnapshot(
    request: protos.google.pubsub.v1.IGetSnapshotRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.IGetSnapshotRequest | undefined,
      {} | undefined
    ]
  >;
  getSnapshot(
    request: protos.google.pubsub.v1.IGetSnapshotRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.IGetSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  getSnapshot(
    request: protos.google.pubsub.v1.IGetSnapshotRequest,
    callback: Callback<
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.IGetSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Gets the configuration details of a snapshot. Snapshots are used in
   * <a href="https://cloud.google.com/pubsub/docs/replay-overview">Seek</a>
   * operations, which allow you to manage message acknowledgments in bulk. That
   * is, you can set the acknowledgment state of messages in an existing
   * subscription to the state captured by a snapshot.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.snapshot
   *   Required. The name of the snapshot to get.
   *   Format is `projects/{project}/snapshots/{snap}`.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Snapshot]{@link google.pubsub.v1.Snapshot}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.getSnapshot(request);
   */
  getSnapshot(
    request: protos.google.pubsub.v1.IGetSnapshotRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.pubsub.v1.ISnapshot,
          protos.google.pubsub.v1.IGetSnapshotRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.IGetSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.IGetSnapshotRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      snapshot: request.snapshot || '',
    });
    this.initialize();
    return this.innerApiCalls.getSnapshot(request, options, callback);
  }
  createSnapshot(
    request: protos.google.pubsub.v1.ICreateSnapshotRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.ICreateSnapshotRequest | undefined,
      {} | undefined
    ]
  >;
  createSnapshot(
    request: protos.google.pubsub.v1.ICreateSnapshotRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.ICreateSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  createSnapshot(
    request: protos.google.pubsub.v1.ICreateSnapshotRequest,
    callback: Callback<
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.ICreateSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Creates a snapshot from the requested subscription. Snapshots are used in
   * [Seek](https://cloud.google.com/pubsub/docs/replay-overview) operations,
   * which allow you to manage message acknowledgments in bulk. That is, you can
   * set the acknowledgment state of messages in an existing subscription to the
   * state captured by a snapshot.
   * If the snapshot already exists, returns `ALREADY_EXISTS`.
   * If the requested subscription doesn't exist, returns `NOT_FOUND`.
   * If the backlog in the subscription is too old -- and the resulting snapshot
   * would expire in less than 1 hour -- then `FAILED_PRECONDITION` is returned.
   * See also the `Snapshot.expire_time` field. If the name is not provided in
   * the request, the server will assign a random
   * name for this snapshot on the same project as the subscription, conforming
   * to the [resource name format]
   * (https://cloud.google.com/pubsub/docs/admin#resource_names). The
   * generated name is populated in the returned Snapshot object. Note that for
   * REST API requests, you must specify a name in the request.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.name
   *   Required. User-provided name for this snapshot. If the name is not provided
   *   in the request, the server will assign a random name for this snapshot on
   *   the same project as the subscription. Note that for REST API requests, you
   *   must specify a name.  See the <a
   *   href="https://cloud.google.com/pubsub/docs/admin#resource_names"> resource
   *   name rules</a>. Format is `projects/{project}/snapshots/{snap}`.
   * @param {string} request.subscription
   *   Required. The subscription whose backlog the snapshot retains.
   *   Specifically, the created snapshot is guaranteed to retain:
   *    (a) The existing backlog on the subscription. More precisely, this is
   *        defined as the messages in the subscription's backlog that are
   *        unacknowledged upon the successful completion of the
   *        `CreateSnapshot` request; as well as:
   *    (b) Any messages published to the subscription's topic following the
   *        successful completion of the CreateSnapshot request.
   *   Format is `projects/{project}/subscriptions/{sub}`.
   * @param {number[]} request.labels
   *   See <a href="https://cloud.google.com/pubsub/docs/labels"> Creating and
   *   managing labels</a>.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Snapshot]{@link google.pubsub.v1.Snapshot}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.createSnapshot(request);
   */
  createSnapshot(
    request: protos.google.pubsub.v1.ICreateSnapshotRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.pubsub.v1.ISnapshot,
          protos.google.pubsub.v1.ICreateSnapshotRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.ICreateSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.ICreateSnapshotRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      name: request.name || '',
    });
    this.initialize();
    return this.innerApiCalls.createSnapshot(request, options, callback);
  }
  updateSnapshot(
    request: protos.google.pubsub.v1.IUpdateSnapshotRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.IUpdateSnapshotRequest | undefined,
      {} | undefined
    ]
  >;
  updateSnapshot(
    request: protos.google.pubsub.v1.IUpdateSnapshotRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.IUpdateSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  updateSnapshot(
    request: protos.google.pubsub.v1.IUpdateSnapshotRequest,
    callback: Callback<
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.IUpdateSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Updates an existing snapshot. Snapshots are used in
   * <a href="https://cloud.google.com/pubsub/docs/replay-overview">Seek</a>
   * operations, which allow
   * you to manage message acknowledgments in bulk. That is, you can set the
   * acknowledgment state of messages in an existing subscription to the state
   * captured by a snapshot.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {google.pubsub.v1.Snapshot} request.snapshot
   *   Required. The updated snapshot object.
   * @param {google.protobuf.FieldMask} request.updateMask
   *   Required. Indicates which fields in the provided snapshot to update.
   *   Must be specified and non-empty.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Snapshot]{@link google.pubsub.v1.Snapshot}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.updateSnapshot(request);
   */
  updateSnapshot(
    request: protos.google.pubsub.v1.IUpdateSnapshotRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.pubsub.v1.ISnapshot,
          protos.google.pubsub.v1.IUpdateSnapshotRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.IUpdateSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.pubsub.v1.ISnapshot,
      protos.google.pubsub.v1.IUpdateSnapshotRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      'snapshot.name': request.snapshot!.name || '',
    });
    this.initialize();
    return this.innerApiCalls.updateSnapshot(request, options, callback);
  }
  deleteSnapshot(
    request: protos.google.pubsub.v1.IDeleteSnapshotRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IDeleteSnapshotRequest | undefined,
      {} | undefined
    ]
  >;
  deleteSnapshot(
    request: protos.google.pubsub.v1.IDeleteSnapshotRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IDeleteSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  deleteSnapshot(
    request: protos.google.pubsub.v1.IDeleteSnapshotRequest,
    callback: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IDeleteSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Removes an existing snapshot. Snapshots are used in [Seek]
   * (https://cloud.google.com/pubsub/docs/replay-overview) operations, which
   * allow you to manage message acknowledgments in bulk. That is, you can set
   * the acknowledgment state of messages in an existing subscription to the
   * state captured by a snapshot.
   * When the snapshot is deleted, all messages retained in the snapshot
   * are immediately dropped. After a snapshot is deleted, a new one may be
   * created with the same name, but the new one has no association with the old
   * snapshot or its subscription, unless the same subscription is specified.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.snapshot
   *   Required. The name of the snapshot to delete.
   *   Format is `projects/{project}/snapshots/{snap}`.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Empty]{@link google.protobuf.Empty}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.deleteSnapshot(request);
   */
  deleteSnapshot(
    request: protos.google.pubsub.v1.IDeleteSnapshotRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.protobuf.IEmpty,
          protos.google.pubsub.v1.IDeleteSnapshotRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IDeleteSnapshotRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.protobuf.IEmpty,
      protos.google.pubsub.v1.IDeleteSnapshotRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      snapshot: request.snapshot || '',
    });
    this.initialize();
    return this.innerApiCalls.deleteSnapshot(request, options, callback);
  }
  seek(
    request: protos.google.pubsub.v1.ISeekRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.pubsub.v1.ISeekResponse,
      protos.google.pubsub.v1.ISeekRequest | undefined,
      {} | undefined
    ]
  >;
  seek(
    request: protos.google.pubsub.v1.ISeekRequest,
    options: CallOptions,
    callback: Callback<
      protos.google.pubsub.v1.ISeekResponse,
      protos.google.pubsub.v1.ISeekRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  seek(
    request: protos.google.pubsub.v1.ISeekRequest,
    callback: Callback<
      protos.google.pubsub.v1.ISeekResponse,
      protos.google.pubsub.v1.ISeekRequest | null | undefined,
      {} | null | undefined
    >
  ): void;
  /**
   * Seeks an existing subscription to a point in time or to a given snapshot,
   * whichever is provided in the request. Snapshots are used in [Seek]
   * (https://cloud.google.com/pubsub/docs/replay-overview) operations, which
   * allow you to manage message acknowledgments in bulk. That is, you can set
   * the acknowledgment state of messages in an existing subscription to the
   * state captured by a snapshot. Note that both the subscription and the
   * snapshot must be on the same topic.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.subscription
   *   Required. The subscription to affect.
   * @param {google.protobuf.Timestamp} request.time
   *   The time to seek to.
   *   Messages retained in the subscription that were published before this
   *   time are marked as acknowledged, and messages retained in the
   *   subscription that were published after this time are marked as
   *   unacknowledged. Note that this operation affects only those messages
   *   retained in the subscription (configured by the combination of
   *   `message_retention_duration` and `retain_acked_messages`). For example,
   *   if `time` corresponds to a point before the message retention
   *   window (or to a point before the system's notion of the subscription
   *   creation time), only retained messages will be marked as unacknowledged,
   *   and already-expunged messages will not be restored.
   * @param {string} request.snapshot
   *   The snapshot to seek to. The snapshot's topic must be the same as that of
   *   the provided subscription.
   *   Format is `projects/{project}/snapshots/{snap}`.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [SeekResponse]{@link google.pubsub.v1.SeekResponse}.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#regular-methods)
   *   for more details and examples.
   * @example
   * const [response] = await client.seek(request);
   */
  seek(
    request: protos.google.pubsub.v1.ISeekRequest,
    optionsOrCallback?:
      | CallOptions
      | Callback<
          protos.google.pubsub.v1.ISeekResponse,
          protos.google.pubsub.v1.ISeekRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      protos.google.pubsub.v1.ISeekResponse,
      protos.google.pubsub.v1.ISeekRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<
    [
      protos.google.pubsub.v1.ISeekResponse,
      protos.google.pubsub.v1.ISeekRequest | undefined,
      {} | undefined
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      subscription: request.subscription || '',
    });
    this.initialize();
    return this.innerApiCalls.seek(request, options, callback);
  }

  /**
   * Establishes a stream with the server, which sends messages down to the
   * client. The client streams acknowledgements and ack deadline modifications
   * back to the server. The server will close the stream and return the status
   * on any error. The server may close the stream with status `UNAVAILABLE` to
   * reassign server-side resources, in which case, the client should
   * re-establish the stream. Flow control can be achieved by configuring the
   * underlying RPC channel.
   *
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Stream}
   *   An object stream which is both readable and writable. It accepts objects
   *   representing [StreamingPullRequest]{@link google.pubsub.v1.StreamingPullRequest} for write() method, and
   *   will emit objects representing [StreamingPullResponse]{@link google.pubsub.v1.StreamingPullResponse} on 'data' event asynchronously.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#bi-directional-streaming)
   *   for more details and examples.
   * @example
   * const stream = client.streamingPull();
   * stream.on('data', (response) => { ... });
   * stream.on('end', () => { ... });
   * stream.write(request);
   * stream.end();
   */
  streamingPull(options?: CallOptions): gax.CancellableStream {
    this.initialize();
    return this.innerApiCalls.streamingPull(options);
  }

  listSubscriptions(
    request: protos.google.pubsub.v1.IListSubscriptionsRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.pubsub.v1.ISubscription[],
      protos.google.pubsub.v1.IListSubscriptionsRequest | null,
      protos.google.pubsub.v1.IListSubscriptionsResponse
    ]
  >;
  listSubscriptions(
    request: protos.google.pubsub.v1.IListSubscriptionsRequest,
    options: CallOptions,
    callback: PaginationCallback<
      protos.google.pubsub.v1.IListSubscriptionsRequest,
      protos.google.pubsub.v1.IListSubscriptionsResponse | null | undefined,
      protos.google.pubsub.v1.ISubscription
    >
  ): void;
  listSubscriptions(
    request: protos.google.pubsub.v1.IListSubscriptionsRequest,
    callback: PaginationCallback<
      protos.google.pubsub.v1.IListSubscriptionsRequest,
      protos.google.pubsub.v1.IListSubscriptionsResponse | null | undefined,
      protos.google.pubsub.v1.ISubscription
    >
  ): void;
  /**
   * Lists matching subscriptions.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.project
   *   Required. The name of the project in which to list subscriptions.
   *   Format is `projects/{project-id}`.
   * @param {number} request.pageSize
   *   Maximum number of subscriptions to return.
   * @param {string} request.pageToken
   *   The value returned by the last `ListSubscriptionsResponse`; indicates that
   *   this is a continuation of a prior `ListSubscriptions` call, and that the
   *   system should return the next page of data.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is Array of [Subscription]{@link google.pubsub.v1.Subscription}.
   *   The client library will perform auto-pagination by default: it will call the API as many
   *   times as needed and will merge results from all the pages into this array.
   *   Note that it can affect your quota.
   *   We recommend using `listSubscriptionsAsync()`
   *   method described below for async iteration which you can stop as needed.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#auto-pagination)
   *   for more details and examples.
   */
  listSubscriptions(
    request: protos.google.pubsub.v1.IListSubscriptionsRequest,
    optionsOrCallback?:
      | CallOptions
      | PaginationCallback<
          protos.google.pubsub.v1.IListSubscriptionsRequest,
          protos.google.pubsub.v1.IListSubscriptionsResponse | null | undefined,
          protos.google.pubsub.v1.ISubscription
        >,
    callback?: PaginationCallback<
      protos.google.pubsub.v1.IListSubscriptionsRequest,
      protos.google.pubsub.v1.IListSubscriptionsResponse | null | undefined,
      protos.google.pubsub.v1.ISubscription
    >
  ): Promise<
    [
      protos.google.pubsub.v1.ISubscription[],
      protos.google.pubsub.v1.IListSubscriptionsRequest | null,
      protos.google.pubsub.v1.IListSubscriptionsResponse
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      project: request.project || '',
    });
    this.initialize();
    return this.innerApiCalls.listSubscriptions(request, options, callback);
  }

  /**
   * Equivalent to `method.name.toCamelCase()`, but returns a NodeJS Stream object.
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.project
   *   Required. The name of the project in which to list subscriptions.
   *   Format is `projects/{project-id}`.
   * @param {number} request.pageSize
   *   Maximum number of subscriptions to return.
   * @param {string} request.pageToken
   *   The value returned by the last `ListSubscriptionsResponse`; indicates that
   *   this is a continuation of a prior `ListSubscriptions` call, and that the
   *   system should return the next page of data.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Stream}
   *   An object stream which emits an object representing [Subscription]{@link google.pubsub.v1.Subscription} on 'data' event.
   *   The client library will perform auto-pagination by default: it will call the API as many
   *   times as needed. Note that it can affect your quota.
   *   We recommend using `listSubscriptionsAsync()`
   *   method described below for async iteration which you can stop as needed.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#auto-pagination)
   *   for more details and examples.
   */
  listSubscriptionsStream(
    request?: protos.google.pubsub.v1.IListSubscriptionsRequest,
    options?: CallOptions
  ): Transform {
    request = request || {};
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      project: request.project || '',
    });
    const callSettings = new gax.CallSettings(options);
    this.initialize();
    return this.descriptors.page.listSubscriptions.createStream(
      this.innerApiCalls.listSubscriptions as gax.GaxCall,
      request,
      callSettings
    );
  }

  /**
   * Equivalent to `listSubscriptions`, but returns an iterable object.
   *
   * `for`-`await`-`of` syntax is used with the iterable to get response elements on-demand.
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.project
   *   Required. The name of the project in which to list subscriptions.
   *   Format is `projects/{project-id}`.
   * @param {number} request.pageSize
   *   Maximum number of subscriptions to return.
   * @param {string} request.pageToken
   *   The value returned by the last `ListSubscriptionsResponse`; indicates that
   *   this is a continuation of a prior `ListSubscriptions` call, and that the
   *   system should return the next page of data.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Object}
   *   An iterable Object that allows [async iteration](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols).
   *   When you iterate the returned iterable, each element will be an object representing
   *   [Subscription]{@link google.pubsub.v1.Subscription}. The API will be called under the hood as needed, once per the page,
   *   so you can stop the iteration when you don't need more results.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#auto-pagination)
   *   for more details and examples.
   * @example
   * const iterable = client.listSubscriptionsAsync(request);
   * for await (const response of iterable) {
   *   // process response
   * }
   */
  listSubscriptionsAsync(
    request?: protos.google.pubsub.v1.IListSubscriptionsRequest,
    options?: CallOptions
  ): AsyncIterable<protos.google.pubsub.v1.ISubscription> {
    request = request || {};
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      project: request.project || '',
    });
    options = options || {};
    const callSettings = new gax.CallSettings(options);
    this.initialize();
    return this.descriptors.page.listSubscriptions.asyncIterate(
      this.innerApiCalls['listSubscriptions'] as GaxCall,
      (request as unknown) as RequestType,
      callSettings
    ) as AsyncIterable<protos.google.pubsub.v1.ISubscription>;
  }
  listSnapshots(
    request: protos.google.pubsub.v1.IListSnapshotsRequest,
    options?: CallOptions
  ): Promise<
    [
      protos.google.pubsub.v1.ISnapshot[],
      protos.google.pubsub.v1.IListSnapshotsRequest | null,
      protos.google.pubsub.v1.IListSnapshotsResponse
    ]
  >;
  listSnapshots(
    request: protos.google.pubsub.v1.IListSnapshotsRequest,
    options: CallOptions,
    callback: PaginationCallback<
      protos.google.pubsub.v1.IListSnapshotsRequest,
      protos.google.pubsub.v1.IListSnapshotsResponse | null | undefined,
      protos.google.pubsub.v1.ISnapshot
    >
  ): void;
  listSnapshots(
    request: protos.google.pubsub.v1.IListSnapshotsRequest,
    callback: PaginationCallback<
      protos.google.pubsub.v1.IListSnapshotsRequest,
      protos.google.pubsub.v1.IListSnapshotsResponse | null | undefined,
      protos.google.pubsub.v1.ISnapshot
    >
  ): void;
  /**
   * Lists the existing snapshots. Snapshots are used in [Seek](
   * https://cloud.google.com/pubsub/docs/replay-overview) operations, which
   * allow you to manage message acknowledgments in bulk. That is, you can set
   * the acknowledgment state of messages in an existing subscription to the
   * state captured by a snapshot.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.project
   *   Required. The name of the project in which to list snapshots.
   *   Format is `projects/{project-id}`.
   * @param {number} request.pageSize
   *   Maximum number of snapshots to return.
   * @param {string} request.pageToken
   *   The value returned by the last `ListSnapshotsResponse`; indicates that this
   *   is a continuation of a prior `ListSnapshots` call, and that the system
   *   should return the next page of data.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is Array of [Snapshot]{@link google.pubsub.v1.Snapshot}.
   *   The client library will perform auto-pagination by default: it will call the API as many
   *   times as needed and will merge results from all the pages into this array.
   *   Note that it can affect your quota.
   *   We recommend using `listSnapshotsAsync()`
   *   method described below for async iteration which you can stop as needed.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#auto-pagination)
   *   for more details and examples.
   */
  listSnapshots(
    request: protos.google.pubsub.v1.IListSnapshotsRequest,
    optionsOrCallback?:
      | CallOptions
      | PaginationCallback<
          protos.google.pubsub.v1.IListSnapshotsRequest,
          protos.google.pubsub.v1.IListSnapshotsResponse | null | undefined,
          protos.google.pubsub.v1.ISnapshot
        >,
    callback?: PaginationCallback<
      protos.google.pubsub.v1.IListSnapshotsRequest,
      protos.google.pubsub.v1.IListSnapshotsResponse | null | undefined,
      protos.google.pubsub.v1.ISnapshot
    >
  ): Promise<
    [
      protos.google.pubsub.v1.ISnapshot[],
      protos.google.pubsub.v1.IListSnapshotsRequest | null,
      protos.google.pubsub.v1.IListSnapshotsResponse
    ]
  > | void {
    request = request || {};
    let options: CallOptions;
    if (typeof optionsOrCallback === 'function' && callback === undefined) {
      callback = optionsOrCallback;
      options = {};
    } else {
      options = optionsOrCallback as CallOptions;
    }
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      project: request.project || '',
    });
    this.initialize();
    return this.innerApiCalls.listSnapshots(request, options, callback);
  }

  /**
   * Equivalent to `method.name.toCamelCase()`, but returns a NodeJS Stream object.
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.project
   *   Required. The name of the project in which to list snapshots.
   *   Format is `projects/{project-id}`.
   * @param {number} request.pageSize
   *   Maximum number of snapshots to return.
   * @param {string} request.pageToken
   *   The value returned by the last `ListSnapshotsResponse`; indicates that this
   *   is a continuation of a prior `ListSnapshots` call, and that the system
   *   should return the next page of data.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Stream}
   *   An object stream which emits an object representing [Snapshot]{@link google.pubsub.v1.Snapshot} on 'data' event.
   *   The client library will perform auto-pagination by default: it will call the API as many
   *   times as needed. Note that it can affect your quota.
   *   We recommend using `listSnapshotsAsync()`
   *   method described below for async iteration which you can stop as needed.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#auto-pagination)
   *   for more details and examples.
   */
  listSnapshotsStream(
    request?: protos.google.pubsub.v1.IListSnapshotsRequest,
    options?: CallOptions
  ): Transform {
    request = request || {};
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      project: request.project || '',
    });
    const callSettings = new gax.CallSettings(options);
    this.initialize();
    return this.descriptors.page.listSnapshots.createStream(
      this.innerApiCalls.listSnapshots as gax.GaxCall,
      request,
      callSettings
    );
  }

  /**
   * Equivalent to `listSnapshots`, but returns an iterable object.
   *
   * `for`-`await`-`of` syntax is used with the iterable to get response elements on-demand.
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.project
   *   Required. The name of the project in which to list snapshots.
   *   Format is `projects/{project-id}`.
   * @param {number} request.pageSize
   *   Maximum number of snapshots to return.
   * @param {string} request.pageToken
   *   The value returned by the last `ListSnapshotsResponse`; indicates that this
   *   is a continuation of a prior `ListSnapshots` call, and that the system
   *   should return the next page of data.
   * @param {object} [options]
   *   Call options. See {@link https://googleapis.dev/nodejs/google-gax/latest/interfaces/CallOptions.html|CallOptions} for more details.
   * @returns {Object}
   *   An iterable Object that allows [async iteration](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols).
   *   When you iterate the returned iterable, each element will be an object representing
   *   [Snapshot]{@link google.pubsub.v1.Snapshot}. The API will be called under the hood as needed, once per the page,
   *   so you can stop the iteration when you don't need more results.
   *   Please see the
   *   [documentation](https://github.com/googleapis/gax-nodejs/blob/master/client-libraries.md#auto-pagination)
   *   for more details and examples.
   * @example
   * const iterable = client.listSnapshotsAsync(request);
   * for await (const response of iterable) {
   *   // process response
   * }
   */
  listSnapshotsAsync(
    request?: protos.google.pubsub.v1.IListSnapshotsRequest,
    options?: CallOptions
  ): AsyncIterable<protos.google.pubsub.v1.ISnapshot> {
    request = request || {};
    options = options || {};
    options.otherArgs = options.otherArgs || {};
    options.otherArgs.headers = options.otherArgs.headers || {};
    options.otherArgs.headers[
      'x-goog-request-params'
    ] = gax.routingHeader.fromParams({
      project: request.project || '',
    });
    options = options || {};
    const callSettings = new gax.CallSettings(options);
    this.initialize();
    return this.descriptors.page.listSnapshots.asyncIterate(
      this.innerApiCalls['listSnapshots'] as GaxCall,
      (request as unknown) as RequestType,
      callSettings
    ) as AsyncIterable<protos.google.pubsub.v1.ISnapshot>;
  }
  /**
   * Gets the access control policy for a resource. Returns an empty policy
   * if the resource exists and does not have a policy set.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.resource
   *   REQUIRED: The resource for which the policy is being requested.
   *   See the operation documentation for the appropriate value for this field.
   * @param {Object} [request.options]
   *   OPTIONAL: A `GetPolicyOptions` object for specifying options to
   *   `GetIamPolicy`. This field is only used by Cloud IAM.
   *
   *   This object should have the same structure as [GetPolicyOptions]{@link google.iam.v1.GetPolicyOptions}
   * @param {Object} [options]
   *   Optional parameters. You can override the default settings for this call, e.g, timeout,
   *   retries, paginations, etc. See [gax.CallOptions]{@link https://googleapis.github.io/gax-nodejs/interfaces/CallOptions.html} for the details.
   * @param {function(?Error, ?Object)} [callback]
   *   The function which will be called with the result of the API call.
   *
   *   The second parameter to the callback is an object representing [Policy]{@link google.iam.v1.Policy}.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [Policy]{@link google.iam.v1.Policy}.
   *   The promise has a method named "cancel" which cancels the ongoing API call.
   */
  getIamPolicy(
    request: IamProtos.google.iam.v1.GetIamPolicyRequest,
    options?:
      | gax.CallOptions
      | Callback<
          IamProtos.google.iam.v1.Policy,
          IamProtos.google.iam.v1.GetIamPolicyRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      IamProtos.google.iam.v1.Policy,
      IamProtos.google.iam.v1.GetIamPolicyRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<IamProtos.google.iam.v1.Policy> {
    return this.iamClient.getIamPolicy(request, options, callback);
  }

  /**
   * Returns permissions that a caller has on the specified resource. If the
   * resource does not exist, this will return an empty set of
   * permissions, not a NOT_FOUND error.
   *
   * Note: This operation is designed to be used for building
   * permission-aware UIs and command-line tools, not for authorization
   * checking. This operation may "fail open" without warning.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.resource
   *   REQUIRED: The resource for which the policy detail is being requested.
   *   See the operation documentation for the appropriate value for this field.
   * @param {string[]} request.permissions
   *   The set of permissions to check for the `resource`. Permissions with
   *   wildcards (such as '*' or 'storage.*') are not allowed. For more
   *   information see
   *   [IAM Overview](https://cloud.google.com/iam/docs/overview#permissions).
   * @param {Object} [options]
   *   Optional parameters. You can override the default settings for this call, e.g, timeout,
   *   retries, paginations, etc. See [gax.CallOptions]{@link https://googleapis.github.io/gax-nodejs/interfaces/CallOptions.html} for the details.
   * @param {function(?Error, ?Object)} [callback]
   *   The function which will be called with the result of the API call.
   *
   *   The second parameter to the callback is an object representing [TestIamPermissionsResponse]{@link google.iam.v1.TestIamPermissionsResponse}.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [TestIamPermissionsResponse]{@link google.iam.v1.TestIamPermissionsResponse}.
   *   The promise has a method named "cancel" which cancels the ongoing API call.
   */
  setIamPolicy(
    request: IamProtos.google.iam.v1.SetIamPolicyRequest,
    options?:
      | gax.CallOptions
      | Callback<
          IamProtos.google.iam.v1.Policy,
          IamProtos.google.iam.v1.SetIamPolicyRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      IamProtos.google.iam.v1.Policy,
      IamProtos.google.iam.v1.SetIamPolicyRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<IamProtos.google.iam.v1.Policy> {
    return this.iamClient.setIamPolicy(request, options, callback);
  }

  /**
   * Returns permissions that a caller has on the specified resource. If the
   * resource does not exist, this will return an empty set of
   * permissions, not a NOT_FOUND error.
   *
   * Note: This operation is designed to be used for building
   * permission-aware UIs and command-line tools, not for authorization
   * checking. This operation may "fail open" without warning.
   *
   * @param {Object} request
   *   The request object that will be sent.
   * @param {string} request.resource
   *   REQUIRED: The resource for which the policy detail is being requested.
   *   See the operation documentation for the appropriate value for this field.
   * @param {string[]} request.permissions
   *   The set of permissions to check for the `resource`. Permissions with
   *   wildcards (such as '*' or 'storage.*') are not allowed. For more
   *   information see
   *   [IAM Overview](https://cloud.google.com/iam/docs/overview#permissions).
   * @param {Object} [options]
   *   Optional parameters. You can override the default settings for this call, e.g, timeout,
   *   retries, paginations, etc. See [gax.CallOptions]{@link https://googleapis.github.io/gax-nodejs/interfaces/CallOptions.html} for the details.
   * @param {function(?Error, ?Object)} [callback]
   *   The function which will be called with the result of the API call.
   *
   *   The second parameter to the callback is an object representing [TestIamPermissionsResponse]{@link google.iam.v1.TestIamPermissionsResponse}.
   * @returns {Promise} - The promise which resolves to an array.
   *   The first element of the array is an object representing [TestIamPermissionsResponse]{@link google.iam.v1.TestIamPermissionsResponse}.
   *   The promise has a method named "cancel" which cancels the ongoing API call.
   *
   */
  testIamPermissions(
    request: IamProtos.google.iam.v1.TestIamPermissionsRequest,
    options?:
      | gax.CallOptions
      | Callback<
          IamProtos.google.iam.v1.TestIamPermissionsResponse,
          IamProtos.google.iam.v1.TestIamPermissionsRequest | null | undefined,
          {} | null | undefined
        >,
    callback?: Callback<
      IamProtos.google.iam.v1.TestIamPermissionsResponse,
      IamProtos.google.iam.v1.TestIamPermissionsRequest | null | undefined,
      {} | null | undefined
    >
  ): Promise<IamProtos.google.iam.v1.TestIamPermissionsResponse> {
    return this.iamClient.testIamPermissions(request, options, callback);
  }

  // --------------------
  // -- Path templates --
  // --------------------

  /**
   * Return a fully-qualified project resource name string.
   *
   * @param {string} project
   * @returns {string} Resource name string.
   */
  projectPath(project: string) {
    return this.pathTemplates.projectPathTemplate.render({
      project: project,
    });
  }

  /**
   * Parse the project from Project resource.
   *
   * @param {string} projectName
   *   A fully-qualified path representing Project resource.
   * @returns {string} A string representing the project.
   */
  matchProjectFromProjectName(projectName: string) {
    return this.pathTemplates.projectPathTemplate.match(projectName).project;
  }

  /**
   * Return a fully-qualified projectTopic resource name string.
   *
   * @param {string} project
   * @param {string} topic
   * @returns {string} Resource name string.
   */
  projectTopicPath(project: string, topic: string) {
    return this.pathTemplates.projectTopicPathTemplate.render({
      project: project,
      topic: topic,
    });
  }

  /**
   * Parse the project from ProjectTopic resource.
   *
   * @param {string} projectTopicName
   *   A fully-qualified path representing project_topic resource.
   * @returns {string} A string representing the project.
   */
  matchProjectFromProjectTopicName(projectTopicName: string) {
    return this.pathTemplates.projectTopicPathTemplate.match(projectTopicName)
      .project;
  }

  /**
   * Parse the topic from ProjectTopic resource.
   *
   * @param {string} projectTopicName
   *   A fully-qualified path representing project_topic resource.
   * @returns {string} A string representing the topic.
   */
  matchTopicFromProjectTopicName(projectTopicName: string) {
    return this.pathTemplates.projectTopicPathTemplate.match(projectTopicName)
      .topic;
  }

  /**
   * Return a fully-qualified schema resource name string.
   *
   * @param {string} project
   * @param {string} schema
   * @returns {string} Resource name string.
   */
  schemaPath(project: string, schema: string) {
    return this.pathTemplates.schemaPathTemplate.render({
      project: project,
      schema: schema,
    });
  }

  /**
   * Parse the project from Schema resource.
   *
   * @param {string} schemaName
   *   A fully-qualified path representing Schema resource.
   * @returns {string} A string representing the project.
   */
  matchProjectFromSchemaName(schemaName: string) {
    return this.pathTemplates.schemaPathTemplate.match(schemaName).project;
  }

  /**
   * Parse the schema from Schema resource.
   *
   * @param {string} schemaName
   *   A fully-qualified path representing Schema resource.
   * @returns {string} A string representing the schema.
   */
  matchSchemaFromSchemaName(schemaName: string) {
    return this.pathTemplates.schemaPathTemplate.match(schemaName).schema;
  }

  /**
   * Return a fully-qualified snapshot resource name string.
   *
   * @param {string} project
   * @param {string} snapshot
   * @returns {string} Resource name string.
   */
  snapshotPath(project: string, snapshot: string) {
    return this.pathTemplates.snapshotPathTemplate.render({
      project: project,
      snapshot: snapshot,
    });
  }

  /**
   * Parse the project from Snapshot resource.
   *
   * @param {string} snapshotName
   *   A fully-qualified path representing Snapshot resource.
   * @returns {string} A string representing the project.
   */
  matchProjectFromSnapshotName(snapshotName: string) {
    return this.pathTemplates.snapshotPathTemplate.match(snapshotName).project;
  }

  /**
   * Parse the snapshot from Snapshot resource.
   *
   * @param {string} snapshotName
   *   A fully-qualified path representing Snapshot resource.
   * @returns {string} A string representing the snapshot.
   */
  matchSnapshotFromSnapshotName(snapshotName: string) {
    return this.pathTemplates.snapshotPathTemplate.match(snapshotName).snapshot;
  }

  /**
   * Return a fully-qualified subscription resource name string.
   *
   * @param {string} project
   * @param {string} subscription
   * @returns {string} Resource name string.
   */
  subscriptionPath(project: string, subscription: string) {
    return this.pathTemplates.subscriptionPathTemplate.render({
      project: project,
      subscription: subscription,
    });
  }

  /**
   * Parse the project from Subscription resource.
   *
   * @param {string} subscriptionName
   *   A fully-qualified path representing Subscription resource.
   * @returns {string} A string representing the project.
   */
  matchProjectFromSubscriptionName(subscriptionName: string) {
    return this.pathTemplates.subscriptionPathTemplate.match(subscriptionName)
      .project;
  }

  /**
   * Parse the subscription from Subscription resource.
   *
   * @param {string} subscriptionName
   *   A fully-qualified path representing Subscription resource.
   * @returns {string} A string representing the subscription.
   */
  matchSubscriptionFromSubscriptionName(subscriptionName: string) {
    return this.pathTemplates.subscriptionPathTemplate.match(subscriptionName)
      .subscription;
  }

  /**
   * Terminate the gRPC channel and close the client.
   *
   * The client will no longer be usable and all future behavior is undefined.
   * @returns {Promise} A promise that resolves when the client is closed.
   */
  close(): Promise<void> {
    this.initialize();
    if (!this._terminated) {
      return this.subscriberStub!.then(stub => {
        this._terminated = true;
        stub.close();
      });
    }
    return Promise.resolve();
  }
}