// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

syntax = "proto3";

package google.cloud.pubsublite.v1;

import "google/cloud/pubsublite/v1/common.proto";
import "google/api/client.proto";

option cc_enable_arenas = true;
option go_package = "google.golang.org/genproto/googleapis/cloud/pubsublite/v1;pubsublite";
option java_multiple_files = true;
option java_outer_classname = "PublisherProto";
option java_package = "com.google.cloud.pubsublite.proto";

// The service that a publisher client application uses to publish messages to
// topics. Published messages are retained by the service for the duration of
// the retention period configured for the respective topic, and are delivered
// to subscriber clients upon request (via the `SubscriberService`).
service PublisherService {
  option (google.api.default_host) = "pubsublite.googleapis.com";
  option (google.api.oauth_scopes) = "https://www.googleapis.com/auth/cloud-platform";

  // Establishes a stream with the server for publishing messages. Once the
  // stream is initialized, the client publishes messages by sending publish
  // requests on the stream. The server responds with a PublishResponse for each
  // PublishRequest sent by the client, in the same order that the requests
  // were sent. Note that multiple PublishRequests can be in flight
  // simultaneously, but they will be processed by the server in the order that
  // they are sent by the client on a given stream.
  rpc Publish(stream PublishRequest) returns (stream PublishResponse) {
  }
}

// The first request that must be sent on a newly-opened stream.
message InitialPublishRequest {
  // The topic to which messages will be written.
  string topic = 1;

  // The partition within the topic to which messages will be written.
  // Partitions are zero indexed, so `partition` must be in the range [0,
  // topic.num_partitions).
  int64 partition = 2;
}

// Response to an InitialPublishRequest.
message InitialPublishResponse {

}

// Request to publish messages to the topic.
message MessagePublishRequest {
  // The messages to publish.
  repeated PubSubMessage messages = 1;
}

// Response to a MessagePublishRequest.
message MessagePublishResponse {
  // The cursor of the first published message in the batch. The cursors for any
  // remaining messages in the batch are guaranteed to be sequential.
  Cursor start_cursor = 1;
}

// Request sent from the client to the server on a stream.
message PublishRequest {
  // The type of request this is.
  oneof request_type {
    // Initial request on the stream.
    InitialPublishRequest initial_request = 1;

    // Request to publish messages.
    MessagePublishRequest message_publish_request = 2;
  }
}

// Response to a PublishRequest.
message PublishResponse {
  // The type of response this is.
  oneof response_type {
    // Initial response on the stream.
    InitialPublishResponse initial_response = 1;

    // Response to publishing messages.
    MessagePublishResponse message_response = 2;
  }
}
