// Copyright 2023 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 cobalt;

import "common.proto";
import "encrypted_message.proto";

option java_multiple_files = true;
option java_package = "com.google.cobalt";

////////////////////////////////////////////////////////////////////////////////
// NOTE: This file is used by the Cobalt client and the Cobalt servers.
// The source-of-truth of this file is located in Google's internsl code
// repository, and the file is copied to Android where it is used by the Cobalt
// client. Do not edit the copy of this file in this Android repo as those edits
// will be overwritten when the file is next copied.
////////////////////////////////////////////////////////////////////////////////

// ObservationMetadata describes the parts of an observation other than the
// secret payload.
message ObservationMetadata {
  // next id: 8

  // An Observation is for a particular Cobalt Report.
  // The following four values together specify that metric.
  uint32 customer_id = 1;
  uint32 project_id = 2;
  uint32 metric_id = 3;
  uint32 report_id = 7;

  // The day on which the observation occurred, expressed as the zero-based
  // index relative to January 1, 1970.
  // i.e. 0 = January 1, 1970
  //      1 = January 2, 1970
  //      etc.
  //
  // We intentionally leave the meaning of this vague and leave it to each
  // Encoder Client to define how to make it precise. Which day it is depends on
  // time zone. The Encoder client is free to use the local time zone or a
  // different time zone. The Encoder client is free to add some random noise to
  // the time at which an event occurred and this might change the day.
  uint32 day_index = 4;

  // The profile of the client system on which the Observation was collected.
  SystemProfile system_profile = 5;

  // We used to have a field called |backend|.
  reserved 6;
  reserved "backend";
}

// A batch of encrypted Observations with common metadata.
// The Observations are encrypted to the public key of an Analyzer so the
// Shuffler cannot read them. |Observation| is defined in Cobalt's
// observation.proto.
//
// ObservationBatches are used for both input to and output from the Shuffler.
// As input they are organized into Envelopes, each Envelope coming from some
// client device. |Envelope| is defined in Cobalt's envelope.proto.
//
// The output from the Shuffler consists of shuffled
// ObservationBatches, each ObservationBatch consisting of Observations
// from many clients.
//
message ObservationBatch {
  // The common Metadata for all of the encrypted observations in this batch.
  ObservationMetadata meta_data = 1;

  // Each EncryptedMessage contains the ciphertext of an Observation that has
  // been encrypted to the public key of the Analyzer.
  repeated EncryptedMessage encrypted_observation = 2;
}