// 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
//
//      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.internal.federatedcompute.v1;

import "fcp/protos/federatedcompute/common.proto";

option java_package = "com.google.internal.federatedcompute.v1";
option java_multiple_files = true;

service EligibilityEvalTasks {
  // A request, sent by the device to request the eligibility-computing task for
  // the population. This task is run by the client to generate a
  // `TaskEligibilityInfo` proto result, which is then included with a
  // subsequent `StartTaskAssignmentRequest` to inform the server which tasks
  // the client is eligible for.
  //
  // Returns NOT_FOUND if the population does not exist.
  rpc RequestEligibilityEvalTask(EligibilityEvalTaskRequest)
      returns (EligibilityEvalTaskResponse) {
  }

  // A request sent by the device to report the result of running the
  // EligibilityEval task provided by `EligibilityEvalTaskResponse`.
  //
  // A result with a status code other than Code.OK indicates client session
  // termination. The client may not send any future requests with the given
  // session_id.
  //
  // Clients should use the same `ForwardingInfo` as used in the
  // `RequestEligibilityEvalTask` request to construct the URI for this request.
  rpc ReportEligibilityEvalTaskResult(ReportEligibilityEvalTaskResultRequest)
      returns (ReportEligibilityEvalTaskResultResponse) {
  }
}

message EligibilityEvalTaskRequest {
  // The name of the population this client belongs to.
  //
  // Note that http clients set this value in the request URL instead of the
  // request body.
  string population_name = 1
      ;

  // The attestation measurement providing evidence of integrity for this
  // client. The measurement is bound to the population_name value in this
  // request.
  //
  // Note that the subsequent `StartTaskAssignmentRequest` will use the same
  // value for this field, since it is considered part of the same logical
  // protocol session as this request.
  AttestationMeasurement attestation_measurement = 2;

  ClientVersion client_version = 3;

  // The client's capabilities when downloading and processing resources.
  ResourceCapabilities resource_capabilities = 4;

  // The client's capabilities when downloading and running Eligibility Eval
  // tasks.
  EligibilityEvalTaskCapabilities eligibility_eval_task_capabilities = 5;
}

// The client's capabilities for determining task eligibility.
message EligibilityEvalTaskCapabilities {
  // Whether the client supports multiple task assignment
  // (/TaskAssignments.PerformMultipleTaskAssignments). If false, the client
  // will not be provided information about tasks that require multiple task
  // assignment.
  bool supports_multiple_task_assignment = 1;
}

message EligibilityEvalTaskResponse {
  // Information to construct the URI to use when calling StartTaskAssignment.
  // This will not be populated if the result below contains a RejectionInfo
  // message since the client should not call StartTaskAssignment in that case.
  //
  // Note that this forwarding info does not apply to
  // `ReportEligibilityEvalTaskResult` which should instead be sent to the same
  // endpoint as `RequestEligibilityEvalTask`.
  ForwardingInfo task_assignment_forwarding_info = 1;

  // Unique identifier for the protocol session. This field will not be set if
  // the result below contains a RejectionInfo.
  string session_id = 2;

  oneof result {
    // If the population has an eligibility-computing task configured, and if
    // the client is compatible with that task, then this field will be set,
    // containing the task's information. The client should run the task and
    // include its `TaskEligibilityInfo` result in the subsequent
    // `StartTaskAssignmentRequest`.
    EligibilityEvalTask eligibility_eval_task = 3;

    // If the population does not have an eligibility-computing task configured,
    // then this field will be set. The client should continue by issuing a
    // `StartTaskAssignmentRequest` without the `task_eligibility_info` field
    // set.
    NoEligibilityEvalConfigured no_eligibility_eval_configured = 4;

    // If the population has an eligibility-computing task configured, but the
    // client is incompatible with that task or if the server is unable to
    // service the request at the moment, then this field will be set.
    RejectionInfo rejection_info = 5;
  }

  // Retry window to use for the next RequestEligibilityEvalTask attempt if
  // the following StartTaskAssignment attempt ends up being subsequently
  // accepted by the server, as in the client received a
  // StartTaskAssignmentResponse with a TaskAssignment. This will not be set if
  // the result above contains a RejectionInfo.
  RetryWindow retry_window_if_accepted = 6;

  // Retry window to use if this request was rejected or if the following
  // StartTaskAssignment attempt is not accepted by the server, as in the client
  // receives a StartTaskAssignmentResponse without a TaskAssignment.
  RetryWindow retry_window_if_rejected = 7;
}

message EligibilityEvalTask {
  // The checkpoint from which to start execution (if any).
  // Optional: This field and `plan` may both be unset if the client supports
  // multiple task assignment but the population does not have an Eligibility
  // Eval task configured.
  Resource init_checkpoint = 1;

  // The task to be used for execution.
  // Optional: This field and `init_checkpoint` may both be unset if the client
  // supports multiple task assignment but the population does not have an
  // Eligibility Eval task configured.
  Resource plan = 2;

  // A serialized PopulationEligibilitySpec describing the eligibility criteria
  // for tasks in the population.
  Resource population_eligibility_spec = 4;

  // The opaque id of the eligibility evaluation task payload the client is
  // being given. This is a string generated by the server and used by the
  // client for logging purposes. This id MUST NOT contain any information that
  // could be used to identify a specific device.
  // Also see the similar `TaskAssignment.execution_phase_id`.
  // Optional: If `plan` is absent, this field may also be absent.
  string execution_id = 3;
}

// Currently-empty message describing the case where a population does not have
// an eligibility-computing task configured.
message NoEligibilityEvalConfigured {}

// Provides the information needed to determine eligibility for tasks in a
// population.
message PopulationEligibilitySpec {
  // Eligibility-related information about each task in the population.
  repeated TaskInfo task_info = 1;

  message TaskInfo {
    // The name of the task.
    string task_name = 1;

    // The TaskAssignments method to use for the task.
    TaskAssignmentMode task_assignment_mode = 2;

    enum TaskAssignmentMode {
      TASK_ASSIGNMENT_MODE_UNSPECIFIED = 0;
      // Task assignment uses /TaskAssignments.StartTaskAssignment.
      TASK_ASSIGNMENT_MODE_SINGLE = 1;
      // Task assignment uses /TaskAssignments.PerformMultipleTaskAssignments.
      TASK_ASSIGNMENT_MODE_MULTIPLE = 2;
    }
  }
}

message ReportEligibilityEvalTaskResultRequest {
  // The name of the population this client belongs to.
  //
  // Note that http clients set this value in the request URL instead of the
  // request body.
  string population_name = 1
      ;

  // The session id returned by the server.
  //
  // Note that http clients set this value in the request URL instead of the
  // request body.
  string session_id = 2
      ;

  // Status code reported by client.
  // Code.OK indicates that client execution completed successfully. Any other
  // code indicates unsuccessful execution and termination of the protocol
  // session.
  int32 status_code = 3;
}

message ReportEligibilityEvalTaskResultResponse {}