/*
 * Copyright (C) 2023 The Android Open Source Project
 *
 * 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 com.android.federatedcompute.proto;

import "google/protobuf/duration.proto";

option java_package = "com.android.federatedcompute.proto";
option java_multiple_files = true;

// Information that tells the client where to send the request for the next
// protocol phase (the immediately following phase only, not any additional
// subsequent phases). For example, this may point to the frontend to which
// a StartTaskAssignmentRequest should be sent, but it should not then be used
// for uploading aggregation results. A ForwardingInfo will always be returned
// to the client unless the client was not selected to continue with the
// protocol.
message ForwardingInfo {
  // A URI prefix for the next service to send the request for the next protocol
  // phase to.
  //
  // The URI prefix must always start with "https://".
  //
  // The URI prefix may end with a trailing '/', but is not required to. During
  // the construction of the next protocol request, a slash will always be
  // inserted by the client between this prefix and the request's URI suffix.
  //
  // For example, if some protocol response's ForwardingInfo contains the prefix
  // "https://foo.bar.com" or "https://foo.bar.com/", and if the subsequent
  // protocol request's URI suffix is "/baz", then the subsequent request's full
  // URI would be "https://foo.bar.com/baz".
  string target_uri_prefix = 1;
  // Request headers that should be included with the next request for the next
  // protocol phase. Note that these headers should only be applied to protocol
  // requests (incl. requests to the long running `Operations` service), but not
  // to any `Resource` fetch requests.
  map<string, string> extra_request_headers = 2;
}

// The attestation measurement providing evidence of integrity for a client.
message AttestationMeasurement {
  string value = 1;
}

message ClientVersion {
  // Version code identifying the client release.
  string version_code = 1;
}

message Resource {
  // A resource can either be downloaded via a URI, or has its data inlined in
  // in this message itself.
  oneof resource {
    // The URI the resource can be downloaded from. Note that
    // `ForwardingInfo.target_uri_prefix` field generally don't apply to these
    // URIs.
    string uri = 1;

    // The inlined data for the resource. This will eventually replace `data`.
    InlineResource inline_resource = 3;
  }

  message InlineResource {
    // The inlined data for the resource.
    bytes data = 1;

    // The compression used for the inlined data, or unset if the data is
    // uncompressed.
    ResourceCompressionFormat compression_format = 2;
  }

  // Stable identifier for this resource, used by the client cache
  // implementation. If this field is not set, the client should not attempt to
  // cache the resource referenced by `uri`. Not set for inline_resources.
  string client_cache_id = 4;

  // The maximum duration for how long the resource should be cached by the
  // client. Not set if `client_cache_id` is not set.
  google.protobuf.Duration max_age = 5;

  reserved 2;
}

// The client's capabilities for processing Resource messages, such as the
// compressed file formats supported.
message ResourceCapabilities {
  // Compression formats supported for resources downloaded via `Resource.uri`.
  // All clients are assumed to support uncompressed payloads.
  repeated ResourceCompressionFormat supported_compression_formats = 1;
}

// Different file formats that may be used to compress resources.
enum ResourceCompressionFormat {
  RESOURCE_COMPRESSION_FORMAT_UNSPECIFIED = 0;
  // Gzip-compressed data. If data is compressed in this way, then the
  // "Content-Type" HTTP response header will have a "+gzip" suffix.
  RESOURCE_COMPRESSION_FORMAT_GZIP = 1;
}

// Currently empty message which is sent when client (device) is rejected for
// participation and is not assigned a task.
message RejectionInfo {}

// A suggestion to the client when to retry the connection to the service next
// time
message RetryWindow {
  // The suggested minimal duration after which the client should
  // retry. If the client retries earlier, it is likely it will be rejected
  // again.
  google.protobuf.Duration delay_min = 1;

  // Required. The suggested maximal duration after which the client should
  // retry, provided scheduling conditions allow. The client is supposed to make
  // a best effort to callback in the min..max window, and should avoid
  // calling before min. If the client calls after max, the likelihood to be
  // rejected again is higher.
  google.protobuf.Duration delay_max = 2;
}

// Information about where to upload data (e.g. aggregation results, client
// stats).
message ByteStreamResource {
  // Information to construct the URI to use for uploading the data.
  ForwardingInfo data_upload_forwarding_info = 1;
  // Resource name to which the data should be uploaded.
  // Clients should use this field as well as the
  // `ForwardingInfo.target_uri_prefix` to create the upload URL:
  // {target_uri_prefix}/upload/v1/media/{resource_name} (where
  // `{resource_name}` should be encoded as a multipath segment, as described
  // in
  // https://github.com/googleapis/googleapis/blob/master/google/api/http.proto).
  string resource_name = 2;
}

// Copied from //google/rpc/status.proto.
message Status {
  // The status code, which should be an enum value of [google.rpc.Code][].
  int32 code = 1;

  string message = 2;
}

// Describes to the server which tasks a client is eligible for.
message TaskEligibilityInfo {
  // A semantic version describing how the set of eligibility descriptors should
  // be interpreted. This fields enables assigning different semantics for how
  // the server should interpret the descriptors, without having to change the
  // wire format (e.g. different ways of interpreting `TaskWeight.weight`).
  int64 version = 1;

  // A list of task weights, which the server may use when assigning the client
  // a task in response to the current request.
  //
  // If none of the `TaskWeight` messages match a given task, then the client
  // must be considered ineligible for that task, and the server must not serve
  // the client that task.
  //
  // Therefore, if a `TaskEligibilityInfo` message is provided but this field is
  // empty then the client should be considered ineligible for all tasks in the
  // population (although in practice the client will simply close the
  // connection in that case, rather than issue a `CheckinRequest` with such an
  // empty list of weights).
  repeated TaskWeight task_weights = 2;
}

// Describes a weight that should be assigned to a specific task.
message TaskWeight {
  // Name of the task this weight applies to.
  string task_name = 1;

  // The weight that should be applied to the specified task.
  //
  // Must be >0.
  //
  // This weight may (or may not) be used by the server to implement some form
  // of task or client prioritization.
  float weight = 2;
}