// SPDX-License-Identifier: MIT
// Copyright © 2022 The Tvix Authors
syntax = "proto3";

package tvix.store.v1;

import "tvix/castore/protos/castore.proto";
import "tvix/store/protos/pathinfo.proto";

option go_package = "code.tvl.fyi/tvix/store-go;storev1";

service PathInfoService {
  // Return a PathInfo message matching the criteria specified in the
  // GetPathInfoRequest message.
  rpc Get(GetPathInfoRequest) returns (PathInfo);

  // Upload a PathInfo object to the remote end. It MUST not return until the
  // PathInfo object has been written on the the remote end.
  //
  // The remote end MAY check if a potential DirectoryNode has already been
  // uploaded.
  //
  // Uploading clients SHOULD obviously not steer other machines to try to
  // substitute before from the remote end before having finished uploading
  // PathInfo, Directories and Blobs.
  // The returned PathInfo object MAY contain additional narinfo signatures, but
  // is otherwise left untouched.
  rpc Put(PathInfo) returns (PathInfo);

  // Calculate the NAR representation of the contents specified by the
  // root_node. The calculation SHOULD be cached server-side for subsequent
  // requests.
  //
  // All references (to blobs or Directory messages) MUST already exist in the
  // store.
  //
  // The method can be used to produce a Nix fixed-output path, which contains
  // the (compressed) sha256 of the NAR content representation in the root_node
  // name (suffixed with the name).
  //
  // It can also be used to calculate arbitrary NAR hashes of output paths, in
  // case a legacy Nix Binary Cache frontend is provided.
  rpc CalculateNAR(tvix.castore.v1.Node) returns (CalculateNARResponse);

  // Return a stream of PathInfo messages matching the criteria specified in
  // ListPathInfoRequest.
  rpc List(ListPathInfoRequest) returns (stream PathInfo);
}

// The parameters that can be used to lookup a (single) PathInfo object.
// Currently, only a lookup by output hash is supported.
message GetPathInfoRequest {
  oneof by_what {
    // The output hash of a nix path (20 bytes).
    // This is the nixbase32-decoded portion of a Nix output path, so to substitute
    // /nix/store/xm35nga2g20mz5sm5l6n8v3bdm86yj83-cowsay-3.04
    // this field would contain nixbase32dec("xm35nga2g20mz5sm5l6n8v3bdm86yj83").
    bytes by_output_hash = 1;
  }
}

// The parameters that can be used to lookup (multiple) PathInfo objects.
// Currently no filtering is possible, all objects are returned.
message ListPathInfoRequest {}

// CalculateNARResponse is the response returned by the CalculateNAR request.
//
// It contains the size of the NAR representation (in bytes), and the sha56
// digest.
message CalculateNARResponse {
  // This size of the NAR file, in bytes.
  uint64 nar_size = 1;

  // The sha256 of the NAR file representation.
  bytes nar_sha256 = 2;
}