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

package tvix.castore.v1;

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

option go_package = "code.tvl.fyi/tvix/castore-go;castorev1";

service DirectoryService {
  // Get retrieves a stream of Directory messages, by using the lookup
  // parameters in GetDirectoryRequest.
  // Keep in mind multiple DirectoryNodes in different parts of the graph might
  // have the same digest if they have the same underlying contents,
  // so sending subsequent ones can be omitted.
  //
  // It is okay for certain implementations to only allow retrieval of
  // Directory digests that are at the "root", aka the last element that's
  // sent in a Put. This makes sense for implementations bundling closures of
  // directories together in batches.
  rpc Get(GetDirectoryRequest) returns (stream Directory);

  // Put uploads a graph of Directory messages.
  // Individual Directory messages need to be send in an order walking up
  // from the leaves to the root - a Directory message can only refer to
  // Directory messages previously sent in the same stream.
  // Keep in mind multiple DirectoryNodes in different parts of the graph might
  // have the same digest if they have the same underlying contents,
  // so sending subsequent ones can be omitted.
  // We might add a separate method, allowing to send partial graphs at a later
  // time, if requiring to send the full graph turns out to be a problem.
  rpc Put(stream Directory) returns (PutDirectoryResponse);
}

message GetDirectoryRequest {
  oneof by_what {
    // The blake3 hash of the (root) Directory message, serialized in
    // protobuf canonical form.
    // Keep in mind this can be a subtree of another root.
    bytes digest = 1;
  }

  // If set to true, recursively resolve all child Directory messages.
  // Directory messages SHOULD be streamed in a recursive breadth-first walk,
  // but other orders are also fine, as long as Directory messages are only
  // sent after they are referred to from previously sent Directory messages.
  bool recursive = 2;
}

message PutDirectoryResponse {
  bytes root_digest = 1;
}