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

package tvix.store.v1;

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

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

service PathInfoService {
    // Return a PathInfo message, identified by the decoded nixbase32 part
    // of a Nix output path.
    //
    // To substitute /nix/store/xm35nga2g20mz5sm5l6n8v3bdm86yj83-
    // cowsay-3.04 the bytes in the request would be
    // nixbase32dec("xm35nga2g20mz5sm5l6n8v3bdm86yj83").
    rpc Get(GetPathInfoRequest) returns (PathInfo);

    // Put uploads 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(Node) returns (CalculateNARResponse);
}

// GetPathInfoRequest describes the lookup parameters that can be used to
// lookup a PathInfo objects.
// 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;
    };
}

// 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.
    uint32 nar_size = 1;

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