// Copyright 2020-2026 Buf Technologies, Inc.
//
// 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 buf.alpha.registry.v1alpha1;

import "google/protobuf/descriptor.proto";

// Provides endpoints for downloading dynamic schemas and for using schemas
// in validation and data transformation functions.
service SchemaService {
  // GetSchema allows the caller to download a schema for one or more requested
  // types, RPC services, or RPC methods.
  rpc GetSchema(GetSchemaRequest) returns (GetSchemaResponse) {
    option idempotency_level = NO_SIDE_EFFECTS;
  }

  // ConvertMessage allows the caller to convert a given message data blob from
  // one format to another by referring to a type schema for the blob.
  rpc ConvertMessage(ConvertMessageRequest) returns (ConvertMessageResponse);
  // TODO: move this to ConvertService and remove its existing, unused endpoint.

  // TODO: batch or streaming endpoint, for more efficient conversion of many messages
}

message GetSchemaRequest {
  // The owner of the repo that contains the schema to retrieve (a user name or
  // organization name).
  string owner = 1;
  // The name of the repo that contains the schema to retrieve.
  string repository = 2;
  // Optional version of the repo. If unspecified, defaults to latest version on
  // the repo's "main" branch.
  string version = 3;

  // Zero or more types names. The names may refer to messages, enums, services,
  // methods, or extensions. All names must be fully-qualified. If any name
  // is unknown, the request will fail and no schema will be returned.
  //
  // If no names are provided, the full schema for the module is returned.
  // Otherwise, the resulting schema contains only the named elements and all of
  // their dependencies. This is enough information for the caller to construct
  // a dynamic message for any requested message types or to dynamically invoke
  // an RPC for any requested methods or services.
  repeated string types = 4;

  // If present, this is a commit that the client already has cached. So if the
  // given module version resolves to this same commit, the server should not
  // send back any descriptors since the client already has them.
  //
  // This allows a client to efficiently poll for updates: after the initial RPC
  // to get a schema, the client can cache the descriptors and the resolved
  // commit. It then includes that commit in subsequent requests in this field,
  // and the server will only reply with a schema (and new commit) if/when the
  // resolved commit changes.
  string if_not_commit = 5;

  // If true, the returned schema will not include extension definitions for custom
  // options that appear on schema elements. When filtering the schema based on the
  // given element names, options on all encountered elements are usually examined
  // as well. But that is not the case if excluding custom options.
  //
  // This flag is ignored if element_names is empty as the entire schema is always
  // returned in that case.
  bool exclude_custom_options = 6;

  // If true, the returned schema will not include known extensions for extendable
  // messages for schema elements. If exclude_custom_options is true, such extensions
  // may still be returned if the applicable descriptor options type is part of the
  // requested schema.
  //
  // This flag is ignored if element_names is empty as the entire schema is always
  // returned in that case.
  bool exclude_known_extensions = 7;

  // TODO: consider providing a way for client to indicate what files the server
  //   can exclude, to reduce response size when caller already knows things
  //   (for example, usually no need to include google/protobuf/descriptor.proto)
}

message GetSchemaResponse {
  // The resolved version of the schema. If the requested version was a commit,
  // this value is the same as that. If the requested version referred to a tag
  // or branch, this is the commit for that tag or latest commit for that
  // branch. If the request did not include any version, this is the latest
  // version for the module's main branch.
  string commit = 1;
  // The schema, which is a set of file descriptors that include the requested elements
  // and their dependencies.
  google.protobuf.FileDescriptorSet schema_files = 2;
}

message ConvertMessageRequest {
  // The owner of the repo that contains the schema to retrieve (a user name or
  // organization name).
  string owner = 1;
  // The name of the repo that contains the schema to retrieve.
  string repository = 2;
  // Optional version of the repo. This can be a tag or branch name or a commit.
  // If unspecified, defaults to latest version on the repo's "main" branch.
  string version = 3;

  // The fully-qualified name of the message. Required.
  string message_name = 4;

  // The format of the input data. Required.
  Format input_format = 5;

  // The input data that is to be converted. Required. This must be
  // a valid encoding of type indicated by message_name in the format
  // indicated by input_format.
  bytes input_data = 6;

  // If true, any unresolvable fields in the input are discarded. For
  // formats other than FORMAT_BINARY, this means that the operation
  // will fail if the input contains unrecognized field names. For
  // FORMAT_BINARY, unrecognized fields can be retained and possibly
  // included in the reformatted output (depending on the requested
  // output format).
  bool discard_unknown = 7;

  oneof output_format {
    BinaryOutputOptions output_binary = 8;
    JSONOutputOptions output_json = 9;
    TextOutputOptions output_text = 10;
  }
}

enum Format {
  FORMAT_UNSPECIFIED = 0;

  FORMAT_BINARY = 1;
  FORMAT_JSON = 2;
  FORMAT_TEXT = 3;
}

message BinaryOutputOptions {}

message JSONOutputOptions {
  // Enum fields will be emitted as numeric values. If false (the default), enum
  // fields are emitted as strings that are the enum values' names.
  bool use_enum_numbers = 3;
  // Includes fields that have their default values. This applies only to fields
  // defined in proto3 syntax that have no explicit "optional" keyword. Other
  // optional fields will be included if present in the input data.
  bool include_defaults = 4;
}

message TextOutputOptions {
  // If true and the input data includes unrecognized fields, the unrecognized
  // fields will be preserved in the text output (using field numbers and raw
  // values).
  bool include_unrecognized = 2;
}

message ConvertMessageResponse {
  // The resolved version of the schema. If the requested version was a commit,
  // this value is the same as that. If the requested version referred to a tag
  // or branch, this is the commit for that tag or latest commit for that
  // branch. If the request did not include any version, this is the latest
  // version for the module's main branch.
  string commit = 1;
  // The reformatted data.
  bytes output_data = 2;
}
