syntax = "proto3";
package eu.zettoit.graph;

service ObjectService{
  rpc Create(Object) returns (Empty);
  rpc Delete(Object) returns (Empty);
  rpc Exists(Object) returns (ExistsResponse);
}

service RelationService {
  rpc Create(Relation) returns (Empty);
  rpc Delete(Relation) returns (Empty);
  rpc Exists(Relation) returns (ExistsResponse);
}

service QueryService {
  // check if one object or objectset is related to another by a relation
  rpc IsRelatedTo(Relation) returns (IsRelatedToResponse);

  // get all objects that are related to one object by a relation
  rpc GetRelatedTo(Set) returns (GetRelatedToResponse);

  // get all objects that the given object has a relation with
  rpc GetRelations(GetRelationsRequest) returns (GetRelationsResponse);
}

message ExistsResponse {
  bool exists = 1;
}

message IsRelatedToResponse{
  bool related = 1;
}

message GetRelatedToResponse{
  repeated Object objects = 1;
}

message GetRelationsRequest{
  Object object = 1;
  string relation = 2;
}
message GetRelationsResponse{
  repeated Object objects = 1;
}

message Object{
  string namespace = 1;
  string id = 2;
}
message Set{
  string namespace = 1;
  string id = 2;
  string relation = 3;
}

message ObjectOrSet {
  oneof object_or_set{
    Object object = 1;
    Set set = 2;
  };
}

message Relation{
  oneof src{
    Object src_obj = 1;
    Set src_set = 2;
  };
  Object dst = 3;
  string relation = 4;
}

message Empty{}