syntax = "proto3";

//
// This is a protobuf file. This is used by gRPC (and nRPC) to define the interface
//  between the front-end and the back-end. Because the front-end is compiled to
//  WebAssembly and has Javascript bindings, there are a few gotchas:
//
//    - A zero-field message will be turned into an empty tuple ()
//    - JS bindings are similar, except with JS Objects
//    - Values can be streamed back- to front-end with a Rust generator stream and a JS callback function
//    - Values can be streamed front- to back-end with a JS generator function and a Rust stream consumer
//
// The generated Rust module and Typescript bindings should provide a good clue as to how to pass parameters
//

package powertools;

// The most amazing nRPC service
service UserEvent {
  // back-end event
  rpc layout (Empty) returns (stream Interactable);

  // front-end event
  rpc event (stream Interaction) returns (Empty);
}

message Empty {}

message Interaction {
  uint64 id = 1;
  ElementValue now = 2;
}

message Interactable {
  ElementType element = 2;
  uint64 id = 1;
  string name = 3;
  string description = 4;
  ElementValue value = 5;
  repeated ElementValue possibleValues = 6;
}

enum ElementType {
  Display = 0;
  Toggle = 1;
  Slider = 2;
  Dropdown = 3;
  Button = 4;
}

message ElementValue {
  optional double number = 1;
  optional string text = 2;
  optional bool boolean = 3;
  optional bytes payload = 4;
  repeated string textList = 5;
}