syntax = "proto3";
package ha.v1;
option go_package = "gitea.nik4nao.com/nik/home-services/gen/ha/v1;hav1";
import "ha/v1/common.proto";

// TODO: implement EventService fan-out.
// Architecture:
//   1. adapters/secondary/ha/websocket.go connects to HA WebSocket,
//      authenticates, and subscribes to state_changed events.
//   2. An internal broker (internal/fanout/broker.go) holds a sync.Map of
//      subscriber channels, one per active Subscribe stream.
//   3. The WebSocket adapter publishes to the broker; the gRPC Subscribe
//      handler reads from its channel and streams to the client.
//   4. On client disconnect (ctx.Done()), the handler deregisters its channel.
service EventService {
  rpc Subscribe(SubscribeRequest) returns (stream StateChangeEvent);
}

message SubscribeRequest {
  repeated string entity_ids = 1;
  repeated string domains    = 2;
}

message StateChangeEvent {
  string               entity_id  = 1;
  optional EntityState old_state  = 2;  // absent on first appearance
  EntityState          new_state  = 3;
  string               event_time = 4;  // RFC3339
}