syntax = "proto3";

package mpc.router.v1;

option go_package = "github.com/rwadurian/mpc-system/api/grpc/router/v1;router";

// MessageRouter service handles MPC message routing
service MessageRouter {
  // RouteMessage routes a message from one party to others
  rpc RouteMessage(RouteMessageRequest) returns (RouteMessageResponse);

  // SubscribeMessages subscribes to messages for a party (streaming)
  rpc SubscribeMessages(SubscribeMessagesRequest) returns (stream MPCMessage);

  // GetPendingMessages retrieves pending messages (polling alternative)
  rpc GetPendingMessages(GetPendingMessagesRequest) returns (GetPendingMessagesResponse);

  // RegisterParty registers a party with the message router (party actively connects)
  rpc RegisterParty(RegisterPartyRequest) returns (RegisterPartyResponse);

  // SubscribeSessionEvents subscribes to session lifecycle events (session start, etc.)
  rpc SubscribeSessionEvents(SubscribeSessionEventsRequest) returns (stream SessionEvent);
}

// RouteMessageRequest routes an MPC message
message RouteMessageRequest {
  string session_id = 1;
  string from_party = 2;
  repeated string to_parties = 3;        // Empty for broadcast
  int32 round_number = 4;
  string message_type = 5;
  bytes payload = 6;                     // Encrypted MPC message
}

// RouteMessageResponse confirms message routing
message RouteMessageResponse {
  bool success = 1;
  string message_id = 2;
}

// SubscribeMessagesRequest subscribes to messages for a party
message SubscribeMessagesRequest {
  string session_id = 1;
  string party_id = 2;
}

// MPCMessage represents an MPC protocol message
message MPCMessage {
  string message_id = 1;
  string session_id = 2;
  string from_party = 3;
  bool is_broadcast = 4;
  int32 round_number = 5;
  string message_type = 6;
  bytes payload = 7;
  int64 created_at = 8;                  // Unix timestamp milliseconds
}

// GetPendingMessagesRequest retrieves pending messages
message GetPendingMessagesRequest {
  string session_id = 1;
  string party_id = 2;
  int64 after_timestamp = 3;             // Get messages after this timestamp
}

// GetPendingMessagesResponse contains pending messages
message GetPendingMessagesResponse {
  repeated MPCMessage messages = 1;
}

// RegisterPartyRequest registers a party with the router
message RegisterPartyRequest {
  string party_id = 1;                       // Unique party identifier
  string party_role = 2;                     // persistent, delegate, or temporary
  string version = 3;                        // Party software version
}

// RegisterPartyResponse confirms party registration
message RegisterPartyResponse {
  bool success = 1;
  string message = 2;
  int64 registered_at = 3;                   // Unix timestamp milliseconds
}

// SubscribeSessionEventsRequest subscribes to session events
message SubscribeSessionEventsRequest {
  string party_id = 1;                       // Party ID subscribing to events
  repeated string event_types = 2;           // Event types to subscribe (empty = all)
}

// SessionEvent represents a session lifecycle event
message SessionEvent {
  string event_id = 1;
  string event_type = 2;                     // session_created, session_started, etc.
  string session_id = 3;
  int32 threshold_n = 4;
  int32 threshold_t = 5;
  repeated string selected_parties = 6;       // PartyIDs selected for this session
  map<string, string> join_tokens = 7;        // PartyID -> JoinToken mapping
  bytes message_hash = 8;                     // For sign sessions
  int64 created_at = 9;                       // Unix timestamp milliseconds
  int64 expires_at = 10;                      // Unix timestamp milliseconds
}