syntax = "proto3";

package x0gp.v1;

option go_package = "github.com/x0gp/server/proto/gen/clientserverpb";

// ============================================================
// Wire protocol between client (browser / mobile) and server.
// ============================================================
//
// In PoC we use JSON via transport/codec.go. This file is the formal spec
// for the binary protobuf wire format we'll switch to in MVP/prod. The
// generated code lives in proto/gen/ and will replace transport/.
//
// Packet envelope (oneof payload):
//   message Packet {
//     uint64 seq = 1;
//     int64  ts_ms = 2;
//     oneof payload {
//       ClientHello   client_hello   = 10;
//       ServerHello   server_hello   = 11;
//       JoinRace      join_race      = 12;
//       LeaveRace     leave_race     = 13;
//       InputState    input_state    = 14;
//       RaceSnapshot  race_snapshot  = 15;
//       InputAck      input_ack      = 16;
//       Correction    correction     = 17;
//       RaceEvent     race_event     = 18;
//       Ping          ping           = 19;
//       Pong          pong           = 20;
//       ErrorMsg      error_msg      = 21;
//       ChatMessage   chat_message   = 22;
//     }
//   }

// --- Client -> Server ---

message ClientHello {
  string version   = 1;
  string token     = 2;   // JWT in prod; empty in dev
  string locale    = 3;
  string client_id = 4;   // for reconnect
}

message JoinRace {
  string race_id  = 1;
  int32  car_slot = 2;    // 0..3
  string car_name = 3;
}

message LeaveRace {
  string race_id = 1;
}

// High-rate control packet (60-120 Hz).
message InputState {
  float steering = 1;     // -1.0 .. 1.0
  float throttle = 2;     //  0.0 .. 1.0
  float brake    = 3;     //  0.0 .. 1.0
  int32 gear     = 4;     // -1 reverse, 0 neutral, 1..6 forward
  uint32 buttons = 5;
}

message Ping {
  int64 client_ts_ms = 1;
}

message ChatMessage {
  string text = 1;
}

// --- Server -> Client ---

message ServerHello {
  string session_id     = 1;
  uint64 race_tick      = 2;
  string server_version = 3;
  ServerConfig config   = 4;
}

message ServerConfig {
  int32 tick_rate_hz     = 1;
  int32 snapshot_rate_hz = 2;
  int32 max_cars         = 3;
}

message RaceSnapshot {
  uint64 tick    = 1;
  int64  ts_ms   = 2;
  double elapsed_s = 3;
  repeated CarInfo cars = 4;
}

message CarInfo {
  string id           = 1;
  string driver_name  = 2;
  double x            = 3;   // metres
  double y            = 4;   // metres
  double heading      = 5;   // radians
  double speed        = 6;   // m/s
  int32  lap          = 7;
  int32  sector       = 8;    // 0..2
  int64  last_lap_ms  = 9;
  int64  best_lap_ms  = 10;
  AppliedInput input_applied = 11;
  bool   dnf          = 12;
}

message AppliedInput {
  double steering = 1;
  double throttle = 2;
  double brake    = 3;
}

message InputAck {
  uint64 seq           = 1;
  int64  applied_at_ms = 2;
  int64  server_tick_ms = 3;
}

message Correction {
  uint64 tick           = 1;
  double delta_steering = 2;
  double delta_throttle = 3;
  string reason         = 4;
}

message RaceEvent {
  string race_id = 1;
  string event   = 2;   // "start" | "lap" | "sector" | "dnf" | "finish" | "joined" | "left"
  string car_id  = 3;
  int32  sector  = 4;
  int64  lap_ms  = 5;
  int64  ts_ms   = 6;
}

message Pong {
  int64 client_ts_ms = 1;
  int64 server_ts_ms = 2;
}

message ErrorMsg {
  string code    = 1;
  string message = 2;
}