// The nối từ wire contract.
//
// This file is the single source of truth for everything crossing the
// WebSocket. Both the Go server and the JavaScript client are generated from
// it; neither side hand-writes a message type. Every frame is a binary
// protobuf message — there is no JSON fallback and no text frame.
//
// Compatibility rules, because a deployed client outlives a deploy:
//   - changes are additive only;
//   - a removed field's tag goes to `reserved`, never to another field;
//   - Hello.protocol_version lets the server refuse an incompatible client
//     with a readable error instead of failing to decode.
syntax = "proto3";

package noitu.v1;

option go_package = "github.com/tiennm99dev/noitu/server/gen/noitu/v1;noituv1";

// Difficulty selects the bot's strategy in a vs-bot game.
enum Difficulty {
  DIFFICULTY_UNSPECIFIED = 0;
  DIFFICULTY_EASY = 1;
  DIFFICULTY_MEDIUM = 2;
  DIFFICULTY_HARD = 3;
}

// RejectReason says why a submitted word was not accepted. It is deliberately
// a separate type from the engine's internal game.RejectReason: the wire
// contract must not change every time the engine is refactored. The mapping
// lives in server/internal/wsapi/convert.go.
enum RejectReason {
  REJECT_REASON_UNSPECIFIED = 0;
  // Fewer than two syllables.
  REJECT_REASON_TOO_FEW_SYLLABLES = 1;
  // First syllable does not match the required syllable.
  REJECT_REASON_WRONG_LINK = 2;
  REJECT_REASON_NOT_IN_DICTIONARY = 3;
  REJECT_REASON_ALREADY_USED = 4;
  REJECT_REASON_NOT_YOUR_TURN = 5;
  // The turn deadline passed before the word arrived.
  REJECT_REASON_TIMEOUT = 6;
  // The game had already finished.
  REJECT_REASON_GAME_OVER = 7;
}

// GameEndReason says how a finished game ended.
enum GameEndReason {
  GAME_END_REASON_UNSPECIFIED = 0;
  GAME_END_REASON_TIMEOUT = 1;
  GAME_END_REASON_NO_LEGAL_MOVE = 2;
  GAME_END_REASON_OPPONENT_LEFT = 3;
  GAME_END_REASON_RESIGNED = 4;
}

// ---------------------------------------------------------------------------
// Client -> server
// ---------------------------------------------------------------------------

// Hello opens a session. nickname is a *request*: the server sanitizes it and
// reports what it actually stored in Welcome.accepted_nickname.
message Hello {
  uint32 protocol_version = 1;
  // Empty on a fresh session; a token from a previous Welcome to resume one.
  string resume_token = 2;
  string nickname = 3;
}

message StartBotGame {
  Difficulty difficulty = 1;
}

message CreateRoom {}

message JoinRoom {
  string room_code = 1;
}

// SubmitWord carries the turn it was typed for. The server rejects a
// turn_seq that is not the current one, which makes a double-submit or a
// submission racing the timeout detectable rather than silently applied.
message SubmitWord {
  string word = 1;
  uint32 turn_seq = 2;
}

message Resign {}

// SetReady is a guest declaring themselves ready, or taking it back.
//
// Only guests have a readiness to set. The owner's is implied by StartGame:
// asking for the game to begin is the same statement, and a second flag they
// would always have to set first buys nothing.
message SetReady {
  bool ready = 1;
}

// StartGame is the owner beginning the game the lobby has agreed on. It is
// refused unless at least one guest is seated and every seated guest is
// connected and ready.
message StartGame {}

// KickPlayer is the owner freeing one seat. Refused while that player is
// ready: readiness is a commitment, and a player who has made it is not
// something the owner gets to overrule.
message KickPlayer {
  // Which seat, from RoomState.players. A room holds up to four people, so
  // "the other one" stopped being an answer.
  string player_id = 1;
}

// LeaveRoom gives up a seat without dropping the connection, which is what
// makes a room outlive one game rather than one visit. Refused while the
// sender is ready — unreadying first is the deliberate friction.
message LeaveRoom {}

// SendChat is one line of text from a seated player to the other.
message SendChat {
  string text = 1;
}

// Ping echoes the client clock so Pong can expose the offset between the two.
message Ping {
  int64 client_time_ms = 1;
}

message ClientMessage {
  // 8 was RequestRematch, retired with the rematch handshake: the lobby is
  // where a next game is agreed now. Reserved at message level because a
  // oneof cannot hold the statement itself.
  reserved 8;

  oneof payload {
    Hello hello = 1;
    StartBotGame start_bot_game = 2;
    CreateRoom create_room = 3;
    JoinRoom join_room = 4;
    SubmitWord submit_word = 5;
    Resign resign = 6;
    Ping ping = 7;
    SetReady set_ready = 9;
    StartGame start_game = 10;
    KickPlayer kick_player = 11;
    LeaveRoom leave_room = 12;
    SendChat send_chat = 13;
  }
}

// ---------------------------------------------------------------------------
// Server -> client
// ---------------------------------------------------------------------------

message Welcome {
  string session_id = 1;
  string resume_token = 2;
  uint32 protocol_version = 3;
  // What the server stored after sanitizing Hello.nickname. The client must
  // display this, not the string it sent.
  string accepted_nickname = 4;
}

// PlayedWord is one accepted move. word is the canonical spelling, which can
// differ from what the player typed; typed preserves the raw input so the UI
// can show that a correction happened instead of silently rewriting the text.
message PlayedWord {
  string word = 1;
  bool by_me = 2;
  uint32 points = 3;
  uint32 syllables = 4;
  string typed = 5;
  // Which seat played it. by_me answers "was this mine"; with four people at
  // the table the chain also has to say whose the other words were, and a seat
  // id says that without the client matching display names.
  string player_id = 6;
  // What the word means, at most five senses. Empty when the dictionary has
  // no definition for the word; the client then says so rather than hiding
  // the row's panel, so every word in the chain behaves the same.
  repeated Sense meanings = 7;
}

// Sense is one definition of a word as Wiktionary gives it: the part of
// speech it sits under, in Vietnamese ("danh từ"), empty when the heading was
// not one the builder knows, and the definition stripped of markup at at most
// 200 characters. Plain text both: the client renders them as text, never as
// markup.
message Sense {
  string pos = 1;
  string gloss = 2;
}

// PlayerSlot is one seat in the room, rendered for one recipient.
//
// The recipient's own row is in the list like everybody else's, marked by
// is_me. That is deliberately the only way to find yourself: a separate
// i_am_owner alongside an is_owner in the list would be two encodings of one
// fact, and two ways for a client to disagree with the server.
message PlayerSlot {
  // Stable for as long as this player holds the seat. Not stable across a
  // seat being vacated and refilled, which is exactly when a name stops
  // meaning the same person too.
  string player_id = 1;
  // Always server-sanitized, as everywhere else another player's name appears.
  string name = 2;
  bool is_me = 3;
  bool is_owner = 4;
  // Always false for the owner, whose readiness is StartGame itself.
  bool ready = 5;
  // False while this player is inside their reconnect window.
  bool connected = 6;
  // How many games this seat has won since the room opened. A room outlives
  // its games, so the tally belongs to the seat rather than to any one of
  // them; it starts again when the seat is vacated, because by then the name
  // on it no longer means the same person.
  uint32 wins = 7;
}

// PlayerScore is one player in a running or finished game.
//
// Separate from PlayerSlot because they answer different questions: a slot is
// about the room, a score is about the game being played in it. A player who
// has been eliminated still has both — being out of the game is not being out
// of the room.
message PlayerScore {
  string player_id = 1;
  string name = 2;
  bool is_me = 3;
  uint32 score = 4;
  // True once this player has been knocked out. They keep their seat, their
  // score and their words; they simply no longer get a turn.
  bool eliminated = 5;
  bool connected = 6;
  // Final placing, 1 for the winner. Zero while the game is still running,
  // which is what tells the two apart without a second field.
  uint32 rank = 7;
}

// GameStarted is rendered per recipient: my_turn is true for exactly one
// player.
message GameStarted {
  string opening_word = 1;
  string current_syllable = 2;
  bool my_turn = 3;
  // Absolute server timestamp. The client counts down to it and never trusts
  // its own clock for authority.
  int64 deadline_unix_ms = 4;
  uint32 turn_seq = 5;
  uint32 turn_limit_ms = 6;
  // Everyone playing, in turn order.
  repeated PlayerScore players = 7;
  // Whose turn it is. my_turn above says whether it is yours; this says whose
  // it is when it is not, which a two-player game never had to.
  string turn_player_id = 8;
  // The opening word's senses, as PlayedWord.meanings for a played word.
  repeated Sense opening_meanings = 9;
}

// TurnUpdate follows every turn change and goes to every player, serialized
// once per recipient so by_me and my_turn are correct for each.
//
// played is absent when the turn moved without a word being played, which is
// what an elimination does: the syllable and the used set survive the player
// who could not answer them.
message TurnUpdate {
  // 6 was my_score and 7 was opponent_score. Both are in players below now,
  // where a four-way game can express them.
  reserved 6, 7;

  PlayedWord played = 1;
  string current_syllable = 2;
  bool my_turn = 3;
  int64 deadline_unix_ms = 4;
  uint32 turn_seq = 5;
  uint32 chain_length = 8;
  // Everyone playing, in turn order, with scores as they stand.
  repeated PlayerScore players = 9;
  string turn_player_id = 10;
}

message MoveRejected {
  RejectReason reason = 1;
  string word = 2;
  uint32 turn_seq = 3;
}

// GameOver is rendered per recipient: i_won is true for exactly one player,
// the one still standing when everybody else had been eliminated.
message GameOver {
  // 3 was my_score, which is now the standings row where is_me is true. 5 was
  // suggestions, which moved to PlayerEliminated: they describe the position a
  // player was stuck on, and by the time a game ends that is no longer the
  // position anyone but the last player out was looking at.
  reserved 3, 5;

  bool i_won = 1;
  GameEndReason reason = 2;
  uint32 chain_length = 4;
  // The final table, best first: the player left standing, then the others in
  // reverse order of elimination. Outlasting somebody is what beats them, so
  // the ranking is finishing order and each score is reported beside it rather
  // than deciding it.
  repeated PlayerScore standings = 6;
}

// PlayerEliminated is one player knocked out of a game that is still running.
//
// Rendered per recipient like everything else in a room, and the only message
// whose contents differ by more than a flag: suggestions are filled in solely
// for the player who went out, because they are the one who was stuck.
message PlayerEliminated {
  string player_id = 1;
  string name = 2;
  bool is_me = 3;
  GameEndReason reason = 4;
  // A few words the position still had, for the player who just lost it. An
  // empty list is itself the answer: nobody could have answered that syllable.
  repeated string suggestions = 5;
}

// ServerError.message is a UI key such as "room_not_found", never prose: all
// Vietnamese copy lives in the frontend so it stays in one place.
message ServerError {
  string code = 1;
  string message = 2;
}

message Pong {
  int64 client_time_ms = 1;
  int64 server_time_ms = 2;
}

// RoomState is the whole room, rendered for one recipient, and it is the only
// thing the lobby screen is built from. Sent on every change a player could
// see — a seat filled or freed, a readiness set, an owner promoted, somebody
// dropping or coming back — and again on resume, so a client that missed a
// frame recovers by being told the state rather than by replaying the events
// that led to it.
//
// It describes the room, not the game, so it is meaningful during one too:
// while a game runs this is what carries presence, which is why there is no
// separate message for a player disconnecting.
message RoomState {
  // 2 was i_am_owner and 4 was i_am_ready: both are in the recipient's own
  // row in players now, and two encodings of one fact are two ways for a
  // client to disagree with the server. 5 through 8 were the opponent_*
  // fields, which could only ever describe a second player.
  reserved 2, 4, 5, 6, 7, 8;

  string room_code = 1;
  // Whether StartGame would be accepted right now. The server decides this
  // because it owns every condition that feeds it.
  bool can_start = 3;
  // Everyone seated, in seat order, which is also the turn order a game will
  // use. Always includes the recipient, marked is_me.
  repeated PlayerSlot players = 9;
  // How many seats the room has and how many players a game needs. Sent
  // rather than compiled in, so the lobby draws whatever the server allows and
  // raising the limit does not need a client deploy.
  uint32 max_players = 10;
  uint32 min_players = 11;
  // How long a seat is held for a player who has dropped. The client counts
  // down against it for anybody whose connected is false; the server still
  // decides when the seat is actually forfeit.
  uint32 grace_ms = 12;
}

// ChatMessage is one line as one recipient sees it. Rendered per recipient
// like every other room message: from_me is the only field that differs, and
// it is what lets the client style its own words without matching names.
message ChatMessage {
  bool from_me = 1;
  // Server-sanitized, as everywhere a name is shown. Empty when the author has
  // left the room: the seat they spoke from may be somebody else's now, and a
  // name outlives neither. The client labels an empty author itself.
  string author = 2;
  string text = 3;
  // Server clock. The client renders it; it never orders by its own clock.
  int64 sent_unix_ms = 4;
  // Which seat spoke, so the client can colour a line by its author instead
  // of by matching display names. Cleared with the author for a line whose
  // seat has been vacated.
  string player_id = 5;
}

// ChatHistory is the whole panel, oldest first, sent when a player is seated in
// a room or resumes into one. A snapshot rather than a replayed stream, for the
// same reason RoomState is one: a client that missed frames is correct again
// from the next one instead of having to catch up on events.
//
// Scoped to the recipient: it carries only what was said while they held their
// seat, which is why it is built per seat rather than broadcast.
message ChatHistory {
  repeated ChatMessage messages = 1;
}

message ServerMessage {
  // 2 was RoomCreated and 3 was RoomJoined: both said part of what RoomState
  // now says in full, and three messages describing one lobby is three ways
  // for a client to hold a different view of it. 11 was RematchState, retired
  // with the rematch handshake. 8 was OpponentLeft, retired with the second
  // seat: presence is per player now, and RoomState already carries it to
  // everyone in the room whether or not a game is running.
  reserved 2, 3, 8, 11;

  oneof payload {
    Welcome welcome = 1;
    GameStarted game_started = 4;
    TurnUpdate turn_update = 5;
    MoveRejected move_rejected = 6;
    GameOver game_over = 7;
    ServerError error = 9;
    Pong pong = 10;
    RoomState room_state = 12;
    ChatMessage chat_message = 13;
    ChatHistory chat_history = 14;
    PlayerEliminated player_eliminated = 15;
  }
}