feat: game session, turn system, lobby, and room events

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

game/lobby.go

@@ -0,0 +1,94 @@
+package game
+
+import (
+	"fmt"
+	"math/rand"
+	"sync"
+)
+
+type RoomStatus int
+
+const (
+	RoomWaiting RoomStatus = iota
+	RoomPlaying
+)
+
+type LobbyRoom struct {
+	Code    string
+	Name    string
+	Players []string
+	Status  RoomStatus
+	Session *GameSession
+}
+
+type Lobby struct {
+	mu    sync.RWMutex
+	rooms map[string]*LobbyRoom
+}
+
+func NewLobby() *Lobby {
+	return &Lobby{rooms: make(map[string]*LobbyRoom)}
+}
+
+func (l *Lobby) CreateRoom(name string) string {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	code := generateCode()
+	for l.rooms[code] != nil {
+		code = generateCode()
+	}
+	l.rooms[code] = &LobbyRoom{
+		Code:   code,
+		Name:   name,
+		Status: RoomWaiting,
+	}
+	return code
+}
+
+func (l *Lobby) JoinRoom(code, playerName string) error {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	room, ok := l.rooms[code]
+	if !ok {
+		return fmt.Errorf("room %s not found", code)
+	}
+	if len(room.Players) >= 4 {
+		return fmt.Errorf("room %s is full", code)
+	}
+	if room.Status != RoomWaiting {
+		return fmt.Errorf("room %s already in progress", code)
+	}
+	room.Players = append(room.Players, playerName)
+	return nil
+}
+
+func (l *Lobby) GetRoom(code string) *LobbyRoom {
+	l.mu.RLock()
+	defer l.mu.RUnlock()
+	return l.rooms[code]
+}
+
+func (l *Lobby) ListRooms() []*LobbyRoom {
+	l.mu.RLock()
+	defer l.mu.RUnlock()
+	result := make([]*LobbyRoom, 0, len(l.rooms))
+	for _, r := range l.rooms {
+		result = append(result, r)
+	}
+	return result
+}
+
+func (l *Lobby) RemoveRoom(code string) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	delete(l.rooms, code)
+}
+
+func generateCode() string {
+	const letters = "ABCDEFGHJKLMNPQRSTUVWXYZ"
+	b := make([]byte, 4)
+	for i := range b {
+		b[i] = letters[rand.Intn(len(letters))]
+	}
+	return string(b)
+}