package hub

import (
	"sync"

	"github.com/gorilla/websocket"
)

// Hub 管理 WebSocket 客户端连接
type Hub struct {
	mu      sync.RWMutex
	clients map[string]map[*websocket.Conn]bool // userID -> connections
}

func NewHub() *Hub {
	return &Hub{
		clients: make(map[string]map[*websocket.Conn]bool),
	}
}

func (h *Hub) Register(userID string, conn *websocket.Conn) {
	h.mu.Lock()
	defer h.mu.Unlock()

	if h.clients[userID] == nil {
		h.clients[userID] = make(map[*websocket.Conn]bool)
	}
	h.clients[userID][conn] = true
}

func (h *Hub) Unregister(userID string, conn *websocket.Conn) {
	h.mu.Lock()
	defer h.mu.Unlock()

	if conns, ok := h.clients[userID]; ok {
		delete(conns, conn)
		if len(conns) == 0 {
			delete(h.clients, userID)
		}
	}
}

// SendToUser 向指定用户的所有连接推送消息
func (h *Hub) SendToUser(userID string, message []byte) error {
	h.mu.RLock()
	defer h.mu.RUnlock()

	conns, ok := h.clients[userID]
	if !ok {
		return nil
	}

	for conn := range conns {
		if err := conn.WriteMessage(websocket.TextMessage, message); err != nil {
			return err
		}
	}
	return nil
}