package ws

import (
	"encoding/json"
	"sync"
)

// OnlineUser 在线成员信息
type OnlineUser struct {
	UserID   int64  `json:"user_id"`
	Nickname string `json:"nickname"`
	Avatar   string `json:"avatar"`
}

// Room 按 family_id 分组的聊天室
type Room struct {
	clients map[int64]*Client // user_id → Client
	mu      sync.RWMutex
}

// Hub 管理所有 Room
type Hub struct {
	rooms map[int64]*Room // family_id → Room
	mu    sync.RWMutex
}

var defaultHub = &Hub{
	rooms: make(map[int64]*Room),
}

func GetHub() *Hub {
	return defaultHub
}

// getOrCreateRoom 获取或创建 Room
func (h *Hub) getOrCreateRoom(familyID int64) *Room {
	h.mu.Lock()
	defer h.mu.Unlock()

	room, ok := h.rooms[familyID]
	if !ok {
		room = &Room{
			clients: make(map[int64]*Client),
		}
		h.rooms[familyID] = room
	}
	return room
}

// Join 用户加入房间，广播 online 事件
func (h *Hub) Join(familyID int64, client *Client) {
	room := h.getOrCreateRoom(familyID)

	room.mu.Lock()
	room.clients[client.userID] = client
	onlineUsers := h.collectOnlineUsers(room)
	room.mu.Unlock()

	h.broadcastOnlineUsers(familyID, onlineUsers)
}

// Leave 用户离开房间，广播 offline 事件
func (h *Hub) Leave(familyID int64, userID int64) {
	room := h.getOrCreateRoom(familyID)

	room.mu.Lock()
	delete(room.clients, userID)
	onlineUsers := h.collectOnlineUsers(room)
	room.mu.Unlock()

	// 广播 offline 给房间内其他人
	msg, _ := json.Marshal(map[string]any{
		"type":    "offline",
		"user_id": userID,
	})
	h.broadcastRaw(familyID, msg)

	// 广播更新后的在线列表
	h.broadcastOnlineUsers(familyID, onlineUsers)
}

// Broadcast 向房间内所有连接广播消息
func (h *Hub) Broadcast(familyID int64, msg any) {
	data, err := json.Marshal(msg)
	if err != nil {
		return
	}
	h.broadcastRaw(familyID, data)
}

// broadcastRaw 向房间内所有连接广播原始字节
func (h *Hub) broadcastRaw(familyID int64, data []byte) {
	h.mu.RLock()
	room, ok := h.rooms[familyID]
	h.mu.RUnlock()
	if !ok {
		return
	}

	room.mu.RLock()
	defer room.mu.RUnlock()

	for _, client := range room.clients {
		select {
		case client.send <- data:
		default:
			// 发送通道满则跳过
		}
	}
}

// collectOnlineUsers 收集在线用户列表（调用方需持有 room.mu 锁）
func (h *Hub) collectOnlineUsers(room *Room) []OnlineUser {
	users := make([]OnlineUser, 0, len(room.clients))
	for _, client := range room.clients {
		users = append(users, OnlineUser{
			UserID:   client.userID,
			Nickname: client.nickname,
			Avatar:   client.avatar,
		})
	}
	return users
}

// broadcastOnlineUsers 广播在线用户列表
func (h *Hub) broadcastOnlineUsers(familyID int64, users []OnlineUser) {
	msg, _ := json.Marshal(map[string]any{
		"type":  "online",
		"users": users,
	})
	h.broadcastRaw(familyID, msg)
}