package routers

import (
	"fmt"
	"log"
	"net/http"
	"sync"

	"github.com/gorilla/websocket"
)

// 用户 websocket 连接池, 用于向用户推送其关注的对象状态变化
// 用户可以添加关注的对象, 当对象状态变化时, 会向用户推送消息
// 用户可以取消关注的对象, 当用户没有关注时, 会从连接池中移除用户的连接
// 用户关注分为两种情况: 1. 当前用户正在查看的对象; 2. 当前用户关注的对象(两个集合的并集, 才是此处的对象推送列表)
// 关注的对象变化事件为有记录的消息, 因而并不需要监听对象的变化, 只需要监听消息盒子的变化即可

type WebSocketManager struct {
	connections map[*websocket.Conn]map[string]string // ws:object_name:object_id
	objects     map[string]map[string]*websocket.Conn // object_name:object_id:ws
	mutex       sync.RWMutex
}

// 获取连接的全部关注对象
func (mgr *WebSocketManager) GetConnectionObjects(conn *websocket.Conn) map[string]string {
	mgr.mutex.RLock()
	defer mgr.mutex.RUnlock()
	return mgr.connections[conn]
}

// 获取对象的全部连接
func (mgr *WebSocketManager) GetObjectConnections(object_name string) map[string]*websocket.Conn {
	mgr.mutex.RLock()
	defer mgr.mutex.RUnlock()
	return mgr.objects[object_name]
}

// 添加一个新连接
func (mgr *WebSocketManager) AddConnection(conn *websocket.Conn) {
	mgr.mutex.Lock()
	defer mgr.mutex.Unlock()
	fmt.Println("添加一个新连接", conn.RemoteAddr().String())
	mgr.connections[conn] = make(map[string]string)
}

// 添加一个新对象
func (mgr *WebSocketManager) AddObject(object_name string, object_id string, conn *websocket.Conn) {
	mgr.mutex.Lock()
	defer mgr.mutex.Unlock()

	// 添加对象
	object, ok := mgr.objects[object_name]
	if !ok {
		object = make(map[string]*websocket.Conn)
		mgr.objects[object_name] = object
	}
	object[object_id] = conn

	// 添加连接
	mgr.connections[conn][object_name] = object_id
}

// 移除一个连接
func (mgr *WebSocketManager) RemoveConnection(conn *websocket.Conn) {
	mgr.mutex.Lock()
	defer mgr.mutex.Unlock()

	// 移除连接时, 需要将此连接关注的对象从连接池中移除
	for object_name, object_id := range mgr.connections[conn] {
		delete(mgr.objects[object_name], object_id)
	}

	delete(mgr.connections, conn)
}

// 移除一个对象
func (mgr *WebSocketManager) RemoveObject(object_name string, object_id string) {
	mgr.mutex.Lock()
	defer mgr.mutex.Unlock()
	defer fmt.Println("移除对象:", object_name, object_id)

	// 先获取监听此对象的所有连接
	object, ok := mgr.objects[object_name]
	if !ok {
		return
	}

	// 向监听此对象的所有连接发送消息, 通知对象已被移除, 并且移除每个连接对此对象的监听
	for _, conn := range object {
		conn.WriteJSON(map[string]interface{}{
			"object_name": object_name,
			"object_id":   object_id,
			"action":      "remove",
		})
		delete(mgr.connections[conn], object_name)
	}
}

// 通知对象状态变化
func (mgr *WebSocketManager) NotifyObjectChange(object_name string, object_id string, data interface{}) {
	mgr.mutex.Lock()
	defer mgr.mutex.Unlock()

	// 先获取监听此对象的所有连接
	object, ok := mgr.objects[object_name]
	if !ok {
		return
	}

	// 向监听此对象的所有连接发送消息
	for _, conn := range object {
		conn.WriteJSON(data)
	}
}

// 创建一个新的连接池
func NewWebSocketManager() *WebSocketManager {
	return &WebSocketManager{
		connections: make(map[*websocket.Conn]map[string]string),
		objects:     make(map[string]map[string]*websocket.Conn),
		mutex:       sync.RWMutex{},
	}
}

var WebSocketMgr = NewWebSocketManager()

// 连接 websocket
func WebSocket(w http.ResponseWriter, r *http.Request) {
	// 是否 websocket
	if r.Header.Get("Upgrade") != "websocket" {
		w.WriteHeader(http.StatusOK)
		w.Write([]byte("只支持 websocket 连接"))
		return
	}

	// 升级连接
	conn, err := (&websocket.Upgrader{}).Upgrade(w, r, nil)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		w.Write([]byte("升级连接失败"))
		return
	}

	// 连接建立时, 加入连接
	WebSocketMgr.AddConnection(conn)

	// 连接关闭时, 移除连接
	conn.SetCloseHandler(func(code int, text string) error {
		log.Println("连接关闭:", conn.RemoteAddr().String())
		WebSocketMgr.RemoveConnection(conn) // 移除连接
		return nil
	})

	// TODO: 载入用户关注的对象

	// 读取连接发送的消息
	for {
		fmt.Println("读取连接发送的消息", conn.RemoteAddr().String())
		var data map[string]interface{}
		err := conn.ReadJSON(&data)
		if err != nil {
			log.Println(err)
			return
		}
		// 处理消息(添加/移除监听对象)
		switch data["action"] {
		case "add":
			WebSocketMgr.AddObject(data["object_name"].(string), data["object_id"].(string), conn)
		case "remove":
			WebSocketMgr.RemoveObject(data["object_name"].(string), data["object_id"].(string))
		default:
			log.Println("未知消息:", data)
		}
	}
}