package websocket

import (
	"encoding/json"
	"log"
	"net/http"
	"sync"
	"time"

	"github.com/gorilla/websocket"
	"sensor-server/internal/models"
)

var upgrader = websocket.Upgrader{
	CheckOrigin: func(r *http.Request) bool {
		return true // 개발 환경에서는 모든 origin 허용
	},
}

// Client WebSocket 클라이언트 정보
type Client struct {
	ID       string
	Conn     *websocket.Conn
	Send     chan []byte
	Hub      *Hub
	mu       sync.Mutex
}

// Hub WebSocket 허브 (연결 관리)
type Hub struct {
	clients    map[*Client]bool
	broadcast  chan []byte
	register   chan *Client
	unregister chan *Client
	mu         sync.RWMutex
}

// NewHub 새로운 허브 생성
func NewHub() *Hub {
	return &Hub{
		clients:    make(map[*Client]bool),
		broadcast:  make(chan []byte),
		register:   make(chan *Client),
		unregister: make(chan *Client),
	}
}

// Run 허브 실행
func (h *Hub) Run() {
	for {
		select {
		case client := <-h.register:
			h.mu.Lock()
			h.clients[client] = true
			h.mu.Unlock()
			log.Printf("Client %s connected. Total clients: %d", client.ID, len(h.clients))

		case client := <-h.unregister:
			h.mu.Lock()
			if _, ok := h.clients[client]; ok {
				delete(h.clients, client)
				close(client.Send)
			}
			h.mu.Unlock()
			log.Printf("Client %s disconnected. Total clients: %d", client.ID, len(h.clients))

		case message := <-h.broadcast:
			h.mu.RLock()
			for client := range h.clients {
				select {
				case client.Send <- message:
				default:
					close(client.Send)
					delete(h.clients, client)
				}
			}
			h.mu.RUnlock()
		}
	}
}

// BroadcastSensorData 센서 데이터 브로드캐스트
func (h *Hub) BroadcastSensorData(reading *models.SensorReading) {
	// 클라이언트가 기대하는 WebSocketMessage 형식으로 변환
	message := map[string]interface{}{
		"type": "sensor_data",
		"data": reading,
		"timestamp": time.Now().Format(time.RFC3339),
		"device_id": reading.DeviceID,
	}
	
	data, err := json.Marshal(message)
	if err != nil {
		log.Printf("Error marshaling sensor data: %v", err)
		return
	}

	log.Printf("Broadcasting sensor data to %d clients: %s", len(h.clients), string(data))
	h.broadcast <- data
}

// readPump 클라이언트로부터 메시지 읽기
func (c *Client) readPump() {
	defer func() {
		c.Hub.unregister <- c
		c.Conn.Close()
	}()

	c.Conn.SetReadLimit(512)
	c.Conn.SetReadDeadline(time.Now().Add(60 * time.Second))
	c.Conn.SetPongHandler(func(string) error {
		c.Conn.SetReadDeadline(time.Now().Add(60 * time.Second))
		return nil
	})

	for {
		_, message, err := c.Conn.ReadMessage()
		if err != nil {
			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
				log.Printf("WebSocket read error: %v", err)
			}
			break
		}

		// 클라이언트로부터 받은 메시지 처리 (필요시)
		log.Printf("Received message from client %s: %s", c.ID, string(message))
	}
}

// writePump 클라이언트로 메시지 쓰기
func (c *Client) writePump() {
	ticker := time.NewTicker(54 * time.Second)
	defer func() {
		ticker.Stop()
		c.Conn.Close()
	}()

	for {
		select {
		case message, ok := <-c.Send:
			c.Conn.SetWriteDeadline(time.Now().Add(10 * time.Second))
			if !ok {
				c.Conn.WriteMessage(websocket.CloseMessage, []byte{})
				return
			}

			w, err := c.Conn.NextWriter(websocket.TextMessage)
			if err != nil {
				return
			}
			w.Write(message)

			if err := w.Close(); err != nil {
				return
			}
		case <-ticker.C:
			c.Conn.SetWriteDeadline(time.Now().Add(10 * time.Second))
			if err := c.Conn.WriteMessage(websocket.PingMessage, nil); err != nil {
				return
			}
		}
	}
}

// ServeWs WebSocket 핸들러
func ServeWs(hub *Hub, w http.ResponseWriter, r *http.Request) {
	conn, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Printf("WebSocket upgrade error: %v", err)
		return
	}

	client := &Client{
		ID:   generateClientID(),
		Hub:  hub,
		Conn: conn,
		Send: make(chan []byte, 256),
	}

	client.Hub.register <- client

	go client.writePump()
	go client.readPump()
}

// generateClientID 클라이언트 ID 생성
func generateClientID() string {
	return time.Now().Format("20060102150405") + "-" + randomString(8)
}

// randomString 랜덤 문자열 생성
func randomString(length int) string {
	const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	b := make([]byte, length)
	for i := range b {
		b[i] = charset[time.Now().UnixNano()%int64(len(charset))]
	}
	return string(b)
}