package handlers

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

	"github.com/gorilla/websocket"

	"task-dashboard/internal/models"
)

var upgrader = websocket.Upgrader{
	ReadBufferSize:  1024,
	WriteBufferSize: 1024,
	CheckOrigin: func(r *http.Request) bool {
		// Allow all connections (CORS disabled for WebSocket)
		return true
	},
}

// WSClient represents a connected browser
type WSClient struct {
	conn *websocket.Conn
	send chan []byte
}

// WSHub manages WebSocket connections
type WSHub struct {
	clients    map[*WSClient]bool
	broadcast  chan []byte
	register   chan *WSClient
	unregister chan *WSClient
	mu         sync.RWMutex
}

var wsHub *WSHub
var hubOnce sync.Once

// GetWSHub returns the singleton WebSocket hub
func GetWSHub() *WSHub {
	hubOnce.Do(func() {
		wsHub = &WSHub{
			clients:    make(map[*WSClient]bool),
			broadcast:  make(chan []byte, 256),
			register:   make(chan *WSClient),
			unregister: make(chan *WSClient),
		}
		go wsHub.run()
	})
	return wsHub
}

// run handles hub operations
func (h *WSHub) run() {
	for {
		select {
		case client := <-h.register:
			h.mu.Lock()
			h.clients[client] = true
			h.mu.Unlock()
			log.Printf("WebSocket client connected, total: %d", 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("WebSocket client disconnected, total: %d", len(h.clients))

		case message := <-h.broadcast:
			h.mu.RLock()
			for client := range h.clients {
				select {
				case client.send <- message:
				default:
					// Client buffer full, skip
				}
			}
			h.mu.RUnlock()
		}
	}
}

// Broadcast sends a message to all connected clients
func (h *WSHub) Broadcast(msg []byte) {
	h.broadcast <- msg
}

// ClientCount returns the number of connected clients
func (h *WSHub) ClientCount() int {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return len(h.clients)
}

// WSMessage is the structure for WebSocket messages
type WSMessage struct {
	Type    string      `json:"type"`
	Payload interface{} `json:"payload"`
}

// BroadcastAgentRequest sends an agent request notification to all browsers
func (h *Handler) BroadcastAgentRequest(session *models.AgentSession, trustLevel models.AgentTrustLevel) {
	hub := GetWSHub()

	payload := AgentRequestPayload{
		RequestToken: session.RequestToken,
		AgentName:    session.AgentName,
		AgentID:      session.AgentID,
		TrustLevel:   trustLevel,
		ExpiresAt:    session.ExpiresAt,
	}

	msg := WSMessage{
		Type:    "agent_request",
		Payload: payload,
	}

	data, err := json.Marshal(msg)
	if err != nil {
		log.Printf("Failed to marshal WebSocket message: %v", err)
		return
	}

	hub.Broadcast(data)
	log.Printf("Broadcasted agent request from %s to %d clients", session.AgentName, hub.ClientCount())
}

// HandleWebSocket handles the WebSocket connection at /ws/notifications
func (h *Handler) HandleWebSocket(w http.ResponseWriter, r *http.Request) {
	// Check if the request is a WebSocket upgrade request
	if !websocket.IsWebSocketUpgrade(r) {
		http.Error(w, "Expected WebSocket Upgrade request", http.StatusBadRequest)
		return
	}

	conn, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Printf("WebSocket upgrade failed: %v", err)
		return
	}

	hub := GetWSHub()
	client := &WSClient{
		conn: conn,
		send: make(chan []byte, 256),
	}

	hub.register <- client

	// Start goroutines for reading and writing
	go client.writePump()
	go client.readPump(hub)
}

// writePump sends messages to the client
func (c *WSClient) writePump() {
	ticker := time.NewTicker(30 * 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 {
				// Channel closed
				c.conn.WriteMessage(websocket.CloseMessage, []byte{})
				return
			}

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

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

// readPump reads messages from the client
func (c *WSClient) readPump(hub *WSHub) {
	defer func() {
		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 {
		_, _, err := c.conn.ReadMessage()
		if err != nil {
			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
				log.Printf("WebSocket error: %v", err)
			}
			break
		}
	}
}