package login

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

	"eq2emu/internal/udp"
)

// Server represents the login server instance
type Server struct {
	config     *ServerConfig
	database   *LoginDB
	udpServer  *udp.Server
	webServer  *http.Server
	clientList *ClientList
	worldList  *WorldList
	running    bool
	startTime  time.Time

	// Synchronization
	mu       sync.RWMutex
	stopChan chan struct{}
	wg       sync.WaitGroup
}

// NewServer creates a new login server instance
func NewServer(config *ServerConfig) (*Server, error) {
	if config == nil {
		return nil, fmt.Errorf("configuration cannot be nil")
	}

	// Validate configuration
	if err := config.Validate(); err != nil {
		return nil, fmt.Errorf("invalid configuration: %w", err)
	}

	// Create database connection
	db, err := NewLoginDB(config.DatabaseDSN)
	if err != nil {
		return nil, fmt.Errorf("failed to initialize database: %w", err)
	}

	// Create login server instance first
	server := &Server{
		config:     config,
		database:   db,
		clientList: NewClientList(),
		worldList:  NewWorldList(),
		running:    false,
		stopChan:   make(chan struct{}),
	}

	// Create UDP server for EverQuest II protocol
	addr := fmt.Sprintf("%s:%d", config.ListenAddr, config.ListenPort)
	udpConfig := udp.Config{
		MaxConnections:    config.MaxClients,
		BufferSize:        1024 * 64, // 64KB buffer
		EnableCompression: true,
		EnableEncryption:  true,
	}

	udpServer, err := udp.NewServer(addr, server.handleUDPPacket, udpConfig)
	if err != nil {
		return nil, fmt.Errorf("failed to create UDP server: %w", err)
	}
	
	server.udpServer = udpServer

	// Initialize web server if enabled
	if config.WebPort > 0 {
		server.initWebServer()
	}

	return server, nil
}

// Start starts the login server
func (s *Server) Start() error {
	s.mu.Lock()
	defer s.mu.Unlock()

	if s.running {
		return fmt.Errorf("server is already running")
	}

	log.Printf("Starting login server on %s:%d", s.config.ListenAddr, s.config.ListenPort)

	// Start UDP server (it doesn't return an error in this implementation)
	go s.udpServer.Start()

	// Start web server if configured
	if s.webServer != nil {
		s.wg.Add(1)
		go func() {
			defer s.wg.Done()
			addr := fmt.Sprintf("%s:%d", s.config.WebAddr, s.config.WebPort)
			log.Printf("Starting web server on %s", addr)
			
			if err := s.webServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
				log.Printf("Web server error: %v", err)
			}
		}()
	}

	// Initialize world servers
	for _, worldInfo := range s.config.WorldServers {
		world := NewWorldServer(worldInfo)
		s.worldList.Add(world)
	}

	s.running = true
	s.startTime = time.Now()

	log.Println("Login server started successfully")
	return nil
}

// Stop stops the login server gracefully
func (s *Server) Stop() error {
	s.mu.Lock()
	defer s.mu.Unlock()

	if !s.running {
		return nil
	}

	log.Println("Stopping login server...")

	// Signal shutdown
	close(s.stopChan)

	// Stop UDP server
	s.udpServer.Stop()

	// Stop web server
	if s.webServer != nil {
		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
		defer cancel()
		
		if err := s.webServer.Shutdown(ctx); err != nil {
			log.Printf("Error stopping web server: %v", err)
		}
	}

	// Disconnect all clients
	s.clientList.DisconnectAll("Server shutdown")

	// Shutdown world servers
	s.worldList.Shutdown()

	// Close database
	if err := s.database.Close(); err != nil {
		log.Printf("Error closing database: %v", err)
	}

	// Wait for all goroutines to finish
	s.wg.Wait()

	s.running = false
	log.Println("Login server stopped")
	return nil
}

// Process runs the main server processing loop
func (s *Server) Process() {
	ticker := time.NewTicker(time.Millisecond * 50) // 20 FPS processing
	defer ticker.Stop()

	statsTicker := time.NewTicker(time.Minute) // Statistics every minute
	defer statsTicker.Stop()

	for {
		select {
		case <-s.stopChan:
			return

		case <-ticker.C:
			// Process clients
			s.clientList.Process()

			// Process world servers
			s.worldList.Process()

		case <-statsTicker.C:
			// Update statistics
			s.updateStatistics()
		}
	}
}

// handleUDPPacket handles incoming UDP packets from clients
func (s *Server) handleUDPPacket(conn *udp.Connection, packet *udp.ApplicationPacket) {
	// Find or create client for this connection
	client := s.clientList.GetByConnection(conn)
	if client == nil {
		client = NewClient(conn, s.database)
		s.clientList.Add(client)
		log.Printf("New client connected from %s", conn.GetClientAddr())
	}

	// Process packet
	if err := client.HandlePacket(packet.Data); err != nil {
		log.Printf("Error handling packet from %s: %v", conn.GetClientAddr(), err)
	}
}

// updateStatistics updates server statistics
func (s *Server) updateStatistics() {
	s.mu.RLock()
	defer s.mu.RUnlock()

	if !s.running {
		return
	}

	clientCount := s.clientList.Count()
	worldCount := s.worldList.Count()
	uptime := time.Since(s.startTime)

	log.Printf("Stats - Clients: %d, Worlds: %d, Uptime: %v", 
		clientCount, worldCount, uptime.Truncate(time.Second))

	// Update database statistics
	if err := s.database.UpdateServerStats("login", clientCount, worldCount); err != nil {
		log.Printf("Failed to update server stats: %v", err)
	}
}

// initWebServer initializes the web interface server
func (s *Server) initWebServer() {
	mux := http.NewServeMux()
	
	// Register web routes
	mux.HandleFunc("/", s.handleWebRoot)
	mux.HandleFunc("/api/status", s.handleAPIStatus)
	mux.HandleFunc("/api/clients", s.handleAPIClients)
	mux.HandleFunc("/api/worlds", s.handleAPIWorlds)

	s.webServer = &http.Server{
		Addr:         fmt.Sprintf("%s:%d", s.config.WebAddr, s.config.WebPort),
		Handler:      mux,
		ReadTimeout:  30 * time.Second,
		WriteTimeout: 30 * time.Second,
		IdleTimeout:  120 * time.Second,
	}
}

// IsRunning returns whether the server is currently running
func (s *Server) IsRunning() bool {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.running
}

// GetUptime returns how long the server has been running
func (s *Server) GetUptime() time.Duration {
	s.mu.RLock()
	defer s.mu.RUnlock()
	
	if !s.running {
		return 0
	}
	return time.Since(s.startTime)
}

// GetClientCount returns the current number of connected clients
func (s *Server) GetClientCount() int {
	return s.clientList.Count()
}

// GetWorldCount returns the current number of registered world servers
func (s *Server) GetWorldCount() int {
	return s.worldList.Count()
}