package server

import (
	"fmt"
	"io"
	"log"
	"net"
	"sync"
	"time"

	"net-tunnel/pkg/proto"
)

// ProxyEntry 表示一个代理条目
type ProxyEntry struct {
	Config      *proto.ProxyConfig
	ClientID    string
	TCPListener net.Listener // 用于 TCP 代理
	TCPConns    sync.Map     // map[remoteAddr]net.Conn 用于 TCP 代理
	UDPConn     *net.UDPConn // 用于 UDP 代理
}

// ProxyManager 管理所有代理
type ProxyManager struct {
	proxies     sync.Map // map[proxyName]*ProxyEntry
	connManager *ConnectionManager
}

// NewProxyManager 创建新的代理管理器
func NewProxyManager(connManager *ConnectionManager) *ProxyManager {
	return &ProxyManager{
		proxies:     sync.Map{},
		connManager: connManager,
	}
}

// RegisterProxy 注册一个新的代理
func (m *ProxyManager) RegisterProxy(clientID string, config *proto.ProxyConfig) error {
	if _, exists := m.proxies.Load(config.Name); exists {
		return fmt.Errorf("proxy %s already registered", config.Name)
	}

	entry := &ProxyEntry{
		Config:   config,
		ClientID: clientID,
	}

	// 根据代理类型启动监听器
	var err error
	if config.Type == proto.ProxyType_TCP {
		err = m.startTCPProxy(entry)
	} else if config.Type == proto.ProxyType_UDP {
		err = m.startUDPProxy(entry)
	} else {
		return fmt.Errorf("unsupported proxy type: %v", config.Type)
	}

	if err != nil {
		return err
	}

	m.proxies.Store(config.Name, entry)
	log.Printf("Registered proxy: %s (type: %s, port: %d)",
		config.Name, config.Type, config.RemotePort)

	return nil
}

// UnregisterProxy 注销一个代理
func (m *ProxyManager) UnregisterProxy(clientID, proxyName string) {
	m.closeProxyLocked(proxyName)
}

// UnregisterAllProxies 注销客户端的所有代理
func (m *ProxyManager) UnregisterAllProxies(clientID string) {
	m.proxies.Range(func(key, value interface{}) bool {
		if entry, ok := value.(*ProxyEntry); ok && entry.ClientID == clientID {
			m.closeProxyLocked(key.(string))
		}
		return true
	})
}

// closeProxyLocked 关闭代理（在持有锁的情况下调用）
func (m *ProxyManager) closeProxyLocked(proxyID string) {
	if entry, exists := m.proxies.Load(proxyID); exists {
		entry := entry.(*ProxyEntry)
		if entry.TCPListener != nil {
			entry.TCPListener.Close()
		}
		if entry.UDPConn != nil {
			entry.UDPConn.Close()
		}
		m.proxies.Delete(proxyID)
		log.Printf("Unregistered proxy: %s", entry.Config.Name)
	}
}

// startTCPProxy 启动一个 TCP 代理
func (m *ProxyManager) startTCPProxy(entry *ProxyEntry) error {
	addr := fmt.Sprintf(":%d", entry.Config.RemotePort)
	listener, err := net.Listen("tcp", addr)
	if err != nil {
		return fmt.Errorf("failed to listen on port %d: %v", entry.Config.RemotePort, err)
	}

	entry.TCPListener = listener

	// 启动协程接受连接
	go m.handleTCPConnections(entry)

	return nil
}

// startUDPProxy 启动一个 UDP 代理
func (m *ProxyManager) startUDPProxy(entry *ProxyEntry) error {
	addr := fmt.Sprintf(":%d", entry.Config.RemotePort)
	udpAddr, err := net.ResolveUDPAddr("udp", addr)
	if err != nil {
		return fmt.Errorf("failed to resolve address %s: %v", addr, err)
	}

	conn, err := net.ListenUDP("udp", udpAddr)
	if err != nil {
		return fmt.Errorf("failed to listen on UDP port %d: %v", entry.Config.RemotePort, err)
	}

	entry.UDPConn = conn

	// 启动协程接收 UDP 数据包
	go m.handleUDPPackets(entry)

	return nil
}

// handleTCPConnections 处理传入的 TCP 连接
func (m *ProxyManager) handleTCPConnections(entry *ProxyEntry) {
	for {
		conn, err := entry.TCPListener.Accept()
		if err != nil {
			// 监听器可能已关闭
			log.Printf("TCP listener for %s closed: %v", entry.Config.Name, err)
			break
		}

		go m.handleTCPConnection(entry, conn)
	}
}

// handleUDPPackets 处理传入的 UDP 数据包
func (m *ProxyManager) handleUDPPackets(entry *ProxyEntry) {
	buffer := make([]byte, 4096)
	for {
		n, addr, err := entry.UDPConn.ReadFromUDP(buffer)
		if err != nil {
			// 连接可能已关闭
			log.Printf("UDP connection for %s closed: %v", entry.Config.Name, err)
			break
		}

		go m.handleUDPPacket(entry, buffer[:n], addr)
	}
}

func (m *ProxyManager) handleTCPConnection(entry *ProxyEntry, conn net.Conn) {
	if tcpConn, ok := conn.(*net.TCPConn); ok {
		_ = tcpConn.SetKeepAlive(true)
		_ = tcpConn.SetKeepAlivePeriod(30 * time.Second)
		_ = tcpConn.SetNoDelay(true) // 对SSH协议很重要，避免数据包延迟
	}
	connID := fmt.Sprintf("%s_%d", conn.RemoteAddr().String(), time.Now().UnixNano())

	defer func() {
		conn.Close()
		entry.TCPConns.Delete(connID)
		log.Printf("TCP connection for %s closed", connID)
	}()

	// 获取客户端的控制连接
	controlConn, ok := m.connManager.GetConnection(entry.ClientID)
	if !ok {
		log.Printf("Control connection not found for client %s", entry.ClientID)
		return
	}

	entry.TCPConns.Store(connID, conn)
	log.Printf("TCP connection for %s accepted", connID)

	wg := sync.WaitGroup{}
	wg.Add(1)
	// 启动数据转发
	go func() {
		defer wg.Done()
		buffer := make([]byte, 4096)
		for {
			n, err := conn.Read(buffer)
			if err != nil {
				if err == io.EOF {
					log.Printf("TCP connection for %s closed", connID)
				} else {
					log.Printf("Failed to read from TCP connection: %v", err)
				}
				return
			}

			// 发送数据到客户端
			err = controlConn.Send(&proto.Message{
				Content: &proto.Message_ProxyData{
					ProxyData: &proto.ProxyData{
						ConnId:      connID,
						ProxyConfig: entry.Config,
						Data:        buffer[:n],
					},
				},
			})
			if err != nil {
				log.Printf("Failed to send proxy data: %v", err)
				return
			}
		}
	}()
	wg.Wait()
}

func (m *ProxyManager) handleUDPPacket(entry *ProxyEntry, data []byte, addr *net.UDPAddr) {
}