package fwd

import (
	"fmt"
	"io"
	"log/slog"
	"net"
	"proxy-server/pkg/utils"
	"proxy-server/server/debug"
	"proxy-server/server/env"
	"proxy-server/server/fwd/metrics"
	"strconv"
	"sync"
	"time"

	"errors"
)

func (s *Service) startDataTun() error {
	dataPort := env.AppDataPort
	slog.Debug("监听数据通道", slog.Uint64("port", uint64(dataPort)))

	// 监听端口
	ls, err := net.Listen("tcp", ":"+strconv.Itoa(int(dataPort)))
	if err != nil {
		return fmt.Errorf("监听数据通道失败: %w", err)
	}
	defer utils.Close(ls)

	go func() {
		<-s.ctx.Done()
		utils.Close(ls)
	}()

	for {
		conn, err := ls.Accept()
		if err != nil {
			return fmt.Errorf("监听数据通道失败: %w", err)
		}

		select {
		case <-s.ctx.Done():
			utils.Close(conn)
			return nil
		default:
			s.dataConnWg.Add(1)
			go func() {
				defer s.dataConnWg.Done()
				defer utils.Close(conn)
				err := s.processDataConn(conn)
				if err != nil {
					slog.Error("建立数据通道失败失败", "err", err)
				}
			}()
		}
	}
}

func (s *Service) processDataConn(client net.Conn) error {

	// 接收 status
	status, err := utils.ReadByte(client)
	if err != nil {
		return fmt.Errorf("从客户端获取 status 失败: %w", err)
	}

	// 接收 tag
	tagLen, err := utils.ReadByte(client)
	if err != nil {
		return fmt.Errorf("从客户端获取 tag 失败: %w", err)
	}
	tagBuf, err := utils.ReadBuffer(client, int(tagLen))
	if err != nil {
		return fmt.Errorf("从客户端获取 tag 失败: %w", err)
	}
	tag := string(tagBuf)

	// 找到用户连接
	user, ok := s.userConnMap.LoadAndDelete(tag)
	if !ok {
		return errors.New("用户连接已关闭，tag：" + tag)
	}
	defer utils.Close(user)
	data := time.Now()

	// 检查状态
	if status != 1 {
		return errors.New("目标地址建立连接失败")
	}

	// 数据转发
	userPipeReader, userPipeWriter := io.Pipe()
	defer utils.Close(userPipeWriter)
	teeUser := io.TeeReader(user, userPipeWriter)
	go func() {
		err := analysisAndLog(user, userPipeReader)
		if err != nil {
			slog.Error("数据解析失败", "err", err)
		}
	}()

	wg := sync.WaitGroup{}
	wg.Add(2)
	go func() {
		defer wg.Done()
		_, err := io.Copy(client, teeUser)
		if err != nil {
			slog.Error("数据转发失败 user->client", "err", err)
		}
	}()
	go func() {
		defer wg.Done()
		_, err := io.Copy(user, client)
		if err != nil {
			slog.Error("数据转发失败 client->user", "err", err)
		}
	}()

	select {
	case <-s.ctx.Done():
	case <-utils.ChanWgWait(s.ctx, &wg):
	}

	proxy := time.Now()

	start, startOk := metrics.TimerStart.Load(user.Conn)
	auth, authOk := metrics.TimerAuth.Load(user.Conn)

	var authDuration time.Duration
	if startOk && authOk {
		authDuration = auth.(time.Time).Sub(start.(time.Time))
	}

	var dataDuration time.Duration
	if authOk {
		dataDuration = data.Sub(auth.(time.Time))
	}

	proxyDuration := proxy.Sub(data)

	var totalDuration time.Duration
	if startOk {
		totalDuration = proxy.Sub(start.(time.Time))
	}

	debug.ConsumingCh <- debug.Consuming{
		Auth:  authDuration,
		Data:  dataDuration,
		Proxy: proxyDuration,
		Total: totalDuration,
	}

	return nil
}