package netforward

import (
	"b612.me/stario"
	"b612.me/starlog"
	"context"
	"errors"
	"fmt"
	"io"
	"net"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"syscall"
	"time"
)

type NetForward struct {
	LocalAddr   string
	LocalPort   int
	RemoteURI   string
	EnableTCP   bool
	EnableUDP   bool
	DelayMilSec int
	DelayToward int
	StdinMode   bool
	IgnoreEof   bool
	DialTimeout time.Duration
	UDPTimeout  time.Duration
	stopCtx     context.Context
	stopFn      context.CancelFunc
	running     int32

	KeepAlivePeriod int
	KeepAliveIdel   int
	KeepAliveCount  int
	UserTimeout     int
	UsingKeepAlive  bool
}

func (n *NetForward) Close() {
	n.stopFn()
}

func (n *NetForward) Status() int32 {
	return atomic.LoadInt32(&n.running)
}

func (n *NetForward) Run() error {
	if n.running > 0 {
		starlog.Errorln("already running")
		return errors.New("already running")
	}
	n.stopCtx, n.stopFn = context.WithCancel(context.Background())
	if n.DialTimeout == 0 {
		n.DialTimeout = time.Second * 5
	}
	if n.StdinMode {
		go func() {
			for {
				cmd := strings.TrimSpace(stario.MessageBox("", "").MustString())
				for strings.Contains(cmd, "  ") {
					cmd = strings.Replace(cmd, "  ", " ", -1)
				}
				starlog.Debugf("Recv Command %s\n", cmd)
				cmds := strings.Split(cmd, " ")
				if len(cmds) < 3 {
					starlog.Errorln("Invalid Command", cmd)
					continue
				}
				switch cmds[0] + cmds[1] {
				case "setremote":
					n.RemoteURI = cmds[2]
					starlog.Noticef("Remote URI Set to %s\n", n.RemoteURI)
				case "setdelaytoward":
					tmp, err := strconv.Atoi(cmds[2])
					if err != nil {
						starlog.Errorln("Invalid Delay Toward Value", cmds[2])
						continue
					}
					n.DelayToward = tmp
					starlog.Noticef("Delay Toward Set to %d\n", n.DelayToward)
				case "setdelay":
					tmp, err := strconv.Atoi(cmds[2])
					if err != nil {
						starlog.Errorln("Invalid Delay Value", cmds[2])
						continue
					}
					n.DelayMilSec = tmp
					starlog.Noticef("Delay Set to %d\n", n.DelayMilSec)
				case "setdialtimeout":
					tmp, err := strconv.Atoi(cmds[2])
					if err != nil {
						starlog.Errorln("Invalid Dial Timeout Value", cmds[2])
						continue
					}
					n.DialTimeout = time.Millisecond * time.Duration(tmp)
					starlog.Noticef("Dial Timeout Set to %d\n", n.DialTimeout)
				case "setudptimeout":
					tmp, err := strconv.Atoi(cmds[2])
					if err != nil {
						starlog.Errorln("Invalid UDP Timeout Value", cmds[2])
						continue
					}
					n.UDPTimeout = time.Millisecond * time.Duration(tmp)
					starlog.Noticef("UDP Timeout Set to %d\n", n.UDPTimeout)
				case "setstdin":
					if cmds[2] == "off" {
						n.StdinMode = false
						starlog.Noticef("Stdin Mode Off\n")
						return
					}
				}
			}
		}()
	}
	if n.EnableTCP {
		go n.runTCP()
	}

	if n.EnableUDP {
		go n.runUDP()
	}
	return nil
}

func (n *NetForward) runTCP() error {
	atomic.AddInt32(&n.running, 1)
	defer atomic.AddInt32(&n.running, -1)
	cfg := net.ListenConfig{
		Control: func(network, address string, c syscall.RawConn) error {
			return c.Control(SetReUseAddr)
		},
	}
	listen, err := cfg.Listen(context.Background(), "tcp", fmt.Sprintf("%s:%d", n.LocalAddr, n.LocalPort))
	if err != nil {
		starlog.Errorln("Listening On Tcp Failed:", err)
		return err
	}
	go func() {
		<-n.stopCtx.Done()
		listen.Close()
	}()
	starlog.Infof("Listening TCP on %v\n", fmt.Sprintf("%s:%d", n.LocalAddr, n.LocalPort))
	for {
		select {
		case <-n.stopCtx.Done():
			return nil
		default:
		}
		conn, err := listen.Accept()
		if err != nil {
			continue
		}
		log := starlog.Std.NewFlag()
		log.Infof("Accept New TCP Conn from %v\n", conn.RemoteAddr().String())
		if n.DelayMilSec > 0 && (n.DelayToward == 0 || n.DelayToward == 1) {
			log.Infof("Delay %d ms\n", n.DelayMilSec)
			time.Sleep(time.Millisecond * time.Duration(n.DelayMilSec))
		}
		err = SetTcpInfo(conn.(*net.TCPConn), n.UsingKeepAlive, n.KeepAliveIdel, n.KeepAlivePeriod, n.KeepAliveCount, n.UserTimeout)
		if err != nil {
			log.Errorf("SetTcpInfo error for %s: %v\n", conn.RemoteAddr().String(), err)
			conn.Close()
			continue
		}
		go func(conn net.Conn) {
			rmt, err := net.DialTimeout("tcp", n.RemoteURI, n.DialTimeout)
			if err != nil {
				log.Errorf("TCP:Dial Remote %s Failed:%v\n", n.RemoteURI, err)
				conn.Close()
				return
			}
			err = SetTcpInfo(rmt.(*net.TCPConn), n.UsingKeepAlive, n.KeepAliveIdel, n.KeepAlivePeriod, n.KeepAliveCount, n.UserTimeout)
			if err != nil {
				log.Errorf("SetTcpInfo error for %s: %v\n", conn.RemoteAddr().String(), err)
				rmt.Close()
				return
			}
			log.Infof("TCP Connect %s <==> %s\n", conn.RemoteAddr().String(), rmt.RemoteAddr().String())
			n.copy(rmt, conn)
			log.Noticef("TCP Connection Closed  %s <==> %s\n", conn.RemoteAddr().String(), n.RemoteURI)
			conn.Close()
			rmt.Close()
		}(conn)
	}
}

type UDPConn struct {
	net.Conn
	listen     *net.UDPConn
	remoteAddr *net.UDPAddr
	lastbeat   int64
}

func (u UDPConn) Write(p []byte) (n int, err error) {
	u.lastbeat = time.Now().Unix()
	return u.Conn.Write(p)
}

func (u UDPConn) Read(p []byte) (n int, err error) {
	u.lastbeat = time.Now().Unix()
	return u.Conn.Read(p)
}

func (u UDPConn) Work(delay int) {
	buf := make([]byte, 8192)
	for {
		if delay > 0 {
			time.Sleep(time.Millisecond * time.Duration(delay))
		}
		count, err := u.Read(buf)
		if err != nil {
			u.Close()
			u.lastbeat = 0
			return
		}
		_, err = u.listen.Write(buf[0:count])
		if err != nil {
			u.lastbeat = 0
			return
		}
	}
}

func (n *NetForward) runUDP() error {
	var mu sync.RWMutex
	atomic.AddInt32(&n.running, 1)
	defer atomic.AddInt32(&n.running, -1)
	udpAddr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%v", n.LocalAddr, n.LocalPort))
	if err != nil {
		return err
	}
	listen, err := net.ListenUDP("udp", udpAddr)
	if err != nil {
		return err
	}
	starlog.Infof("Listening UDP on %v\n", fmt.Sprintf("%s:%d", n.LocalAddr, n.LocalPort))
	go func() {
		<-n.stopCtx.Done()
		listen.Close()
	}()
	udpMap := make(map[string]UDPConn)
	go func() {
		for {
			select {
			case <-n.stopCtx.Done():
				return
			case <-time.After(time.Second * 60):
				mu.Lock()
				for k, v := range udpMap {
					if time.Now().Unix() > int64(n.UDPTimeout.Seconds())+v.lastbeat {
						delete(udpMap, k)
						starlog.Noticef("UDP Connection Closed  %s <==> %s\n", v.remoteAddr.String(), n.RemoteURI)
					}
				}
				mu.Unlock()
			}
		}
	}()
	buf := make([]byte, 8192)
	for {
		select {
		case <-n.stopCtx.Done():
			return nil
		default:
		}
		count, rmt, err := listen.ReadFromUDP(buf)
		if err != nil || rmt.String() == n.RemoteURI {
			continue
		}
		go func(data []byte, rmt *net.UDPAddr) {
			log := starlog.Std.NewFlag()
			mu.Lock()
			addr, ok := udpMap[rmt.String()]
			if !ok {
				log.Infof("Accept New UDP Conn from %v\n", rmt.String())
				conn, err := net.Dial("udp", n.RemoteURI)
				if err != nil {
					log.Errorf("UDP:Dial Remote %s Failed:%v\n", n.RemoteURI, err)
					mu.Unlock()
					return
				}
				addr = UDPConn{
					Conn:       conn,
					remoteAddr: rmt,
					listen:     listen,
					lastbeat:   time.Now().Unix(),
				}
				udpMap[rmt.String()] = addr
				go addr.Work(n.DelayMilSec)
				log.Infof("UDP Connect %s <==> %s\n", rmt.String(), n.RemoteURI)
			}
			mu.Unlock()
			if n.DelayMilSec > 0 || (n.DelayToward == 0 || n.DelayToward == 1) {
				time.Sleep(time.Millisecond * time.Duration(n.DelayMilSec))
			}
			_, err := addr.Write(data)
			if err != nil {
				mu.Lock()
				addr.Close()
				delete(udpMap, addr.remoteAddr.String())
				mu.Unlock()
				log.Noticef("UDP Connection Closed  %s <==> %s\n", rmt.String(), n.RemoteURI)
			}
		}(buf[0:count], rmt)
	}
}

func (n *NetForward) copy(dst, src net.Conn) {
	var wg sync.WaitGroup
	wg.Add(2)
	go func() {
		defer wg.Done()
		bufsize := make([]byte, 32*1024)
		for {
			count, err := src.Read(bufsize)
			if err != nil {
				if n.IgnoreEof && err == io.EOF {
					continue
				}
				dst.Close()
				src.Close()
				return
			}
			_, err = dst.Write(bufsize[:count])
			if err != nil {
				src.Close()
				dst.Close()
				return
			}
			if n.DelayMilSec > 0 && (n.DelayToward == 0 || n.DelayToward == 1) {
				time.Sleep(time.Millisecond * time.Duration(n.DelayMilSec))
			}
		}
	}()
	go func() {
		defer wg.Done()
		bufsize := make([]byte, 32*1024)
		for {
			count, err := dst.Read(bufsize)
			if err != nil {
				if n.IgnoreEof && err == io.EOF {
					continue
				}
				src.Close()
				dst.Close()
				return
			}
			_, err = src.Write(bufsize[:count])
			if err != nil {
				src.Close()
				dst.Close()
				return
			}
			if n.DelayMilSec > 0 && (n.DelayToward == 0 || n.DelayToward == 2) {
				time.Sleep(time.Millisecond * time.Duration(n.DelayMilSec))
			}
		}
	}()
	wg.Wait()
}