package main

import (
	"container/list"
	"flag"
	"fmt"
	"io"
	"io/fs"
	"io/ioutil"
	"log"
	"net"
	"net/http"
	"os"
	"path/filepath"
	"time"
)

var (
	ipcenteraddr      = flag.String("centeraddr", "127.0.0.1:60910", "IP代理中心地址") //IP代理中心地址
	addr              = flag.String("addr", ":18080", "跳板socks5监听地址")
	monitorAddr       = flag.String("maddr", ":18081", "监控地址")
	connectTimeout    = flag.Int64("cto", 90, "网络链接超时")
	currentTargetAddr = "" //当前环境IP
	cache             = list.New()
	diskCacheDir      = flag.String("cachedir", "./cache_dir", "用户缓存目录位置")
	//userDataDir       = flag.String("userdir", "./user_dir", "用户数据目录位置")
	//poolMinLimit      = flag.Int("pl", 3, "IP池最少容量")
	//ipOilLifeLimit    = flag.Int("ipol", 90, "IP剩余最少可用秒数")
	//no                = flag.String("no", "1", "编号")
	//ip                *IpPool
)

// init
func init() {
	flag.Parse()
}

// forward
func forward(src, dest io.ReadWriteCloser) {
	defer func() {
		//fmt.Print("@")
		if src != nil {
			_ = src.Close()
		}
		if dest != nil {
			_ = dest.Close()
		}
	}()
	if src == nil || dest == nil {
		return
	}
	_, _ = io.Copy(src, dest)
}

// processClient
func processClient(client net.Conn) {
	defer func() {
		if err := recover(); err != nil {
			fmt.Printf("{err %v}", err)
		}
	}()
	var targetConn net.Conn
	var err error
	for {
		//默认复用上一次可用IP
		targetConn, err = net.DialTimeout("tcp", currentTargetAddr, time.Duration(*connectTimeout)*time.Second)
		//fmt.Println("check ip:", currentTargetAddr)
		if err == nil {
			break
		}
		//跳板主动切换IP
		currentTargetAddr = getIp()
		fmt.Println("自主检测，切换本机IP：", currentTargetAddr)
	}
	//fmt.Printf("{%s %s}", *no, currentTargetAddr)
	cache.PushBack([2]net.Conn{client, targetConn})
	go forward(client, targetConn)
	go forward(targetConn, client)
}

// changeIp 切换代理IP，被动切换IP
func changeIp() {
	currentTargetAddr = getIp()
	fmt.Println("ChangeIp：", currentTargetAddr)
	for e := cache.Front(); e != nil; e = e.Next() {
		connes, _ := e.Value.([2](net.Conn))
		if connes[0].Close() != nil {
			connes[0].Close()
		}
		if connes[1].Close() != nil {
			connes[0].Close()
		}
	}
}

// clearTrace
func clearTrace() {
	if *diskCacheDir != "" {
		filepath.Walk(*diskCacheDir,
			func(path string,
				info fs.FileInfo, err error) error {
				if err == nil && info != nil && !info.IsDir() {
					os.Remove(path)
				}
				return nil
			})
	}
}

// monitor
func monitor() {
	//最好是单实例调用
	http.HandleFunc("/changeip", func(w http.ResponseWriter, r *http.Request) {
		changeIp()
		w.Write([]byte("ok"))
	})
	http.HandleFunc("/cleartrace", func(w http.ResponseWriter, r *http.Request) {
		clearTrace()
		w.Write([]byte("ok"))
	})
	http.ListenAndServe(*monitorAddr, nil)
}

func getIp() string {
	defer Catch()
	var ip string
	for i := 1; i <= 3; i++ {
		url := "http://" + *ipcenteraddr + "/getip"
		client := &http.Client{Timeout: time.Second * 5}
		resp, err := client.Get(url)
		//resp, err := http.Get(url)
		if err != nil {
			continue
		}
		bs, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			continue
		}
		resp.Body.Close()
		ip = string(bs)
		break
	}
	return ip
}

// main
func main() {
	conn, err := net.Listen("tcp", *addr)
	if err != nil {
		log.Fatal(err)
		return
	}
	//
	go monitor()
	//
	currentTargetAddr = getIp()
	fmt.Println("当前环境IP：", currentTargetAddr)
	//
	for {
		client, err := conn.Accept()
		if err != nil {
			log.Fatalf("Listen failed: %v\n", err)
			continue
		}
		go processClient(client)
	}
}