package main

import (
	"context"
	"flag"
	"io"
	"net"

	"git.wntrmute.dev/kyle/goutils/die"
	"git.wntrmute.dev/kyle/goutils/lib"
)

func proxy(conn net.Conn, inside string) error {
	proxyConn, err := (&net.Dialer{}).DialContext(context.Background(), "tcp", inside)
	if err != nil {
		return err
	}

	defer proxyConn.Close()
	defer conn.Close()

	go func() {
		_, _ = io.Copy(conn, proxyConn)
	}()
	_, err = io.Copy(proxyConn, conn)
	return err
}

func main() {
	var outside, inside string
	flag.StringVar(&outside, "f", "8080", "outside port")
	flag.StringVar(&inside, "p", "4000", "inside port")
	flag.Parse()

	lc := &net.ListenConfig{}
	l, err := lc.Listen(context.Background(), "tcp", "0.0.0.0:"+outside)
	die.If(err)

	for {
		var conn net.Conn
		conn, err = l.Accept()
		if err != nil {
			_, _ = lib.Warn(err, "accept failed")
			continue
		}

		go func() {
			if err = proxy(conn, "127.0.0.1:"+inside); err != nil {
				_, _ = lib.Warn(err, "proxy error")
			}
		}()
	}
}