package main

import (
	"flag"
	"fmt"
	"io"
	"log"
	"net"
	"os"

	"0xacab.org/leap/obfsvpn"

	"github.com/kalikaneko/socks5"
	"github.com/xtaci/kcp-go"
)

func main() {
	// Setup logging.
	logger := log.New(os.Stderr, "", log.LstdFlags)
	debug := log.New(io.Discard, "DEBUG ", log.LstdFlags)

	// setup command line flags.
	var (
		verbose     bool
		obfs4Cert   string
		obfs4Remote string
		socksPort   string
		socksHost   string
	)

	socksPort = "8080"
	socksHost = "127.0.0.1"

	flags := flag.NewFlagSet(os.Args[0], flag.ContinueOnError)
	flags.BoolVar(&verbose, "v", verbose, "Enable verbose logging")
	flags.StringVar(&obfs4Cert, "c", obfs4Cert, "The remote obfs4 certificate")
	flags.StringVar(&obfs4Remote, "r", obfs4Remote, "The remote obfs4 endpoint (ip:port)")
	flags.StringVar(&socksPort, "p", socksPort, "The port for the local socks5 proxy (default: 8080)")
	flags.StringVar(&socksHost, "i", socksHost, "The host for the local socks5 proxy (default: localhost)")
	err := flags.Parse(os.Args[1:])
	if err != nil {
		logger.Fatalf("error parsing flags: %v", err)
	}
	// Configure logging.
	if verbose {
		debug.SetOutput(os.Stderr)
	}

	kcpTransport := false
	// TODO make this configurable via a Config struct
	// TODO make sure we're disabling all the crypto options for KCP
	if os.Getenv("KCP") == "1" {
		kcpTransport = true
	}

	socksAddr := net.JoinHostPort(socksHost, socksPort)
	client := NewClient(kcpTransport, socksAddr, obfs4Cert)
	client.Start()
}

type Client struct {
	kcp       bool
	socksAddr string
	obfs4Cert string
}

func NewClient(kcp bool, socksAddr, obfs4Cert string) *Client {
	return &Client{
		kcp:       kcp,
		socksAddr: socksAddr,
		obfs4Cert: obfs4Cert,
	}
}

func (c *Client) Start() bool {
	server := &socks5.Server{
		Addr:   c.socksAddr,
		BindIP: "127.0.0.1",
	}

	dialer, err := obfsvpn.NewDialerFromCert(c.obfs4Cert)
	if err != nil {
		log.Printf("Error getting dialer: %v\n", err)
		return false
	}

	if c.kcp {
		dialer.DialFunc = func(network, address string) (net.Conn, error) {
			log.Printf("Dialing kcp://%s\n", address)
			return kcp.Dial(address)
		}
	}

	server.Dial = dialer.Dial

	fmt.Printf("[+] Starting socks5 proxy at %s\n", c.socksAddr)
	if err := server.ListenAndServe(); err != nil {
		log.Printf("error while listening: %v\n", err)
		return false
	}
	return true
}