package main

import (
	"flag"
	"log"
	"net"
	"os"
	"os/signal"
	"strconv"
	"syscall"

	"github.com/pion/logging"
	"github.com/pion/turn/v2"
)

func main() {
	publicIP := flag.String("public-ip", "", "IP Address that TURN can be contacted by.")
	port := flag.Int("port", 3478, "Listening port.")
	authSecret := flag.String("authSecret", "", "Shared secret for the Long Term Credential Mechanism")
	realm := flag.String("realm", "pion.ly", "Realm (defaults to \"pion.ly\")")
	flag.Parse()

	if len(*publicIP) == 0 {
		log.Fatalf("'public-ip' is required")
	} else if len(*authSecret) == 0 {
		log.Fatalf("'authSecret' is required")
	}

	// Create a UDP listener to pass into pion/turn
	// pion/turn itself doesn't allocate any UDP sockets, but lets the user pass them in
	// this allows us to add logging, storage or modify inbound/outbound traffic
	udpListener, err := net.ListenPacket("udp4", "0.0.0.0:"+strconv.Itoa(*port))
	if err != nil {
		log.Panicf("Failed to create TURN server listener: %s", err)
	}

	// NewLongTermAuthHandler takes a pion.LeveledLogger. This allows you to intercept messages
	// and process them yourself.
	logger := logging.NewDefaultLeveledLoggerForScope("lt-creds", logging.LogLevelTrace, os.Stdout)

	s, err := turn.NewServer(turn.ServerConfig{
		Realm: *realm,
		// Set AuthHandler callback
		// This is called everytime a user tries to authenticate with the TURN server
		// Return the key for that user, or false when no user is found
		AuthHandler: turn.NewLongTermAuthHandler(*authSecret, logger),
		// PacketConnConfigs is a list of UDP Listeners and the configuration around them
		PacketConnConfigs: []turn.PacketConnConfig{
			{
				PacketConn: udpListener,
				RelayAddressGenerator: &turn.RelayAddressGeneratorStatic{
					RelayAddress: net.ParseIP(*publicIP), // Claim that we are listening on IP passed by user (This should be your Public IP)
					Address:      "0.0.0.0",              // But actually be listening on every interface
				},
			},
		},
	})
	if err != nil {
		log.Panic(err)
	}

	// Block until user sends SIGINT or SIGTERM
	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
	<-sigs

	if err = s.Close(); err != nil {
		log.Panic(err)
	}
}
