package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"os"
	"os/signal"
	"syscall"

	"github.com/libp2p/go-libp2p"
	"github.com/libp2p/go-libp2p/core/peer"
	peerstore "github.com/libp2p/go-libp2p/core/peer"
	"github.com/libp2p/go-libp2p/p2p/protocol/circuitv2/client"
	"github.com/libp2p/go-libp2p/p2p/protocol/circuitv2/relay"
	"github.com/libp2p/go-libp2p/p2p/protocol/ping"
	"github.com/libp2p/go-libp2p/p2p/security/noise"
	"github.com/libp2p/go-libp2p/p2p/transport/tcp"
	multiaddr "github.com/multiformats/go-multiaddr"
)

const help = `pear [options] [<multiaddr>]

Options:
  -help      Output this help
  -relay     Run in relay mode
  -reserve   Reserve a slot with relay
  -holepunch Enable holepunching
  -via       Relay to use
  -with      Peer to connect with
  -port      Port to listen on
`

func main() {
	var (
		helpFlag      bool
		relayFlag     bool
		reserveFlag   bool
		holepunchFlag bool
		viaFlag       string
		withFlag      string
		portFlag      string
	)

	flag.BoolVar(&helpFlag, "help", false, "Output help")
	flag.BoolVar(&relayFlag, "relay", false, "Run in relay mode")
	flag.BoolVar(&reserveFlag, "reserve", false, "Reserve a slot with relay")
	flag.BoolVar(&holepunchFlag, "holepunch", false, "Enable holepunching")
	flag.StringVar(&viaFlag, "via", "", "Relay to use")
	flag.StringVar(&withFlag, "with", "", "Peer to connect to")
	flag.StringVar(&portFlag, "port", "9000", "Port to listen on")
	flag.Parse()

	if helpFlag {
		fmt.Printf(help)
		os.Exit(0)
	}

	opts := []libp2p.Option{
		libp2p.RandomIdentity,
		libp2p.DisableMetrics(),
		libp2p.Security(noise.ID, noise.New),
		libp2p.Transport(tcp.NewTCPTransport),
		libp2p.DefaultPeerstore,
		libp2p.DefaultConnectionManager,
		libp2p.DefaultMuxers,
		libp2p.ListenAddrStrings(fmt.Sprintf("/ip4/0.0.0.0/tcp/%s", portFlag)),
		libp2p.NATPortMap(),
		libp2p.EnableRelay(),
	}

	if holepunchFlag {
		opts = append(opts, libp2p.EnableHolePunching())
	}

	pear, err := libp2p.NewWithoutDefaults(opts...)
	if err != nil {
		log.Fatalf("failed to initialise libp2p: %s", err)
	}

	peerId, err := multiaddr.NewMultiaddr(
		fmt.Sprintf("/p2p/%s", pear.ID().Pretty()),
	)
	if err != nil {
		log.Fatalf("failed to create new multiaddr: %s", err)
	}

	for _, addr := range pear.Addrs() {
		fmt.Println(addr.Encapsulate(peerId))
	}

	if relayFlag {
		_, err = relay.New(pear)
		if err != nil {
			log.Fatalf("failed to instantiate the relay: %v", err)
		}
	}

	pingService := &ping.PingService{Host: pear}
	pear.SetStreamHandler(ping.ID, pingService.PingHandler)
	if withFlag != "" {
		if viaFlag != "" {
			viaAddr, err := multiaddr.NewMultiaddr(viaFlag)
			if err != nil {
				log.Fatalf("via: failed to parse %s: %s", viaFlag, err)
			}

			viaAddrInfo, err := peerstore.AddrInfoFromP2pAddr(viaAddr)
			if err != nil {
				log.Fatalf("viaAddr: failed to add %s to peer store: %s", viaAddr, err)
			}

			if err := pear.Connect(context.Background(), *viaAddrInfo); err != nil {
				log.Fatalf("pear -> viaPeer: failed to connect to %s: %s", viaAddrInfo, err)
			}

			withAddr, err := multiaddr.NewMultiaddr(withFlag)
			if err != nil {
				log.Fatalf("withAddr: failed to parse %s: %s", withFlag, err)
			}

			withAddrInfo, err := peerstore.AddrInfoFromP2pAddr(withAddr)
			if err != nil {
				log.Fatalf("withAddr: failed to add %s to peer store: %s", withAddr, err)
			}

			relayAddr, err := multiaddr.NewMultiaddr("/p2p/" + viaAddrInfo.ID.String() + "/p2p-circuit/p2p/" + withAddrInfo.ID.String())
			if err != nil {
				log.Fatalf("failed to create relayAddr: %s", err)
			}

			withViaInfo := peer.AddrInfo{
				ID:    withAddrInfo.ID,
				Addrs: []multiaddr.Multiaddr{relayAddr},
			}

			if err := pear.Connect(context.Background(), withViaInfo); err != nil {
				log.Fatalf("peer -> relayPeer: failed to connect to %s: %s", withViaInfo, err)
			}

			ch := pingService.Ping(context.Background(), withViaInfo.ID)
			for i := 0; i < 5; i++ {
				res := <-ch
				fmt.Println("pinged", withAddrInfo, "in", res.RTT)
			}
		} else {
			addr, err := multiaddr.NewMultiaddr(withFlag)
			if err != nil {
				log.Fatalf("failed to parse %s: %s", withFlag, err)
			}

			peer, err := peerstore.AddrInfoFromP2pAddr(addr)
			if err != nil {
				log.Fatalf("failed to add %s to peer store: %s", addr, err)
			}

			if reserveFlag {
				_, err = client.Reserve(context.Background(), pear, *peer)
				if err != nil {
					log.Fatalf("reserve: failed to receive a relay reservation: %v", err)
				}
			}

			if err := pear.Connect(context.Background(), *peer); err != nil {
				log.Fatalf("failed to connect to %s: %s", peer, err)
			}

			ch := pingService.Ping(context.Background(), peer.ID)
			for i := 0; i < 5; i++ {
				res := <-ch
				fmt.Println("pinged", addr, "in", res.RTT)
			}
		}
	}

	ch := make(chan os.Signal, 1)
	signal.Notify(ch, syscall.SIGINT, syscall.SIGTERM)
	<-ch

	if err := pear.Close(); err != nil {
		log.Fatalf("failed to shutdown: %s", err)
	}
}