// startListening on the network addresses
func startListening(ctx context.Context, host p2phost.Host, cfg *config.Config) error {
	listenAddrs, err := listenAddresses(cfg)
	if err != nil {
		return err
	}

	// make sure we error out if our config does not have addresses we can use
	log.Debugf("Config.Addresses.Swarm:%s", listenAddrs)
	filteredAddrs := addrutil.FilterUsableAddrs(listenAddrs)
	log.Debugf("Config.Addresses.Swarm:%s (filtered)", filteredAddrs)
	if len(filteredAddrs) < 1 {
		return fmt.Errorf("addresses in config not usable: %s", listenAddrs)
	}

	// Actually start listening:
	if err := host.Network().Listen(filteredAddrs...); err != nil {
		return err
	}

	// list out our addresses
	addrs, err := host.Network().InterfaceListenAddresses()
	if err != nil {
		return err
	}
	log.Infof("Swarm listening at: %s", addrs)
	return nil
}

func NewIDService(h host.Host) *IDService {
	s := &IDService{
		Host:   h,
		currid: make(map[inet.Conn]chan struct{}),
	}
	h.SetStreamHandler(ID, s.RequestHandler)
	return s
}

func NewRelayService(h host.Host, sh inet.StreamHandler) *RelayService {
	s := &RelayService{
		host:    h,
		handler: sh,
	}
	h.SetStreamHandler(ID, s.requestHandler)
	return s
}

// NewDiagnostics instantiates a new diagnostics service running on the given network
func NewDiagnostics(self peer.ID, h host.Host) *Diagnostics {
	d := &Diagnostics{
		host:    h,
		self:    self,
		birth:   time.Now(),
		diagMap: make(map[string]time.Time),
	}

	h.SetStreamHandler(ProtocolDiag, d.handleNewStream)
	return d
}

// NewFromIpfsHost returns a BitSwapNetwork supported by underlying IPFS host
func NewFromIpfsHost(host host.Host, r routing.IpfsRouting) BitSwapNetwork {
	bitswapNetwork := impl{
		host:    host,
		routing: r,
	}
	host.SetStreamHandler(ProtocolBitswap, bitswapNetwork.handleNewStream)
	host.Network().Notify((*netNotifiee)(&bitswapNetwork))
	// TODO: StopNotify.

	return &bitswapNetwork
}

func testHasProtocolVersions(t *testing.T, h host.Host, p peer.ID) {
	v, err := h.Peerstore().Get(p, "ProtocolVersion")
	if v == nil {
		t.Error("no protocol version")
		return
	}
	if v.(string) != identify.IpfsVersion {
		t.Error("protocol mismatch", err)
	}
	v, err = h.Peerstore().Get(p, "AgentVersion")
	if v.(string) != identify.ClientVersion {
		t.Error("agent version mismatch", err)
	}
}

func getDialableListenAddrs(ph host.Host) ([]*net.TCPAddr, error) {
	var out []*net.TCPAddr
	for _, addr := range ph.Addrs() {
		na, err := manet.ToNetAddr(addr)
		if err != nil {
			continue
		}
		tcp, ok := na.(*net.TCPAddr)
		if ok {
			out = append(out, tcp)
		}
	}
	if len(out) == 0 {
		return nil, errors.New("failed to find good external addr from peerhost")
	}
	return out, nil
}

func testKnowsAddrs(t *testing.T, h host.Host, p peer.ID, expected []ma.Multiaddr) {
	actual := h.Peerstore().Addrs(p)

	if len(actual) != len(expected) {
		t.Error("dont have the same addresses")
	}

	have := map[string]struct{}{}
	for _, addr := range actual {
		have[addr.String()] = struct{}{}
	}
	for _, addr := range expected {
		if _, found := have[addr.String()]; !found {
			t.Errorf("%s did not have addr for %s: %s", h.ID(), p, addr)
			// panic("ahhhhhhh")
		}
	}
}

func bootstrapRound(ctx context.Context, host host.Host, cfg BootstrapConfig) error {

	ctx, cancel := context.WithTimeout(ctx, cfg.ConnectionTimeout)
	defer cancel()
	id := host.ID()

	// get bootstrap peers from config. retrieving them here makes
	// sure we remain observant of changes to client configuration.
	peers := cfg.BootstrapPeers()

	// determine how many bootstrap connections to open
	connected := host.Network().Peers()
	if len(connected) >= cfg.MinPeerThreshold {
		log.Event(ctx, "bootstrapSkip", id)
		log.Debugf("%s core bootstrap skipped -- connected to %d (> %d) nodes",
			id, len(connected), cfg.MinPeerThreshold)
		return nil
	}
	numToDial := cfg.MinPeerThreshold - len(connected)

	// filter out bootstrap nodes we are already connected to
	var notConnected []peer.PeerInfo
	for _, p := range peers {
		if host.Network().Connectedness(p.ID) != inet.Connected {
			notConnected = append(notConnected, p)
		}
	}

	// if connected to all bootstrap peer candidates, exit
	if len(notConnected) < 1 {
		log.Debugf("%s no more bootstrap peers to create %d connections", id, numToDial)
		return ErrNotEnoughBootstrapPeers
	}

	// connect to a random susbset of bootstrap candidates
	randSubset := randomSubsetOfPeers(notConnected, numToDial)

	defer log.EventBegin(ctx, "bootstrapStart", id).Done()
	log.Debugf("%s bootstrapping to %d nodes: %s", id, numToDial, randSubset)
	if err := bootstrapConnect(ctx, host, randSubset); err != nil {
		return err
	}
	return nil
}

func NewMdnsService(peerhost host.Host, interval time.Duration) (Service, error) {

	// TODO: dont let mdns use logging...
	golog.SetOutput(ioutil.Discard)

	var ipaddrs []net.IP
	port := 4001

	addrs, err := getDialableListenAddrs(peerhost)
	if err != nil {
		log.Warning(err)
	} else {
		port = addrs[0].Port
		for _, a := range addrs {
			ipaddrs = append(ipaddrs, a.IP)
		}
	}

	myid := peerhost.ID().Pretty()

	info := []string{myid}
	service, err := mdns.NewMDNSService(myid, ServiceTag, "", "", port, ipaddrs, info)
	if err != nil {
		return nil, err
	}

	// Create the mDNS server, defer shutdown
	server, err := mdns.NewServer(&mdns.Config{Zone: service})
	if err != nil {
		return nil, err
	}

	s := &mdnsService{
		server:   server,
		service:  service,
		host:     peerhost,
		interval: interval,
	}

	go s.pollForEntries()

	return s, nil
}

// NewDHT creates a new DHT object with the given peer as the 'local' host
func NewDHT(ctx context.Context, h host.Host, dstore ds.ThreadSafeDatastore) *IpfsDHT {
	dht := new(IpfsDHT)
	dht.datastore = dstore
	dht.self = h.ID()
	dht.peerstore = h.Peerstore()
	dht.host = h

	// register for network notifs.
	dht.host.Network().Notify((*netNotifiee)(dht))

	dht.proc = goprocess.WithTeardown(func() error {
		// remove ourselves from network notifs.
		dht.host.Network().StopNotify((*netNotifiee)(dht))
		return nil
	})

	dht.ctx = ctx

	h.SetStreamHandler(ProtocolDHT, dht.handleNewStream)
	dht.providers = NewProviderManager(dht.ctx, dht.self)
	dht.proc.AddChild(dht.providers.proc)
	goprocessctx.CloseAfterContext(dht.proc, ctx)

	dht.routingTable = kb.NewRoutingTable(20, kb.ConvertPeerID(dht.self), time.Minute, dht.peerstore)
	dht.birth = time.Now()

	dht.Validator = make(record.Validator)
	dht.Validator["pk"] = record.PublicKeyValidator

	return dht
}

func bootstrapConnect(ctx context.Context, ph host.Host, peers []peer.PeerInfo) error {
	if len(peers) < 1 {
		return ErrNotEnoughBootstrapPeers
	}

	errs := make(chan error, len(peers))
	var wg sync.WaitGroup
	for _, p := range peers {

		// performed asynchronously because when performed synchronously, if
		// one `Connect` call hangs, subsequent calls are more likely to
		// fail/abort due to an expiring context.
		// Also, performed asynchronously for dial speed.

		wg.Add(1)
		go func(p peer.PeerInfo) {
			defer wg.Done()
			defer log.EventBegin(ctx, "bootstrapDial", ph.ID(), p.ID).Done()
			log.Debugf("%s bootstrapping to %s", ph.ID(), p.ID)

			ph.Peerstore().AddAddrs(p.ID, p.Addrs, peer.PermanentAddrTTL)
			if err := ph.Connect(ctx, p); err != nil {
				log.Event(ctx, "bootstrapDialFailed", p.ID)
				log.Debugf("failed to bootstrap with %v: %s", p.ID, err)
				errs <- err
				return
			}
			log.Event(ctx, "bootstrapDialSuccess", p.ID)
			log.Infof("bootstrapped with %v", p.ID)
		}(p)
	}
	wg.Wait()

	// our failure condition is when no connection attempt succeeded.
	// So drain the errs channel, counting the results.
	close(errs)
	count := 0
	var err error
	for err = range errs {
		if err != nil {
			count++
		}
	}
	if count == len(peers) {
		return fmt.Errorf("failed to bootstrap. %s", err)
	}
	return nil
}

func NewPingService(h host.Host) *PingService {
	ps := &PingService{h}
	h.SetStreamHandler(ID, ps.PingHandler)
	return ps
}