// NewDHT creates a new DHT object with the given peer as the 'local' host
func NewDHT(ctx context.Context, h host.Host, dstore ds.Datastore) *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

	dht.Selector = make(record.Selector)
	dht.Selector["pk"] = record.PublicKeySelector

	return dht
}

func NewResultBuilder(q Query) *ResultBuilder {
	b := &ResultBuilder{
		Query:  q,
		Output: make(chan Result),
	}
	b.Process = goprocess.WithTeardown(func() error {
		close(b.Output)
		return nil
	})
	return b
}

func NewStream(w io.Writer, r io.Reader) *stream {
	s := &stream{
		Reader:    r,
		Writer:    w,
		toDeliver: make(chan *transportObject),
	}

	s.proc = process.WithTeardown(s.teardown)
	s.proc.Go(s.transport)
	return s
}

// WithContextAndTeardown is a helper function to set teardown at initiation
// of WithContext
func WithContextAndTeardown(ctx context.Context, tf goprocess.TeardownFunc) goprocess.Process {
	if ctx == nil {
		panic("nil Context")
	}
	p := goprocess.WithTeardown(tf)
	go func() {
		<-ctx.Done()
		p.Close()
	}()
	return p
}

func newConn(ln, rn *peernet, l *link) *conn {
	c := &conn{net: ln, link: l}
	c.local = ln.peer
	c.remote = rn.peer

	c.localAddr = ln.ps.Addrs(ln.peer)[0]
	c.remoteAddr = rn.ps.Addrs(rn.peer)[0]

	c.localPrivKey = ln.ps.PrivKey(ln.peer)
	c.remotePubKey = rn.ps.PubKey(rn.peer)

	c.proc = process.WithTeardown(c.teardown)
	return c
}

// New initializes a BitSwap instance that communicates over the provided
// BitSwapNetwork. This function registers the returned instance as the network
// delegate.
// Runs until context is cancelled.
func New(parent context.Context, p peer.ID, network bsnet.BitSwapNetwork,
	bstore blockstore.Blockstore, nice bool) exchange.Interface {

	// important to use provided parent context (since it may include important
	// loggable data). It's probably not a good idea to allow bitswap to be
	// coupled to the concerns of the IPFS daemon in this way.
	//
	// FIXME(btc) Now that bitswap manages itself using a process, it probably
	// shouldn't accept a context anymore. Clients should probably use Close()
	// exclusively. We should probably find another way to share logging data
	ctx, cancelFunc := context.WithCancel(parent)

	notif := notifications.New()
	px := process.WithTeardown(func() error {
		notif.Shutdown()
		return nil
	})

	bs := &Bitswap{
		self:          p,
		blockstore:    bstore,
		notifications: notif,
		engine:        decision.NewEngine(ctx, bstore), // TODO close the engine with Close() method
		network:       network,
		findKeys:      make(chan *blockRequest, sizeBatchRequestChan),
		process:       px,
		newBlocks:     make(chan *blocks.Block, HasBlockBufferSize),
		provideKeys:   make(chan key.Key, provideKeysBufferSize),
		wm:            NewWantManager(ctx, network),
	}
	go bs.wm.Run()
	network.SetDelegate(bs)

	// Start up bitswaps async worker routines
	bs.startWorkers(px, ctx)

	// bind the context and process.
	// do it over here to avoid closing before all setup is done.
	go func() {
		<-px.Closing() // process closes first
		cancelFunc()
	}()
	procctx.CloseAfterContext(px, ctx) // parent cancelled first

	return bs
}

// NewMapping attemps to construct a mapping on protocol and internal port
// It will also periodically renew the mapping until the returned Mapping
// -- or its parent NAT -- is Closed.
//
// May not succeed, and mappings may change over time;
// NAT devices may not respect our port requests, and even lie.
// Clients should not store the mapped results, but rather always
// poll our object for the latest mappings.
func (nat *NAT) NewMapping(maddr ma.Multiaddr) (Mapping, error) {
	if nat == nil {
		return nil, fmt.Errorf("no nat available")
	}

	network, addr, err := manet.DialArgs(maddr)
	if err != nil {
		return nil, fmt.Errorf("DialArgs failed on addr:", maddr.String())
	}

	switch network {
	case "tcp", "tcp4", "tcp6":
		network = "tcp"
	case "udp", "udp4", "udp6":
		network = "udp"
	default:
		return nil, fmt.Errorf("transport not supported by NAT: %s", network)
	}

	intports := strings.Split(addr, ":")[1]
	intport, err := strconv.Atoi(intports)
	if err != nil {
		return nil, err
	}

	m := &mapping{
		nat:     nat,
		proto:   network,
		intport: intport,
		intaddr: maddr,
	}
	m.proc = goprocess.WithTeardown(func() error {
		nat.rmMapping(m)
		return nil
	})
	nat.addMapping(m)

	m.proc.AddChild(periodic.Every(MappingDuration/3, func(worker goprocess.Process) {
		nat.establishMapping(m)
	}))

	// do it once synchronously, so first mapping is done right away, and before exiting,
	// allowing users -- in the optimistic case -- to use results right after.
	nat.establishMapping(m)
	return m, nil
}

// New constructs and sets up a new *BasicHost with given Network
func New(net inet.Network, opts ...interface{}) *BasicHost {
	h := &BasicHost{
		network: net,
		mux:     msmux.NewMultistreamMuxer(),
		bwc:     metrics.NewBandwidthCounter(),
	}

	h.proc = goprocess.WithTeardown(func() error {
		if h.natmgr != nil {
			h.natmgr.Close()
		}

		return h.Network().Close()
	})

	// setup host services
	h.ids = identify.NewIDService(h)

	muxh := h.Mux().Handle
	handle := func(s inet.Stream) {
		muxh(s)
	}
	h.relay = relay.NewRelayService(h, handle)

	for _, o := range opts {
		switch o := o.(type) {
		case Option:
			switch o {
			case NATPortMap:
				h.natmgr = newNatManager(h)
			}
		case metrics.Reporter:
			h.bwc = o
		}
	}

	net.SetConnHandler(h.newConnHandler)
	net.SetStreamHandler(h.newStreamHandler)

	return h
}

func newNatManager(host *BasicHost) *natManager {
	nmgr := &natManager{
		host:  host,
		ready: make(chan struct{}),
		proc:  goprocess.WithParent(host.proc),
	}

	// teardown
	nmgr.proc = goprocess.WithTeardown(func() error {
		// on closing, unregister from network notifications.
		host.Network().StopNotify((*nmgrNetNotifiee)(nmgr))
		return nil
	})

	// host is our parent. close when host closes.
	host.proc.AddChild(nmgr.proc)

	// discover the nat.
	nmgr.discoverNAT()
	return nmgr
}

// WithContextAndTeardown is a helper function to set teardown at initiation
// of WithContext
func WithContextAndTeardown(ctx context.Context, tf goprocess.TeardownFunc) goprocess.Process {
	p := goprocess.WithTeardown(tf)
	CloseAfterContext(p, ctx)
	return p
}