// TODO: Maybe put these in some sort of "ipfs_testutil" package
func _randPeer() *peer.Peer {
	p := new(peer.Peer)
	p.ID = make(peer.ID, 16)
	p.Addresses = []*ma.Multiaddr{nil}
	crand.Read(p.ID)
	return p
}

// Ping a peer, log the time it took
func (dht *IpfsDHT) Ping(p *peer.Peer, timeout time.Duration) error {
	// Thoughts: maybe this should accept an ID and do a peer lookup?
	u.DOut("Enter Ping.\n")

	pmes := Message{ID: swarm.GenerateMessageID(), Type: PBDHTMessage_PING}
	mes := swarm.NewMessage(p, pmes.ToProtobuf())

	before := time.Now()
	responseChan := dht.listener.Listen(pmes.ID, 1, time.Minute)
	dht.netChan.Outgoing <- mes

	tout := time.After(timeout)
	select {
	case <-responseChan:
		roundtrip := time.Since(before)
		p.SetLatency(roundtrip)
		u.DOut("Ping took %s.\n", roundtrip.String())
		return nil
	case <-tout:
		// Timed out, think about removing peer from network
		u.DOut("[%s] Ping peer [%s] timed out.", dht.self.ID.Pretty(), p.ID.Pretty())
		dht.listener.Unlisten(pmes.ID)
		return u.ErrTimeout
	}
}

// Handle getting ID from this peer and adding it into the map
func (s *Swarm) handleNewConn(nconn net.Conn) {
	p := new(peer.Peer)

	conn := &Conn{
		Peer: p,
		Addr: nil,
		Conn: nconn,
	}
	newConnChans(conn)

	sin, sout, err := ident.Handshake(s.local, p, conn.Incoming.MsgChan, conn.Outgoing.MsgChan)
	if err != nil {
		u.PErr("%v\n", err.Error())
		conn.Close()
		return
	}

	// Get address to contact remote peer from
	addr := <-sin
	maddr, err := ma.NewMultiaddr(string(addr))
	if err != nil {
		u.PErr("Got invalid address from peer.")
		s.Error(err)
		return
	}
	p.AddAddress(maddr)

	conn.secIn = sin
	conn.secOut = sout

	err = s.StartConn(conn)
	if err != nil {
		s.Error(err)
	}
}

// If less than K nodes are in the entire network, it should fail when we make
// a GET rpc and nobody has the value
func TestLessThanKResponses(t *testing.T) {
	u.Debug = false
	fn := newFauxNet()
	fn.Listen()

	local := new(peer.Peer)
	local.ID = peer.ID("test_peer")

	d := NewDHT(local, fn, ds.NewMapDatastore())
	d.Start()

	var ps []*peer.Peer
	for i := 0; i < 5; i++ {
		ps = append(ps, _randPeer())
		d.Update(ps[i])
	}
	other := _randPeer()

	// Reply with random peers to every message
	fn.AddHandler(func(mes *swarm.Message) *swarm.Message {
		pmes := new(PBDHTMessage)
		err := proto.Unmarshal(mes.Data, pmes)
		if err != nil {
			t.Fatal(err)
		}

		switch pmes.GetType() {
		case PBDHTMessage_GET_VALUE:
			resp := Message{
				Type:     pmes.GetType(),
				ID:       pmes.GetId(),
				Response: true,
				Success:  false,
				Peers:    []*peer.Peer{other},
			}

			return swarm.NewMessage(mes.Peer, resp.ToProtobuf())
		default:
			panic("Shouldnt recieve this.")
		}

	})

	_, err := d.GetValue(u.Key("hello"), time.Second*30)
	if err != nil {
		switch err {
		case u.ErrNotFound:
			//Success!
			return
		case u.ErrTimeout:
			t.Fatal("Should not have gotten timeout!")
		default:
			t.Fatalf("Got unexpected error: %s", err)
		}
	}
	t.Fatal("Expected to recieve an error.")
}

func (bs *BitSwap) getLedger(p *peer.Peer) *Ledger {
	l, ok := bs.partners[p.Key()]
	if ok {
		return l
	}

	l = new(Ledger)
	l.Strategy = bs.strategy
	l.Partner = p
	bs.partners[p.Key()] = l
	return l
}

// ConnectNew is for connecting to a peer when you dont know their ID,
// Should only be used when you are sure that you arent already connected to peer in question
func (s *Swarm) ConnectNew(addr *ma.Multiaddr) (*peer.Peer, error) {
	if addr == nil {
		return nil, errors.New("nil Multiaddr passed to swarm.Connect()")
	}
	npeer := new(peer.Peer)
	npeer.AddAddress(addr)

	conn, err := Dial("tcp", npeer)
	if err != nil {
		return nil, err
	}

	err = s.handleDialedCon(conn)
	return npeer, err
}

// Update adds or moves the given peer to the front of its respective bucket
// If a peer gets removed from a bucket, it is returned
func (rt *RoutingTable) Update(p *peer.Peer) *peer.Peer {
	rt.tabLock.Lock()
	defer rt.tabLock.Unlock()
	peerID := ConvertPeerID(p.ID)
	cpl := xor(peerID, rt.local).commonPrefixLen()

	bucketID := cpl
	if bucketID >= len(rt.Buckets) {
		bucketID = len(rt.Buckets) - 1
	}

	bucket := rt.Buckets[bucketID]
	e := bucket.find(p.ID)
	if e == nil {
		// New peer, add to bucket
		if p.GetLatency() > rt.maxLatency {
			// Connection doesnt meet requirements, skip!
			return nil
		}
		bucket.pushFront(p)

		// Are we past the max bucket size?
		if bucket.len() > rt.bucketsize {
			if bucketID == len(rt.Buckets)-1 {
				newBucket := bucket.Split(bucketID, rt.local)
				rt.Buckets = append(rt.Buckets, newBucket)
				if newBucket.len() > rt.bucketsize {
					// TODO: This is a very rare and annoying case
					panic("Case not handled.")
				}

				// If all elements were on left side of split...
				if bucket.len() > rt.bucketsize {
					return bucket.popBack()
				}
			} else {
				// If the bucket cant split kick out least active node
				return bucket.popBack()
			}
		}
		return nil
	}
	// If the peer is already in the table, move it to the front.
	// This signifies that it it "more active" and the less active nodes
	// Will as a result tend towards the back of the list
	bucket.moveToFront(e)
	return nil
}

// Dial connects to a particular peer, over a given network
// Example: Dial("udp", peer)
func Dial(network string, peer *peer.Peer) (*Conn, error) {
	addr := peer.NetAddress(network)
	if addr == nil {
		return nil, fmt.Errorf("No address for network %s", network)
	}

	network, host, err := addr.DialArgs()
	if err != nil {
		return nil, err
	}

	nconn, err := net.Dial(network, host)
	if err != nil {
		return nil, err
	}

	conn := &Conn{
		Peer: peer,
		Addr: addr,
		Conn: nconn,
	}

	newConnChans(conn)
	return conn, nil
}

// Dial connects to a peer.
//
// The idea is that the client of Swarm does not need to know what network
// the connection will happen over. Swarm can use whichever it choses.
// This allows us to use various transport protocols, do NAT traversal/relay,
// etc. to achive connection.
//
// For now, Dial uses only TCP. This will be extended.
func (s *Swarm) Dial(peer *peer.Peer) (*Conn, error) {
	k := peer.Key()

	// check if we already have an open connection first
	s.connsLock.RLock()
	conn, found := s.conns[k]
	s.connsLock.RUnlock()
	if found {
		return conn, nil
	}

	// open connection to peer
	conn, err := Dial("tcp", peer)
	if err != nil {
		return nil, err
	}

	// add to conns
	s.connsLock.Lock()
	s.conns[k] = conn
	s.connsLock.Unlock()

	// kick off reader goroutine
	go s.fanIn(conn)
	return conn, nil
}

// Dial connects to a peer.
//
// The idea is that the client of Swarm does not need to know what network
// the connection will happen over. Swarm can use whichever it choses.
// This allows us to use various transport protocols, do NAT traversal/relay,
// etc. to achive connection.
//
// For now, Dial uses only TCP. This will be extended.
func (s *Swarm) Dial(peer *peer.Peer) (*Conn, error, bool) {
	k := peer.Key()

	// check if we already have an open connection first
	s.connsLock.RLock()
	conn, found := s.conns[k]
	s.connsLock.RUnlock()
	if found {
		return conn, nil, true
	}

	// open connection to peer
	conn, err := Dial("tcp", peer)
	if err != nil {
		return nil, err, false
	}

	return conn, nil, false
}

func makePeer(addr *ma.Multiaddr) *peer.Peer {
	p := new(peer.Peer)
	p.AddAddress(addr)
	sk, pk, err := ci.GenerateKeyPair(ci.RSA, 512)
	if err != nil {
		panic(err)
	}
	p.PrivKey = sk
	p.PubKey = pk
	id, err := identify.IDFromPubKey(pk)
	if err != nil {
		panic(err)
	}

	p.ID = id
	return p
}

func setupDHTS(n int, t *testing.T) ([]*ma.Multiaddr, []*peer.Peer, []*IpfsDHT) {
	var addrs []*ma.Multiaddr
	for i := 0; i < 4; i++ {
		a, err := ma.NewMultiaddr(fmt.Sprintf("/ip4/127.0.0.1/tcp/%d", 5000+i))
		if err != nil {
			t.Fatal(err)
		}
		addrs = append(addrs, a)
	}

	var peers []*peer.Peer
	for i := 0; i < 4; i++ {
		p := new(peer.Peer)
		p.AddAddress(addrs[i])
		sk, pk, err := ci.GenerateKeyPair(ci.RSA, 512)
		if err != nil {
			panic(err)
		}
		p.PubKey = pk
		p.PrivKey = sk
		id, err := identify.IDFromPubKey(pk)
		if err != nil {
			panic(err)
		}
		p.ID = id
		peers = append(peers, p)
	}

	var dhts []*IpfsDHT
	for i := 0; i < 4; i++ {
		net := swarm.NewSwarm(peers[i])
		err := net.Listen()
		if err != nil {
			t.Fatal(err)
		}
		d := NewDHT(peers[i], net, ds.NewMapDatastore())
		dhts = append(dhts, d)
		d.Start()
	}

	return addrs, peers, dhts
}

func _randPeer() *peer.Peer {
	p := new(peer.Peer)
	p.ID = make(peer.ID, 16)
	crand.Read(p.ID)
	return p
}

func TestGetFailures(t *testing.T) {
	fn := newFauxNet()
	fn.Listen()

	local := new(peer.Peer)
	local.ID = peer.ID("test_peer")

	d := NewDHT(local, fn, ds.NewMapDatastore())

	other := &peer.Peer{ID: peer.ID("other_peer")}

	d.Start()

	d.Update(other)

	// This one should time out
	_, err := d.GetValue(u.Key("test"), time.Millisecond*10)
	if err != nil {
		if err != u.ErrTimeout {
			t.Fatal("Got different error than we expected.")
		}
	} else {
		t.Fatal("Did not get expected error!")
	}

	// Reply with failures to every message
	fn.AddHandler(func(mes *swarm.Message) *swarm.Message {
		pmes := new(PBDHTMessage)
		err := proto.Unmarshal(mes.Data, pmes)
		if err != nil {
			t.Fatal(err)
		}

		resp := Message{
			Type:     pmes.GetType(),
			ID:       pmes.GetId(),
			Response: true,
			Success:  false,
		}
		return swarm.NewMessage(mes.Peer, resp.ToProtobuf())
	})

	// This one should fail with NotFound
	_, err = d.GetValue(u.Key("test"), time.Millisecond*1000)
	if err != nil {
		if err != u.ErrNotFound {
			t.Fatalf("Expected ErrNotFound, got: %s", err)
		}
	} else {
		t.Fatal("expected error, got none.")
	}

	success := make(chan struct{})
	fn.handlers = nil
	fn.AddHandler(func(mes *swarm.Message) *swarm.Message {
		resp := new(PBDHTMessage)
		err := proto.Unmarshal(mes.Data, resp)
		if err != nil {
			t.Fatal(err)
		}
		if resp.GetSuccess() {
			t.Fatal("Get returned success when it shouldnt have.")
		}
		success <- struct{}{}
		return nil
	})

	// Now we test this DHT's handleGetValue failure
	req := Message{
		Type:  PBDHTMessage_GET_VALUE,
		Key:   "hello",
		ID:    swarm.GenerateMessageID(),
		Value: []byte{0},
	}
	fn.Chan.Incoming <- swarm.NewMessage(other, req.ToProtobuf())

	<-success
}