// betterPeerToQuery returns nearestPeersToQuery, but iff closer than self.
func (dht *IpfsDHT) betterPeersToQuery(pmes *pb.Message, count int) []peer.Peer {
	closer := dht.nearestPeersToQuery(pmes, count)

	// no node? nil
	if closer == nil {
		return nil
	}

	// == to self? thats bad
	for _, p := range closer {
		if p.ID().Equal(dht.self.ID()) {
			log.Error("Attempted to return self! this shouldnt happen...")
			return nil
		}
	}

	var filtered []peer.Peer
	for _, p := range closer {
		// must all be closer than self
		key := u.Key(pmes.GetKey())
		if !kb.Closer(dht.self.ID(), p.ID(), key) {
			filtered = append(filtered, p)
		}
	}

	// ok seems like closer nodes
	return filtered
}

func (dht *IpfsDHT) handleAddProvider(p peer.Peer, pmes *pb.Message) (*pb.Message, error) {
	key := u.Key(pmes.GetKey())

	log.Debugf("%s adding %s as a provider for '%s'\n", dht.self, p, peer.ID(key))

	// add provider should use the address given in the message
	for _, pb := range pmes.GetProviderPeers() {
		pid := peer.ID(pb.GetId())
		if pid.Equal(p.ID()) {

			addr, err := pb.Address()
			if err != nil {
				log.Errorf("provider %s error with address %s", p, *pb.Addr)
				continue
			}

			log.Infof("received provider %s %s for %s", p, addr, key)
			p.AddAddress(addr)
			dht.providers.AddProvider(key, p)

		} else {
			log.Errorf("handleAddProvider received provider %s from %s", pid, p)
		}
	}

	return pmes, nil // send back same msg as confirmation.
}

// nearestPeersToQuery returns the routing tables closest peers.
func (dht *IpfsDHT) nearestPeersToQuery(pmes *pb.Message, count int) []peer.Peer {
	level := pmes.GetClusterLevel()
	cluster := dht.routingTables[level]

	key := u.Key(pmes.GetKey())
	closer := cluster.NearestPeers(kb.ConvertKey(key), count)
	return closer
}

// HandleMessage implements the inet.Handler interface.
func (dht *IpfsDHT) HandleMessage(ctx context.Context, mes msg.NetMessage) msg.NetMessage {

	mData := mes.Data()
	if mData == nil {
		log.Error("Message contained nil data.")
		return nil
	}

	mPeer := mes.Peer()
	if mPeer == nil {
		log.Error("Message contained nil peer.")
		return nil
	}

	// deserialize msg
	pmes := new(pb.Message)
	err := proto.Unmarshal(mData, pmes)
	if err != nil {
		log.Error("Error unmarshaling data")
		return nil
	}

	// update the peer (on valid msgs only)
	dht.Update(ctx, mPeer)

	log.Event(ctx, "foo", dht.self, mPeer, pmes)

	// get handler for this msg type.
	handler := dht.handlerForMsgType(pmes.GetType())
	if handler == nil {
		log.Error("got back nil handler from handlerForMsgType")
		return nil
	}

	// dispatch handler.
	rpmes, err := handler(mPeer, pmes)
	if err != nil {
		log.Errorf("handle message error: %s", err)
		return nil
	}

	// if nil response, return it before serializing
	if rpmes == nil {
		log.Warning("Got back nil response from request.")
		return nil
	}

	// serialize response msg
	rmes, err := msg.FromObject(mPeer, rpmes)
	if err != nil {
		log.Errorf("serialze response error: %s", err)
		return nil
	}

	return rmes
}

func (dht *IpfsDHT) handleFindPeer(p peer.Peer, pmes *pb.Message) (*pb.Message, error) {
	resp := pb.NewMessage(pmes.GetType(), "", pmes.GetClusterLevel())
	var closest []peer.Peer

	// if looking for self... special case where we send it on CloserPeers.
	if peer.ID(pmes.GetKey()).Equal(dht.self.ID()) {
		closest = []peer.Peer{dht.self}
	} else {
		closest = dht.betterPeersToQuery(pmes, CloserPeerCount)
	}

	if closest == nil {
		log.Errorf("handleFindPeer: could not find anything.")
		return resp, nil
	}

	var withAddresses []peer.Peer
	for _, p := range closest {
		if len(p.Addresses()) > 0 {
			withAddresses = append(withAddresses, p)
		}
	}

	for _, p := range withAddresses {
		log.Debugf("handleFindPeer: sending back '%s'", p)
	}
	resp.CloserPeers = pb.PeersToPBPeers(withAddresses)
	return resp, nil
}

// Store a value in this peer local storage
func (dht *IpfsDHT) handlePutValue(p peer.Peer, pmes *pb.Message) (*pb.Message, error) {
	dht.dslock.Lock()
	defer dht.dslock.Unlock()
	dskey := u.Key(pmes.GetKey()).DsKey()

	err := dht.verifyRecord(pmes.GetRecord())
	if err != nil {
		fmt.Println(u.Key(pmes.GetRecord().GetAuthor()))
		log.Error("Bad dht record in put request")
		return nil, err
	}

	data, err := proto.Marshal(pmes.GetRecord())
	if err != nil {
		return nil, err
	}

	err = dht.datastore.Put(dskey, data)
	log.Debugf("%s handlePutValue %v\n", dht.self, dskey)
	return pmes, 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) {
	// t.Skip("skipping test because it makes a lot of output")

	ctx := context.Background()
	u.Debug = false
	fn := &fauxNet{}
	fs := &fauxSender{}
	local := makePeer(nil)
	peerstore := peer.NewPeerstore()
	peerstore.Add(local)

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

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

	// Reply with random peers to every message
	fs.AddHandler(func(mes msg.NetMessage) msg.NetMessage {
		pmes := new(pb.Message)
		err := proto.Unmarshal(mes.Data(), pmes)
		if err != nil {
			t.Fatal(err)
		}

		switch pmes.GetType() {
		case pb.Message_GET_VALUE:
			resp := &pb.Message{
				Type:        pmes.Type,
				CloserPeers: pb.PeersToPBPeers([]peer.Peer{other}),
			}

			mes, err := msg.FromObject(mes.Peer(), resp)
			if err != nil {
				t.Error(err)
			}
			return mes
		default:
			panic("Shouldnt recieve this.")
		}

	})

	ctx, _ = context.WithTimeout(ctx, time.Second*30)
	_, err := d.GetValue(ctx, u.Key("hello"))
	if err != nil {
		switch err {
		case routing.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 TestNotFound(t *testing.T) {
	if testing.Short() {
		t.SkipNow()
	}

	ctx := context.Background()
	fn := &fauxNet{}
	fs := &fauxSender{}

	local := makePeer(nil)
	peerstore := peer.NewPeerstore()
	peerstore.Add(local)

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

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

	// Reply with random peers to every message
	fs.AddHandler(func(mes msg.NetMessage) msg.NetMessage {
		pmes := new(pb.Message)
		err := proto.Unmarshal(mes.Data(), pmes)
		if err != nil {
			t.Fatal(err)
		}

		switch pmes.GetType() {
		case pb.Message_GET_VALUE:
			resp := &pb.Message{Type: pmes.Type}

			peers := []peer.Peer{}
			for i := 0; i < 7; i++ {
				peers = append(peers, _randPeer())
			}
			resp.CloserPeers = pb.PeersToPBPeers(peers)
			mes, err := msg.FromObject(mes.Peer(), resp)
			if err != nil {
				t.Error(err)
			}
			return mes
		default:
			panic("Shouldnt recieve this.")
		}

	})

	ctx, _ = context.WithTimeout(ctx, time.Second*5)
	v, err := d.GetValue(ctx, u.Key("hello"))
	log.Debugf("get value got %v", v)
	if err != nil {
		switch err {
		case routing.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 TestGetFailures(t *testing.T) {
	if testing.Short() {
		t.SkipNow()
	}

	ctx := context.Background()
	fn := &fauxNet{}
	fs := &fauxSender{}

	peerstore := peer.NewPeerstore()
	local := makePeer(nil)

	d := NewDHT(ctx, local, peerstore, fn, fs, ds.NewMapDatastore())
	other := makePeer(nil)
	d.Update(ctx, other)

	// This one should time out
	// u.POut("Timout Test\n")
	ctx1, _ := context.WithTimeout(context.Background(), time.Second)
	_, err := d.GetValue(ctx1, u.Key("test"))
	if err != nil {
		if err != context.DeadlineExceeded {
			t.Fatal("Got different error than we expected", err)
		}
	} else {
		t.Fatal("Did not get expected error!")
	}

	// u.POut("NotFound Test\n")
	// Reply with failures to every message
	fs.AddHandler(func(mes msg.NetMessage) msg.NetMessage {
		pmes := new(pb.Message)
		err := proto.Unmarshal(mes.Data(), pmes)
		if err != nil {
			t.Fatal(err)
		}

		resp := &pb.Message{
			Type: pmes.Type,
		}
		m, err := msg.FromObject(mes.Peer(), resp)
		return m
	})

	// This one should fail with NotFound
	ctx2, _ := context.WithTimeout(context.Background(), time.Second)
	_, err = d.GetValue(ctx2, u.Key("test"))
	if err != nil {
		if err != routing.ErrNotFound {
			t.Fatalf("Expected ErrNotFound, got: %s", err)
		}
	} else {
		t.Fatal("expected error, got none.")
	}

	fs.handlers = nil
	// Now we test this DHT's handleGetValue failure
	typ := pb.Message_GET_VALUE
	str := "hello"
	rec, err := d.makePutRecord(u.Key(str), []byte("blah"))
	if err != nil {
		t.Fatal(err)
	}
	req := pb.Message{
		Type:   &typ,
		Key:    &str,
		Record: rec,
	}

	// u.POut("handleGetValue Test\n")
	mes, err := msg.FromObject(other, &req)
	if err != nil {
		t.Error(err)
	}

	mes = d.HandleMessage(ctx, mes)

	pmes := new(pb.Message)
	err = proto.Unmarshal(mes.Data(), pmes)
	if err != nil {
		t.Fatal(err)
	}
	if pmes.GetRecord() != nil {
		t.Fatal("shouldnt have value")
	}
	if pmes.GetProviderPeers() != nil {
		t.Fatal("shouldnt have provider peers")
	}

}

func (dht *IpfsDHT) handleGetValue(p peer.Peer, pmes *pb.Message) (*pb.Message, error) {
	log.Debugf("%s handleGetValue for key: %s\n", dht.self, pmes.GetKey())

	// setup response
	resp := pb.NewMessage(pmes.GetType(), pmes.GetKey(), pmes.GetClusterLevel())

	// first, is the key even a key?
	key := pmes.GetKey()
	if key == "" {
		return nil, errors.New("handleGetValue but no key was provided")
	}

	// let's first check if we have the value locally.
	log.Debugf("%s handleGetValue looking into ds", dht.self)
	dskey := u.Key(pmes.GetKey()).DsKey()
	iVal, err := dht.datastore.Get(dskey)
	log.Debugf("%s handleGetValue looking into ds GOT %v", dht.self, iVal)

	// if we got an unexpected error, bail.
	if err != nil && err != ds.ErrNotFound {
		return nil, err
	}

	// Note: changed the behavior here to return _as much_ info as possible
	// (potentially all of {value, closer peers, provider})

	// if we have the value, send it back
	if err == nil {
		log.Debugf("%s handleGetValue success!", dht.self)

		byts, ok := iVal.([]byte)
		if !ok {
			return nil, fmt.Errorf("datastore had non byte-slice value for %v", dskey)
		}

		rec := new(pb.Record)
		err := proto.Unmarshal(byts, rec)
		if err != nil {
			log.Error("Failed to unmarshal dht record from datastore")
			return nil, err
		}

		resp.Record = rec
	}

	// if we know any providers for the requested value, return those.
	provs := dht.providers.GetProviders(u.Key(pmes.GetKey()))
	if len(provs) > 0 {
		log.Debugf("handleGetValue returning %d provider[s]", len(provs))
		resp.ProviderPeers = pb.PeersToPBPeers(provs)
	}

	// Find closest peer on given cluster to desired key and reply with that info
	closer := dht.betterPeersToQuery(pmes, CloserPeerCount)
	if closer != nil {
		for _, p := range closer {
			log.Debugf("handleGetValue returning closer peer: '%s'", p)
			if len(p.Addresses()) < 1 {
				log.Critical("no addresses on peer being sent!")
			}
		}
		resp.CloserPeers = pb.PeersToPBPeers(closer)
	}

	return resp, nil
}

func (dht *IpfsDHT) handleGetProviders(p peer.Peer, pmes *pb.Message) (*pb.Message, error) {
	resp := pb.NewMessage(pmes.GetType(), pmes.GetKey(), pmes.GetClusterLevel())

	// check if we have this value, to add ourselves as provider.
	log.Debugf("handling GetProviders: '%s'", u.Key(pmes.GetKey()))
	dsk := u.Key(pmes.GetKey()).DsKey()
	has, err := dht.datastore.Has(dsk)
	if err != nil && err != ds.ErrNotFound {
		log.Errorf("unexpected datastore error: %v\n", err)
		has = false
	}

	// setup providers
	providers := dht.providers.GetProviders(u.Key(pmes.GetKey()))
	if has {
		providers = append(providers, dht.self)
	}

	// if we've got providers, send thos those.
	if providers != nil && len(providers) > 0 {
		resp.ProviderPeers = pb.PeersToPBPeers(providers)
	}

	// Also send closer peers.
	closer := dht.betterPeersToQuery(pmes, CloserPeerCount)
	if closer != nil {
		resp.CloserPeers = pb.PeersToPBPeers(closer)
	}

	return resp, nil
}