// GetValue searches for the value corresponding to given Key.
// If the search does not succeed, a multiaddr string of a closer peer is
// returned along with util.ErrSearchIncomplete
func (dht *IpfsDHT) GetValue(ctx context.Context, key key.Key) ([]byte, error) {
	// If we have it local, dont bother doing an RPC!
	val, err := dht.getLocal(key)
	if err == nil {
		log.Debug("have it locally")
		return val, nil
	} else {
		log.Debug("failed to get value locally: %s", err)
	}

	// get closest peers in the routing table
	rtp := dht.routingTable.NearestPeers(kb.ConvertKey(key), AlphaValue)
	log.Debugf("peers in rt: %s", len(rtp), rtp)
	if len(rtp) == 0 {
		log.Warning("No peers from routing table!")
		return nil, kb.ErrLookupFailure
	}

	// setup the Query
	parent := ctx
	query := dht.newQuery(key, func(ctx context.Context, p peer.ID) (*dhtQueryResult, error) {
		notif.PublishQueryEvent(parent, &notif.QueryEvent{
			Type: notif.SendingQuery,
			ID:   p,
		})

		val, peers, err := dht.getValueOrPeers(ctx, p, key)
		if err != nil {
			return nil, err
		}

		res := &dhtQueryResult{value: val, closerPeers: peers}
		if val != nil {
			res.success = true
		}

		notif.PublishQueryEvent(parent, &notif.QueryEvent{
			Type:      notif.PeerResponse,
			ID:        p,
			Responses: pointerizePeerInfos(peers),
		})

		return res, nil
	})

	// run it!
	result, err := query.Run(ctx, rtp)
	if err != nil {
		return nil, err
	}

	log.Debugf("GetValue %v %v", key, result.value)
	if result.value == nil {
		return nil, routing.ErrNotFound
	}

	return result.value, nil
}

// PingRoutine periodically pings nearest neighbors.
func (dht *IpfsDHT) PingRoutine(t time.Duration) {
	defer dht.Children().Done()

	tick := time.Tick(t)
	for {
		select {
		case <-tick:
			id := make([]byte, 16)
			rand.Read(id)
			peers := dht.routingTable.NearestPeers(kb.ConvertKey(key.Key(id)), 5)
			for _, p := range peers {
				ctx, cancel := context.WithTimeout(dht.Context(), time.Second*5)
				_, err := dht.Ping(ctx, p)
				if err != nil {
					log.Debugf("Ping error: %s", err)
				}
				cancel()
			}
		case <-dht.Closing():
			return
		}
	}
}

func sortedByKey(peers []peer.ID, skey string) []peer.ID {
	target := kbucket.ConvertKey(key.Key(skey))
	return kbucket.SortClosestPeers(peers, target)
}

func (dht *IpfsDHT) findProvidersAsyncRoutine(ctx context.Context, key key.Key, count int, peerOut chan peer.PeerInfo) {
	defer log.EventBegin(ctx, "findProvidersAsync", &key).Done()
	defer close(peerOut)

	ps := pset.NewLimited(count)
	provs := dht.providers.GetProviders(ctx, key)
	for _, p := range provs {
		// NOTE: assuming that this list of peers is unique
		if ps.TryAdd(p) {
			select {
			case peerOut <- dht.peerstore.PeerInfo(p):
			case <-ctx.Done():
				return
			}
		}

		// If we have enough peers locally, dont bother with remote RPC
		if ps.Size() >= count {
			return
		}
	}

	// setup the Query
	parent := ctx
	query := dht.newQuery(key, func(ctx context.Context, p peer.ID) (*dhtQueryResult, error) {
		notif.PublishQueryEvent(parent, &notif.QueryEvent{
			Type: notif.SendingQuery,
			ID:   p,
		})
		pmes, err := dht.findProvidersSingle(ctx, p, key)
		if err != nil {
			return nil, err
		}

		log.Debugf("%d provider entries", len(pmes.GetProviderPeers()))
		provs := pb.PBPeersToPeerInfos(pmes.GetProviderPeers())
		log.Debugf("%d provider entries decoded", len(provs))

		// Add unique providers from request, up to 'count'
		for _, prov := range provs {
			log.Debugf("got provider: %s", prov)
			if ps.TryAdd(prov.ID) {
				log.Debugf("using provider: %s", prov)
				select {
				case peerOut <- prov:
				case <-ctx.Done():
					log.Debug("Context timed out sending more providers")
					return nil, ctx.Err()
				}
			}
			if ps.Size() >= count {
				log.Debugf("got enough providers (%d/%d)", ps.Size(), count)
				return &dhtQueryResult{success: true}, nil
			}
		}

		// Give closer peers back to the query to be queried
		closer := pmes.GetCloserPeers()
		clpeers := pb.PBPeersToPeerInfos(closer)
		log.Debugf("got closer peers: %d %s", len(clpeers), clpeers)

		notif.PublishQueryEvent(parent, &notif.QueryEvent{
			Type:      notif.PeerResponse,
			ID:        p,
			Responses: pointerizePeerInfos(clpeers),
		})
		return &dhtQueryResult{closerPeers: clpeers}, nil
	})

	peers := dht.routingTable.NearestPeers(kb.ConvertKey(key), AlphaValue)
	_, err := query.Run(ctx, peers)
	if err != nil {
		log.Debugf("Query error: %s", err)
		notif.PublishQueryEvent(ctx, &notif.QueryEvent{
			Type:  notif.QueryError,
			Extra: err.Error(),
		})
	}
}

// nearestPeersToQuery returns the routing tables closest peers.
func (dht *IpfsDHT) nearestPeersToQuery(pmes *pb.Message, count int) []peer.ID {
	key := key.Key(pmes.GetKey())
	closer := dht.routingTable.NearestPeers(kb.ConvertKey(key), count)
	return closer
}

func (dht *IpfsDHT) GetValues(ctx context.Context, key key.Key, nvals int) ([]routing.RecvdVal, error) {
	var vals []routing.RecvdVal
	var valslock sync.Mutex

	// If we have it local, dont bother doing an RPC!
	lrec, err := dht.getLocal(key)
	if err == nil {
		// TODO: this is tricky, we dont always want to trust our own value
		// what if the authoritative source updated it?
		log.Debug("have it locally")
		vals = append(vals, routing.RecvdVal{
			Val:  lrec.GetValue(),
			From: dht.self,
		})

		if nvals <= 1 {
			return vals, nil
		}
	} else if nvals == 0 {
		return nil, err
	}

	// get closest peers in the routing table
	rtp := dht.routingTable.NearestPeers(kb.ConvertKey(key), KValue)
	log.Debugf("peers in rt: %s", len(rtp), rtp)
	if len(rtp) == 0 {
		log.Warning("No peers from routing table!")
		return nil, kb.ErrLookupFailure
	}

	// setup the Query
	parent := ctx
	query := dht.newQuery(key, func(ctx context.Context, p peer.ID) (*dhtQueryResult, error) {
		notif.PublishQueryEvent(parent, &notif.QueryEvent{
			Type: notif.SendingQuery,
			ID:   p,
		})

		rec, peers, err := dht.getValueOrPeers(ctx, p, key)
		switch err {
		case routing.ErrNotFound:
			// in this case, they responded with nothing,
			// still send a notification so listeners can know the
			// request has completed 'successfully'
			notif.PublishQueryEvent(parent, &notif.QueryEvent{
				Type: notif.PeerResponse,
				ID:   p,
			})
			return nil, err
		default:
			return nil, err

		case nil, errInvalidRecord:
			// in either of these cases, we want to keep going
		}

		res := &dhtQueryResult{closerPeers: peers}

		if rec.GetValue() != nil || err == errInvalidRecord {
			rv := routing.RecvdVal{
				Val:  rec.GetValue(),
				From: p,
			}
			valslock.Lock()
			vals = append(vals, rv)

			// If weve collected enough records, we're done
			if len(vals) >= nvals {
				res.success = true
			}
			valslock.Unlock()
		}

		notif.PublishQueryEvent(parent, &notif.QueryEvent{
			Type:      notif.PeerResponse,
			ID:        p,
			Responses: pointerizePeerInfos(peers),
		})

		return res, nil
	})

	// run it!
	_, err = query.Run(ctx, rtp)
	if len(vals) == 0 {
		if err != nil {
			return nil, err
		}
	}

	return vals, nil

}

// Kademlia 'node lookup' operation. Returns a channel of the K closest peers
// to the given key
func (dht *IpfsDHT) GetClosestPeers(ctx context.Context, key key.Key) (<-chan peer.ID, error) {
	e := log.EventBegin(ctx, "getClosestPeers", &key)
	tablepeers := dht.routingTable.NearestPeers(kb.ConvertKey(key), KValue)
	if len(tablepeers) == 0 {
		return nil, kb.ErrLookupFailure
	}

	out := make(chan peer.ID, KValue)
	peerset := pset.NewLimited(KValue)

	for _, p := range tablepeers {
		select {
		case out <- p:
		case <-ctx.Done():
			return nil, ctx.Err()
		}
		peerset.Add(p)
	}

	// since the query doesnt actually pass our context down
	// we have to hack this here. whyrusleeping isnt a huge fan of goprocess
	parent := ctx
	query := dht.newQuery(key, func(ctx context.Context, p peer.ID) (*dhtQueryResult, error) {
		// For DHT query command
		notif.PublishQueryEvent(parent, &notif.QueryEvent{
			Type: notif.SendingQuery,
			ID:   p,
		})

		closer, err := dht.closerPeersSingle(ctx, key, p)
		if err != nil {
			log.Debugf("error getting closer peers: %s", err)
			return nil, err
		}

		var filtered []peer.PeerInfo
		for _, clp := range closer {
			if kb.Closer(clp, dht.self, key) && peerset.TryAdd(clp) {
				select {
				case out <- clp:
				case <-ctx.Done():
					return nil, ctx.Err()
				}
				filtered = append(filtered, dht.peerstore.PeerInfo(clp))
			}
		}

		// For DHT query command
		notif.PublishQueryEvent(parent, &notif.QueryEvent{
			Type:      notif.PeerResponse,
			ID:        p,
			Responses: pointerizePeerInfos(filtered),
		})

		return &dhtQueryResult{closerPeers: filtered}, nil
	})

	go func() {
		defer close(out)
		defer e.Done()
		// run it!
		_, err := query.Run(ctx, tablepeers)
		if err != nil {
			log.Debugf("closestPeers query run error: %s", err)
		}
	}()

	return out, nil
}