// IDFromPublicKey returns the Peer ID corresponding to pk
func IDFromPublicKey(pk ic.PubKey) (ID, error) {
	b, err := pk.Bytes()
	if err != nil {
		return "", err
	}
	hash := u.Hash(b)
	return ID(hash), nil
}

func CheckRecordSig(r *pb.Record, pk ci.PubKey) error {
	blob := RecordBlobForSig(r)
	good, err := pk.Verify(blob, r.Signature)
	if err != nil {
		return nil
	}
	if !good {
		return errors.New("invalid record signature")
	}
	return nil
}

func PublishPublicKey(ctx context.Context, r routing.IpfsRouting, k key.Key, pubk ci.PubKey) error {
	log.Debugf("Storing pubkey at: %s", k)
	pkbytes, err := pubk.Bytes()
	if err != nil {
		return err
	}

	// Store associated public key
	timectx, cancel := context.WithTimeout(ctx, PublishPutValTimeout)
	defer cancel()
	err = r.PutValue(timectx, k, pkbytes)
	if err != nil {
		return err
	}

	return nil
}

// resolveOnce implements resolver. Uses the IPFS routing system to
// resolve SFS-like names.
func (r *routingResolver) resolveOnce(ctx context.Context, name string) (path.Path, error) {
	log.Debugf("RoutingResolve: '%s'", name)
	cached, ok := r.cacheGet(name)
	if ok {
		return cached, nil
	}

	hash, err := mh.FromB58String(name)
	if err != nil {
		// name should be a multihash. if it isn't, error out here.
		log.Warningf("RoutingResolve: bad input hash: [%s]\n", name)
		return "", err
	}

	// use the routing system to get the name.
	// /ipns/<name>
	h := []byte("/ipns/" + string(hash))

	var entry *pb.IpnsEntry
	var pubkey ci.PubKey

	resp := make(chan error, 2)
	go func() {
		ipnsKey := key.Key(h)
		val, err := r.routing.GetValue(ctx, ipnsKey)
		if err != nil {
			log.Warning("RoutingResolve get failed.")
			resp <- err
		}

		entry = new(pb.IpnsEntry)
		err = proto.Unmarshal(val, entry)
		if err != nil {
			resp <- err
		}
		resp <- nil
	}()

	go func() {
		// name should be a public key retrievable from ipfs
		pubk, err := routing.GetPublicKey(r.routing, ctx, hash)
		if err != nil {
			resp <- err
		}
		pubkey = pubk
		resp <- nil
	}()

	for i := 0; i < 2; i++ {
		err = <-resp
		if err != nil {
			return "", err
		}
	}

	hsh, _ := pubkey.Hash()
	log.Debugf("pk hash = %s", key.Key(hsh))

	// check sig with pk
	if ok, err := pubkey.Verify(ipnsEntryDataForSig(entry), entry.GetSignature()); err != nil || !ok {
		return "", fmt.Errorf("Invalid value. Not signed by PrivateKey corresponding to %v", pubkey)
	}

	// ok sig checks out. this is a valid name.

	// check for old style record:
	valh, err := mh.Cast(entry.GetValue())
	if err != nil {
		// Not a multihash, probably a new record
		p, err := path.ParsePath(string(entry.GetValue()))
		if err != nil {
			return "", err
		}

		r.cacheSet(name, p, entry)
		return p, nil
	} else {
		// Its an old style multihash record
		log.Warning("Detected old style multihash record")
		p := path.FromKey(key.Key(valh))
		r.cacheSet(name, p, entry)
		return p, nil
	}
}