// getLocal attempts to retrieve the value from the datastore
func (dht *IpfsDHT) getLocal(key key.Key) ([]byte, error) {

	log.Debug("getLocal %s", key)
	v, err := dht.datastore.Get(key.DsKey())
	if err != nil {
		return nil, err
	}
	log.Debug("found in db")

	byt, ok := v.([]byte)
	if !ok {
		return nil, errors.New("value stored in datastore not []byte")
	}
	rec := new(pb.Record)
	err = proto.Unmarshal(byt, rec)
	if err != nil {
		return nil, err
	}

	// TODO: 'if paranoid'
	if u.Debug {
		err = dht.verifyRecordLocally(rec)
		if err != nil {
			log.Debugf("local record verify failed: %s (discarded)", err)
			return nil, err
		}
	}

	return rec.GetValue(), nil
}

// FIXME(brian): is this method meant to simulate putting a value into the network?
func (c *client) PutValue(ctx context.Context, key key.Key, val []byte) error {
	log.Debugf("PutValue: %s", key)
	rec := new(dhtpb.Record)
	rec.Value = val
	rec.Key = proto.String(string(key))
	rec.TimeReceived = proto.String(u.FormatRFC3339(time.Now()))
	data, err := proto.Marshal(rec)
	if err != nil {
		return err
	}

	return c.datastore.Put(key.DsKey(), data)
}

func verify(ps peer.Peerstore, r *dhtpb.Record) error {
	v := make(record.Validator)
	v["pk"] = record.PublicKeyValidator
	p := peer.ID(r.GetAuthor())
	pk := ps.PubKey(p)
	if pk == nil {
		return fmt.Errorf("do not have public key for %s", p)
	}
	if err := record.CheckRecordSig(r, pk); err != nil {
		return err
	}
	if err := v.VerifyRecord(r); err != nil {
		return err
	}
	return nil
}

// verifyRecordLocally attempts to verify a record. if we do not have the public
// key, we fail. we do not search the dht.
func (dht *IpfsDHT) verifyRecordLocally(r *pb.Record) error {

	if len(r.Signature) > 0 {
		// First, validate the signature
		p := peer.ID(r.GetAuthor())
		pk := dht.peerstore.PubKey(p)
		if pk == nil {
			return fmt.Errorf("do not have public key for %s", p)
		}

		if err := record.CheckRecordSig(r, pk); err != nil {
			return err
		}
	}

	return dht.Validator.VerifyRecord(r)
}

// verifyRecordOnline verifies a record, searching the DHT for the public key
// if necessary. The reason there is a distinction in the functions is that
// retrieving arbitrary public keys from the DHT as a result of passively
// receiving records (e.g. through a PUT_VALUE or ADD_PROVIDER) can cause a
// massive amplification attack on the dht. Use with care.
func (dht *IpfsDHT) verifyRecordOnline(ctx context.Context, r *pb.Record) error {

	if len(r.Signature) > 0 {
		// get the public key, search for it if necessary.
		p := peer.ID(r.GetAuthor())
		pk, err := dht.GetPublicKey(ctx, p)
		if err != nil {
			return err
		}

		err = record.CheckRecordSig(r, pk)
		if err != nil {
			return err
		}
	}

	return dht.Validator.VerifyRecord(r)
}

// FIXME(brian): is this method meant to simulate getting a value from the network?
func (c *client) GetValue(ctx context.Context, key key.Key) ([]byte, error) {
	log.Debugf("GetValue: %s", key)
	v, err := c.datastore.Get(key.DsKey())
	if err != nil {
		return nil, err
	}

	data, ok := v.([]byte)
	if !ok {
		return nil, errors.New("could not cast value from datastore")
	}

	rec := new(dhtpb.Record)
	err = proto.Unmarshal(data, rec)
	if err != nil {
		return nil, err
	}

	return rec.GetValue(), nil
}

func (p *ipnsPublisher) getPreviousSeqNo(ctx context.Context, ipnskey key.Key) (uint64, error) {
	prevrec, err := p.ds.Get(ipnskey.DsKey())
	if err != nil && err != ds.ErrNotFound {
		// None found, lets start at zero!
		return 0, err
	}
	var val []byte
	if err == nil {
		prbytes, ok := prevrec.([]byte)
		if !ok {
			return 0, fmt.Errorf("unexpected type returned from datastore: %#v", prevrec)
		}
		dhtrec := new(dhtpb.Record)
		err := proto.Unmarshal(prbytes, dhtrec)
		if err != nil {
			return 0, err
		}

		val = dhtrec.GetValue()
	} else {
		// try and check the dht for a record
		ctx, cancel := context.WithTimeout(ctx, time.Second*30)
		defer cancel()

		rv, err := p.routing.GetValue(ctx, ipnskey)
		if err != nil {
			// no such record found, start at zero!
			return 0, nil
		}

		val = rv
	}

	e := new(pb.IpnsEntry)
	err = proto.Unmarshal(val, e)
	if err != nil {
		return 0, err
	}

	return e.GetSequence(), nil
}

func (rp *Republisher) getLastVal(k key.Key) (path.Path, uint64, error) {
	ival, err := rp.ds.Get(k.DsKey())
	if err != nil {
		// not found means we dont have a previously published entry
		return "", 0, errNoEntry
	}

	val := ival.([]byte)
	dhtrec := new(dhtpb.Record)
	err = proto.Unmarshal(val, dhtrec)
	if err != nil {
		return "", 0, err
	}

	// extract published data from record
	e := new(pb.IpnsEntry)
	err = proto.Unmarshal(dhtrec.GetValue(), e)
	if err != nil {
		return "", 0, err
	}
	return path.Path(e.Value), e.GetSequence(), nil
}

// VerifyRecord checks a record and ensures it is still valid.
// It runs needed validators
func (v Validator) VerifyRecord(r *pb.Record) error {
	// Now, check validity func
	parts := path.SplitList(r.GetKey())
	if len(parts) < 3 {
		log.Infof("Record key does not have validator: %s", key.Key(r.GetKey()))
		return nil
	}

	val, ok := v[parts[1]]
	if !ok {
		log.Infof("Unrecognized key prefix: %s", parts[1])
		return ErrInvalidRecordType
	}

	return val.Func(key.Key(r.GetKey()), r.GetValue())
}

// MakePutRecord creates and signs a dht record for the given key/value pair
func MakePutRecord(sk ci.PrivKey, key key.Key, value []byte, sign bool) (*pb.Record, error) {
	record := new(pb.Record)

	record.Key = proto.String(string(key))
	record.Value = value

	pkh, err := sk.GetPublic().Hash()
	if err != nil {
		return nil, err
	}

	record.Author = proto.String(string(pkh))
	if sign {
		blob := RecordBlobForSig(record)

		sig, err := sk.Sign(blob)
		if err != nil {
			return nil, err
		}

		record.Signature = sig
	}
	return record, nil
}

// RecordBlobForSig returns the blob protected by the record signature
func RecordBlobForSig(r *pb.Record) []byte {
	k := []byte(r.GetKey())
	v := []byte(r.GetValue())
	a := []byte(r.GetAuthor())
	return bytes.Join([][]byte{k, v, a}, []byte{})
}

func (dht *IpfsDHT) checkLocalDatastore(k key.Key) (*pb.Record, error) {
	log.Debugf("%s handleGetValue looking into ds", dht.self)
	dskey := k.DsKey()
	iVal, err := dht.datastore.Get(dskey)
	log.Debugf("%s handleGetValue looking into ds GOT %v", dht.self, iVal)

	if err == ds.ErrNotFound {
		return nil, nil
	}

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

	// if we have the value, send it back
	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.Debug("Failed to unmarshal dht record from datastore")
		return nil, err
	}

	// if its our record, dont bother checking the times on it
	if peer.ID(rec.GetAuthor()) == dht.self {
		return rec, nil
	}

	var recordIsBad bool
	recvtime, err := u.ParseRFC3339(rec.GetTimeReceived())
	if err != nil {
		log.Info("either no receive time set on record, or it was invalid: ", err)
		recordIsBad = true
	}

	if time.Now().Sub(recvtime) > MaxRecordAge {
		log.Debug("old record found, tossing.")
		recordIsBad = true
	}

	// NOTE: we do not verify the record here beyond checking these timestamps.
	// we put the burden of checking the records on the requester as checking a record
	// may be computationally expensive

	if recordIsBad {
		err := dht.datastore.Delete(dskey)
		if err != nil {
			log.Error("Failed to delete bad record from datastore: ", err)
		}

		return nil, nil // can treat this as not having the record at all
	}

	return rec, nil
}