// fetchOpenChannel
func fetchOpenChannel(bucket walletdb.Bucket, nodeID [32]byte,
	addrmgr *waddrmgr.Manager) (*OpenChannel, error) {

	// Grab the bucket dedicated to storing data related to this particular
	// node.
	nodeBucket := bucket.Bucket(nodeID[:])
	if nodeBucket == nil {
		return nil, fmt.Errorf("channel bucket for node does not exist")
	}

	serializedChannel := nodeBucket.Get(activeChanKey)
	if serializedChannel == nil {
		// TODO(roasbeef): make proper in error.go
		return nil, fmt.Errorf("node has no open channels")
	}

	// Decode the serialized channel state, using the addrmgr to decrypt
	// sensitive information.
	channel := &OpenChannel{}
	reader := bytes.NewReader(serializedChannel)
	if err := channel.Decode(reader, addrmgr); err != nil {
		return nil, err
	}

	return channel, nil
}

// rangeUnminedTransactions executes the function f with TxDetails for every
// unmined transaction.  f is not executed if no unmined transactions exist.
// Error returns from f (if any) are propigated to the caller.  Returns true
// (signaling breaking out of a RangeTransactions) iff f executes and returns
// true.
func (s *Store) rangeUnminedTransactions(ns walletdb.Bucket, f func([]TxDetails) (bool, error)) (bool, error) {
	var details []TxDetails
	err := ns.Bucket(bucketUnmined).ForEach(func(k, v []byte) error {
		if len(k) < 32 {
			str := fmt.Sprintf("%s: short key (expected %d "+
				"bytes, read %d)", bucketUnmined, 32, len(k))
			return storeError(ErrData, str, nil)
		}

		var txHash wire.ShaHash
		copy(txHash[:], k)
		detail, err := s.unminedTxDetails(ns, &txHash, v)
		if err != nil {
			return err
		}

		// Because the key was created while foreach-ing over the
		// bucket, it should be impossible for unminedTxDetails to ever
		// successfully return a nil details struct.
		details = append(details, *detail)
		return nil
	})
	if err == nil && len(details) > 0 {
		return f(details)
	}
	return false, err
}

func putRawUnmined(ns walletdb.Bucket, k, v []byte) error {
	err := ns.Bucket(bucketUnmined).Put(k, v)
	if err != nil {
		str := "failed to put unmined record"
		return storeError(ErrDatabase, str, err)
	}
	return nil
}

func putRawCredit(ns walletdb.Bucket, k, v []byte) error {
	err := ns.Bucket(bucketCredits).Put(k, v)
	if err != nil {
		str := "failed to put credit"
		return storeError(ErrDatabase, str, err)
	}
	return nil
}

func fetchTxRecord(ns walletdb.Bucket, txHash *wire.ShaHash, block *Block) (*TxRecord, error) {
	k := keyTxRecord(txHash, block)
	v := ns.Bucket(bucketTxRecords).Get(k)

	rec := new(TxRecord)
	err := readRawTxRecord(txHash, v, rec)
	return rec, err
}

func putRawTxRecord(ns walletdb.Bucket, k, v []byte) error {
	err := ns.Bucket(bucketTxRecords).Put(k, v)
	if err != nil {
		str := fmt.Sprintf("%s: put failed", bucketTxRecords)
		return storeError(ErrDatabase, str, err)
	}
	return nil
}

func deleteRawUnmined(ns walletdb.Bucket, k []byte) error {
	err := ns.Bucket(bucketUnmined).Delete(k)
	if err != nil {
		str := "failed to delete unmined record"
		return storeError(ErrDatabase, str, err)
	}
	return nil
}

func deleteRawDebit(ns walletdb.Bucket, k []byte) error {
	err := ns.Bucket(bucketDebits).Delete(k)
	if err != nil {
		str := "failed to delete debit"
		return storeError(ErrDatabase, str, err)
	}
	return nil
}

func putRawBlockRecord(ns walletdb.Bucket, k, v []byte) error {
	err := ns.Bucket(bucketBlocks).Put(k, v)
	if err != nil {
		str := "failed to store block"
		return storeError(ErrDatabase, str, err)
	}
	return nil
}

func putRawUnspent(ns walletdb.Bucket, k, v []byte) error {
	err := ns.Bucket(bucketUnspent).Put(k, v)
	if err != nil {
		str := "cannot put unspent"
		return storeError(ErrDatabase, str, err)
	}
	return nil
}

func fetchMinedBalance(ns walletdb.Bucket) (btcutil.Amount, error) {
	v := ns.Get(rootMinedBalance)
	if len(v) != 8 {
		str := fmt.Sprintf("balance: short read (expected 8 bytes, "+
			"read %v)", len(v))
		return 0, storeError(ErrData, str, nil)
	}
	return btcutil.Amount(byteOrder.Uint64(v)), nil
}

func fetchBlockTime(ns walletdb.Bucket, height int32) (time.Time, error) {
	k := keyBlockRecord(height)
	v := ns.Bucket(bucketBlocks).Get(k)
	if len(v) < 44 {
		str := fmt.Sprintf("%s: short read (expected %d bytes, read %d)",
			bucketBlocks, 44, len(v))
		return time.Time{}, storeError(ErrData, str, nil)
	}
	return time.Unix(int64(byteOrder.Uint64(v[32:40])), 0), nil
}

// testDeleteValues removes all of the provided key/value pairs from the
// provided bucket.
func testDeleteValues(tc *testContext, bucket walletdb.Bucket, values map[string]string) bool {
	for k := range values {
		if err := bucket.Delete([]byte(k)); err != nil {
			tc.t.Errorf("Delete: unexpected error: %v", err)
			return false
		}
	}

	return true
}

func putUnspent(ns walletdb.Bucket, outPoint *wire.OutPoint, block *Block) error {
	k := canonicalOutPoint(&outPoint.Hash, outPoint.Index)
	v := valueUnspent(block)
	err := ns.Bucket(bucketUnspent).Put(k, v)
	if err != nil {
		str := "cannot put unspent"
		return storeError(ErrDatabase, str, err)
	}
	return nil
}

func putMinedBalance(ns walletdb.Bucket, amt btcutil.Amount) error {
	v := make([]byte, 8)
	byteOrder.PutUint64(v, uint64(amt))
	err := ns.Put(rootMinedBalance, v)
	if err != nil {
		str := "failed to put balance"
		return storeError(ErrDatabase, str, err)
	}
	return nil
}

// latestTxRecord searches for the newest recorded mined transaction record with
// a matching hash.  In case of a hash collision, the record from the newest
// block is returned.  Returns (nil, nil) if no matching transactions are found.
func latestTxRecord(ns walletdb.Bucket, txHash *wire.ShaHash) (k, v []byte) {
	prefix := txHash[:]
	c := ns.Bucket(bucketTxRecords).Cursor()
	ck, cv := c.Seek(prefix)
	var lastKey, lastVal []byte
	for bytes.HasPrefix(ck, prefix) {
		lastKey, lastVal = ck, cv
		ck, cv = c.Next()
	}
	return lastKey, lastVal
}

// spendRawCredit marks the credit with a given key as mined at some particular
// block as spent by the input at some transaction incidence.  The debited
// amount is returned.
func spendCredit(ns walletdb.Bucket, k []byte, spender *indexedIncidence) (btcutil.Amount, error) {
	v := ns.Bucket(bucketCredits).Get(k)
	newv := make([]byte, 81)
	copy(newv, v)
	v = newv
	v[8] |= 1 << 0
	copy(v[9:41], spender.txHash[:])
	byteOrder.PutUint32(v[41:45], uint32(spender.block.Height))
	copy(v[45:77], spender.block.Hash[:])
	byteOrder.PutUint32(v[77:81], spender.index)

	return btcutil.Amount(byteOrder.Uint64(v[0:8])), putRawCredit(ns, k, v)
}

func putTxRecord(ns walletdb.Bucket, rec *TxRecord, block *Block) error {
	k := keyTxRecord(&rec.Hash, block)
	v, err := valueTxRecord(rec)
	if err != nil {
		return err
	}
	err = ns.Bucket(bucketTxRecords).Put(k, v)
	if err != nil {
		str := fmt.Sprintf("%s: put failed for %v", bucketTxRecords, rec.Hash)
		return storeError(ErrDatabase, str, err)
	}
	return nil
}

// existsDebit checks for the existance of a debit.  If found, the debit and
// previous credit keys are returned.  If the debit does not exist, both keys
// are nil.
func existsDebit(ns walletdb.Bucket, txHash *wire.ShaHash, index uint32, block *Block) (k, credKey []byte, err error) {
	k = keyDebit(txHash, index, block)
	v := ns.Bucket(bucketDebits).Get(k)
	if v == nil {
		return nil, nil, nil
	}
	if len(v) < 80 {
		str := fmt.Sprintf("%s: short read (expected 80 bytes, read %v)",
			bucketDebits, len(v))
		return nil, nil, storeError(ErrData, str, nil)
	}
	return k, v[8:80], nil
}

// existsRawUnspent returns the credit key if there exists an output recorded
// for the raw unspent key.  It returns nil if the k/v pair does not exist.
func existsRawUnspent(ns walletdb.Bucket, k []byte) (credKey []byte) {
	if len(k) < 36 {
		return nil
	}
	v := ns.Bucket(bucketUnspent).Get(k)
	if len(v) < 36 {
		return nil
	}
	credKey = make([]byte, 72)
	copy(credKey, k[:32])
	copy(credKey[32:68], v)
	copy(credKey[68:72], k[32:36])
	return credKey
}