lbcwallet/wallet/wallet.go

// Copyright (c) 2013-2017 The btcsuite developers
// Copyright (c) 2015-2016 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.

package wallet

import (
	"encoding/hex"
	"errors"
	"fmt"
	"sort"
	"sync"
	"time"

	"github.com/btcsuite/btcd/blockchain"
	"github.com/btcsuite/btcd/btcec"
	"github.com/btcsuite/btcd/btcjson"
	"github.com/btcsuite/btcd/chaincfg"
	"github.com/btcsuite/btcd/chaincfg/chainhash"
	"github.com/btcsuite/btcd/txscript"
	"github.com/btcsuite/btcd/wire"
	"github.com/btcsuite/btcutil"
	"github.com/btcsuite/btcutil/hdkeychain"
	"github.com/btcsuite/btcwallet/chain"
	"github.com/btcsuite/btcwallet/waddrmgr"
	"github.com/btcsuite/btcwallet/wallet/txauthor"
	"github.com/btcsuite/btcwallet/wallet/txrules"
	"github.com/btcsuite/btcwallet/walletdb"
	"github.com/btcsuite/btcwallet/wtxmgr"
)

const (
	// InsecurePubPassphrase is the default outer encryption passphrase used
	// for public data (everything but private keys).  Using a non-default
	// public passphrase can prevent an attacker without the public
	// passphrase from discovering all past and future wallet addresses if
	// they gain access to the wallet database.
	//
	// NOTE: at time of writing, public encryption only applies to public
	// data in the waddrmgr namespace.  Transactions are not yet encrypted.
	InsecurePubPassphrase = "public"

	walletDbWatchingOnlyName = "wowallet.db"
)

// ErrNotSynced describes an error where an operation cannot complete
// due wallet being out of sync (and perhaps currently syncing with)
// the remote chain server.
var ErrNotSynced = errors.New("wallet is not synchronized with the chain server")

// Namespace bucket keys.
var (
	waddrmgrNamespaceKey = []byte("waddrmgr")
	wtxmgrNamespaceKey   = []byte("wtxmgr")
)

// Wallet is a structure containing all the components for a
// complete wallet.  It contains the Armory-style key store
// addresses and keys),
type Wallet struct {
	publicPassphrase []byte

	// Data stores
	db      walletdb.DB
	Manager *waddrmgr.Manager
	TxStore *wtxmgr.Store

	chainClient        *chain.RPCClient
	chainClientLock    sync.Mutex
	chainClientSynced  bool
	chainClientSyncMtx sync.Mutex

	lockedOutpoints map[wire.OutPoint]struct{}
	relayFee        btcutil.Amount
	relayFeeMu      sync.Mutex

	// Channels for rescan processing.  Requests are added and merged with
	// any waiting requests, before being sent to another goroutine to
	// call the rescan RPC.
	rescanAddJob        chan *RescanJob
	rescanBatch         chan *rescanBatch
	rescanNotifications chan interface{} // From chain server
	rescanProgress      chan *RescanProgressMsg
	rescanFinished      chan *RescanFinishedMsg

	// Channel for transaction creation requests.
	createTxRequests chan createTxRequest

	// Channels for the manager locker.
	unlockRequests     chan unlockRequest
	lockRequests       chan struct{}
	holdUnlockRequests chan chan heldUnlock
	lockState          chan bool
	changePassphrase   chan changePassphraseRequest

	// Information for reorganization handling.
	reorganizingLock sync.Mutex
	reorganizeToHash chainhash.Hash
	reorganizing     bool

	NtfnServer *NotificationServer

	chainParams *chaincfg.Params
	wg          sync.WaitGroup

	started bool
	quit    chan struct{}
	quitMu  sync.Mutex
}

// Start starts the goroutines necessary to manage a wallet.
func (w *Wallet) Start() {
	w.quitMu.Lock()
	select {
	case <-w.quit:
		// Restart the wallet goroutines after shutdown finishes.
		w.WaitForShutdown()
		w.quit = make(chan struct{})
	default:
		// Ignore when the wallet is still running.
		if w.started {
			w.quitMu.Unlock()
			return
		}
		w.started = true
	}
	w.quitMu.Unlock()

	w.wg.Add(2)
	go w.txCreator()
	go w.walletLocker()
}

// SynchronizeRPC associates the wallet with the consensus RPC client,
// synchronizes the wallet with the latest changes to the blockchain, and
// continuously updates the wallet through RPC notifications.
//
// This method is unstable and will be removed when all syncing logic is moved
// outside of the wallet package.
func (w *Wallet) SynchronizeRPC(chainClient *chain.RPCClient) {
	w.quitMu.Lock()
	select {
	case <-w.quit:
		w.quitMu.Unlock()
		return
	default:
	}
	w.quitMu.Unlock()

	// TODO: Ignoring the new client when one is already set breaks callers
	// who are replacing the client, perhaps after a disconnect.
	w.chainClientLock.Lock()
	if w.chainClient != nil {
		w.chainClientLock.Unlock()
		return
	}
	w.chainClient = chainClient
	w.chainClientLock.Unlock()

	// TODO: It would be preferable to either run these goroutines
	// separately from the wallet (use wallet mutator functions to
	// make changes from the RPC client) and not have to stop and
	// restart them each time the client disconnects and reconnets.
	w.wg.Add(4)
	go w.handleChainNotifications()
	go w.rescanBatchHandler()
	go w.rescanProgressHandler()
	go w.rescanRPCHandler()
}

// requireChainClient marks that a wallet method can only be completed when the
// consensus RPC server is set.  This function and all functions that call it
// are unstable and will need to be moved when the syncing code is moved out of
// the wallet.
func (w *Wallet) requireChainClient() (*chain.RPCClient, error) {
	w.chainClientLock.Lock()
	chainClient := w.chainClient
	w.chainClientLock.Unlock()
	if chainClient == nil {
		return nil, errors.New("blockchain RPC is inactive")
	}
	return chainClient, nil
}

// ChainClient returns the optional consensus RPC client associated with the
// wallet.
//
// This function is unstable and will be removed once sync logic is moved out of
// the wallet.
func (w *Wallet) ChainClient() *chain.RPCClient {
	w.chainClientLock.Lock()
	chainClient := w.chainClient
	w.chainClientLock.Unlock()
	return chainClient
}

// RelayFee returns the current minimum relay fee (per kB of serialized
// transaction) used when constructing transactions.
func (w *Wallet) RelayFee() btcutil.Amount {
	w.relayFeeMu.Lock()
	relayFee := w.relayFee
	w.relayFeeMu.Unlock()
	return relayFee
}

// SetRelayFee sets a new minimum relay fee (per kB of serialized
// transaction) used when constructing transactions.
func (w *Wallet) SetRelayFee(relayFee btcutil.Amount) {
	w.relayFeeMu.Lock()
	w.relayFee = relayFee
	w.relayFeeMu.Unlock()
}

// quitChan atomically reads the quit channel.
func (w *Wallet) quitChan() <-chan struct{} {
	w.quitMu.Lock()
	c := w.quit
	w.quitMu.Unlock()
	return c
}

// Stop signals all wallet goroutines to shutdown.
func (w *Wallet) Stop() {
	w.quitMu.Lock()
	quit := w.quit
	w.quitMu.Unlock()

	select {
	case <-quit:
	default:
		close(quit)
		w.chainClientLock.Lock()
		if w.chainClient != nil {
			w.chainClient.Stop()
			w.chainClient = nil
		}
		w.chainClientLock.Unlock()
	}
}

// ShuttingDown returns whether the wallet is currently in the process of
// shutting down or not.
func (w *Wallet) ShuttingDown() bool {
	select {
	case <-w.quitChan():
		return true
	default:
		return false
	}
}

// WaitForShutdown blocks until all wallet goroutines have finished executing.
func (w *Wallet) WaitForShutdown() {
	w.chainClientLock.Lock()
	if w.chainClient != nil {
		w.chainClient.WaitForShutdown()
	}
	w.chainClientLock.Unlock()
	w.wg.Wait()
}

// SynchronizingToNetwork returns whether the wallet is currently synchronizing
// with the Bitcoin network.
func (w *Wallet) SynchronizingToNetwork() bool {
	// At the moment, RPC is the only synchronization method.  In the
	// future, when SPV is added, a separate check will also be needed, or
	// SPV could always be enabled if RPC was not explicitly specified when
	// creating the wallet.
	w.chainClientSyncMtx.Lock()
	syncing := w.chainClient != nil
	w.chainClientSyncMtx.Unlock()
	return syncing
}

// ChainSynced returns whether the wallet has been attached to a chain server
// and synced up to the best block on the main chain.
func (w *Wallet) ChainSynced() bool {
	w.chainClientSyncMtx.Lock()
	synced := w.chainClientSynced
	w.chainClientSyncMtx.Unlock()
	return synced
}

// SetChainSynced marks whether the wallet is connected to and currently in sync
// with the latest block notified by the chain server.
//
// NOTE: Due to an API limitation with btcrpcclient, this may return true after
// the client disconnected (and is attempting a reconnect).  This will be unknown
// until the reconnect notification is received, at which point the wallet can be
// marked out of sync again until after the next rescan completes.
func (w *Wallet) SetChainSynced(synced bool) {
	w.chainClientSyncMtx.Lock()
	w.chainClientSynced = synced
	w.chainClientSyncMtx.Unlock()
}

// activeData returns the currently-active receiving addresses and all unspent
// outputs.  This is primarely intended to provide the parameters for a
// rescan request.
func (w *Wallet) activeData(dbtx walletdb.ReadTx) ([]btcutil.Address, []wtxmgr.Credit, error) {
	addrmgrNs := dbtx.ReadBucket(waddrmgrNamespaceKey)
	txmgrNs := dbtx.ReadBucket(wtxmgrNamespaceKey)

	var addrs []btcutil.Address
	err := w.Manager.ForEachActiveAddress(addrmgrNs, func(addr btcutil.Address) error {
		addrs = append(addrs, addr)
		return nil
	})
	if err != nil {
		return nil, nil, err
	}
	unspent, err := w.TxStore.UnspentOutputs(txmgrNs)
	return addrs, unspent, err
}

// syncWithChain brings the wallet up to date with the current chain server
// connection.  It creates a rescan request and blocks until the rescan has
// finished.
//
func (w *Wallet) syncWithChain() error {
	chainClient, err := w.requireChainClient()
	if err != nil {
		return err
	}

	// Request notifications for connected and disconnected blocks.
	//
	// TODO(jrick): Either request this notification only once, or when
	// btcrpcclient is modified to allow some notification request to not
	// automatically resent on reconnect, include the notifyblocks request
	// as well.  I am leaning towards allowing off all btcrpcclient
	// notification re-registrations, in which case the code here should be
	// left as is.
	err = chainClient.NotifyBlocks()
	if err != nil {
		return err
	}

	// Request notifications for transactions sending to all wallet
	// addresses.
	var (
		addrs   []btcutil.Address
		unspent []wtxmgr.Credit
	)
	err = walletdb.View(w.db, func(dbtx walletdb.ReadTx) error {
		var err error
		addrs, unspent, err = w.activeData(dbtx)
		return err
	})
	if err != nil {
		return err
	}

	// TODO(jrick): How should this handle a synced height earlier than
	// the chain server best block?

	// When no addresses have been generated for the wallet, the rescan can
	// be skipped.
	//
	// TODO: This is only correct because activeData above returns all
	// addresses ever created, including those that don't need to be watched
	// anymore.  This code should be updated when this assumption is no
	// longer true, but worst case would result in an unnecessary rescan.
	if len(addrs) == 0 && len(unspent) == 0 {
		// TODO: It would be ideal if on initial sync wallet saved the
		// last several recent blocks rather than just one.  This would
		// avoid a full rescan for a one block reorg of the current
		// chain tip.
		hash, height, err := chainClient.GetBestBlock()
		if err != nil {
			return err
		}
		return walletdb.Update(w.db, func(tx walletdb.ReadWriteTx) error {
			ns := tx.ReadWriteBucket(waddrmgrNamespaceKey)
			return w.Manager.SetSyncedTo(ns, &waddrmgr.BlockStamp{
				Hash:   *hash,
				Height: height,
			})
		})
	}

	// Compare previously-seen blocks against the chain server.  If any of
	// these blocks no longer exist, rollback all of the missing blocks
	// before catching up with the rescan.
	iter := w.Manager.NewIterateRecentBlocks()
	rollback := iter == nil
	syncBlock := waddrmgr.BlockStamp{
		Hash:   *w.chainParams.GenesisHash,
		Height: 0,
	}
	for cont := iter != nil; cont; cont = iter.Prev() {
		bs := iter.BlockStamp()
		log.Debugf("Checking for previous saved block with height %v hash %v",
			bs.Height, bs.Hash)
		_, err = chainClient.GetBlock(&bs.Hash)
		if err != nil {
			rollback = true
			continue
		}

		log.Debug("Found matching block.")
		syncBlock = bs
		break
	}

	if rollback {
		err := walletdb.Update(w.db, func(tx walletdb.ReadWriteTx) error {
			addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)
			txmgrNs := tx.ReadWriteBucket(wtxmgrNamespaceKey)
			err := w.Manager.SetSyncedTo(addrmgrNs, &syncBlock)
			if err != nil {
				return err
			}
			// Rollback unconfirms transactions at and beyond the passed
			// height, so add one to the new synced-to height to prevent
			// unconfirming txs from the synced-to block.
			return w.TxStore.Rollback(txmgrNs, syncBlock.Height+1)
		})
		if err != nil {
			return err
		}
	}

	return w.Rescan(addrs, unspent)
}

type (
	createTxRequest struct {
		account uint32
		outputs []*wire.TxOut
		minconf int32
		resp    chan createTxResponse
	}
	createTxResponse struct {
		tx  *txauthor.AuthoredTx
		err error
	}
)

// txCreator is responsible for the input selection and creation of
// transactions.  These functions are the responsibility of this method
// (designed to be run as its own goroutine) since input selection must be
// serialized, or else it is possible to create double spends by choosing the
// same inputs for multiple transactions.  Along with input selection, this
// method is also responsible for the signing of transactions, since we don't
// want to end up in a situation where we run out of inputs as multiple
// transactions are being created.  In this situation, it would then be possible
// for both requests, rather than just one, to fail due to not enough available
// inputs.
func (w *Wallet) txCreator() {
	quit := w.quitChan()
out:
	for {
		select {
		case txr := <-w.createTxRequests:
			heldUnlock, err := w.holdUnlock()
			if err != nil {
				txr.resp <- createTxResponse{nil, err}
				continue
			}
			tx, err := w.txToOutputs(txr.outputs, txr.account,
				txr.minconf)
			heldUnlock.release()
			txr.resp <- createTxResponse{tx, err}
		case <-quit:
			break out
		}
	}
	w.wg.Done()
}

// CreateSimpleTx creates a new signed transaction spending unspent P2PKH
// outputs with at laest minconf confirmations spending to any number of
// address/amount pairs.  Change and an appropriate transaction fee are
// automatically included, if necessary.  All transaction creation through this
// function is serialized to prevent the creation of many transactions which
// spend the same outputs.
func (w *Wallet) CreateSimpleTx(account uint32, outputs []*wire.TxOut,
	minconf int32) (*txauthor.AuthoredTx, error) {

	req := createTxRequest{
		account: account,
		outputs: outputs,
		minconf: minconf,
		resp:    make(chan createTxResponse),
	}
	w.createTxRequests <- req
	resp := <-req.resp
	return resp.tx, resp.err
}

type (
	unlockRequest struct {
		passphrase []byte
		lockAfter  <-chan time.Time // nil prevents the timeout.
		err        chan error
	}

	changePassphraseRequest struct {
		old, new []byte
		err      chan error
	}

	// heldUnlock is a tool to prevent the wallet from automatically
	// locking after some timeout before an operation which needed
	// the unlocked wallet has finished.  Any aquired heldUnlock
	// *must* be released (preferably with a defer) or the wallet
	// will forever remain unlocked.
	heldUnlock chan struct{}
)

// walletLocker manages the locked/unlocked state of a wallet.
func (w *Wallet) walletLocker() {
	var timeout <-chan time.Time
	holdChan := make(heldUnlock)
	quit := w.quitChan()
out:
	for {
		select {
		case req := <-w.unlockRequests:
			err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
				addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
				return w.Manager.Unlock(addrmgrNs, req.passphrase)
			})
			if err != nil {
				req.err <- err
				continue
			}
			timeout = req.lockAfter
			if timeout == nil {
				log.Info("The wallet has been unlocked without a time limit")
			} else {
				log.Info("The wallet has been temporarily unlocked")
			}
			req.err <- nil
			continue

		case req := <-w.changePassphrase:
			err := walletdb.Update(w.db, func(tx walletdb.ReadWriteTx) error {
				addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)
				return w.Manager.ChangePassphrase(addrmgrNs, req.old,
					req.new, true, &waddrmgr.DefaultScryptOptions)
			})
			req.err <- err
			continue

		case req := <-w.holdUnlockRequests:
			if w.Manager.IsLocked() {
				close(req)
				continue
			}

			req <- holdChan
			<-holdChan // Block until the lock is released.

			// If, after holding onto the unlocked wallet for some
			// time, the timeout has expired, lock it now instead
			// of hoping it gets unlocked next time the top level
			// select runs.
			select {
			case <-timeout:
				// Let the top level select fallthrough so the
				// wallet is locked.
			default:
				continue
			}

		case w.lockState <- w.Manager.IsLocked():
			continue

		case <-quit:
			break out

		case <-w.lockRequests:
		case <-timeout:
		}

		// Select statement fell through by an explicit lock or the
		// timer expiring.  Lock the manager here.
		timeout = nil
		err := w.Manager.Lock()
		if err != nil && !waddrmgr.IsError(err, waddrmgr.ErrLocked) {
			log.Errorf("Could not lock wallet: %v", err)
		} else {
			log.Info("The wallet has been locked")
		}
	}
	w.wg.Done()
}

// Unlock unlocks the wallet's address manager and relocks it after timeout has
// expired.  If the wallet is already unlocked and the new passphrase is
// correct, the current timeout is replaced with the new one.  The wallet will
// be locked if the passphrase is incorrect or any other error occurs during the
// unlock.
func (w *Wallet) Unlock(passphrase []byte, lock <-chan time.Time) error {
	err := make(chan error, 1)
	w.unlockRequests <- unlockRequest{
		passphrase: passphrase,
		lockAfter:  lock,
		err:        err,
	}
	return <-err
}

// Lock locks the wallet's address manager.
func (w *Wallet) Lock() {
	w.lockRequests <- struct{}{}
}

// Locked returns whether the account manager for a wallet is locked.
func (w *Wallet) Locked() bool {
	return <-w.lockState
}

// holdUnlock prevents the wallet from being locked.  The heldUnlock object
// *must* be released, or the wallet will forever remain unlocked.
//
// TODO: To prevent the above scenario, perhaps closures should be passed
// to the walletLocker goroutine and disallow callers from explicitly
// handling the locking mechanism.
func (w *Wallet) holdUnlock() (heldUnlock, error) {
	req := make(chan heldUnlock)
	w.holdUnlockRequests <- req
	hl, ok := <-req
	if !ok {
		// TODO(davec): This should be defined and exported from
		// waddrmgr.
		return nil, waddrmgr.ManagerError{
			ErrorCode:   waddrmgr.ErrLocked,
			Description: "address manager is locked",
		}
	}
	return hl, nil
}

// release releases the hold on the unlocked-state of the wallet and allows the
// wallet to be locked again.  If a lock timeout has already expired, the
// wallet is locked again as soon as release is called.
func (c heldUnlock) release() {
	c <- struct{}{}
}

// ChangePrivatePassphrase attempts to change the passphrase for a wallet from
// old to new.  Changing the passphrase is synchronized with all other address
// manager locking and unlocking.  The lock state will be the same as it was
// before the password change.
func (w *Wallet) ChangePrivatePassphrase(old, new []byte) error {
	err := make(chan error, 1)
	w.changePassphrase <- changePassphraseRequest{
		old: old,
		new: new,
		err: err,
	}
	return <-err
}

// ChangePublicPassphrase modifies the public passphrase of the wallet.
func (w *Wallet) ChangePublicPassphrase(old, new []byte) error {
	return walletdb.Update(w.db, func(tx walletdb.ReadWriteTx) error {
		addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)
		return w.Manager.ChangePassphrase(addrmgrNs, old, new, false,
			&waddrmgr.DefaultScryptOptions)
	})
}

// accountUsed returns whether there are any recorded transactions spending to
// a given account. It returns true if atleast one address in the account was
// used and false if no address in the account was used.
func (w *Wallet) accountUsed(addrmgrNs walletdb.ReadWriteBucket, account uint32) (bool, error) {
	var used bool
	err := w.Manager.ForEachAccountAddress(addrmgrNs, account,
		func(maddr waddrmgr.ManagedAddress) error {
			used = maddr.Used(addrmgrNs)
			if used {
				return waddrmgr.Break
			}
			return nil
		})
	if err == waddrmgr.Break {
		err = nil
	}
	return used, err
}

// AccountAddresses returns the addresses for every created address for an
// account.
func (w *Wallet) AccountAddresses(account uint32) (addrs []btcutil.Address, err error) {
	err = walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		return w.Manager.ForEachAccountAddress(addrmgrNs, account, func(maddr waddrmgr.ManagedAddress) error {
			addrs = append(addrs, maddr.Address())
			return nil
		})
	})
	return
}

// CalculateBalance sums the amounts of all unspent transaction
// outputs to addresses of a wallet and returns the balance.
//
// If confirmations is 0, all UTXOs, even those not present in a
// block (height -1), will be used to get the balance.  Otherwise,
// a UTXO must be in a block.  If confirmations is 1 or greater,
// the balance will be calculated based on how many how many blocks
// include a UTXO.
func (w *Wallet) CalculateBalance(confirms int32) (btcutil.Amount, error) {
	var balance btcutil.Amount
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)
		var err error
		blk := w.Manager.SyncedTo()
		balance, err = w.TxStore.Balance(txmgrNs, confirms, blk.Height)
		return err
	})
	return balance, err
}

// Balances records total, spendable (by policy), and immature coinbase
// reward balance amounts.
type Balances struct {
	Total          btcutil.Amount
	Spendable      btcutil.Amount
	ImmatureReward btcutil.Amount
}

// CalculateAccountBalances sums the amounts of all unspent transaction
// outputs to the given account of a wallet and returns the balance.
//
// This function is much slower than it needs to be since transactions outputs
// are not indexed by the accounts they credit to, and all unspent transaction
// outputs must be iterated.
func (w *Wallet) CalculateAccountBalances(account uint32, confirms int32) (Balances, error) {
	var bals Balances
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)

		// Get current block.  The block height used for calculating
		// the number of tx confirmations.
		syncBlock := w.Manager.SyncedTo()

		unspent, err := w.TxStore.UnspentOutputs(txmgrNs)
		if err != nil {
			return err
		}
		for i := range unspent {
			output := &unspent[i]

			var outputAcct uint32
			_, addrs, _, err := txscript.ExtractPkScriptAddrs(
				output.PkScript, w.chainParams)
			if err == nil && len(addrs) > 0 {
				outputAcct, err = w.Manager.AddrAccount(addrmgrNs, addrs[0])
			}
			if err != nil || outputAcct != account {
				continue
			}

			bals.Total += output.Amount
			if output.FromCoinBase && !confirmed(int32(w.chainParams.CoinbaseMaturity),
				output.Height, syncBlock.Height) {
				bals.ImmatureReward += output.Amount
			} else if confirmed(confirms, output.Height, syncBlock.Height) {
				bals.Spendable += output.Amount
			}
		}
		return nil
	})
	return bals, err
}

// CurrentAddress gets the most recently requested Bitcoin payment address
// from a wallet.  If the address has already been used (there is at least
// one transaction spending to it in the blockchain or btcd mempool), the next
// chained address is returned.
func (w *Wallet) CurrentAddress(account uint32) (btcutil.Address, error) {
	var addr btcutil.Address
	err := walletdb.Update(w.db, func(tx walletdb.ReadWriteTx) error {
		addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)
		maddr, err := w.Manager.LastExternalAddress(addrmgrNs, account)
		if err != nil {
			// If no address exists yet, create the first external address
			if waddrmgr.IsError(err, waddrmgr.ErrAddressNotFound) {
				addr, err = w.newAddress(addrmgrNs, account)
			}
			return err
		}

		// Get next chained address if the last one has already been used.
		if maddr.Used(addrmgrNs) {
			addr, err = w.newAddress(addrmgrNs, account)
			return err
		}

		addr = maddr.Address()
		return nil
	})
	return addr, err
}

// PubKeyForAddress looks up the associated public key for a P2PKH address.
func (w *Wallet) PubKeyForAddress(a btcutil.Address) (*btcec.PublicKey, error) {
	var pubKey *btcec.PublicKey
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		managedAddr, err := w.Manager.Address(addrmgrNs, a)
		if err != nil {
			return err
		}
		managedPubKeyAddr, ok := managedAddr.(waddrmgr.ManagedPubKeyAddress)
		if !ok {
			return errors.New("address does not have an associated public key")
		}
		pubKey = managedPubKeyAddr.PubKey()
		return nil
	})
	return pubKey, err
}

// PrivKeyForAddress looks up the associated private key for a P2PKH or P2PK
// address.
func (w *Wallet) PrivKeyForAddress(a btcutil.Address) (*btcec.PrivateKey, error) {
	var privKey *btcec.PrivateKey
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		managedAddr, err := w.Manager.Address(addrmgrNs, a)
		if err != nil {
			return err
		}
		managedPubKeyAddr, ok := managedAddr.(waddrmgr.ManagedPubKeyAddress)
		if !ok {
			return errors.New("address does not have an associated private key")
		}
		privKey, err = managedPubKeyAddr.PrivKey()
		return err
	})
	return privKey, err
}

// HaveAddress returns whether the wallet is the owner of the address a.
func (w *Wallet) HaveAddress(a btcutil.Address) (bool, error) {
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		_, err := w.Manager.Address(addrmgrNs, a)
		return err
	})
	if err == nil {
		return true, nil
	}
	if waddrmgr.IsError(err, waddrmgr.ErrAddressNotFound) {
		return false, nil
	}
	return false, err
}

// AccountOfAddress finds the account that an address is associated with.
func (w *Wallet) AccountOfAddress(a btcutil.Address) (uint32, error) {
	var account uint32
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		var err error
		account, err = w.Manager.AddrAccount(addrmgrNs, a)
		return err
	})
	return account, err
}

// AddressInfo returns detailed information regarding a wallet address.
func (w *Wallet) AddressInfo(a btcutil.Address) (waddrmgr.ManagedAddress, error) {
	var managedAddress waddrmgr.ManagedAddress
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		var err error
		managedAddress, err = w.Manager.Address(addrmgrNs, a)
		return err
	})
	return managedAddress, err
}

// AccountNumber returns the account number for an account name.
func (w *Wallet) AccountNumber(accountName string) (uint32, error) {
	var account uint32
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		var err error
		account, err = w.Manager.LookupAccount(addrmgrNs, accountName)
		return err
	})
	return account, err
}

// AccountName returns the name of an account.
func (w *Wallet) AccountName(accountNumber uint32) (string, error) {
	var accountName string
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		var err error
		accountName, err = w.Manager.AccountName(addrmgrNs, accountNumber)
		return err
	})
	return accountName, err
}

// AccountProperties returns the properties of an account, including address
// indexes and name. It first fetches the desynced information from the address
// manager, then updates the indexes based on the address pools.
func (w *Wallet) AccountProperties(acct uint32) (*waddrmgr.AccountProperties, error) {
	var props *waddrmgr.AccountProperties
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		waddrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		var err error
		props, err = w.Manager.AccountProperties(waddrmgrNs, acct)
		return err
	})
	return props, err
}

// RenameAccount sets the name for an account number to newName.
func (w *Wallet) RenameAccount(account uint32, newName string) error {
	var props *waddrmgr.AccountProperties
	err := walletdb.Update(w.db, func(tx walletdb.ReadWriteTx) error {
		addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)
		err := w.Manager.RenameAccount(addrmgrNs, account, newName)
		if err != nil {
			return err
		}
		props, err = w.Manager.AccountProperties(addrmgrNs, account)
		return err
	})
	if err == nil {
		w.NtfnServer.notifyAccountProperties(props)
	}
	return err
}

const maxEmptyAccounts = 100

// NextAccount creates the next account and returns its account number.  The
// name must be unique to the account.  In order to support automatic seed
// restoring, new accounts may not be created when all of the previous 100
// accounts have no transaction history (this is a deviation from the BIP0044
// spec, which allows no unused account gaps).
func (w *Wallet) NextAccount(name string) (uint32, error) {
	var account uint32
	var props *waddrmgr.AccountProperties
	err := walletdb.Update(w.db, func(tx walletdb.ReadWriteTx) error {
		addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)
		var err error
		account, err = w.Manager.NewAccount(addrmgrNs, name)
		if err != nil {
			return err
		}
		props, err = w.Manager.AccountProperties(addrmgrNs, account)
		return err
	})
	if err != nil {
		log.Errorf("Cannot fetch new account properties for notification "+
			"after account creation: %v", err)
	} else {
		w.NtfnServer.notifyAccountProperties(props)
	}
	return account, err
}

// CreditCategory describes the type of wallet transaction output.  The category
// of "sent transactions" (debits) is always "send", and is not expressed by
// this type.
//
// TODO: This is a requirement of the RPC server and should be moved.
type CreditCategory byte

// These constants define the possible credit categories.
const (
	CreditReceive CreditCategory = iota
	CreditGenerate
	CreditImmature
)

// String returns the category as a string.  This string may be used as the
// JSON string for categories as part of listtransactions and gettransaction
// RPC responses.
func (c CreditCategory) String() string {
	switch c {
	case CreditReceive:
		return "receive"
	case CreditGenerate:
		return "generate"
	case CreditImmature:
		return "immature"
	default:
		return "unknown"
	}
}

// RecvCategory returns the category of received credit outputs from a
// transaction record.  The passed block chain height is used to distinguish
// immature from mature coinbase outputs.
//
// TODO: This is intended for use by the RPC server and should be moved out of
// this package at a later time.
func RecvCategory(details *wtxmgr.TxDetails, syncHeight int32, net *chaincfg.Params) CreditCategory {
	if blockchain.IsCoinBaseTx(&details.MsgTx) {
		if confirmed(int32(net.CoinbaseMaturity), details.Block.Height,
			syncHeight) {
			return CreditGenerate
		}
		return CreditImmature
	}
	return CreditReceive
}

// listTransactions creates a object that may be marshalled to a response result
// for a listtransactions RPC.
//
// TODO: This should be moved to the legacyrpc package.
func listTransactions(tx walletdb.ReadTx, details *wtxmgr.TxDetails, addrMgr *waddrmgr.Manager,
	syncHeight int32, net *chaincfg.Params) []btcjson.ListTransactionsResult {

	addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)

	var (
		blockHashStr  string
		blockTime     int64
		confirmations int64
	)
	if details.Block.Height != -1 {
		blockHashStr = details.Block.Hash.String()
		blockTime = details.Block.Time.Unix()
		confirmations = int64(confirms(details.Block.Height, syncHeight))
	}

	results := []btcjson.ListTransactionsResult{}
	txHashStr := details.Hash.String()
	received := details.Received.Unix()
	generated := blockchain.IsCoinBaseTx(&details.MsgTx)
	recvCat := RecvCategory(details, syncHeight, net).String()

	send := len(details.Debits) != 0

	// Fee can only be determined if every input is a debit.
	var feeF64 float64
	if len(details.Debits) == len(details.MsgTx.TxIn) {
		var debitTotal btcutil.Amount
		for _, deb := range details.Debits {
			debitTotal += deb.Amount
		}
		var outputTotal btcutil.Amount
		for _, output := range details.MsgTx.TxOut {
			outputTotal += btcutil.Amount(output.Value)
		}
		// Note: The actual fee is debitTotal - outputTotal.  However,
		// this RPC reports negative numbers for fees, so the inverse
		// is calculated.
		feeF64 = (outputTotal - debitTotal).ToBTC()
	}

outputs:
	for i, output := range details.MsgTx.TxOut {
		// Determine if this output is a credit, and if so, determine
		// its spentness.
		var isCredit bool
		var spentCredit bool
		for _, cred := range details.Credits {
			if cred.Index == uint32(i) {
				// Change outputs are ignored.
				if cred.Change {
					continue outputs
				}

				isCredit = true
				spentCredit = cred.Spent
				break
			}
		}

		var address string
		var accountName string
		_, addrs, _, _ := txscript.ExtractPkScriptAddrs(output.PkScript, net)
		if len(addrs) == 1 {
			addr := addrs[0]
			address = addr.EncodeAddress()
			account, err := addrMgr.AddrAccount(addrmgrNs, addrs[0])
			if err == nil {
				accountName, err = addrMgr.AccountName(addrmgrNs, account)
				if err != nil {
					accountName = ""
				}
			}
		}

		amountF64 := btcutil.Amount(output.Value).ToBTC()
		result := btcjson.ListTransactionsResult{
			// Fields left zeroed:
			//   InvolvesWatchOnly
			//   BlockIndex
			//
			// Fields set below:
			//   Account (only for non-"send" categories)
			//   Category
			//   Amount
			//   Fee
			Address:         address,
			Vout:            uint32(i),
			Confirmations:   confirmations,
			Generated:       generated,
			BlockHash:       blockHashStr,
			BlockTime:       blockTime,
			TxID:            txHashStr,
			WalletConflicts: []string{},
			Time:            received,
			TimeReceived:    received,
		}

		// Add a received/generated/immature result if this is a credit.
		// If the output was spent, create a second result under the
		// send category with the inverse of the output amount.  It is
		// therefore possible that a single output may be included in
		// the results set zero, one, or two times.
		//
		// Since credits are not saved for outputs that are not
		// controlled by this wallet, all non-credits from transactions
		// with debits are grouped under the send category.

		if send || spentCredit {
			result.Category = "send"
			result.Amount = -amountF64
			result.Fee = &feeF64
			results = append(results, result)
		}
		if isCredit {
			result.Account = accountName
			result.Category = recvCat
			result.Amount = amountF64
			result.Fee = nil
			results = append(results, result)
		}
	}
	return results
}

// ListSinceBlock returns a slice of objects with details about transactions
// since the given block. If the block is -1 then all transactions are included.
// This is intended to be used for listsinceblock RPC replies.
func (w *Wallet) ListSinceBlock(start, end, syncHeight int32) ([]btcjson.ListTransactionsResult, error) {
	txList := []btcjson.ListTransactionsResult{}
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)

		rangeFn := func(details []wtxmgr.TxDetails) (bool, error) {
			for _, detail := range details {
				jsonResults := listTransactions(tx, &detail,
					w.Manager, syncHeight, w.chainParams)
				txList = append(txList, jsonResults...)
			}
			return false, nil
		}

		return w.TxStore.RangeTransactions(txmgrNs, start, end, rangeFn)
	})
	return txList, err
}

// ListTransactions returns a slice of objects with details about a recorded
// transaction.  This is intended to be used for listtransactions RPC
// replies.
func (w *Wallet) ListTransactions(from, count int) ([]btcjson.ListTransactionsResult, error) {
	txList := []btcjson.ListTransactionsResult{}

	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)

		// Get current block.  The block height used for calculating
		// the number of tx confirmations.
		syncBlock := w.Manager.SyncedTo()

		// Need to skip the first from transactions, and after those, only
		// include the next count transactions.
		skipped := 0
		n := 0

		rangeFn := func(details []wtxmgr.TxDetails) (bool, error) {
			// Iterate over transactions at this height in reverse order.
			// This does nothing for unmined transactions, which are
			// unsorted, but it will process mined transactions in the
			// reverse order they were marked mined.
			for i := len(details) - 1; i >= 0; i-- {
				if from > skipped {
					skipped++
					continue
				}

				n++
				if n > count {
					return true, nil
				}

				jsonResults := listTransactions(tx, &details[i],
					w.Manager, syncBlock.Height, w.chainParams)
				txList = append(txList, jsonResults...)

				if len(jsonResults) > 0 {
					n++
				}
			}

			return false, nil
		}

		// Return newer results first by starting at mempool height and working
		// down to the genesis block.
		return w.TxStore.RangeTransactions(txmgrNs, -1, 0, rangeFn)
	})
	return txList, err
}

// ListAddressTransactions returns a slice of objects with details about
// recorded transactions to or from any address belonging to a set.  This is
// intended to be used for listaddresstransactions RPC replies.
func (w *Wallet) ListAddressTransactions(pkHashes map[string]struct{}) ([]btcjson.ListTransactionsResult, error) {
	txList := []btcjson.ListTransactionsResult{}
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)

		// Get current block.  The block height used for calculating
		// the number of tx confirmations.
		syncBlock := w.Manager.SyncedTo()
		rangeFn := func(details []wtxmgr.TxDetails) (bool, error) {
		loopDetails:
			for i := range details {
				detail := &details[i]

				for _, cred := range detail.Credits {
					pkScript := detail.MsgTx.TxOut[cred.Index].PkScript
					_, addrs, _, err := txscript.ExtractPkScriptAddrs(
						pkScript, w.chainParams)
					if err != nil || len(addrs) != 1 {
						continue
					}
					apkh, ok := addrs[0].(*btcutil.AddressPubKeyHash)
					if !ok {
						continue
					}
					_, ok = pkHashes[string(apkh.ScriptAddress())]
					if !ok {
						continue
					}

					jsonResults := listTransactions(tx, detail,
						w.Manager, syncBlock.Height, w.chainParams)
					if err != nil {
						return false, err
					}
					txList = append(txList, jsonResults...)
					continue loopDetails
				}
			}
			return false, nil
		}

		return w.TxStore.RangeTransactions(txmgrNs, 0, -1, rangeFn)
	})
	return txList, err
}

// ListAllTransactions returns a slice of objects with details about a recorded
// transaction.  This is intended to be used for listalltransactions RPC
// replies.
func (w *Wallet) ListAllTransactions() ([]btcjson.ListTransactionsResult, error) {
	txList := []btcjson.ListTransactionsResult{}
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)

		// Get current block.  The block height used for calculating
		// the number of tx confirmations.
		syncBlock := w.Manager.SyncedTo()

		rangeFn := func(details []wtxmgr.TxDetails) (bool, error) {
			// Iterate over transactions at this height in reverse order.
			// This does nothing for unmined transactions, which are
			// unsorted, but it will process mined transactions in the
			// reverse order they were marked mined.
			for i := len(details) - 1; i >= 0; i-- {
				jsonResults := listTransactions(tx, &details[i], w.Manager,
					syncBlock.Height, w.chainParams)
				txList = append(txList, jsonResults...)
			}
			return false, nil
		}

		// Return newer results first by starting at mempool height and
		// working down to the genesis block.
		return w.TxStore.RangeTransactions(txmgrNs, -1, 0, rangeFn)
	})
	return txList, err
}

// BlockIdentifier identifies a block by either a height or a hash.
type BlockIdentifier struct {
	height int32
	hash   *chainhash.Hash
}

// NewBlockIdentifierFromHeight constructs a BlockIdentifier for a block height.
func NewBlockIdentifierFromHeight(height int32) *BlockIdentifier {
	return &BlockIdentifier{height: height}
}

// NewBlockIdentifierFromHash constructs a BlockIdentifier for a block hash.
func NewBlockIdentifierFromHash(hash *chainhash.Hash) *BlockIdentifier {
	return &BlockIdentifier{hash: hash}
}

// GetTransactionsResult is the result of the wallet's GetTransactions method.
// See GetTransactions for more details.
type GetTransactionsResult struct {
	MinedTransactions   []Block
	UnminedTransactions []TransactionSummary
}

// GetTransactions returns transaction results between a starting and ending
// block.  Blocks in the block range may be specified by either a height or a
// hash.
//
// Because this is a possibly lenghtly operation, a cancel channel is provided
// to cancel the task.  If this channel unblocks, the results created thus far
// will be returned.
//
// Transaction results are organized by blocks in ascending order and unmined
// transactions in an unspecified order.  Mined transactions are saved in a
// Block structure which records properties about the block.
func (w *Wallet) GetTransactions(startBlock, endBlock *BlockIdentifier, cancel <-chan struct{}) (*GetTransactionsResult, error) {
	var start, end int32 = 0, -1

	w.chainClientLock.Lock()
	chainClient := w.chainClient
	w.chainClientLock.Unlock()

	// TODO: Fetching block heights by their hashes is inherently racy
	// because not all block headers are saved but when they are for SPV the
	// db can be queried directly without this.
	var startResp, endResp btcrpcclient.FutureGetBlockVerboseResult
	if startBlock != nil {
		if startBlock.hash == nil {
			start = startBlock.height
		} else {
			if chainClient == nil {
				return nil, errors.New("no chain server client")
			}
			startResp = chainClient.GetBlockVerboseTxAsync(startBlock.hash)
		}
	}
	if endBlock != nil {
		if endBlock.hash == nil {
			end = endBlock.height
		} else {
			if chainClient == nil {
				return nil, errors.New("no chain server client")
			}
			endResp = chainClient.GetBlockVerboseTxAsync(endBlock.hash)
		}
	}
	if startResp != nil {
		resp, err := startResp.Receive()
		if err != nil {
			return nil, err
		}
		start = int32(resp.Height)
	}
	if endResp != nil {
		resp, err := endResp.Receive()
		if err != nil {
			return nil, err
		}
		end = int32(resp.Height)
	}

	var res GetTransactionsResult
	err := walletdb.View(w.db, func(dbtx walletdb.ReadTx) error {
		txmgrNs := dbtx.ReadBucket(wtxmgrNamespaceKey)

		rangeFn := func(details []wtxmgr.TxDetails) (bool, error) {
			// TODO: probably should make RangeTransactions not reuse the
			// details backing array memory.
			dets := make([]wtxmgr.TxDetails, len(details))
			copy(dets, details)
			details = dets

			txs := make([]TransactionSummary, 0, len(details))
			for i := range details {
				txs = append(txs, makeTxSummary(dbtx, w, &details[i]))
			}

			if details[0].Block.Height != -1 {
				blockHash := details[0].Block.Hash
				res.MinedTransactions = append(res.MinedTransactions, Block{
					Hash:         &blockHash,
					Height:       details[0].Block.Height,
					Timestamp:    details[0].Block.Time.Unix(),
					Transactions: txs,
				})
			} else {
				res.UnminedTransactions = txs
			}

			select {
			case <-cancel:
				return true, nil
			default:
				return false, nil
			}
		}

		return w.TxStore.RangeTransactions(txmgrNs, start, end, rangeFn)
	})
	return &res, err
}

// AccountResult is a single account result for the AccountsResult type.
type AccountResult struct {
	waddrmgr.AccountProperties
	TotalBalance btcutil.Amount
}

// AccountsResult is the resutl of the wallet's Accounts method.  See that
// method for more details.
type AccountsResult struct {
	Accounts           []AccountResult
	CurrentBlockHash   *chainhash.Hash
	CurrentBlockHeight int32
}

// Accounts returns the current names, numbers, and total balances of all
// accounts in the wallet.  The current chain tip is included in the result for
// atomicity reasons.
//
// TODO(jrick): Is the chain tip really needed, since only the total balances
// are included?
func (w *Wallet) Accounts() (*AccountsResult, error) {
	var (
		accounts        []AccountResult
		syncBlockHash   *chainhash.Hash
		syncBlockHeight int32
	)
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)

		syncBlock := w.Manager.SyncedTo()
		syncBlockHash = &syncBlock.Hash
		syncBlockHeight = syncBlock.Height
		unspent, err := w.TxStore.UnspentOutputs(txmgrNs)
		if err != nil {
			return err
		}
		err = w.Manager.ForEachAccount(addrmgrNs, func(acct uint32) error {
			props, err := w.Manager.AccountProperties(addrmgrNs, acct)
			if err != nil {
				return err
			}
			accounts = append(accounts, AccountResult{
				AccountProperties: *props,
				// TotalBalance set below
			})
			return nil
		})
		if err != nil {
			return err
		}
		m := make(map[uint32]*btcutil.Amount)
		for i := range accounts {
			a := &accounts[i]
			m[a.AccountNumber] = &a.TotalBalance
		}
		for i := range unspent {
			output := unspent[i]
			var outputAcct uint32
			_, addrs, _, err := txscript.ExtractPkScriptAddrs(output.PkScript, w.chainParams)
			if err == nil && len(addrs) > 0 {
				outputAcct, err = w.Manager.AddrAccount(addrmgrNs, addrs[0])
			}
			if err == nil {
				amt, ok := m[outputAcct]
				if ok {
					*amt += output.Amount
				}
			}
		}
		return nil
	})
	return &AccountsResult{
		Accounts:           accounts,
		CurrentBlockHash:   syncBlockHash,
		CurrentBlockHeight: syncBlockHeight,
	}, err
}

// AccountBalanceResult is a single result for the Wallet.AccountBalances method.
type AccountBalanceResult struct {
	AccountNumber  uint32
	AccountName    string
	AccountBalance btcutil.Amount
}

// AccountBalances returns all accounts in the wallet and their balances.
// Balances are determined by excluding transactions that have not met
// requiredConfs confirmations.
func (w *Wallet) AccountBalances(requiredConfs int32) ([]AccountBalanceResult, error) {
	var results []AccountBalanceResult
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)

		syncBlock := w.Manager.SyncedTo()

		return w.Manager.ForEachAccount(addrmgrNs, func(account uint32) error {
			accountName, err := w.Manager.AccountName(addrmgrNs, account)
			if err != nil {
				return err
			}
			balance, err := w.TxStore.Balance(txmgrNs, requiredConfs, syncBlock.Height)
			if err != nil {
				return err
			}
			results = append(results, AccountBalanceResult{
				AccountNumber:  account,
				AccountName:    accountName,
				AccountBalance: balance,
			})
			return nil
		})
	})
	return results, err
}

// creditSlice satisifies the sort.Interface interface to provide sorting
// transaction credits from oldest to newest.  Credits with the same receive
// time and mined in the same block are not guaranteed to be sorted by the order
// they appear in the block.  Credits from the same transaction are sorted by
// output index.
type creditSlice []wtxmgr.Credit

func (s creditSlice) Len() int {
	return len(s)
}

func (s creditSlice) Less(i, j int) bool {
	switch {
	// If both credits are from the same tx, sort by output index.
	case s[i].OutPoint.Hash == s[j].OutPoint.Hash:
		return s[i].OutPoint.Index < s[j].OutPoint.Index

	// If both transactions are unmined, sort by their received date.
	case s[i].Height == -1 && s[j].Height == -1:
		return s[i].Received.Before(s[j].Received)

	// Unmined (newer) txs always come last.
	case s[i].Height == -1:
		return false
	case s[j].Height == -1:
		return true

	// If both txs are mined in different blocks, sort by block height.
	default:
		return s[i].Height < s[j].Height
	}
}

func (s creditSlice) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
}

// ListUnspent returns a slice of objects representing the unspent wallet
// transactions fitting the given criteria. The confirmations will be more than
// minconf, less than maxconf and if addresses is populated only the addresses
// contained within it will be considered.  If we know nothing about a
// transaction an empty array will be returned.
func (w *Wallet) ListUnspent(minconf, maxconf int32, addresses map[string]struct{}) ([]*btcjson.ListUnspentResult, error) {
	var results []*btcjson.ListUnspentResult
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)

		syncBlock := w.Manager.SyncedTo()

		filter := len(addresses) != 0
		unspent, err := w.TxStore.UnspentOutputs(txmgrNs)
		if err != nil {
			return err
		}
		sort.Sort(sort.Reverse(creditSlice(unspent)))

		defaultAccountName, err := w.Manager.AccountName(addrmgrNs,
			waddrmgr.DefaultAccountNum)
		if err != nil {
			return err
		}

		results = make([]*btcjson.ListUnspentResult, 0, len(unspent))
		for i := range unspent {
			output := unspent[i]

			// Outputs with fewer confirmations than the minimum or more
			// confs than the maximum are excluded.
			confs := confirms(output.Height, syncBlock.Height)
			if confs < minconf || confs > maxconf {
				continue
			}

			// Only mature coinbase outputs are included.
			if output.FromCoinBase {
				target := int32(w.ChainParams().CoinbaseMaturity)
				if !confirmed(target, output.Height, syncBlock.Height) {
					continue
				}
			}

			// Exclude locked outputs from the result set.
			if w.LockedOutpoint(output.OutPoint) {
				continue
			}

			// Lookup the associated account for the output.  Use the
			// default account name in case there is no associated account
			// for some reason, although this should never happen.
			//
			// This will be unnecessary once transactions and outputs are
			// grouped under the associated account in the db.
			acctName := defaultAccountName
			sc, addrs, _, err := txscript.ExtractPkScriptAddrs(
				output.PkScript, w.chainParams)
			if err != nil {
				continue
			}
			if len(addrs) > 0 {
				acct, err := w.Manager.AddrAccount(addrmgrNs, addrs[0])
				if err == nil {
					s, err := w.Manager.AccountName(addrmgrNs, acct)
					if err == nil {
						acctName = s
					}
				}
			}

			if filter {
				for _, addr := range addrs {
					_, ok := addresses[addr.EncodeAddress()]
					if ok {
						goto include
					}
				}
				continue
			}

		include:
			// At the moment watch-only addresses are not supported, so all
			// recorded outputs that are not multisig are "spendable".
			// Multisig outputs are only "spendable" if all keys are
			// controlled by this wallet.
			//
			// TODO: Each case will need updates when watch-only addrs
			// is added.  For P2PK, P2PKH, and P2SH, the address must be
			// looked up and not be watching-only.  For multisig, all
			// pubkeys must belong to the manager with the associated
			// private key (currently it only checks whether the pubkey
			// exists, since the private key is required at the moment).
			var spendable bool
		scSwitch:
			switch sc {
			case txscript.PubKeyHashTy:
				spendable = true
			case txscript.PubKeyTy:
				spendable = true
			case txscript.ScriptHashTy:
				spendable = true
			case txscript.MultiSigTy:
				for _, a := range addrs {
					_, err := w.Manager.Address(addrmgrNs, a)
					if err == nil {
						continue
					}
					if waddrmgr.IsError(err, waddrmgr.ErrAddressNotFound) {
						break scSwitch
					}
					return err
				}
				spendable = true
			}

			result := &btcjson.ListUnspentResult{
				TxID:          output.OutPoint.Hash.String(),
				Vout:          output.OutPoint.Index,
				Account:       acctName,
				ScriptPubKey:  hex.EncodeToString(output.PkScript),
				Amount:        output.Amount.ToBTC(),
				Confirmations: int64(confs),
				Spendable:     spendable,
			}

			// BUG: this should be a JSON array so that all
			// addresses can be included, or removed (and the
			// caller extracts addresses from the pkScript).
			if len(addrs) > 0 {
				result.Address = addrs[0].EncodeAddress()
			}

			results = append(results, result)
		}
		return nil
	})
	return results, err
}

// DumpPrivKeys returns the WIF-encoded private keys for all addresses with
// private keys in a wallet.
func (w *Wallet) DumpPrivKeys() ([]string, error) {
	var privkeys []string
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		// Iterate over each active address, appending the private key to
		// privkeys.
		return w.Manager.ForEachActiveAddress(addrmgrNs, func(addr btcutil.Address) error {
			ma, err := w.Manager.Address(addrmgrNs, addr)
			if err != nil {
				return err
			}

			// Only those addresses with keys needed.
			pka, ok := ma.(waddrmgr.ManagedPubKeyAddress)
			if !ok {
				return nil
			}

			wif, err := pka.ExportPrivKey()
			if err != nil {
				// It would be nice to zero out the array here. However,
				// since strings in go are immutable, and we have no
				// control over the caller I don't think we can. :(
				return err
			}
			privkeys = append(privkeys, wif.String())
			return nil
		})
	})
	return privkeys, err
}

// DumpWIFPrivateKey returns the WIF encoded private key for a
// single wallet address.
func (w *Wallet) DumpWIFPrivateKey(addr btcutil.Address) (string, error) {
	var maddr waddrmgr.ManagedAddress
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		waddrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		// Get private key from wallet if it exists.
		var err error
		maddr, err = w.Manager.Address(waddrmgrNs, addr)
		return err
	})
	if err != nil {
		return "", err
	}

	pka, ok := maddr.(waddrmgr.ManagedPubKeyAddress)
	if !ok {
		return "", fmt.Errorf("address %s is not a key type", addr)
	}

	wif, err := pka.ExportPrivKey()
	if err != nil {
		return "", err
	}
	return wif.String(), nil
}

// ImportPrivateKey imports a private key to the wallet and writes the new
// wallet to disk.
func (w *Wallet) ImportPrivateKey(wif *btcutil.WIF, bs *waddrmgr.BlockStamp,
	rescan bool) (string, error) {

	// The starting block for the key is the genesis block unless otherwise
	// specified.
	if bs == nil {
		bs = &waddrmgr.BlockStamp{
			Hash:   *w.chainParams.GenesisHash,
			Height: 0,
		}
	}

	// Attempt to import private key into wallet.
	var addr btcutil.Address
	var props *waddrmgr.AccountProperties
	err := walletdb.Update(w.db, func(tx walletdb.ReadWriteTx) error {
		addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)
		maddr, err := w.Manager.ImportPrivateKey(addrmgrNs, wif, bs)
		if err == nil {
			addr = maddr.Address()
			props, err = w.Manager.AccountProperties(
				addrmgrNs, waddrmgr.ImportedAddrAccount)
		}
		return err
	})
	if err != nil {
		return "", err
	}

	// Rescan blockchain for transactions with txout scripts paying to the
	// imported address.
	if rescan {
		job := &RescanJob{
			Addrs:      []btcutil.Address{addr},
			OutPoints:  nil,
			BlockStamp: *bs,
		}

		// Submit rescan job and log when the import has completed.
		// Do not block on finishing the rescan.  The rescan success
		// or failure is logged elsewhere, and the channel is not
		// required to be read, so discard the return value.
		_ = w.SubmitRescan(job)
	} else {
		err := w.chainClient.NotifyReceived([]btcutil.Address{addr})
		if err != nil {
			return "", fmt.Errorf("Failed to subscribe for address ntfns for "+
				"address %s: %s", addr.EncodeAddress(), err)
		}
	}

	addrStr := addr.EncodeAddress()
	log.Infof("Imported payment address %s", addrStr)

	w.NtfnServer.notifyAccountProperties(props)

	// Return the payment address string of the imported private key.
	return addrStr, nil
}

// LockedOutpoint returns whether an outpoint has been marked as locked and
// should not be used as an input for created transactions.
func (w *Wallet) LockedOutpoint(op wire.OutPoint) bool {
	_, locked := w.lockedOutpoints[op]
	return locked
}

// LockOutpoint marks an outpoint as locked, that is, it should not be used as
// an input for newly created transactions.
func (w *Wallet) LockOutpoint(op wire.OutPoint) {
	w.lockedOutpoints[op] = struct{}{}
}

// UnlockOutpoint marks an outpoint as unlocked, that is, it may be used as an
// input for newly created transactions.
func (w *Wallet) UnlockOutpoint(op wire.OutPoint) {
	delete(w.lockedOutpoints, op)
}

// ResetLockedOutpoints resets the set of locked outpoints so all may be used
// as inputs for new transactions.
func (w *Wallet) ResetLockedOutpoints() {
	w.lockedOutpoints = map[wire.OutPoint]struct{}{}
}

// LockedOutpoints returns a slice of currently locked outpoints.  This is
// intended to be used by marshaling the result as a JSON array for
// listlockunspent RPC results.
func (w *Wallet) LockedOutpoints() []btcjson.TransactionInput {
	locked := make([]btcjson.TransactionInput, len(w.lockedOutpoints))
	i := 0
	for op := range w.lockedOutpoints {
		locked[i] = btcjson.TransactionInput{
			Txid: op.Hash.String(),
			Vout: op.Index,
		}
		i++
	}
	return locked
}

// resendUnminedTxs iterates through all transactions that spend from wallet
// credits that are not known to have been mined into a block, and attempts
// to send each to the chain server for relay.
func (w *Wallet) resendUnminedTxs() {
	chainClient, err := w.requireChainClient()
	if err != nil {
		log.Errorf("No chain server available to resend unmined transactions")
		return
	}

	var txs []*wire.MsgTx
	err = walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)
		var err error
		txs, err = w.TxStore.UnminedTxs(txmgrNs)
		return err
	})
	if err != nil {
		log.Errorf("Cannot load unmined transactions for resending: %v", err)
		return
	}

	for _, tx := range txs {
		resp, err := chainClient.SendRawTransaction(tx, false)
		if err != nil {
			// TODO(jrick): Check error for if this tx is a double spend,
			// remove it if so.
			log.Debugf("Could not resend transaction %v: %v",
				tx.TxHash(), err)
			continue
		}
		log.Debugf("Resent unmined transaction %v", resp)
	}
}

// SortedActivePaymentAddresses returns a slice of all active payment
// addresses in a wallet.
func (w *Wallet) SortedActivePaymentAddresses() ([]string, error) {
	var addrStrs []string
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		return w.Manager.ForEachActiveAddress(addrmgrNs, func(addr btcutil.Address) error {
			addrStrs = append(addrStrs, addr.EncodeAddress())
			return nil
		})
	})
	if err != nil {
		return nil, err
	}

	sort.Sort(sort.StringSlice(addrStrs))
	return addrStrs, nil
}

// NewAddress returns the next external chained address for a wallet.
func (w *Wallet) NewAddress(account uint32) (addr btcutil.Address, err error) {
	err = walletdb.Update(w.db, func(tx walletdb.ReadWriteTx) error {
		addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)
		var err error
		addr, err = w.newAddress(addrmgrNs, account)
		return err
	})
	return
}

func (w *Wallet) newAddress(addrmgrNs walletdb.ReadWriteBucket, account uint32) (btcutil.Address, error) {
	// Get next address from wallet.
	addrs, err := w.Manager.NextExternalAddresses(addrmgrNs, account, 1)
	if err != nil {
		return nil, err
	}

	// Request updates from btcd for new transactions sent to this address.
	utilAddrs := make([]btcutil.Address, len(addrs))
	for i, addr := range addrs {
		utilAddrs[i] = addr.Address()
	}
	w.chainClientLock.Lock()
	chainClient := w.chainClient
	w.chainClientLock.Unlock()
	if chainClient != nil {
		err := chainClient.NotifyReceived(utilAddrs)
		if err != nil {
			return nil, err
		}
	}

	props, err := w.Manager.AccountProperties(addrmgrNs, account)
	if err != nil {
		log.Errorf("Cannot fetch account properties for notification "+
			"after deriving next external address: %v", err)
	} else {
		w.NtfnServer.notifyAccountProperties(props)
	}

	return utilAddrs[0], nil
}

// NewChangeAddress returns a new change address for a wallet.
func (w *Wallet) NewChangeAddress(account uint32) (addr btcutil.Address, err error) {
	err = walletdb.Update(w.db, func(tx walletdb.ReadWriteTx) error {
		addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)
		var err error
		addr, err = w.newChangeAddress(addrmgrNs, account)
		return err
	})
	return
}

func (w *Wallet) newChangeAddress(addrmgrNs walletdb.ReadWriteBucket, account uint32) (btcutil.Address, error) {
	// Get next chained change address from wallet for account.
	addrs, err := w.Manager.NextInternalAddresses(addrmgrNs, account, 1)
	if err != nil {
		return nil, err
	}

	// Request updates from btcd for new transactions sent to this address.
	utilAddrs := make([]btcutil.Address, len(addrs))
	for i, addr := range addrs {
		utilAddrs[i] = addr.Address()
	}

	chainClient, err := w.requireChainClient()
	if err == nil {
		err = chainClient.NotifyReceived(utilAddrs)
		if err != nil {
			return nil, err
		}
	}

	return utilAddrs[0], nil
}

// confirmed checks whether a transaction at height txHeight has met minconf
// confirmations for a blockchain at height curHeight.
func confirmed(minconf, txHeight, curHeight int32) bool {
	return confirms(txHeight, curHeight) >= minconf
}

// confirms returns the number of confirmations for a transaction in a block at
// height txHeight (or -1 for an unconfirmed tx) given the chain height
// curHeight.
func confirms(txHeight, curHeight int32) int32 {
	switch {
	case txHeight == -1, txHeight > curHeight:
		return 0
	default:
		return curHeight - txHeight + 1
	}
}

// AccountTotalReceivedResult is a single result for the
// Wallet.TotalReceivedForAccounts method.
type AccountTotalReceivedResult struct {
	AccountNumber    uint32
	AccountName      string
	TotalReceived    btcutil.Amount
	LastConfirmation int32
}

// TotalReceivedForAccounts iterates through a wallet's transaction history,
// returning the total amount of decred received for all accounts.
func (w *Wallet) TotalReceivedForAccounts(minConf int32) ([]AccountTotalReceivedResult, error) {
	var results []AccountTotalReceivedResult
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)

		syncBlock := w.Manager.SyncedTo()

		err := w.Manager.ForEachAccount(addrmgrNs, func(account uint32) error {
			accountName, err := w.Manager.AccountName(addrmgrNs, account)
			if err != nil {
				return err
			}
			results = append(results, AccountTotalReceivedResult{
				AccountNumber: account,
				AccountName:   accountName,
			})
			return nil
		})
		if err != nil {
			return err
		}

		var stopHeight int32

		if minConf > 0 {
			stopHeight = syncBlock.Height - minConf + 1
		} else {
			stopHeight = -1
		}

		rangeFn := func(details []wtxmgr.TxDetails) (bool, error) {
			for i := range details {
				detail := &details[i]
				for _, cred := range detail.Credits {
					pkScript := detail.MsgTx.TxOut[cred.Index].PkScript
					var outputAcct uint32
					_, addrs, _, err := txscript.ExtractPkScriptAddrs(pkScript, w.chainParams)
					if err == nil && len(addrs) > 0 {
						outputAcct, err = w.Manager.AddrAccount(addrmgrNs, addrs[0])
					}
					if err == nil {
						acctIndex := int(outputAcct)
						if outputAcct == waddrmgr.ImportedAddrAccount {
							acctIndex = len(results) - 1
						}
						res := &results[acctIndex]
						res.TotalReceived += cred.Amount
						res.LastConfirmation = confirms(
							detail.Block.Height, syncBlock.Height)
					}
				}
			}
			return false, nil
		}
		return w.TxStore.RangeTransactions(txmgrNs, 0, stopHeight, rangeFn)
	})
	return results, err
}

// TotalReceivedForAddr iterates through a wallet's transaction history,
// returning the total amount of bitcoins received for a single wallet
// address.
func (w *Wallet) TotalReceivedForAddr(addr btcutil.Address, minConf int32) (btcutil.Amount, error) {
	var amount btcutil.Amount
	err := walletdb.View(w.db, func(tx walletdb.ReadTx) error {
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)

		syncBlock := w.Manager.SyncedTo()

		var (
			addrStr    = addr.EncodeAddress()
			stopHeight int32
		)

		if minConf > 0 {
			stopHeight = syncBlock.Height - minConf + 1
		} else {
			stopHeight = -1
		}
		rangeFn := func(details []wtxmgr.TxDetails) (bool, error) {
			for i := range details {
				detail := &details[i]
				for _, cred := range detail.Credits {
					pkScript := detail.MsgTx.TxOut[cred.Index].PkScript
					_, addrs, _, err := txscript.ExtractPkScriptAddrs(pkScript,
						w.chainParams)
					// An error creating addresses from the output script only
					// indicates a non-standard script, so ignore this credit.
					if err != nil {
						continue
					}
					for _, a := range addrs {
						if addrStr == a.EncodeAddress() {
							amount += cred.Amount
							break
						}
					}
				}
			}
			return false, nil
		}
		return w.TxStore.RangeTransactions(txmgrNs, 0, stopHeight, rangeFn)
	})
	return amount, err
}

// SendOutputs creates and sends payment transactions. It returns the
// transaction hash upon success.
func (w *Wallet) SendOutputs(outputs []*wire.TxOut, account uint32,
	minconf int32) (*chainhash.Hash, error) {

	chainClient, err := w.requireChainClient()
	if err != nil {
		return nil, err
	}

	relayFee := w.RelayFee()
	for _, output := range outputs {
		err = txrules.CheckOutput(output, relayFee)
		if err != nil {
			return nil, err
		}
	}

	// Create transaction, replying with an error if the creation
	// was not successful.
	createdTx, err := w.CreateSimpleTx(account, outputs, minconf)
	if err != nil {
		return nil, err
	}

	// Create transaction record and insert into the db.
	rec, err := wtxmgr.NewTxRecordFromMsgTx(createdTx.Tx, time.Now())
	if err != nil {
		log.Errorf("Cannot create record for created transaction: %v", err)
		return nil, err
	}
	err = walletdb.Update(w.db, func(tx walletdb.ReadWriteTx) error {
		txmgrNs := tx.ReadWriteBucket(wtxmgrNamespaceKey)
		err := w.TxStore.InsertTx(txmgrNs, rec, nil)
		if err != nil {
			return err
		}

		if createdTx.ChangeIndex >= 0 {
			err = w.TxStore.AddCredit(txmgrNs, rec, nil, uint32(createdTx.ChangeIndex), true)
			if err != nil {
				log.Errorf("Error adding change address for sent "+
					"tx: %v", err)
				return err
			}
		}
		return nil
	})
	if err != nil {
		return nil, err
	}

	// TODO: The record already has the serialized tx, so no need to
	// serialize it again.
	return chainClient.SendRawTransaction(&rec.MsgTx, false)
}

// SignatureError records the underlying error when validating a transaction
// input signature.
type SignatureError struct {
	InputIndex uint32
	Error      error
}

// SignTransaction uses secrets of the wallet, as well as additional secrets
// passed in by the caller, to create and add input signatures to a transaction.
//
// Transaction input script validation is used to confirm that all signatures
// are valid.  For any invalid input, a SignatureError is added to the returns.
// The final error return is reserved for unexpected or fatal errors, such as
// being unable to determine a previous output script to redeem.
//
// The transaction pointed to by tx is modified by this function.
func (w *Wallet) SignTransaction(tx *wire.MsgTx, hashType txscript.SigHashType,
	additionalPrevScripts map[wire.OutPoint][]byte,
	additionalKeysByAddress map[string]*btcutil.WIF,
	p2shRedeemScriptsByAddress map[string][]byte) ([]SignatureError, error) {

	var signErrors []SignatureError
	err := walletdb.View(w.db, func(dbtx walletdb.ReadTx) error {
		addrmgrNs := dbtx.ReadBucket(waddrmgrNamespaceKey)
		txmgrNs := dbtx.ReadBucket(wtxmgrNamespaceKey)

		for i, txIn := range tx.TxIn {
			prevOutScript, ok := additionalPrevScripts[txIn.PreviousOutPoint]
			if !ok {
				prevHash := &txIn.PreviousOutPoint.Hash
				prevIndex := txIn.PreviousOutPoint.Index
				txDetails, err := w.TxStore.TxDetails(txmgrNs, prevHash)
				if err != nil {
					return fmt.Errorf("cannot query previous transaction "+
						"details for %v: %v", txIn.PreviousOutPoint, err)
				}
				if txDetails == nil {
					return fmt.Errorf("%v not found",
						txIn.PreviousOutPoint)
				}
				prevOutScript = txDetails.MsgTx.TxOut[prevIndex].PkScript
			}

			// Set up our callbacks that we pass to txscript so it can
			// look up the appropriate keys and scripts by address.
			getKey := txscript.KeyClosure(func(addr btcutil.Address) (*btcec.PrivateKey, bool, error) {
				if len(additionalKeysByAddress) != 0 {
					addrStr := addr.EncodeAddress()
					wif, ok := additionalKeysByAddress[addrStr]
					if !ok {
						return nil, false,
							errors.New("no key for address")
					}
					return wif.PrivKey, wif.CompressPubKey, nil
				}
				address, err := w.Manager.Address(addrmgrNs, addr)
				if err != nil {
					return nil, false, err
				}

				pka, ok := address.(waddrmgr.ManagedPubKeyAddress)
				if !ok {
					return nil, false, fmt.Errorf("address %v is not "+
						"a pubkey address", address.Address().EncodeAddress())
				}

				key, err := pka.PrivKey()
				if err != nil {
					return nil, false, err
				}

				return key, pka.Compressed(), nil
			})
			getScript := txscript.ScriptClosure(func(addr btcutil.Address) ([]byte, error) {
				// If keys were provided then we can only use the
				// redeem scripts provided with our inputs, too.
				if len(additionalKeysByAddress) != 0 {
					addrStr := addr.EncodeAddress()
					script, ok := p2shRedeemScriptsByAddress[addrStr]
					if !ok {
						return nil, errors.New("no script for address")
					}
					return script, nil
				}
				address, err := w.Manager.Address(addrmgrNs, addr)
				if err != nil {
					return nil, err
				}
				sa, ok := address.(waddrmgr.ManagedScriptAddress)
				if !ok {
					return nil, errors.New("address is not a script" +
						" address")
				}

				return sa.Script()
			})

			// SigHashSingle inputs can only be signed if there's a
			// corresponding output. However this could be already signed,
			// so we always verify the output.
			if (hashType&txscript.SigHashSingle) !=
				txscript.SigHashSingle || i < len(tx.TxOut) {

				script, err := txscript.SignTxOutput(w.ChainParams(),
					tx, i, prevOutScript, hashType, getKey,
					getScript, txIn.SignatureScript)
				// Failure to sign isn't an error, it just means that
				// the tx isn't complete.
				if err != nil {
					signErrors = append(signErrors, SignatureError{
						InputIndex: uint32(i),
						Error:      err,
					})
					continue
				}
				txIn.SignatureScript = script
			}

			// Either it was already signed or we just signed it.
			// Find out if it is completely satisfied or still needs more.
			vm, err := txscript.NewEngine(prevOutScript, tx, i,
				txscript.StandardVerifyFlags, nil)
			if err == nil {
				err = vm.Execute()
			}
			if err != nil {
				signErrors = append(signErrors, SignatureError{
					InputIndex: uint32(i),
					Error:      err,
				})
			}
		}
		return nil
	})
	return signErrors, err
}

// PublishTransaction sends the transaction to the consensus RPC server so it
// can be propigated to other nodes and eventually mined.
//
// This function is unstable and will be removed once syncing code is moved out
// of the wallet.
func (w *Wallet) PublishTransaction(tx *wire.MsgTx) error {
	server, err := w.requireChainClient()
	if err != nil {
		return err
	}

	_, err = server.SendRawTransaction(tx, false)
	return err
}

// ChainParams returns the network parameters for the blockchain the wallet
// belongs to.
func (w *Wallet) ChainParams() *chaincfg.Params {
	return w.chainParams
}

// Database returns the underlying walletdb database. This method is provided
// in order to allow applications wrapping btcwallet to store app-specific data
// with the wallet's database.
func (w *Wallet) Database() walletdb.DB {
	return w.db
}

// Create creates an new wallet, writing it to an empty database.  If the passed
// seed is non-nil, it is used.  Otherwise, a secure random seed of the
// recommended length is generated.
func Create(db walletdb.DB, pubPass, privPass, seed []byte, params *chaincfg.Params) error {
	// If a seed was provided, ensure that it is of valid length. Otherwise,
	// we generate a random seed for the wallet with the recommended seed
	// length.
	if seed == nil {
		hdSeed, err := hdkeychain.GenerateSeed(
			hdkeychain.RecommendedSeedLen)
		if err != nil {
			return err
		}
		seed = hdSeed
	}
	if len(seed) < hdkeychain.MinSeedBytes ||
		len(seed) > hdkeychain.MaxSeedBytes {
		return hdkeychain.ErrInvalidSeedLen
	}

	return walletdb.Update(db, func(tx walletdb.ReadWriteTx) error {
		addrmgrNs, err := tx.CreateTopLevelBucket(waddrmgrNamespaceKey)
		if err != nil {
			return err
		}
		txmgrNs, err := tx.CreateTopLevelBucket(wtxmgrNamespaceKey)
		if err != nil {
			return err
		}

		err = waddrmgr.Create(addrmgrNs, seed, pubPass, privPass,
			params, nil)
		if err != nil {
			return err
		}
		return wtxmgr.Create(txmgrNs)
	})
}

// Open loads an already-created wallet from the passed database and namespaces.
func Open(db walletdb.DB, pubPass []byte, cbs *waddrmgr.OpenCallbacks, params *chaincfg.Params) (*Wallet, error) {
	err := walletdb.View(db, func(tx walletdb.ReadTx) error {
		waddrmgrBucket := tx.ReadBucket(waddrmgrNamespaceKey)
		if waddrmgrBucket == nil {
			return errors.New("missing address manager namespace")
		}
		wtxmgrBucket := tx.ReadBucket(wtxmgrNamespaceKey)
		if wtxmgrBucket == nil {
			return errors.New("missing transaction manager namespace")
		}
		return nil
	})
	if err != nil {
		return nil, err
	}

	// Perform upgrades as necessary.  Each upgrade is done under its own
	// transaction, which is managed by each package itself, so the entire
	// DB is passed instead of passing already opened write transaction.
	//
	// This will need to change later when upgrades in one package depend on
	// data in another (such as removing chain synchronization from address
	// manager).
	err = waddrmgr.DoUpgrades(db, waddrmgrNamespaceKey, pubPass, params, cbs)
	if err != nil {
		return nil, err
	}
	err = wtxmgr.DoUpgrades(db, wtxmgrNamespaceKey)
	if err != nil {
		return nil, err
	}

	// Open database abstraction instances
	var (
		addrMgr *waddrmgr.Manager
		txMgr   *wtxmgr.Store
	)
	err = walletdb.View(db, func(tx walletdb.ReadTx) error {
		addrmgrNs := tx.ReadBucket(waddrmgrNamespaceKey)
		txmgrNs := tx.ReadBucket(wtxmgrNamespaceKey)
		var err error
		addrMgr, err = waddrmgr.Open(addrmgrNs, pubPass, params)
		if err != nil {
			return err
		}
		txMgr, err = wtxmgr.Open(txmgrNs, params)
		return err
	})
	if err != nil {
		return nil, err
	}

	log.Infof("Opened wallet") // TODO: log balance? last sync height?
	w := &Wallet{
		publicPassphrase:    pubPass,
		db:                  db,
		Manager:             addrMgr,
		TxStore:             txMgr,
		lockedOutpoints:     map[wire.OutPoint]struct{}{},
		relayFee:            txrules.DefaultRelayFeePerKb,
		rescanAddJob:        make(chan *RescanJob),
		rescanBatch:         make(chan *rescanBatch),
		rescanNotifications: make(chan interface{}),
		rescanProgress:      make(chan *RescanProgressMsg),
		rescanFinished:      make(chan *RescanFinishedMsg),
		createTxRequests:    make(chan createTxRequest),
		unlockRequests:      make(chan unlockRequest),
		lockRequests:        make(chan struct{}),
		holdUnlockRequests:  make(chan chan heldUnlock),
		lockState:           make(chan bool),
		changePassphrase:    make(chan changePassphraseRequest),
		chainParams:         params,
		quit:                make(chan struct{}),
	}
	w.NtfnServer = newNotificationServer(w)
	w.TxStore.NotifyUnspent = func(hash *chainhash.Hash, index uint32) {
		w.NtfnServer.notifyUnspentOutput(0, hash, index)
	}
	return w, nil
}