# Electrum - lightweight Bitcoin client
# Copyright (C) 2015 Thomas Voegtlin
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# Wallet classes:
#   - ImportedAddressWallet: imported address, no keystore
#   - ImportedPrivkeyWallet: imported private keys, keystore
#   - Standard_Wallet: one keystore, P2PKH
#   - Multisig_Wallet: several keystores, P2SH


import os
import threading
import random
import time
import json
import copy
import errno
from collections import defaultdict
from decimal import Decimal as PyDecimal  # Qt 5.12 also exports Decimal
from functools import partial

from .i18n import _
from .util import NotEnoughFunds, ExcessiveFee, PrintError, UserCancelled, profiler, format_satoshis, format_time, finalization_print_error

from .address import Address, Script, ScriptOutput, PublicKey
from .bitcoin import *
from .version import *
from .keystore import load_keystore, Hardware_KeyStore, Imported_KeyStore, BIP32_KeyStore, xpubkey_to_address
from . import networks
from .storage import multisig_type

from . import transaction
from .transaction import Transaction
from .plugins import run_hook
from . import bitcoin
from . import coinchooser
from .synchronizer import Synchronizer
from .verifier import SPV

from . import paymentrequest
from .paymentrequest import PR_PAID, PR_UNPAID, PR_UNKNOWN, PR_EXPIRED
from .paymentrequest import InvoiceStore
from .contacts import Contacts

TX_STATUS = [
    _('Unconfirmed parent'),
    _('Low fee'),
    _('Unconfirmed'),
    _('Not Verified'),
]



def relayfee(network):
    RELAY_FEE = 5000
    MAX_RELAY_FEE = 50000
    f = network.relay_fee if network and network.relay_fee else RELAY_FEE
    return min(f, MAX_RELAY_FEE)

def dust_threshold(network):
    # Change < dust threshold is added to the tx fee
    #return 182 * 3 * relayfee(network) / 1000 # original Electrum logic
    #return 1 # <-- was this value until late Sept. 2018
    return 546 # hard-coded Bitcoin Cash dust threshold. Was changed to this as of Sept. 2018


def append_utxos_to_inputs(inputs, network, pubkey, txin_type, imax):
    if txin_type == 'p2pkh':
        address = Address.from_pubkey(pubkey)
    else:
        address = PublicKey.from_pubkey(pubkey)
    sh = address.to_scripthash_hex()
    u = network.synchronous_get(('blockchain.scripthash.listunspent', [sh]))
    for item in u:
        if len(inputs) >= imax:
            break
        item['address'] = address
        item['type'] = txin_type
        item['prevout_hash'] = item['tx_hash']
        item['prevout_n'] = item['tx_pos']
        item['pubkeys'] = [pubkey]
        item['x_pubkeys'] = [pubkey]
        item['signatures'] = [None]
        item['num_sig'] = 1
        inputs.append(item)

def sweep_preparations(privkeys, network, imax=100):

    def find_utxos_for_privkey(txin_type, privkey, compressed):
        pubkey = bitcoin.public_key_from_private_key(privkey, compressed)
        append_utxos_to_inputs(inputs, network, pubkey, txin_type, imax)
        keypairs[pubkey] = privkey, compressed

    inputs = []
    keypairs = {}
    for sec in privkeys:
        txin_type, privkey, compressed = bitcoin.deserialize_privkey(sec)
        find_utxos_for_privkey(txin_type, privkey, compressed)
        # do other lookups to increase support coverage
        if is_minikey(sec):
            # minikeys don't have a compressed byte
            # we lookup both compressed and uncompressed pubkeys
            find_utxos_for_privkey(txin_type, privkey, not compressed)
        elif txin_type == 'p2pkh':
            # WIF serialization does not distinguish p2pkh and p2pk
            # we also search for pay-to-pubkey outputs
            find_utxos_for_privkey('p2pk', privkey, compressed)
    if not inputs:
        raise BaseException(_('No inputs found. (Note that inputs need to be confirmed)'))
    return inputs, keypairs


def sweep(privkeys, network, config, recipient, fee=None, imax=100):
    inputs, keypairs = sweep_preparations(privkeys, network, imax)
    total = sum(i.get('value') for i in inputs)
    if fee is None:
        outputs = [(TYPE_ADDRESS, recipient, total)]
        tx = Transaction.from_io(inputs, outputs)
        fee = config.estimate_fee(tx.estimated_size())
    if total - fee < 0:
        raise BaseException(_('Not enough funds on address.') + '\nTotal: %d satoshis\nFee: %d'%(total, fee))
    if total - fee < dust_threshold(network):
        raise BaseException(_('Not enough funds on address.') + '\nTotal: %d satoshis\nFee: %d\nDust Threshold: %d'%(total, fee, dust_threshold(network)))

    outputs = [(TYPE_ADDRESS, recipient, total - fee)]
    locktime = network.get_local_height()

    tx = Transaction.from_io(inputs, outputs, locktime=locktime)
    tx.BIP_LI01_sort()
    tx.sign(keypairs)
    return tx


class Abstract_Wallet(PrintError):
    """
    Wallet classes are created to handle various address generation methods.
    Completion states (watching-only, single account, no seed, etc) are handled inside classes.
    """

    max_change_outputs = 3

    def __init__(self, storage):
        self.electrum_version = PACKAGE_VERSION
        self.storage = storage
        self.thread = None  # this is used by the qt main_window to store a QThread. We just make sure it's always defined as an attribute here.
        self.network = None
        # verifier (SPV) and synchronizer are started in start_threads
        self.synchronizer = None
        self.verifier = None

        # Cache of Address -> (c,u,x) balance. This cache is used by
        # get_addr_balance to significantly speed it up (it is called a lot).
        # Cache entries are invalidated when tx's are seen involving this
        # address (address history chages). Entries to this cache are added
        # only inside get_addr_balance.
        # Note that this data structure is touched by the network and GUI
        # thread concurrently without the use of locks, because Python GIL
        # allows us to get away with such things. As such do not iterate over
        # this dict, but simply add/remove items to/from it in 1-liners (which
        # Python's GIL makes thread-safe implicitly).
        self._addr_bal_cache = {}

        self.gap_limit_for_change = 20 # constant
        # saved fields
        self.use_change            = storage.get('use_change', True)
        self.multiple_change       = storage.get('multiple_change', False)
        self.labels                = storage.get('labels', {})
        # Frozen addresses
        frozen_addresses = storage.get('frozen_addresses',[])
        self.frozen_addresses = set(Address.from_string(addr)
                                    for addr in frozen_addresses)
        # Frozen coins (UTXOs) -- note that we have 2 independent levels of "freezing": address-level and coin-level.
        # The two types of freezing are flagged independently of each other and 'spendable' is defined as a coin that satisfies
        # BOTH levels of freezing.
        self.frozen_coins = set(storage.get('frozen_coins', []))
        # address -> list(txid, height)
        history = storage.get('addr_history',{})
        self._history = self.to_Address_dict(history)

        # there is a difference between wallet.up_to_date and interface.is_up_to_date()
        # interface.is_up_to_date() returns true when all requests have been answered and processed
        # wallet.up_to_date is true when the wallet is synchronized (stronger requirement)
        self.up_to_date = False

        # locks: if you need to take multiple ones, acquire them in the order they are defined here!
        self.lock = threading.RLock()
        self.transaction_lock = threading.RLock()

        # load requests
        requests = self.storage.get('payment_requests', {})
        for key, req in requests.items():
            req['address'] = Address.from_string(key)
        self.receive_requests = {req['address']: req
                                 for req in requests.values()}

        # Transactions pending verification.  A map from tx hash to transaction
        # height.  Access is contended so a lock is needed. Client code should
        # use get_unverified_tx to get a thread-safe copy of this dict.
        self.unverified_tx = defaultdict(int)

        # Verified transactions.  Each value is a (height, timestamp, block_pos) tuple.  Access with self.lock.
        self.verified_tx = storage.get('verified_tx3', {})

        # save wallet type the first time
        if self.storage.get('wallet_type') is None:
            self.storage.put('wallet_type', self.wallet_type)

        # invoices and contacts
        self.invoices = InvoiceStore(self.storage)
        self.contacts = Contacts(self.storage)

        # Now, finally, after object is constructed -- we can do this
        self.load_keystore()
        self.load_addresses()
        self.load_transactions()
        self.build_reverse_history()

        self.check_history()

        # Print debug message on finalization
        finalization_print_error(self, "[{}/{}] finalized".format(__class__.__name__, self.diagnostic_name()))

    @classmethod
    def to_Address_dict(cls, d):
        '''Convert a dict of strings to a dict of Adddress objects.'''
        return {Address.from_string(text): value for text, value in d.items()}

    @classmethod
    def from_Address_dict(cls, d):
        '''Convert a dict of Address objects to a dict of strings.'''
        return {addr.to_string(Address.FMT_LEGACY): value
                for addr, value in d.items()}

    def diagnostic_name(self):
        return self.basename()

    def __str__(self):
        return self.basename()

    def get_master_public_key(self):
        return None

    @profiler
    def load_transactions(self):
        txi = self.storage.get('txi', {})
        self.txi = {tx_hash: self.to_Address_dict(value)
                    for tx_hash, value in txi.items()}
        txo = self.storage.get('txo', {})
        self.txo = {tx_hash: self.to_Address_dict(value)
                    for tx_hash, value in txo.items()}
        self.tx_fees = self.storage.get('tx_fees', {})
        self.pruned_txo = self.storage.get('pruned_txo', {})
        tx_list = self.storage.get('transactions', {})
        self.transactions = {}
        for tx_hash, raw in tx_list.items():
            tx = Transaction(raw)
            self.transactions[tx_hash] = tx
            if self.txi.get(tx_hash) is None and self.txo.get(tx_hash) is None and (tx_hash not in self.pruned_txo.values()):
                self.print_error("removing unreferenced tx", tx_hash)
                self.transactions.pop(tx_hash)

    @profiler
    def save_transactions(self, write=False):
        with self.transaction_lock:
            tx = {}
            for k,v in self.transactions.items():
                tx[k] = str(v)
            self.storage.put('transactions', tx)
            txi = {tx_hash: self.from_Address_dict(value)
                   for tx_hash, value in self.txi.items()}
            txo = {tx_hash: self.from_Address_dict(value)
                   for tx_hash, value in self.txo.items()}
            self.storage.put('txi', txi)
            self.storage.put('txo', txo)
            self.storage.put('tx_fees', self.tx_fees)
            self.storage.put('pruned_txo', self.pruned_txo)
            history = self.from_Address_dict(self._history)
            self.storage.put('addr_history', history)
            if write:
                self.storage.write()

    def save_verified_tx(self, write=False):
        with self.lock:
            self.storage.put('verified_tx3', self.verified_tx)
            if write:
                self.storage.write()

    def clear_history(self):
        with self.lock, self.transaction_lock:
            self.txi = {}
            self.txo = {}
            self.tx_fees = {}
            self.pruned_txo = {}
            self.save_transactions()
            self._addr_bal_cache = {}
            self._history = {}
            self.tx_addr_hist = defaultdict(set)

    @profiler
    def build_reverse_history(self):
        self.tx_addr_hist = defaultdict(set)
        for addr, hist in self._history.items():
            for tx_hash, h in hist:
                self.tx_addr_hist[tx_hash].add(addr)

    @profiler
    def check_history(self):
        save = False
        my_addrs = [addr for addr in self._history if self.is_mine(addr)]

        for addr in set(self._history) - set(my_addrs):
            self._history.pop(addr)
            save = True

        for addr in my_addrs:
            hist = self._history[addr]

            for tx_hash, tx_height in hist:
                if tx_hash in self.pruned_txo.values() or self.txi.get(tx_hash) or self.txo.get(tx_hash):
                    continue
                tx = self.transactions.get(tx_hash)
                if tx is not None:
                    self.add_transaction(tx_hash, tx)
                    save = True
        if save:
            self.save_transactions()

    def basename(self):
        return os.path.basename(self.storage.path)

    def save_addresses(self):
        addr_dict = {
            'receiving': [addr.to_storage_string()
                          for addr in self.receiving_addresses],
            'change': [addr.to_storage_string()
                       for addr in self.change_addresses],
        }
        self.storage.put('addresses', addr_dict)

    def load_addresses(self):
        d = self.storage.get('addresses', {})
        if not isinstance(d, dict):
            d = {}
        self.receiving_addresses = Address.from_strings(d.get('receiving', []))
        self.change_addresses = Address.from_strings(d.get('change', []))

    def synchronize(self):
        pass

    def is_deterministic(self):
        return self.keystore.is_deterministic()

    def set_up_to_date(self, up_to_date):
        with self.lock:
            self.up_to_date = up_to_date
            if up_to_date:
                self.save_transactions(write=True)
                # if the verifier is also up to date, persist that too;
                # otherwise it will persist its results when it finishes
                if self.verifier and self.verifier.is_up_to_date():
                    self.save_verified_tx(write=True)

    def is_up_to_date(self):
        with self.lock: return self.up_to_date

    def set_label(self, name, text = None):
        with self.lock:
            if isinstance(name, Address):
                name = name.to_storage_string()
            changed = False
            old_text = self.labels.get(name)
            if text:
                text = text.replace("\n", " ")
                if old_text != text:
                    self.labels[name] = text
                    changed = True
            else:
                if old_text:
                    self.labels.pop(name)
                    changed = True

            if changed:
                run_hook('set_label', self, name, text)
                self.storage.put('labels', self.labels)

            return changed

    def is_mine(self, address):
        assert not isinstance(address, str)
        return address in self.get_addresses()

    def is_change(self, address):
        assert not isinstance(address, str)
        return address in self.change_addresses

    def get_address_index(self, address):
        try:
            return False, self.receiving_addresses.index(address)
        except ValueError:
            pass
        try:
            return True, self.change_addresses.index(address)
        except ValueError:
            pass
        assert not isinstance(address, str)
        raise Exception("Address {} not found".format(address))

    def export_private_key(self, address, password):
        """ extended WIF format """
        if self.is_watching_only():
            return []
        index = self.get_address_index(address)
        pk, compressed = self.keystore.get_private_key(index, password)
        return bitcoin.serialize_privkey(pk, compressed, self.txin_type)

    def get_public_keys(self, address):
        sequence = self.get_address_index(address)
        return self.get_pubkeys(*sequence)

    def add_unverified_tx(self, tx_hash, tx_height):
        with self.lock:
            if tx_height == 0 and tx_hash in self.verified_tx:
                self.verified_tx.pop(tx_hash)
                if self.verifier:
                    self.verifier.merkle_roots.pop(tx_hash, None)

            # tx will be verified only if height > 0
            if tx_hash not in self.verified_tx:
                self.unverified_tx[tx_hash] = tx_height

    def add_verified_tx(self, tx_hash, info):
        # Remove from the unverified map and add to the verified map and
        with self.lock:
            self.unverified_tx.pop(tx_hash, None)
            self.verified_tx[tx_hash] = info  # (tx_height, timestamp, pos)
            height, conf, timestamp = self.get_tx_height(tx_hash)
        self.network.trigger_callback('verified2', self, tx_hash, height, conf, timestamp)

    def get_unverified_txs(self):
        '''Returns a map from tx hash to transaction height'''
        with self.lock:
            return self.unverified_tx.copy()

    def get_unverified_tx_pending_count(self):
        ''' Returns the number of unverified tx's that are confirmed and are
        still in process and should be verified soon.'''
        with self.lock:
            return len([1 for height in self.unverified_tx.values() if height > 0])

    def undo_verifications(self, blockchain, height):
        '''Used by the verifier when a reorg has happened'''
        txs = set()
        with self.lock:
            for tx_hash, item in list(self.verified_tx.items()):
                tx_height, timestamp, pos = item
                if tx_height >= height:
                    header = blockchain.read_header(tx_height)
                    # fixme: use block hash, not timestamp
                    if not header or header.get('timestamp') != timestamp:
                        self.verified_tx.pop(tx_hash, None)
                        txs.add(tx_hash)
        if txs:
            self._addr_bal_cache = {}  # this is probably not necessary -- as the receive_history_callback will invalidate bad cache items -- but just to be paranoid we clear the whole balance cache on reorg anyway as a safety measure
        return txs

    def get_local_height(self):
        """ return last known height if we are offline """
        return self.network.get_local_height() if self.network else self.storage.get('stored_height', 0)

    def get_tx_height(self, tx_hash):
        """ return the height and timestamp of a verified transaction. """
        with self.lock:
            if tx_hash in self.verified_tx:
                height, timestamp, pos = self.verified_tx[tx_hash]
                conf = max(self.get_local_height() - height + 1, 0)
                return height, conf, timestamp
            elif tx_hash in self.unverified_tx:
                height = self.unverified_tx[tx_hash]
                return height, 0, 0
            else:
                return 0, 0, 0

    def get_txpos(self, tx_hash):
        "return position, even if the tx is unverified"
        with self.lock:
            if tx_hash in self.verified_tx:
                height, timestamp, pos = self.verified_tx[tx_hash]
                return height, pos
            elif tx_hash in self.unverified_tx:
                height = self.unverified_tx[tx_hash]
                return (height, 0) if height > 0 else ((1e9 - height), 0)
            else:
                return (1e9+1, 0)

    def is_found(self):
        return any(value for value in self._history.values())

    def get_num_tx(self, address):
        """ return number of transactions where address is involved """
        return len(self.get_address_history(address))

    def get_tx_delta(self, tx_hash, address):
        assert isinstance(address, Address)
        "effect of tx on address"
        # pruned
        if tx_hash in self.pruned_txo.values():
            return None
        delta = 0
        # substract the value of coins sent from address
        d = self.txi.get(tx_hash, {}).get(address, [])
        for n, v in d:
            delta -= v
        # add the value of the coins received at address
        d = self.txo.get(tx_hash, {}).get(address, [])
        for n, v, cb in d:
            delta += v
        return delta

    def get_wallet_delta(self, tx):
        """ effect of tx on wallet """
        addresses = self.get_addresses()
        is_relevant = False
        is_mine = False
        is_pruned = False
        is_partial = False
        v_in = v_out = v_out_mine = 0
        for item in tx.inputs():
            addr = item['address']
            if addr in addresses:
                is_mine = True
                is_relevant = True
                d = self.txo.get(item['prevout_hash'], {}).get(addr, [])
                for n, v, cb in d:
                    if n == item['prevout_n']:
                        value = v
                        break
                else:
                    value = None
                if value is None:
                    is_pruned = True
                else:
                    v_in += value
            else:
                is_partial = True
        if not is_mine:
            is_partial = False
        for addr, value in tx.get_outputs():
            v_out += value
            if addr in addresses:
                v_out_mine += value
                is_relevant = True
        if is_pruned:
            # some inputs are mine:
            fee = None
            if is_mine:
                v = v_out_mine - v_out
            else:
                # no input is mine
                v = v_out_mine
        else:
            v = v_out_mine - v_in
            if is_partial:
                # some inputs are mine, but not all
                fee = None
            else:
                # all inputs are mine
                fee = v_in - v_out
        if not is_mine:
            fee = None
        return is_relevant, is_mine, v, fee

    def get_tx_info(self, tx):
        is_relevant, is_mine, v, fee = self.get_wallet_delta(tx)
        exp_n = None
        can_broadcast = False
        label = ''
        height = conf = timestamp = None
        tx_hash = tx.txid()
        if tx.is_complete():
            if tx_hash in self.transactions:
                label = self.get_label(tx_hash)
                height, conf, timestamp = self.get_tx_height(tx_hash)
                if height > 0:
                    if conf:
                        status = _("{} confirmations").format(conf)
                    else:
                        status = _('Not verified')
                else:
                    status = _('Unconfirmed')
                    if fee is None:
                        fee = self.tx_fees.get(tx_hash)
                    if fee and self.network and self.network.config.has_fee_estimates():
                        # NB: this branch will not be taken as has_fee_estimates()
                        # will always return false since we disabled querying
                        # the fee histogram as it's useless for BCH anyway.
                        size = tx.estimated_size()
                        fee_per_kb = fee * 1000 / size
                        exp_n = self.network.config.reverse_dynfee(fee_per_kb)
            else:
                status = _("Signed")
                can_broadcast = self.network is not None
        else:
            s, r = tx.signature_count()
            status = _("Unsigned") if s == 0 else _('Partially signed') + ' (%d/%d)'%(s,r)

        if is_relevant:
            if is_mine:
                if fee is not None:
                    amount = v + fee
                else:
                    amount = v
            else:
                amount = v
        else:
            amount = None

        return tx_hash, status, label, can_broadcast, amount, fee, height, conf, timestamp, exp_n

    def get_addr_io(self, address):
        h = self.get_address_history(address)
        received = {}
        sent = {}
        for tx_hash, height in h:
            l = self.txo.get(tx_hash, {}).get(address, [])
            for n, v, is_cb in l:
                received[tx_hash + ':%d'%n] = (height, v, is_cb)
        for tx_hash, height in h:
            l = self.txi.get(tx_hash, {}).get(address, [])
            for txi, v in l:
                sent[txi] = height
        return received, sent

    def get_addr_utxo(self, address):
        coins, spent = self.get_addr_io(address)
        for txi in spent:
            coins.pop(txi)
            # cleanup/detect if the 'frozen coin' was spent and remove it from the frozen coin set
            self.frozen_coins.discard(txi)
        out = {}
        for txo, v in coins.items():
            tx_height, value, is_cb = v
            prevout_hash, prevout_n = txo.split(':')
            x = {
                'address':address,
                'value':value,
                'prevout_n':int(prevout_n),
                'prevout_hash':prevout_hash,
                'height':tx_height,
                'coinbase':is_cb,
                'is_frozen_coin':txo in self.frozen_coins
            }
            out[txo] = x
        return out

    # return the total amount ever received by an address
    def get_addr_received(self, address):
        received, sent = self.get_addr_io(address)
        return sum([v for height, v, is_cb in received.values()])

    # return the balance of a bitcoin address: confirmed and matured, unconfirmed, unmatured
    # Note that 'exclude_frozen_coins = True' only checks for coin-level freezing, not address-level.
    def get_addr_balance(self, address, exclude_frozen_coins=False):
        assert isinstance(address, Address)
        if not exclude_frozen_coins:  # we do not use the cache when excluding frozen coins as frozen status is a dynamic quantity that can change at any time in the UI
            cached = self._addr_bal_cache.get(address)
            if cached is not None:
                return cached
        received, sent = self.get_addr_io(address)
        c = u = x = 0
        had_cb = False
        for txo, (tx_height, v, is_cb) in received.items():
            if exclude_frozen_coins and txo in self.frozen_coins:
                continue
            had_cb = had_cb or is_cb  # remember if this address has ever seen a coinbase txo
            if is_cb and tx_height + COINBASE_MATURITY > self.get_local_height():
                x += v
            elif tx_height > 0:
                c += v
            else:
                u += v
            if txo in sent:
                if sent[txo] > 0:
                    c -= v
                else:
                    u -= v
        result = c, u, x
        if not exclude_frozen_coins and not had_cb:
            # Cache the results.
            # Cache needs to be invalidated if a transaction is added to/
            # removed from addr history.  (See self._addr_bal_cache calls
            # related to this littered throughout this file).
            #
            # Note that as a performance tweak we don't ever cache balances for
            # addresses involving coinbase coins. The rationale being as
            # follows: Caching of balances of the coinbase addresses involves
            # a dynamic quantity: maturity of the coin (which considers the
            # ever-changing block height).
            #
            # There wasn't a good place in this codebase to signal the maturity
            # happening (and thus invalidate the cache entry for the exact
            # address that holds the coinbase coin in question when a new
            # block is found that matures a coinbase coin).
            #
            # In light of that fact, a possible approach would be to invalidate
            # this entire cache when a new block arrives (this is what Electrum
            # does). However, for Electron Cash with its focus on many addresses
            # for future privacy features such as integrated CashShuffle --
            # being notified in the wallet and invalidating the *entire* cache
            # whenever a new block arrives (which is the exact time you do
            # the most GUI refreshing and calling of this function) seems a bit
            # heavy-handed, just for sake of the (relatively rare, for the
            # average user) coinbase-carrying addresses.
            #
            # It's not a huge performance hit for the coinbase addresses to
            # simply not cache their results, and have this function recompute
            # their balance on each call, when you consider that as a
            # consequence of this policy, all the other addresses that are
            # non-coinbase can benefit from a cache that stays valid for longer
            # than 1 block (so long as their balances haven't changed).
            self._addr_bal_cache[address] = result
        return result

    def get_spendable_coins(self, domain, config, isInvoice = False):
        confirmed_only = config.get('confirmed_only', False)
        if (isInvoice):
            confirmed_only = True
        return self.get_utxos(domain, exclude_frozen=True, mature=True, confirmed_only=confirmed_only)

    def get_utxos(self, domain = None, exclude_frozen = False, mature = False, confirmed_only = False):
        ''' Note that exclude_frozen = True checks for BOTH address-level and coin-level frozen status. '''
        with self.lock:
            with self.transaction_lock:
                coins = []
                if domain is None:
                    domain = self.get_addresses()
                if exclude_frozen:
                    domain = set(domain) - self.frozen_addresses
                for addr in domain:
                    utxos = self.get_addr_utxo(addr)
                    for x in utxos.values():
                        if exclude_frozen and x['is_frozen_coin']:
                            continue
                        if confirmed_only and x['height'] <= 0:
                            continue
                        if mature and x['coinbase'] and x['height'] + COINBASE_MATURITY > self.get_local_height():
                            continue
                        coins.append(x)
                        continue
                return coins

    def dummy_address(self):
        return self.get_receiving_addresses()[0]

    def get_addresses(self):
        return self.get_receiving_addresses() + self.get_change_addresses()

    def get_change_addresses(self):
        ''' Reimplemented in subclasses for wallets that have a change address set/derivation path. '''
        return []

    def get_frozen_balance(self):
        if not self.frozen_coins:
            # performance short-cut -- get the balance of the frozen address set only IFF we don't have any frozen coins
            return self.get_balance(self.frozen_addresses)
        # otherwise, do this more costly calculation...
        cc_no_f, uu_no_f, xx_no_f = self.get_balance(None, exclude_frozen_coins = True, exclude_frozen_addresses = True)
        cc_all, uu_all, xx_all = self.get_balance(None, exclude_frozen_coins = False, exclude_frozen_addresses = False)
        return (cc_all-cc_no_f), (uu_all-uu_no_f), (xx_all-xx_no_f)

    def get_balance(self, domain=None, exclude_frozen_coins=False, exclude_frozen_addresses=False):
        if domain is None:
            domain = self.get_addresses()
        if exclude_frozen_addresses:
            domain = set(domain) - self.frozen_addresses
        cc = uu = xx = 0
        for addr in domain:
            c, u, x = self.get_addr_balance(addr, exclude_frozen_coins)
            cc += c
            uu += u
            xx += x
        return cc, uu, xx

    def get_address_history(self, address):
        assert isinstance(address, Address)
        return self._history.get(address, [])

    def add_transaction(self, tx_hash, tx):
        is_coinbase = tx.inputs()[0]['type'] == 'coinbase'
        with self.transaction_lock:
            # add inputs
            self.txi[tx_hash] = d = {}
            for txi in tx.inputs():
                addr = txi.get('address')
                if txi['type'] != 'coinbase':
                    prevout_hash = txi['prevout_hash']
                    prevout_n = txi['prevout_n']
                    ser = prevout_hash + ':%d'%prevout_n
                # find value from prev output
                if self.is_mine(addr):
                    dd = self.txo.get(prevout_hash, {})
                    for n, v, is_cb in dd.get(addr, []):
                        if n == prevout_n:
                            if d.get(addr) is None:
                                d[addr] = []
                            d[addr].append((ser, v))
                            break
                    else:
                        self.pruned_txo[ser] = tx_hash
                    self._addr_bal_cache.pop(addr, None)  # invalidate cache entry

            # add outputs
            self.txo[tx_hash] = d = {}
            for n, txo in enumerate(tx.outputs()):
                ser = tx_hash + ':%d'%n
                _type, addr, v = txo
                if self.is_mine(addr):
                    if not addr in d:
                        d[addr] = []
                    d[addr].append((n, v, is_coinbase))
                    self._addr_bal_cache.pop(addr, None)  # invalidate cache entry
                # give v to txi that spends me
                next_tx = self.pruned_txo.get(ser)
                if next_tx is not None:
                    self.pruned_txo.pop(ser)
                    dd = self.txi.get(next_tx, {})
                    if dd.get(addr) is None:
                        dd[addr] = []
                    dd[addr].append((ser, v))
            # save
            self.transactions[tx_hash] = tx

    def remove_transaction(self, tx_hash):
        with self.transaction_lock:
            self.print_error("removing tx from history", tx_hash)
            #tx = self.transactions.pop(tx_hash, None)
            for ser, hh in list(self.pruned_txo.items()):
                if hh == tx_hash:
                    self.pruned_txo.pop(ser)
            # add tx to pruned_txo, and undo the txi addition
            for next_tx, dd in self.txi.items():
                for addr, l in list(dd.items()):
                    ll = l[:]
                    for item in ll:
                        ser, v = item
                        prev_hash, prev_n = ser.split(':')
                        if prev_hash == tx_hash:
                            self._addr_bal_cache.pop(addr, None)  # invalidate cache entry
                            l.remove(item)
                            self.pruned_txo[ser] = next_tx
                    if l == []:
                        dd.pop(addr)
                    else:
                        dd[addr] = l

            # invalidate addr_bal_cache for outputs involving this tx
            d = self.txo.get(tx_hash, {})
            for addr in d:
                self._addr_bal_cache.pop(addr, None)  # invalidate cache entry

            try: self.txi.pop(tx_hash)
            except KeyError: self.print_error("tx was not in input history", tx_hash)
            try: self.txo.pop(tx_hash)
            except KeyError: self.print_error("tx was not in output history", tx_hash)


    def receive_tx_callback(self, tx_hash, tx, tx_height):
        self.add_transaction(tx_hash, tx)
        self.add_unverified_tx(tx_hash, tx_height)

    def receive_history_callback(self, addr, hist, tx_fees):
        with self.lock, self.transaction_lock:
            old_hist = self.get_address_history(addr)
            for tx_hash, height in old_hist:
                if (tx_hash, height) not in hist:
                    s = self.tx_addr_hist.get(tx_hash)
                    if s:
                        s.discard(addr)
                    if not s:
                        # if no address references this tx anymore, kill it
                        # from txi/txo dicts.
                        if s is not None:
                            # We won't keep empty sets around.
                            self.tx_addr_hist.pop(tx_hash)
                        # note this call doesn't actually remove the tx from
                        # storage, it merely removes it from the self.txi
                        # and self.txo dicts
                        self.remove_transaction(tx_hash)
            self._addr_bal_cache.pop(addr, None)  # unconditionally invalidate cache entry
            self._history[addr] = hist

            for tx_hash, tx_height in hist:
                # add it in case it was previously unconfirmed
                self.add_unverified_tx(tx_hash, tx_height)
                # add reference in tx_addr_hist
                self.tx_addr_hist[tx_hash].add(addr)
                # if addr is new, we have to recompute txi and txo
                tx = self.transactions.get(tx_hash)
                if tx is not None and self.txi.get(tx_hash, {}).get(addr) is None and self.txo.get(tx_hash, {}).get(addr) is None:
                    self.add_transaction(tx_hash, tx)

            # Store fees
            self.tx_fees.update(tx_fees)

        if self.network:
            self.network.trigger_callback('on_history', self)

    def get_history(self, domain=None, *, reverse=False):
        # get domain
        if domain is None:
            domain = self.get_addresses()
        # 1. Get the history of each address in the domain, maintain the
        #    delta of a tx as the sum of its deltas on domain addresses
        tx_deltas = defaultdict(int)
        for addr in domain:
            h = self.get_address_history(addr)
            for tx_hash, height in h:
                delta = self.get_tx_delta(tx_hash, addr)
                if delta is None or tx_deltas[tx_hash] is None:
                    tx_deltas[tx_hash] = None
                else:
                    tx_deltas[tx_hash] += delta

        # 2. create sorted history
        history = []
        for tx_hash in tx_deltas:
            delta = tx_deltas[tx_hash]
            height, conf, timestamp = self.get_tx_height(tx_hash)
            history.append((tx_hash, height, conf, timestamp, delta))
        history.sort(key = lambda x: self.get_txpos(x[0]), reverse=True)

        # 3. add balance
        c, u, x = self.get_balance(domain)
        balance = c + u + x
        h2 = []
        for tx_hash, height, conf, timestamp, delta in history:
            h2.append((tx_hash, height, conf, timestamp, delta, balance))
            if balance is None or delta is None:
                balance = None
            else:
                balance -= delta
        if not reverse:
            h2.reverse()

        return h2

    def export_history(self, domain=None, from_timestamp=None, to_timestamp=None, fx=None, show_addresses=False):
        from .util import timestamp_to_datetime
        h = self.get_history(domain)
        out = []
        for tx_hash, height, conf, timestamp, value, balance in h:
            if from_timestamp and timestamp < from_timestamp:
                continue
            if to_timestamp and timestamp >= to_timestamp:
                continue
            item = {
                'txid':tx_hash,
                'height':height,
                'confirmations':conf,
                'timestamp':timestamp,
                'value': format_satoshis(value, is_diff=True) if value is not None else '--',
                'balance': format_satoshis(balance)
            }
            if item['height']>0:
                date_str = format_time(timestamp) if timestamp is not None else _("unverified")
            else:
                date_str = _("unconfirmed")
            item['date'] = date_str
            item['label'] = self.get_label(tx_hash)
            if show_addresses:
                tx = self.transactions.get(tx_hash)
                tx.deserialize()
                input_addresses = []
                output_addresses = []
                for x in tx.inputs():
                    if x['type'] == 'coinbase': continue
                    addr = x.get('address')
                    if addr == None: continue
                    input_addresses.append(addr.to_ui_string())
                for addr, v in tx.get_outputs():
                    output_addresses.append(addr.to_ui_string())
                item['input_addresses'] = input_addresses
                item['output_addresses'] = output_addresses
            if fx is not None:
                date = timestamp_to_datetime(time.time() if conf <= 0 else timestamp)
                item['fiat_value'] = fx.historical_value_str(value, date)
                item['fiat_balance'] = fx.historical_value_str(balance, date)
            out.append(item)
        return out

    def get_label(self, tx_hash):
        label = self.labels.get(tx_hash, '')
        if label is '':
            label = self.get_default_label(tx_hash)
        return label

    def get_default_label(self, tx_hash):
        if self.txi.get(tx_hash) == {}:
            d = self.txo.get(tx_hash, {})
            labels = []
            for addr in d.keys():
                label = self.labels.get(addr.to_storage_string())
                if label:
                    labels.append(label)
            return ', '.join(labels)
        return ''

    def get_tx_status(self, tx_hash, height, conf, timestamp):
        if conf == 0:
            tx = self.transactions.get(tx_hash)
            if not tx:
                return 3, 'unknown'
            fee = self.tx_fees.get(tx_hash)
            # we disable fee estimates in BCH for now.
            #if fee and self.network and self.network.config.has_fee_estimates():
            #    size = len(tx.raw)/2
            #    low_fee = int(self.network.config.dynfee(0)*size/1000)
            #    is_lowfee = fee < low_fee * 0.5
            #else:
            #    is_lowfee = False
            # and instead if it's less than 1.0 sats/B we flag it as low_fee
            try:
                # NB len(tx.raw) is 2x the byte size as it's hex encoded.
                is_lowfee = int(fee) / (int(len(tx.raw)) / 2.0) < 1.0  # if less than 1.0 sats/B, complain. otherwise don't.
            except (TypeError, ValueError):  # If for some reason fee was None or invalid, just pass on through.
                is_lowfee = False
            # /
            if height < 0:
                status = 0
            elif height == 0 and is_lowfee:
                status = 1
            elif height == 0:
                status = 2
            else:
                status = 3
        else:
            status = 3 + min(conf, 6)
        time_str = format_time(timestamp) if timestamp else _("unknown")
        status_str = TX_STATUS[status] if status < 4 else time_str
        return status, status_str

    def relayfee(self):
        return relayfee(self.network)

    def dust_threshold(self):
        return dust_threshold(self.network)

    def make_unsigned_transaction(self, inputs, outputs, config, fixed_fee=None, change_addr=None):
        # check outputs
        i_max = None
        for i, o in enumerate(outputs):
            _type, data, value = o
            if value == '!':
                if i_max is not None:
                    raise BaseException("More than one output set to spend max")
                i_max = i

        # Avoid index-out-of-range with inputs[0] below
        if not inputs:
            raise NotEnoughFunds()

        if fixed_fee is None and config.fee_per_kb() is None:
            raise BaseException('Dynamic fee estimates not available')

        for item in inputs:
            self.add_input_info(item)

        # change address
        if change_addr:
            change_addrs = [change_addr]
        else:
            # This new hook is for 'Cashshuffle Enabled' mode which will:
            # Reserve a brand new change address if spending shuffled-only *or* unshuffled-only coins and
            # disregard the "use_change" setting since to preserve privacy we must use a new change address each time.
            # Pick and lock a new change address. This "locked" change address will not be used by the shuffle threads.
            # Note that subsequent calls to this function will return the same change address until that address is involved
            # in a tx and has a history, at which point a new address will get generated and "locked".
            change_addrs = run_hook("get_change_addrs", self)
            if not change_addrs: # hook gave us nothing, so find a change addr based on classic Electron Cash rules.
                addrs = self.get_change_addresses()[-self.gap_limit_for_change:]
                if self.use_change and addrs:
                    # New change addresses are created only after a few
                    # confirmations.  Select the unused addresses within the
                    # gap limit; if none take one at random
                    change_addrs = [addr for addr in addrs if
                                    self.get_num_tx(addr) == 0]
                    if not change_addrs:
                        change_addrs = [random.choice(addrs)]
                else:
                    change_addrs = [inputs[0]['address']]

        assert all(isinstance(addr, Address) for addr in change_addrs)

        # Fee estimator
        if fixed_fee is None:
            fee_estimator = config.estimate_fee
        else:
            fee_estimator = lambda size: fixed_fee

        if i_max is None:
            # Let the coin chooser select the coins to spend
            max_change = self.max_change_outputs if self.multiple_change else 1
            coin_chooser = coinchooser.CoinChooserPrivacy()
            tx = coin_chooser.make_tx(inputs, outputs, change_addrs[:max_change],
                                      fee_estimator, self.dust_threshold())
        else:
            sendable = sum(map(lambda x:x['value'], inputs))
            _type, data, value = outputs[i_max]
            outputs[i_max] = (_type, data, 0)
            tx = Transaction.from_io(inputs, outputs)
            fee = fee_estimator(tx.estimated_size())
            amount = max(0, sendable - tx.output_value() - fee)
            outputs[i_max] = (_type, data, amount)
            tx = Transaction.from_io(inputs, outputs)

        # If user tries to send too big of a fee (more than 50 sat/byte), stop them from shooting themselves in the foot
        tx_in_bytes=tx.estimated_size()
        fee_in_satoshis=tx.get_fee()
        sats_per_byte=fee_in_satoshis/tx_in_bytes
        if (sats_per_byte > 50):
            raise ExcessiveFee()
            return

        # Sort the inputs and outputs deterministically
        tx.BIP_LI01_sort()
        # Timelock tx to current height.
        locktime = self.get_local_height()
        if locktime == -1: # We have no local height data (no headers synced).
            locktime = 0
        tx.locktime = locktime
        run_hook('make_unsigned_transaction', self, tx)
        return tx

    def mktx(self, outputs, password, config, fee=None, change_addr=None, domain=None):
        coins = self.get_spendable_coins(domain, config)
        tx = self.make_unsigned_transaction(coins, outputs, config, fee, change_addr)
        self.sign_transaction(tx, password)
        return tx

    def is_frozen(self, addr):
        ''' Address-level frozen query. Note: this is set/unset independent of 'coin' level freezing. '''
        assert isinstance(addr, Address)
        return addr in self.frozen_addresses

    def is_frozen_coin(self, utxo):
        ''' 'coin' level frozen query. `utxo' is a prevout:n string, or a dict as returned from get_utxos().
            Note: this is set/unset independent of 'address' level freezing. '''
        assert isinstance(utxo, (str, dict))
        if isinstance(utxo, dict):
            ret = ("{}:{}".format(utxo['prevout_hash'], utxo['prevout_n'])) in self.frozen_coins
            if ret != utxo['is_frozen_coin']:
                self.print_error("*** WARNING: utxo has stale is_frozen_coin flag")
                utxo['is_frozen_coin'] = ret # update stale flag
            return ret
        return utxo in self.frozen_coins

    def set_frozen_state(self, addrs, freeze):
        ''' Set frozen state of the addresses to FREEZE, True or False
            Note that address-level freezing is set/unset independent of coin-level freezing, however both must
            be satisfied for a coin to be defined as spendable.. '''
        if all(self.is_mine(addr) for addr in addrs):
            if freeze:
                self.frozen_addresses |= set(addrs)
            else:
                self.frozen_addresses -= set(addrs)
            frozen_addresses = [addr.to_storage_string()
                                for addr in self.frozen_addresses]
            self.storage.put('frozen_addresses', frozen_addresses)
            return True
        return False

    def set_frozen_coin_state(self, utxos, freeze):
        ''' Set frozen state of the COINS to FREEZE, True or False.
            utxos is a (possibly mixed) list of either "prevout:n" strings and/or coin-dicts as returned from get_utxos().
            Note that if passing prevout:n strings as input, 'is_mine()' status is not checked for the specified coin.
            Also note that coin-level freezing is set/unset independent of address-level freezing, however both must
            be satisfied for a coin to be defined as spendable. '''
        with self.lock:
            ok = 0
            for utxo in utxos:
                if isinstance(utxo, str):
                    if freeze:
                        self.frozen_coins.add( utxo )
                    else:
                        self.frozen_coins.discard( utxo )
                    ok += 1
                elif isinstance(utxo, dict) and self.is_mine(utxo['address']):
                    txo = "{}:{}".format(utxo['prevout_hash'], utxo['prevout_n'])
                    if freeze:
                        self.frozen_coins.add( txo )
                    else:
                        self.frozen_coins.discard( txo )
                    utxo['is_frozen_coin'] = bool(freeze)
                    ok += 1
            if ok:
                self.storage.put('frozen_coins', list(self.frozen_coins))
            return ok

    def prepare_for_verifier(self):
        # review transactions that are in the history
        for addr, hist in self._history.items():
            for tx_hash, tx_height in hist:
                # add it in case it was previously unconfirmed
                self.add_unverified_tx(tx_hash, tx_height)

        # if we are on a pruning server, remove unverified transactions
        with self.lock:
            vr = list(self.verified_tx.keys()) + list(self.unverified_tx.keys())
        for tx_hash in list(self.transactions):
            if tx_hash not in vr:
                self.print_error("removing transaction", tx_hash)
                self.transactions.pop(tx_hash)

    def start_threads(self, network):
        self.network = network
        if self.network is not None:
            self.prepare_for_verifier()
            self.verifier = SPV(self.network, self)
            self.synchronizer = Synchronizer(self, network)
            finalization_print_error(self.verifier, "[{}.{}] finalized".format(self.diagnostic_name(), self.verifier.diagnostic_name()))
            finalization_print_error(self.synchronizer, "[{}.{}] finalized".format(self.diagnostic_name(), self.synchronizer.diagnostic_name()))
            network.add_jobs([self.verifier, self.synchronizer])
        else:
            self.verifier = None
            self.synchronizer = None

    def stop_threads(self):
        if self.network:
            # Note: syncrhonizer and verifier will remove themselves from the
            # network thread the next time they run, as a result of the below
            # release() calls.
            # It is done this way (as opposed to an immediate clean-up here)
            # because these objects need to do thier clean-up actions in a
            # thread-safe fashion from within the thread where they normally
            # operate on their data structures.
            self.synchronizer.release()
            self.verifier.release()
            self.synchronizer = None
            self.verifier = None
            # Now no references to the syncronizer or verifier
            # remain so they will be GC-ed
            self.storage.put('stored_height', self.get_local_height())
        self.save_transactions()
        self.save_verified_tx()
        self.storage.put('frozen_coins', list(self.frozen_coins))
        self.storage.write()

    def wait_until_synchronized(self, callback=None):
        def wait_for_wallet():
            self.set_up_to_date(False)
            while not self.is_up_to_date():
                if callback:
                    msg = "%s\n%s %d"%(
                        _("Please wait..."),
                        _("Addresses generated:"),
                        len(self.addresses(True)))
                    callback(msg)
                time.sleep(0.1)
        def wait_for_network():
            while not self.network.is_connected():
                if callback:
                    msg = "%s \n" % (_("Connecting..."))
                    callback(msg)
                time.sleep(0.1)
        # wait until we are connected, because the user
        # might have selected another server
        if self.network:
            wait_for_network()
            wait_for_wallet()
        else:
            self.synchronize()

    def can_export(self):
        return not self.is_watching_only() and hasattr(self.keystore, 'get_private_key')

    def is_used(self, address):
        return self.get_address_history(address) and not self.is_empty(address)

    def is_empty(self, address):
        assert isinstance(address, Address)
        return any(self.get_addr_balance(address))

    def address_is_old(self, address, age_limit=2):
        age = -1
        local_height = self.get_local_height()
        for tx_hash, tx_height in self.get_address_history(address):
            if tx_height == 0:
                tx_age = 0
            else:
                tx_age = local_height - tx_height + 1
            if tx_age > age:
                age = tx_age
            if age > age_limit:
                break # ok, it's old. not need to keep looping
        return age > age_limit

    def cpfp(self, tx, fee):
        txid = tx.txid()
        for i, o in enumerate(tx.outputs()):
            otype, address, value = o
            if otype == TYPE_ADDRESS and self.is_mine(address):
                break
        else:
            return
        coins = self.get_addr_utxo(address)
        item = coins.get(txid+':%d'%i)
        if not item:
            return
        self.add_input_info(item)
        inputs = [item]
        outputs = [(TYPE_ADDRESS, address, value - fee)]
        locktime = self.get_local_height()
        # note: no need to call tx.BIP_LI01_sort() here - single input/output
        return Transaction.from_io(inputs, outputs, locktime=locktime)

    def add_input_info(self, txin):
        address = txin['address']
        if self.is_mine(address):
            txin['type'] = self.get_txin_type(address)
            # Bitcoin Cash needs value to sign
            received, spent = self.get_addr_io(address)
            item = received.get(txin['prevout_hash']+':%d'%txin['prevout_n'])
            tx_height, value, is_cb = item
            txin['value'] = value
            self.add_input_sig_info(txin, address)

    def can_sign(self, tx):
        if tx.is_complete():
            return False
        for k in self.get_keystores():
            # setup "wallet advice" so Xpub wallets know how to sign 'fd' type tx inputs
            # by giving them the sequence number ahead of time
            if isinstance(k, BIP32_KeyStore):
                for txin in tx.inputs():
                    for x_pubkey in txin['x_pubkeys']:
                        _, addr = xpubkey_to_address(x_pubkey)
                        try:
                            c, index = self.get_address_index(addr)
                        except:
                            continue
                        if index is not None:
                            k.set_wallet_advice(addr, [c,index])
            if k.can_sign(tx):
                return True
        return False

    def get_input_tx(self, tx_hash):
        # First look up an input transaction in the wallet where it
        # will likely be.  If co-signing a transaction it may not have
        # all the input txs, in which case we ask the network.
        tx = self.transactions.get(tx_hash)
        if not tx and self.network:
            request = ('blockchain.transaction.get', [tx_hash])
            tx = Transaction(self.network.synchronous_get(request))
        return tx

    def add_input_values_to_tx(self, tx):
        """ add input values to the tx, for signing"""
        for txin in tx.inputs():
            if 'value' not in txin:
                inputtx = self.get_input_tx(txin['prevout_hash'])
                if inputtx is not None:
                    out_zero, out_addr, out_val = inputtx.outputs()[txin['prevout_n']]
                    txin['value'] = out_val
                    txin['prev_tx'] = inputtx   # may be needed by hardware wallets

    def add_hw_info(self, tx):
        # add previous tx for hw wallets, if needed and not already there
        if any([(isinstance(k, Hardware_KeyStore) and k.can_sign(tx) and k.needs_prevtx()) for k in self.get_keystores()]):
            for txin in tx.inputs():
                if 'prev_tx' not in txin:
                    txin['prev_tx'] = self.get_input_tx(txin['prevout_hash'])
        # add output info for hw wallets
        info = {}
        xpubs = self.get_master_public_keys()
        for txout in tx.outputs():
            _type, addr, amount = txout
            if self.is_change(addr):
                index = self.get_address_index(addr)
                pubkeys = self.get_public_keys(addr)
                # sort xpubs using the order of pubkeys
                sorted_pubkeys, sorted_xpubs = zip(*sorted(zip(pubkeys, xpubs)))
                info[addr] = index, sorted_xpubs, self.m if isinstance(self, Multisig_Wallet) else None
        tx.output_info = info

    def sign_transaction(self, tx, password):
        if self.is_watching_only():
            return
        # add input values for signing
        self.add_input_values_to_tx(tx)
        # hardware wallets require extra info
        if any([(isinstance(k, Hardware_KeyStore) and k.can_sign(tx)) for k in self.get_keystores()]):
            self.add_hw_info(tx)
        # sign
        for k in self.get_keystores():
            try:
                if k.can_sign(tx):
                    k.sign_transaction(tx, password)
            except UserCancelled:
                continue

    def get_unused_addresses(self, *, for_change=False):
        assert type(for_change) is bool
        # fixme: use slots from expired requests
        with self.lock, self.transaction_lock:
            domain = self.get_receiving_addresses() if not for_change else (self.get_change_addresses() or self.get_receiving_addresses())
            return [addr for addr in domain
                    if not self.get_address_history(addr)
                    and addr not in self.receive_requests]

    def get_unused_address(self, *, for_change=False):
        assert type(for_change) is bool
        addrs = self.get_unused_addresses(for_change=for_change)
        if addrs:
            return addrs[0]

    def get_receiving_address(self):
        '''Returns a receiving address or None.'''
        domain = self.get_unused_addresses() or self.get_receiving_addresses()
        if domain:
            return domain[0]

    def get_payment_status(self, address, amount):
        local_height = self.get_local_height()
        received, sent = self.get_addr_io(address)
        l = []
        for txo, x in received.items():
            h, v, is_cb = x
            txid, n = txo.split(':')
            info = self.verified_tx.get(txid)
            if info:
                tx_height, timestamp, pos = info
                conf = local_height - tx_height
            else:
                conf = 0
            l.append((conf, v))
        vsum = 0
        for conf, v in reversed(sorted(l)):
            vsum += v
            if vsum >= amount:
                return True, conf
        return False, None

    def get_payment_request(self, addr, config):
        assert isinstance(addr, Address)
        r = self.receive_requests.get(addr)
        if not r:
            return
        out = copy.copy(r)
        addr_text = addr.to_ui_string()
        amount_text = format_satoshis(r['amount'])
        out['URI'] = '{}:{}?amount={}'.format(networks.net.CASHADDR_PREFIX,
                                              addr_text, amount_text)
        status, conf = self.get_request_status(addr)
        out['status'] = status
        if conf is not None:
            out['confirmations'] = conf
        # check if bip70 file exists
        rdir = config.get('requests_dir')
        if rdir:
            key = out.get('id', addr.to_storage_string())
            path = os.path.join(rdir, 'req', key[0], key[1], key)
            if os.path.exists(path):
                baseurl = 'file://' + rdir
                rewrite = config.get('url_rewrite')
                if rewrite:
                    baseurl = baseurl.replace(*rewrite)
                out['request_url'] = os.path.join(baseurl, 'req', key[0], key[1], key, key)
                out['URI'] += '&r=' + out['request_url']
                out['index_url'] = os.path.join(baseurl, 'index.html') + '?id=' + key
                websocket_server_announce = config.get('websocket_server_announce')
                if websocket_server_announce:
                    out['websocket_server'] = websocket_server_announce
                else:
                    out['websocket_server'] = config.get('websocket_server', 'localhost')
                websocket_port_announce = config.get('websocket_port_announce')
                if websocket_port_announce:
                    out['websocket_port'] = websocket_port_announce
                else:
                    out['websocket_port'] = config.get('websocket_port', 9999)
        return out

    def get_request_status(self, key):
        r = self.receive_requests.get(key)
        if r is None:
            return PR_UNKNOWN
        address = r['address']
        amount = r.get('amount')
        timestamp = r.get('time', 0)
        if timestamp and type(timestamp) != int:
            timestamp = 0
        expiration = r.get('exp')
        if expiration and type(expiration) != int:
            expiration = 0
        conf = None
        if amount:
            if self.up_to_date:
                paid, conf = self.get_payment_status(address, amount)
                status = PR_PAID if paid else PR_UNPAID
                if status == PR_UNPAID and expiration is not None and time.time() > timestamp + expiration:
                    status = PR_EXPIRED
            else:
                status = PR_UNKNOWN
        else:
            status = PR_UNKNOWN
        return status, conf

    def make_payment_request(self, addr, amount, message, expiration=None):
        assert isinstance(addr, Address)
        timestamp = int(time.time())
        _id = bh2u(Hash(addr.to_storage_string() + "%d" % timestamp))[0:10]
        return {
            'time': timestamp,
            'amount': amount,
            'exp': expiration,
            'address': addr,
            'memo': message,
            'id': _id
        }

    def serialize_request(self, r):
        result = r.copy()
        result['address'] = r['address'].to_storage_string()
        return result

    def save_payment_requests(self):
        def delete_address(value):
            del value['address']
            return value

        requests = {addr.to_storage_string() : delete_address(value.copy())
                    for addr, value in self.receive_requests.items()}
        self.storage.put('payment_requests', requests)
        self.storage.write()

    def sign_payment_request(self, key, alias, alias_addr, password):
        req = self.receive_requests.get(key)
        alias_privkey = self.export_private_key(alias_addr, password)
        pr = paymentrequest.make_unsigned_request(req)
        paymentrequest.sign_request_with_alias(pr, alias, alias_privkey)
        req['name'] = pr.pki_data
        req['sig'] = bh2u(pr.signature)
        self.receive_requests[key] = req
        self.save_payment_requests()

    def add_payment_request(self, req, config, set_address_label=True):
        addr = req['address']
        addr_text = addr.to_storage_string()
        amount = req['amount']
        message = req['memo']
        self.receive_requests[addr] = req
        self.save_payment_requests()
        if set_address_label:
            self.set_label(addr_text, message) # should be a default label

        rdir = config.get('requests_dir')
        if rdir and amount is not None:
            key = req.get('id', addr_text)
            pr = paymentrequest.make_request(config, req)
            path = os.path.join(rdir, 'req', key[0], key[1], key)
            if not os.path.exists(path):
                try:
                    os.makedirs(path)
                except OSError as exc:
                    if exc.errno != errno.EEXIST:
                        raise
            with open(os.path.join(path, key), 'wb') as f:
                f.write(pr.SerializeToString())
            # reload
            req = self.get_payment_request(addr, config)
            req['address'] = req['address'].to_ui_string()
            with open(os.path.join(path, key + '.json'), 'w', encoding='utf-8') as f:
                f.write(json.dumps(req))

    def remove_payment_request(self, addr, config, clear_address_label_if_no_tx=True):
        if isinstance(addr, str):
            addr = Address.from_string(addr)
        if addr not in self.receive_requests:
            return False
        r = self.receive_requests.pop(addr)
        if clear_address_label_if_no_tx and not self.get_address_history(addr):
            memo = r.get('memo')
            # clear it only if the user didn't overwrite it with something else
            if memo and memo == self.labels.get(addr.to_storage_string()):
                self.set_label(addr, None)

        rdir = config.get('requests_dir')
        if rdir:
            key = r.get('id', addr.to_storage_string())
            for s in ['.json', '']:
                n = os.path.join(rdir, 'req', key[0], key[1], key, key + s)
                if os.path.exists(n):
                    os.unlink(n)
        self.save_payment_requests()
        return True

    def get_sorted_requests(self, config):
        m = map(lambda x: self.get_payment_request(x, config), self.receive_requests.keys())
        try:
            def f(x):
                try:
                    addr = x['address']
                    return self.get_address_index(addr) or addr
                except:
                    return addr
            return sorted(m, key=f)
        except TypeError:
            # See issue #1231 -- can get inhomogenous results in the above
            # sorting function due to the 'or addr' possible return.
            # This can happen if addresses for some reason drop out of wallet
            # while, say, the history rescan is running and it can't yet find
            # an address index for an address.  In that case we will
            # return an unsorted list to the caller.
            return list(m)

    def get_fingerprint(self):
        raise NotImplementedError()

    def can_import_privkey(self):
        return False

    def can_import_address(self):
        return False

    def can_delete_address(self):
        return False

    def is_multisig(self):
        # Subclass Multisig_Wallet overrides this
        return False

    def add_address(self, address):
        assert isinstance(address, Address)
        self._addr_bal_cache.pop(address, None)  # paranoia, not really necessary -- just want to maintain the invariant that when we modify address history below we invalidate cache.
        if address not in self._history:
            self._history[address] = []
        if self.synchronizer:
            self.synchronizer.add(address)

    def has_password(self):
        return self.storage.get('use_encryption', False)

    def check_password(self, password):
        self.keystore.check_password(password)

    def sign_message(self, address, message, password):
        index = self.get_address_index(address)
        return self.keystore.sign_message(index, message, password)

    def decrypt_message(self, pubkey, message, password):
        addr = self.pubkeys_to_address(pubkey)
        index = self.get_address_index(addr)
        return self.keystore.decrypt_message(index, message, password)

    def rebuild_history(self):
        ''' This is an advanced function for use in the GUI when the user
        wants to resynch the whole wallet from scratch, preserving labels
        and contacts.  Right now this implementation is beta-quality but
        appears to work great for the most part. '''
        if not self.network or not self.network.is_connected():
            raise RuntimeError('Refusing to rebuild wallet without a valid server connection!')
        if not self.synchronizer or not self.verifier:
            raise RuntimeError('Refusing to rebuild a stopped wallet!')
        network = self.network
        self.stop_threads()
        do_addr_save = False
        with self.lock, self.transaction_lock:
            self.transactions.clear(); self.unverified_tx.clear(); self.verified_tx.clear()
            self.clear_history()
            if isinstance(self, Standard_Wallet):
                # reset the address list to default too, just in case. New synchronizer will pick up the addresses again.
                self.receiving_addresses, self.change_addresses = self.receiving_addresses[:self.gap_limit], self.change_addresses[:self.gap_limit_for_change]
                do_addr_save = True
        if do_addr_save:
            self.save_addresses()
        self.save_transactions()
        self.save_verified_tx()
        self.storage.write()
        self.start_threads(network)
        self.network.trigger_callback('wallet_updated', self)


class Simple_Wallet(Abstract_Wallet):
    # wallet with a single keystore

    def get_keystore(self):
        return self.keystore

    def get_keystores(self):
        return [self.keystore]

    def is_watching_only(self):
        return self.keystore.is_watching_only()

    def can_change_password(self):
        return self.keystore.can_change_password()

    def update_password(self, old_pw, new_pw, encrypt=False):
        if old_pw is None and self.has_password():
            raise InvalidPassword()
        if self.keystore is not None:
            self.keystore.update_password(old_pw, new_pw)
            self.save_keystore()
        self.storage.set_password(new_pw, encrypt)
        self.storage.write()

    def save_keystore(self):
        self.storage.put('keystore', self.keystore.dump())


class ImportedWalletBase(Simple_Wallet):

    txin_type = 'p2pkh'

    def get_txin_type(self, address):
        return self.txin_type

    def can_delete_address(self):
        return True

    def has_seed(self):
        return False

    def is_deterministic(self):
        return False

    def is_change(self, address):
        return False

    def get_master_public_keys(self):
        return []

    def is_beyond_limit(self, address, is_change):
        return False

    def get_fingerprint(self):
        return ''

    def get_receiving_addresses(self):
        return self.get_addresses()

    def delete_address(self, address):
        assert isinstance(address, Address)
        if address not in self.get_addresses():
            return

        transactions_to_remove = set()  # only referred to by this address
        transactions_new = set()  # txs that are not only referred to by address
        with self.lock:
            for addr, details in self._history.items():
                if addr == address:
                    for tx_hash, height in details:
                        transactions_to_remove.add(tx_hash)
                        self.tx_addr_hist[tx_hash].discard(address)
                        if not self.tx_addr_hist.get(tx_hash):
                            self.tx_addr_hist.pop(tx_hash, None)
                else:
                    for tx_hash, height in details:
                        transactions_new.add(tx_hash)
            transactions_to_remove -= transactions_new
            self._history.pop(address, None)

            for tx_hash in transactions_to_remove:
                self.remove_transaction(tx_hash)
                self.tx_fees.pop(tx_hash, None)
                self.verified_tx.pop(tx_hash, None)
                self.unverified_tx.pop(tx_hash, None)
                self.transactions.pop(tx_hash, None)
                self._addr_bal_cache.pop(address, None)  # not strictly necessary, above calls also have this side-effect. but here to be safe. :)
                if self.verifier:
                    # TX is now gone. Toss its SPV proof in case we have it
                    # in memory. This allows user to re-add PK again and it
                    # will avoid the situation where the UI says "not verified"
                    # erroneously!
                    self.verifier.remove_spv_proof_for_tx(tx_hash)
                # FIXME: what about pruned_txo?

            self.storage.put('verified_tx3', self.verified_tx)

        self.save_transactions()

        self.set_label(address, None)
        self.remove_payment_request(address, {})
        self.set_frozen_state([address], False)

        self.delete_address_derived(address)
        self.save_addresses()


class ImportedAddressWallet(ImportedWalletBase):
    # Watch-only wallet of imported addresses

    wallet_type = 'imported_addr'

    def __init__(self, storage):
        self._sorted = None
        super().__init__(storage)

    @classmethod
    def from_text(cls, storage, text):
        wallet = cls(storage)
        for address in text.split():
            wallet.import_address(Address.from_string(address))
        return wallet

    def is_watching_only(self):
        return True

    def get_keystores(self):
        return []

    def can_import_privkey(self):
        return False

    def load_keystore(self):
        self.keystore = None

    def save_keystore(self):
        pass

    def load_addresses(self):
        addresses = self.storage.get('addresses', [])
        self.addresses = [Address.from_string(addr) for addr in addresses]

    def save_addresses(self):
        self.storage.put('addresses', [addr.to_storage_string()
                                       for addr in self.addresses])
        self.storage.write()

    def can_change_password(self):
        return False

    def can_import_address(self):
        return True

    def get_addresses(self, include_change=False):
        if not self._sorted:
            self._sorted = sorted(self.addresses,
                                  key=lambda addr: addr.to_ui_string())
        return self._sorted

    def import_address(self, address):
        assert isinstance(address, Address)
        if address in self.addresses:
            return False
        self.addresses.append(address)
        self.save_addresses()
        self.storage.write()
        self.add_address(address)
        self._sorted = None
        return True

    def delete_address_derived(self, address):
        self.addresses.remove(address)
        self._sorted.remove(address)

    def add_input_sig_info(self, txin, address):
        x_pubkey = 'fd' + address.to_script_hex()
        txin['x_pubkeys'] = [x_pubkey]
        txin['signatures'] = [None]


class ImportedPrivkeyWallet(ImportedWalletBase):
    # wallet made of imported private keys

    wallet_type = 'imported_privkey'

    def __init__(self, storage):
        Abstract_Wallet.__init__(self, storage)

    @classmethod
    def from_text(cls, storage, text, password=None):
        wallet = cls(storage)
        storage.put('use_encryption', bool(password))
        for privkey in text.split():
            wallet.import_private_key(privkey, password)
        return wallet

    def is_watching_only(self):
        return False

    def get_keystores(self):
        return [self.keystore]

    def can_import_privkey(self):
        return True

    def load_keystore(self):
        if self.storage.get('keystore'):
            self.keystore = load_keystore(self.storage, 'keystore')
        else:
            self.keystore = Imported_KeyStore({})

    def save_keystore(self):
        self.storage.put('keystore', self.keystore.dump())

    def load_addresses(self):
        pass

    def save_addresses(self):
        pass

    def can_change_password(self):
        return True

    def can_import_address(self):
        return False

    def get_addresses(self, include_change=False):
        return self.keystore.get_addresses()

    def delete_address_derived(self, address):
        self.keystore.remove_address(address)
        self.save_keystore()

    def get_address_index(self, address):
        return self.get_public_key(address)

    def get_public_key(self, address):
        return self.keystore.address_to_pubkey(address)

    def import_private_key(self, sec, pw):
        pubkey = self.keystore.import_privkey(sec, pw)
        self.save_keystore()
        self.storage.write()
        self.add_address(pubkey.address)
        return pubkey.address.to_ui_string()

    def export_private_key(self, address, password):
        '''Returned in WIF format.'''
        pubkey = self.keystore.address_to_pubkey(address)
        return self.keystore.export_private_key(pubkey, password)

    def add_input_sig_info(self, txin, address):
        assert txin['type'] == 'p2pkh'
        pubkey = self.keystore.address_to_pubkey(address)
        txin['num_sig'] = 1
        txin['x_pubkeys'] = [pubkey.to_ui_string()]
        txin['signatures'] = [None]

    def pubkeys_to_address(self, pubkey):
        pubkey = PublicKey.from_string(pubkey)
        if pubkey in self.keystore.keypairs:
            return pubkey.address


class Deterministic_Wallet(Abstract_Wallet):

    def __init__(self, storage):
        Abstract_Wallet.__init__(self, storage)
        self.gap_limit = storage.get('gap_limit', 20)

    def has_seed(self):
        return self.keystore.has_seed()

    def get_receiving_addresses(self):
        return self.receiving_addresses

    def get_change_addresses(self):
        return self.change_addresses

    def get_seed(self, password):
        return self.keystore.get_seed(password)

    def add_seed(self, seed, pw):
        self.keystore.add_seed(seed, pw)

    def change_gap_limit(self, value):
        '''This method is not called in the code, it is kept for console use'''
        if value >= self.gap_limit:
            self.gap_limit = value
            self.storage.put('gap_limit', self.gap_limit)
            return True
        elif value >= self.min_acceptable_gap():
            addresses = self.get_receiving_addresses()
            k = self.num_unused_trailing_addresses(addresses)
            n = len(addresses) - k + value
            self.receiving_addresses = self.receiving_addresses[0:n]
            self.gap_limit = value
            self.storage.put('gap_limit', self.gap_limit)
            self.save_addresses()
            return True
        else:
            return False

    def num_unused_trailing_addresses(self, addresses):
        k = 0
        for addr in reversed(addresses):
            if addr in self._history:
                break
            k = k + 1
        return k

    def min_acceptable_gap(self):
        # fixme: this assumes wallet is synchronized
        n = 0
        nmax = 0
        addresses = self.get_receiving_addresses()
        k = self.num_unused_trailing_addresses(addresses)
        for a in addresses[0:-k]:
            if a in self._history:
                n = 0
            else:
                n += 1
                if n > nmax: nmax = n
        return nmax + 1

    def create_new_address(self, for_change=False):
        assert type(for_change) is bool
        with self.lock:
            addr_list = self.change_addresses if for_change else self.receiving_addresses
            n = len(addr_list)
            x = self.derive_pubkeys(for_change, n)
            address = self.pubkeys_to_address(x)
            addr_list.append(address)
            self.save_addresses()
            self.add_address(address)
            return address

    def synchronize_sequence(self, for_change):
        limit = self.gap_limit_for_change if for_change else self.gap_limit
        while True:
            addresses = self.get_change_addresses() if for_change else self.get_receiving_addresses()
            if len(addresses) < limit:
                self.create_new_address(for_change)
                continue
            if all(map(lambda a: not self.address_is_old(a), addresses[-limit:] )):
                break
            else:
                self.create_new_address(for_change)

    def synchronize(self):
        with self.lock:
            self.synchronize_sequence(False)
            self.synchronize_sequence(True)

    def is_beyond_limit(self, address, is_change):
        if is_change:
            addr_list = self.get_change_addresses()
            limit = self.gap_limit_for_change
        else:
            addr_list = self.get_receiving_addresses()
            limit = self.gap_limit
        idx = addr_list.index(address)
        if idx < limit:
            return False
        for addr in addr_list[-limit:]:
            if addr in self._history:
                return False
        return True

    def get_master_public_keys(self):
        return [self.get_master_public_key()]

    def get_fingerprint(self):
        return self.get_master_public_key()

    def get_txin_type(self, address):
        return self.txin_type


class Simple_Deterministic_Wallet(Simple_Wallet, Deterministic_Wallet):

    """ Deterministic Wallet with a single pubkey per address """

    def __init__(self, storage):
        Deterministic_Wallet.__init__(self, storage)

    def get_public_key(self, address):
        sequence = self.get_address_index(address)
        pubkey = self.get_pubkey(*sequence)
        return pubkey

    def load_keystore(self):
        self.keystore = load_keystore(self.storage, 'keystore')
        try:
            xtype = bitcoin.xpub_type(self.keystore.xpub)
        except:
            xtype = 'standard'
        self.txin_type = 'p2pkh' if xtype == 'standard' else xtype

    def get_pubkey(self, c, i):
        return self.derive_pubkeys(c, i)

    def get_public_keys(self, address):
        return [self.get_public_key(address)]

    def add_input_sig_info(self, txin, address):
        derivation = self.get_address_index(address)
        x_pubkey = self.keystore.get_xpubkey(*derivation)
        txin['x_pubkeys'] = [x_pubkey]
        txin['signatures'] = [None]
        txin['num_sig'] = 1

    def get_master_public_key(self):
        return self.keystore.get_master_public_key()

    def derive_pubkeys(self, c, i):
        return self.keystore.derive_pubkey(c, i)






class Standard_Wallet(Simple_Deterministic_Wallet):
    wallet_type = 'standard'

    def pubkeys_to_address(self, pubkey):
        return Address.from_pubkey(pubkey)


class Multisig_Wallet(Deterministic_Wallet):
    # generic m of n
    gap_limit = 20

    def __init__(self, storage):
        self.wallet_type = storage.get('wallet_type')
        self.m, self.n = multisig_type(self.wallet_type)
        Deterministic_Wallet.__init__(self, storage)

    def get_pubkeys(self, c, i):
        return self.derive_pubkeys(c, i)

    def pubkeys_to_address(self, pubkeys):
        pubkeys = [bytes.fromhex(pubkey) for pubkey in pubkeys]
        redeem_script = self.pubkeys_to_redeem_script(pubkeys)
        return Address.from_multisig_script(redeem_script)

    def pubkeys_to_redeem_script(self, pubkeys):
        return Script.multisig_script(self.m, sorted(pubkeys))

    def derive_pubkeys(self, c, i):
        return [k.derive_pubkey(c, i) for k in self.get_keystores()]

    def load_keystore(self):
        self.keystores = {}
        for i in range(self.n):
            name = 'x%d/'%(i+1)
            self.keystores[name] = load_keystore(self.storage, name)
        self.keystore = self.keystores['x1/']
        xtype = bitcoin.xpub_type(self.keystore.xpub)
        self.txin_type = 'p2sh' if xtype == 'standard' else xtype

    def save_keystore(self):
        for name, k in self.keystores.items():
            self.storage.put(name, k.dump())

    def get_keystore(self):
        return self.keystores.get('x1/')

    def get_keystores(self):
        return [self.keystores[i] for i in sorted(self.keystores.keys())]

    def update_password(self, old_pw, new_pw, encrypt=False):
        if old_pw is None and self.has_password():
            raise InvalidPassword()
        for name, keystore in self.keystores.items():
            if keystore.can_change_password():
                keystore.update_password(old_pw, new_pw)
                self.storage.put(name, keystore.dump())
        self.storage.set_password(new_pw, encrypt)
        self.storage.write()

    def has_seed(self):
        return self.keystore.has_seed()

    def can_change_password(self):
        return self.keystore.can_change_password()

    def is_watching_only(self):
        return not any([not k.is_watching_only() for k in self.get_keystores()])

    def get_master_public_key(self):
        return self.keystore.get_master_public_key()

    def get_master_public_keys(self):
        return [k.get_master_public_key() for k in self.get_keystores()]

    def get_fingerprint(self):
        return ''.join(sorted(self.get_master_public_keys()))

    def add_input_sig_info(self, txin, address):
        # x_pubkeys are not sorted here because it would be too slow
        # they are sorted in transaction.get_sorted_pubkeys
        derivation = self.get_address_index(address)
        txin['x_pubkeys'] = [k.get_xpubkey(*derivation) for k in self.get_keystores()]
        txin['pubkeys'] = None
        # we need n place holders
        txin['signatures'] = [None] * self.n
        txin['num_sig'] = self.m

    def is_multisig(self):
        return True


wallet_types = ['standard', 'multisig', 'imported']

def register_wallet_type(category):
    wallet_types.append(category)

wallet_constructors = {
    'standard': Standard_Wallet,
    'old': Standard_Wallet,
    'xpub': Standard_Wallet,
    'imported_privkey': ImportedPrivkeyWallet,
    'imported_addr': ImportedAddressWallet,
}

def register_constructor(wallet_type, constructor):
    wallet_constructors[wallet_type] = constructor

class UnknownWalletType(RuntimeError):
    ''' Raised if encountering an unknown wallet type '''
    pass

# former WalletFactory
class Wallet(object):
    """The main wallet "entry point".
    This class is actually a factory that will return a wallet of the correct
    type when passed a WalletStorage instance."""

    def __new__(self, storage):
        wallet_type = storage.get('wallet_type')
        WalletClass = Wallet.wallet_class(wallet_type)
        wallet = WalletClass(storage)
        # Convert hardware wallets restored with older versions of
        # Electrum to BIP44 wallets.  A hardware wallet does not have
        # a seed and plugins do not need to handle having one.
        rwc = getattr(wallet, 'restore_wallet_class', None)
        if rwc and storage.get('seed', ''):
            storage.print_error("converting wallet type to " + rwc.wallet_type)
            storage.put('wallet_type', rwc.wallet_type)
            wallet = rwc(storage)
        return wallet

    @staticmethod
    def wallet_class(wallet_type):
        if multisig_type(wallet_type):
            return Multisig_Wallet
        if wallet_type in wallet_constructors:
            return wallet_constructors[wallet_type]
        raise UnknownWalletType("Unknown wallet type: " + str(wallet_type))
