#!/usr/bin/env python
#
# 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.

import socket
import os
import requests
import json
from urllib.parse import urljoin
from urllib.parse import quote

import electrum
from electrum import bitcoin
from electrum import keystore
from electrum.bitcoin import *
from electrum.mnemonic import Mnemonic
from electrum import version
from electrum.wallet import Multisig_Wallet, Deterministic_Wallet
from electrum.i18n import _
from electrum.plugins import BasePlugin, hook
from electrum.util import NotEnoughFunds

# signing_xpub is hardcoded so that the wallet can be restored from seed, without TrustedCoin's server
signing_xpub = "xpub661MyMwAqRbcGnMkaTx2594P9EDuiEqMq25PM2aeG6UmwzaohgA6uDmNsvSUV8ubqwA3Wpste1hg69XHgjUuCD5HLcEp2QPzyV1HMrPppsL"
billing_xpub = "xpub6DTBdtBB8qUmH5c77v8qVGVoYk7WjJNpGvutqjLasNG1mbux6KsojaLrYf2sRhXAVU4NaFuHhbD9SvVPRt1MB1MaMooRuhHcAZH1yhQ1qDU"

SEED_PREFIX = version.SEED_PREFIX_2FA

DISCLAIMER = [
    _("Two-factor authentication is a service provided by TrustedCoin.  "
      "It uses a multi-signature wallet, where you own 2 of 3 keys.  "
      "The third key is stored on a remote server that signs transactions on "
      "your behalf.  To use this service, you will need a smartphone with "
      "Google Authenticator installed."),
    _("A small fee will be charged on each transaction that uses the "
      "remote server.  You may check and modify your billing preferences "
      "once the installation is complete."),
    _("Note that your coins are not locked in this service.  You may withdraw "
      "your funds at any time and at no cost, without the remote server, by "
      "using the 'restore wallet' option with your wallet seed."),
    _("The next step will generate the seed of your wallet.  This seed will "
      "NOT be saved in your computer, and it must be stored on paper.  "
      "To be safe from malware, you may want to do this on an offline "
      "computer, and move your wallet later to an online computer."),
]
RESTORE_MSG = _("Enter the seed for your 2-factor wallet:")

class TrustedCoinException(Exception):
    def __init__(self, message, status_code=0):
        Exception.__init__(self, message)
        self.status_code = status_code

class TrustedCoinCosignerClient(object):
    def __init__(self, user_agent=None, base_url='https://api.trustedcoin.com/2/'):
        self.base_url = base_url
        self.debug = False
        self.user_agent = user_agent

    def send_request(self, method, relative_url, data=None):
        kwargs = {'headers': {}}
        if self.user_agent:
            kwargs['headers']['user-agent'] = self.user_agent
        if method == 'get' and data:
            kwargs['params'] = data
        elif method == 'post' and data:
            kwargs['data'] = json.dumps(data)
            kwargs['headers']['content-type'] = 'application/json'
        url = urljoin(self.base_url, relative_url)
        if self.debug:
            print('%s %s %s' % (method, url, data))
        response = requests.request(method, url, **kwargs)
        if self.debug:
            print(response.text)
        if response.status_code != 200:
            message = str(response.text)
            if response.headers.get('content-type') == 'application/json':
                r = response.json()
                if 'message' in r:
                    message = r['message']
            raise TrustedCoinException(message, response.status_code)
        if response.headers.get('content-type') == 'application/json':
            return response.json()
        else:
            return response.text

    def get_terms_of_service(self, billing_plan='electrum-per-tx-otp'):
        """
        Returns the TOS for the given billing plan as a plain/text unicode string.
        :param billing_plan: the plan to return the terms for
        """
        payload = {'billing_plan': billing_plan}
        return self.send_request('get', 'tos', payload)

    def create(self, xpubkey1, xpubkey2, email, billing_plan='electrum-per-tx-otp'):
        """
        Creates a new cosigner resource.
        :param xpubkey1: a bip32 extended public key (customarily the hot key)
        :param xpubkey2: a bip32 extended public key (customarily the cold key)
        :param email: a contact email
        :param billing_plan: the billing plan for the cosigner
        """
        payload = {
            'email': email,
            'xpubkey1': xpubkey1,
            'xpubkey2': xpubkey2,
            'billing_plan': billing_plan,
        }
        return self.send_request('post', 'cosigner', payload)

    def auth(self, id, otp):
        """
        Attempt to authenticate for a particular cosigner.
        :param id: the id of the cosigner
        :param otp: the one time password
        """
        payload = {'otp': otp}
        return self.send_request('post', 'cosigner/%s/auth' % quote(id), payload)

    def get(self, id):
        """ Get billing info """
        return self.send_request('get', 'cosigner/%s' % quote(id))

    def get_challenge(self, id):
        """ Get challenge to reset Google Auth secret """
        return self.send_request('get', 'cosigner/%s/otp_secret' % quote(id))

    def reset_auth(self, id, challenge, signatures):
        """ Reset Google Auth secret """
        payload = {'challenge':challenge, 'signatures':signatures}
        return self.send_request('post', 'cosigner/%s/otp_secret' % quote(id), payload)

    def sign(self, id, transaction, otp):
        """
        Attempt to authenticate for a particular cosigner.
        :param id: the id of the cosigner
        :param transaction: the hex encoded [partially signed] compact transaction to sign
        :param otp: the one time password
        """
        payload = {
            'otp': otp,
            'transaction': transaction
        }
        return self.send_request('post', 'cosigner/%s/sign' % quote(id), payload)

    def transfer_credit(self, id, recipient, otp, signature_callback):
        """
        Tranfer a cosigner's credits to another cosigner.
        :param id: the id of the sending cosigner
        :param recipient: the id of the recipient cosigner
        :param otp: the one time password (of the sender)
        :param signature_callback: a callback that signs a text message using xpubkey1/0/0 returning a compact sig
        """
        payload = {
            'otp': otp,
            'recipient': recipient,
            'timestamp': int(time.time()),

        }
        relative_url = 'cosigner/%s/transfer' % quote(id)
        full_url = urljoin(self.base_url, relative_url)
        headers = {
            'x-signature': signature_callback(full_url + '\n' + json.dumps(payload))
        }
        return self.send_request('post', relative_url, payload, headers)


server = TrustedCoinCosignerClient(user_agent="Electrum/" + version.ELECTRUM_VERSION)

class Wallet_2fa(Multisig_Wallet):

    wallet_type = '2fa'

    def __init__(self, storage):
        self.m, self.n = 2, 3
        Deterministic_Wallet.__init__(self, storage)
        self.is_billing = False
        self.billing_info = None

    def can_sign_without_server(self):
        return not self.keystores['x2/'].is_watching_only()

    def get_user_id(self):
        return get_user_id(self.storage)

    def get_max_amount(self, config, inputs, recipient, fee):
        from electrum.transaction import Transaction
        sendable = sum(map(lambda x:x['value'], inputs))
        for i in inputs:
            self.add_input_info(i)
        xf = self.extra_fee(config)
        _type, addr = recipient
        if xf and sendable >= xf:
            billing_address = self.billing_info['billing_address']
            sendable -= xf
            outputs = [(_type, addr, sendable),
                       (TYPE_ADDRESS, billing_address, xf)]
        else:
            outputs = [(_type, addr, sendable)]
        dummy_tx = Transaction.from_io(inputs, outputs)
        if fee is None:
            fee = self.estimate_fee(config, dummy_tx.estimated_size())
        amount = max(0, sendable - fee)
        return amount, fee

    def min_prepay(self):
        return min(self.price_per_tx.keys())

    def num_prepay(self, config):
        default = self.min_prepay()
        n = config.get('trustedcoin_prepay', default)
        if n not in self.price_per_tx:
            n = default
        return n

    def extra_fee(self, config):
        if self.can_sign_without_server():
            return 0
        if self.billing_info is None:
            self.plugin.start_request_thread(self)
            return 0
        if self.billing_info.get('tx_remaining'):
            return 0
        if self.is_billing:
            return 0
        n = self.num_prepay(config)
        price = int(self.price_per_tx[n])
        assert price <= 100000 * n
        return price

    def make_unsigned_transaction(self, coins, outputs, config,
                                  fixed_fee=None, change_addr=None):
        mk_tx = lambda o: Multisig_Wallet.make_unsigned_transaction(
            self, coins, o, config, fixed_fee, change_addr)
        fee = self.extra_fee(config)
        if fee:
            address = self.billing_info['billing_address']
            fee_output = (TYPE_ADDRESS, address, fee)
            try:
                tx = mk_tx(outputs + [fee_output])
            except NotEnoughFunds:
                # trustedcoin won't charge if the total inputs is
                # lower than their fee
                tx = mk_tx(outputs)
                if tx.input_value() >= fee:
                    raise
                self.print_error("not charging for this tx")
        else:
            tx = mk_tx(outputs)
        return tx

    def sign_transaction(self, tx, password):
        Multisig_Wallet.sign_transaction(self, tx, password)
        if tx.is_complete():
            return
        if not self.auth_code:
            self.print_error("sign_transaction: no auth code")
            return
        long_user_id, short_id = self.get_user_id()
        tx_dict = tx.as_dict()
        raw_tx = tx_dict["hex"]
        r = server.sign(short_id, raw_tx, self.auth_code)
        if r:
            raw_tx = r.get('transaction')
            tx.update(raw_tx)
        self.print_error("twofactor: is complete", tx.is_complete())
        # reset billing_info
        self.billing_info = None


# Utility functions

def get_user_id(storage):
    def make_long_id(xpub_hot, xpub_cold):
        return bitcoin.sha256(''.join(sorted([xpub_hot, xpub_cold])))
    xpub1 = storage.get('x1/')['xpub']
    xpub2 = storage.get('x2/')['xpub']
    long_id = make_long_id(xpub1, xpub2)
    short_id = hashlib.sha256(long_id).hexdigest()
    return long_id, short_id

def make_xpub(xpub, s):
    version, _, _, _, c, cK = deserialize_xpub(xpub)
    cK2, c2 = bitcoin._CKD_pub(cK, c, s)
    return bitcoin.serialize_xpub(version, c2, cK2)

def make_billing_address(wallet, num):
    long_id, short_id = wallet.get_user_id()
    xpub = make_xpub(billing_xpub, long_id)
    version, _, _, _, c, cK = deserialize_xpub(xpub)
    cK, c = bitcoin.CKD_pub(cK, c, num)
    return bitcoin.public_key_to_p2pkh(cK)


class TrustedCoinPlugin(BasePlugin):
    wallet_class = Wallet_2fa

    def __init__(self, parent, config, name):
        BasePlugin.__init__(self, parent, config, name)
        self.wallet_class.plugin = self
        self.requesting = False

    @staticmethod
    def is_valid_seed(seed):
        return bitcoin.is_new_seed(seed, SEED_PREFIX)

    def is_available(self):
        return True

    def is_enabled(self):
        return True

    def can_user_disable(self):
        return False

    @hook
    def get_tx_extra_fee(self, wallet, tx):
        if type(wallet) != Wallet_2fa:
            return
        address = wallet.billing_info['billing_address']
        for _type, addr, amount in tx.outputs():
            if _type == TYPE_ADDRESS and addr == address:
                return address, amount

    def request_billing_info(self, wallet):
        self.print_error("request billing info")
        billing_info = server.get(wallet.get_user_id()[1])
        billing_address = make_billing_address(wallet, billing_info['billing_index'])
        assert billing_address == billing_info['billing_address']
        wallet.billing_info = billing_info
        wallet.price_per_tx = dict(billing_info['price_per_tx'])
        wallet.price_per_tx.pop(1)
        self.requesting = False
        return True

    def start_request_thread(self, wallet):
        from threading import Thread
        if self.requesting is False:
            self.requesting = True
            t = Thread(target=self.request_billing_info, args=(wallet,))
            t.setDaemon(True)
            t.start()
            return t

    def make_seed(self):
        return Mnemonic('english').make_seed(seed_type='2fa', num_bits=128)

    @hook
    def do_clear(self, window):
        window.wallet.is_billing = False

    def show_disclaimer(self, wizard):
        wizard.set_icon(':icons/trustedcoin-wizard.png')
        wizard.stack = []
        wizard.confirm_dialog(title='Disclaimer', message='\n\n'.join(DISCLAIMER), run_next = lambda x: wizard.run('choose_seed'))

    def choose_seed(self, wizard):
        title = _('Create or restore')
        message = _('Do you want to create a new seed, or to restore a wallet using an existing seed?')
        choices = [
            ('create_seed', _('Create a new seed')),
            ('restore_wallet', _('I already have a seed')),
        ]
        wizard.choice_dialog(title=title, message=message, choices=choices, run_next=wizard.run)

    def create_seed(self, wizard):
        seed = self.make_seed()
        f = lambda x: wizard.request_passphrase(seed, x)
        wizard.show_seed_dialog(run_next=f, seed_text=seed)

    def get_xkeys(self, seed, passphrase, derivation):
        from electrum.mnemonic import Mnemonic
        from electrum.keystore import bip32_root, bip32_private_derivation
        bip32_seed = Mnemonic.mnemonic_to_seed(seed, passphrase)
        xprv, xpub = bip32_root(bip32_seed, 'standard')
        xprv, xpub = bip32_private_derivation(xprv, "m/", derivation)
        return xprv, xpub

    def xkeys_from_seed(self, seed, passphrase):
        words = seed.split()
        n = len(words)
        # old version use long seed phrases
        if n >= 24:
            assert passphrase == ''
            xprv1, xpub1 = self.get_xkeys(' '.join(words[0:12]), '', "m/")
            xprv2, xpub2 = self.get_xkeys(' '.join(words[12:]), '', "m/")
        elif n==12:
            xprv1, xpub1 = self.get_xkeys(seed, passphrase, "m/0'/")
            xprv2, xpub2 = self.get_xkeys(seed, passphrase, "m/1'/")
        else:
            raise BaseException('unrecognized seed length')
        return xprv1, xpub1, xprv2, xpub2

    def create_keystore(self, wizard, seed, passphrase):
        # this overloads the wizard's method
        xprv1, xpub1, xprv2, xpub2 = self.xkeys_from_seed(seed, passphrase)
        k1 = keystore.from_xprv(xprv1)
        k2 = keystore.from_xpub(xpub2)
        wizard.request_password(run_next=lambda pw, encrypt: self.on_password(wizard, pw, encrypt, k1, k2))

    def on_password(self, wizard, password, encrypt, k1, k2):
        k1.update_password(None, password)
        wizard.storage.set_password(password, encrypt)
        wizard.storage.put('x1/', k1.dump())
        wizard.storage.put('x2/', k2.dump())
        wizard.storage.write()
        msg = [
            _("Your wallet file is: %s.")%os.path.abspath(wizard.storage.path),
            _("You need to be online in order to complete the creation of "
              "your wallet.  If you generated your seed on an offline "
              'computer, click on "%s" to close this window, move your '
              "wallet file to an online computer, and reopen it with "
              "Electrum.") % _('Cancel'),
            _('If you are online, click on "%s" to continue.') % _('Next')
        ]
        msg = '\n\n'.join(msg)
        wizard.stack = []
        wizard.confirm_dialog(title='', message=msg, run_next = lambda x: wizard.run('create_remote_key'))

    def restore_wallet(self, wizard):
        wizard.opt_bip39 = False
        wizard.opt_ext = True
        title = _("Restore two-factor Wallet")
        f = lambda seed, is_bip39, is_ext: wizard.run('on_restore_seed', seed, is_ext)
        wizard.restore_seed_dialog(run_next=f, test=self.is_valid_seed)

    def on_restore_seed(self, wizard, seed, is_ext):
        f = lambda x: self.restore_choice(wizard, seed, x)
        wizard.passphrase_dialog(run_next=f) if is_ext else f('')

    def restore_choice(self, wizard, seed, passphrase):
        wizard.set_icon(':icons/trustedcoin-wizard.png')
        wizard.stack = []
        title = _('Restore 2FA wallet')
        msg = ' '.join([
            'You are going to restore a wallet protected with two-factor authentication.',
            'Do you want to keep using two-factor authentication with this wallet,',
            'or do you want to disable it, and have two master private keys in your wallet?'
        ])
        choices = [('keep', 'Keep'), ('disable', 'Disable')]
        f = lambda x: self.on_choice(wizard, seed, passphrase, x)
        wizard.choice_dialog(choices=choices, message=msg, title=title, run_next=f)

    def on_choice(self, wizard, seed, passphrase, x):
        if x == 'disable':
            f = lambda pw, encrypt: wizard.run('on_restore_pw', seed, passphrase, pw, encrypt)
            wizard.request_password(run_next=f)
        else:
            self.create_keystore(wizard, seed, passphrase)

    def on_restore_pw(self, wizard, seed, passphrase, password, encrypt):
        storage = wizard.storage
        xprv1, xpub1, xprv2, xpub2 = self.xkeys_from_seed(seed, passphrase)
        k1 = keystore.from_xprv(xprv1)
        k2 = keystore.from_xprv(xprv2)
        k1.add_seed(seed)
        k1.update_password(None, password)
        k2.update_password(None, password)
        storage.put('x1/', k1.dump())
        storage.put('x2/', k2.dump())
        long_user_id, short_id = get_user_id(storage)
        xpub3 = make_xpub(signing_xpub, long_user_id)
        k3 = keystore.from_xpub(xpub3)
        storage.put('x3/', k3.dump())
        storage.set_password(password, encrypt)
        wizard.wallet = Wallet_2fa(storage)
        wizard.create_addresses()

    def create_remote_key(self, wizard):
        email = self.accept_terms_of_use(wizard)
        xpub1 = wizard.storage.get('x1/')['xpub']
        xpub2 = wizard.storage.get('x2/')['xpub']
        # Generate third key deterministically.
        long_user_id, short_id = get_user_id(wizard.storage)
        xpub3 = make_xpub(signing_xpub, long_user_id)
        # secret must be sent by the server
        try:
            r = server.create(xpub1, xpub2, email)
        except socket.error:
            wizard.show_message('Server not reachable, aborting')
            return
        except TrustedCoinException as e:
            if e.status_code == 409:
                r = None
            else:
                wizard.show_message(str(e))
                return
        if r is None:
            otp_secret = None
        else:
            otp_secret = r.get('otp_secret')
            if not otp_secret:
                wizard.show_message(_('Error'))
                return
            _xpub3 = r['xpubkey_cosigner']
            _id = r['id']
            try:
                assert _id == short_id, ("user id error", _id, short_id)
                assert xpub3 == _xpub3, ("xpub3 error", xpub3, _xpub3)
            except Exception as e:
                wizard.show_message(str(e))
                return
        self.check_otp(wizard, short_id, otp_secret, xpub3)

    def check_otp(self, wizard, short_id, otp_secret, xpub3):
        otp, reset = self.request_otp_dialog(wizard, short_id, otp_secret)
        if otp:
            self.do_auth(wizard, short_id, otp, xpub3)
        elif reset:
            wizard.opt_bip39 = False
            wizard.opt_ext = True
            f = lambda seed, is_bip39, is_ext: wizard.run('on_reset_seed', short_id, seed, is_ext, xpub3)
            wizard.restore_seed_dialog(run_next=f, test=self.is_valid_seed)

    def on_reset_seed(self, wizard, short_id, seed, is_ext, xpub3):
        f = lambda passphrase: wizard.run('on_reset_auth', short_id, seed, passphrase, xpub3)
        wizard.passphrase_dialog(run_next=f) if is_ext else f('')

    def do_auth(self, wizard, short_id, otp, xpub3):
        try:
            server.auth(short_id, otp)
        except:
            wizard.show_message(_('Incorrect password'))
            return
        k3 = keystore.from_xpub(xpub3)
        wizard.storage.put('x3/', k3.dump())
        wizard.storage.put('use_trustedcoin', True)
        wizard.storage.write()
        wizard.wallet = Wallet_2fa(wizard.storage)
        wizard.run('create_addresses')

    def on_reset_auth(self, wizard, short_id, seed, passphrase, xpub3):
        xprv1, xpub1, xprv2, xpub2 = self.xkeys_from_seed(seed, passphrase)
        try:
            assert xpub1 == wizard.storage.get('x1/')['xpub']
            assert xpub2 == wizard.storage.get('x2/')['xpub']
        except:
            wizard.show_message(_('Incorrect seed'))
            return
        r = server.get_challenge(short_id)
        challenge = r.get('challenge')
        message = 'TRUSTEDCOIN CHALLENGE: ' + challenge
        def f(xprv):
            _, _, _, _, c, k = deserialize_xprv(xprv)
            pk = bip32_private_key([0, 0], k, c)
            key = regenerate_key(pk)
            sig = key.sign_message(message, True)
            return base64.b64encode(sig).decode()

        signatures = [f(x) for x in [xprv1, xprv2]]
        r = server.reset_auth(short_id, challenge, signatures)
        new_secret = r.get('otp_secret')
        if not new_secret:
            wizard.show_message(_('Request rejected by server'))
            return
        self.check_otp(wizard, short_id, new_secret, xpub3)

    @hook
    def get_action(self, storage):
        if storage.get('wallet_type') != '2fa':
            return
        if not storage.get('x1/'):
            return self, 'show_disclaimer'
        if not storage.get('x2/'):
            return self, 'show_disclaimer'
        if not storage.get('x3/'):
            return self, 'create_remote_key'