text: import time
  from struct import pack
  
  from electrum_ltc.i18n import _
  from electrum_ltc.util import PrintError, UserCancelled
  from electrum_ltc.keystore import bip39_normalize_passphrase
  from electrum_ltc.bitcoin import serialize_xpub
  
  
  class GuiMixin(object):
      # Requires: self.proto, self.device
  
      messages = {
          3: _("Confirm the transaction output on your %s device"),
          4: _("Confirm internal entropy on your %s device to begin"),
          5: _("Write down the seed word shown on your %s"),
          6: _("Confirm on your %s that you want to wipe it clean"),
          7: _("Confirm on your %s device the message to sign"),
          8: _("Confirm the total amount spent and the transaction fee on your "
               "%s device"),
          10: _("Confirm wallet address on your %s device"),
          'default': _("Check your %s device to continue"),
      }
  
      def callback_Failure(self, msg):
          # BaseClient's unfortunate call() implementation forces us to
          # raise exceptions on failure in order to unwind the stack.
          # However, making the user acknowledge they cancelled
          # gets old very quickly, so we suppress those.  The NotInitialized
          # one is misnamed and indicates a passphrase request was cancelled.
          if msg.code in (self.types.Failure_PinCancelled,
                          self.types.Failure_ActionCancelled,
                          self.types.Failure_NotInitialized):
              raise UserCancelled()
          raise RuntimeError(msg.message)
  
      def callback_ButtonRequest(self, msg):
          message = self.msg
          if not message:
              message = self.messages.get(msg.code, self.messages['default'])
          self.handler.show_message(message % self.device, self.cancel)
          return self.proto.ButtonAck()
  
      def callback_PinMatrixRequest(self, msg):
          if msg.type == 2:
              msg = _("Enter a new PIN for your %s:")
          elif msg.type == 3:
              msg = (_("Re-enter the new PIN for your %s.\n\n"
                       "NOTE: the positions of the numbers have changed!"))
          else:
              msg = _("Enter your current %s PIN:")
          pin = self.handler.get_pin(msg % self.device)
          if not pin:
              return self.proto.Cancel()
          return self.proto.PinMatrixAck(pin=pin)
  
      def callback_PassphraseRequest(self, req):
          if self.creating_wallet:
              msg = _("Enter a passphrase to generate this wallet.  Each time "
                      "you use this wallet your %s will prompt you for the "
                      "passphrase.  If you forget the passphrase you cannot "
                      "access the litecoins in the wallet.") % self.device
          else:
              msg = _("Enter the passphrase to unlock this wallet:")
          passphrase = self.handler.get_passphrase(msg, self.creating_wallet)
          if passphrase is None:
              return self.proto.Cancel()
          passphrase = bip39_normalize_passphrase(passphrase)
          return self.proto.PassphraseAck(passphrase=passphrase)
  
      def callback_WordRequest(self, msg):
          self.step += 1
          msg = _("Step %d/24.  Enter seed word as explained on "
                  "your %s:") % (self.step, self.device)
          word = self.handler.get_word(msg)
          # Unfortunately the device can't handle self.proto.Cancel()
          return self.proto.WordAck(word=word)
  
      def callback_CharacterRequest(self, msg):
          char_info = self.handler.get_char(msg)
          if not char_info:
              return self.proto.Cancel()
          return self.proto.CharacterAck(**char_info)
  
  
  class TrezorClientBase(GuiMixin, PrintError):
  
      def __init__(self, handler, plugin, proto):
          assert hasattr(self, 'tx_api')  # ProtocolMixin already constructed?
          self.proto = proto
          self.device = plugin.device
          self.handler = handler
          self.tx_api = plugin
          self.types = plugin.types
          self.msg = None
          self.creating_wallet = False
          self.used()
  
      def __str__(self):
          return "%s/%s" % (self.label(), self.features.device_id)
  
      def label(self):
          '''The name given by the user to the device.'''
          return self.features.label
  
      def is_initialized(self):
          '''True if initialized, False if wiped.'''
          return self.features.initialized
  
      def is_pairable(self):
          return not self.features.bootloader_mode
  
      def used(self):
          self.last_operation = time.time()
  
      def prevent_timeouts(self):
          self.last_operation = float('inf')
  
      def timeout(self, cutoff):
          '''Time out the client if the last operation was before cutoff.'''
          if self.last_operation < cutoff:
              self.print_error("timed out")
              self.clear_session()
  
      @staticmethod
      def expand_path(n):
          '''Convert bip32 path to list of uint32 integers with prime flags
          0/-1/1' -> [0, 0x80000001, 0x80000001]'''
          # This code is similar to code in trezorlib where it unforunately
          # is not declared as a staticmethod.  Our n has an extra element.
          PRIME_DERIVATION_FLAG = 0x80000000
          path = []
          for x in n.split('/')[1:]:
              prime = 0
              if x.endswith("'"):
                  x = x.replace('\'', '')
                  prime = PRIME_DERIVATION_FLAG
              if x.startswith('-'):
                  prime = PRIME_DERIVATION_FLAG
              path.append(abs(int(x)) | prime)
          return path
  
      def cancel(self):
          '''Provided here as in keepkeylib but not trezorlib.'''
          self.transport.write(self.proto.Cancel())
  
      def i4b(self, x):
          return pack('>I', x)
  
      def get_xpub(self, bip32_path):
          address_n = self.expand_path(bip32_path)
          creating = False #self.next_account_number() == 0
          node = self.get_public_node(address_n, creating).node
          return serialize_xpub(0, node.chain_code, node.public_key, node.depth, self.i4b(node.fingerprint), self.i4b(node.child_num))
  
      #def address_from_derivation(self, derivation):
      #    return self.get_address('Litecoin', self.expand_path(derivation))
  
      def toggle_passphrase(self):
          if self.features.passphrase_protection:
              self.msg = _("Confirm on your %s device to disable passphrases")
          else:
              self.msg = _("Confirm on your %s device to enable passphrases")
          enabled = not self.features.passphrase_protection
          self.apply_settings(use_passphrase=enabled)
  
      def change_label(self, label):
          self.msg = _("Confirm the new label on your %s device")
          self.apply_settings(label=label)
  
      def change_homescreen(self, homescreen):
          self.msg = _("Confirm on your %s device to change your home screen")
          self.apply_settings(homescreen=homescreen)
  
      def set_pin(self, remove):
          if remove:
              self.msg = _("Confirm on your %s device to disable PIN protection")
          elif self.features.pin_protection:
              self.msg = _("Confirm on your %s device to change your PIN")
          else:
              self.msg = _("Confirm on your %s device to set a PIN")
          self.change_pin(remove)
  
      def clear_session(self):
          '''Clear the session to force pin (and passphrase if enabled)
          re-entry.  Does not leak exceptions.'''
          self.print_error("clear session:", self)
          self.prevent_timeouts()
          try:
              super(TrezorClientBase, self).clear_session()
          except BaseException as e:
              # If the device was removed it has the same effect...
              self.print_error("clear_session: ignoring error", str(e))
              pass
  
      def get_public_node(self, address_n, creating):
          self.creating_wallet = creating
          return super(TrezorClientBase, self).get_public_node(address_n)
  
      def close(self):
          '''Called when Our wallet was closed or the device removed.'''
          self.print_error("closing client")
          self.clear_session()
          # Release the device
          self.transport.close()
  
      def firmware_version(self):
          f = self.features
          return (f.major_version, f.minor_version, f.patch_version)
  
      def atleast_version(self, major, minor=0, patch=0):
          return cmp(self.firmware_version(), (major, minor, patch)) >= 0
  
      @staticmethod
      def wrapper(func):
          '''Wrap methods to clear any message box they opened.'''
  
          def wrapped(self, *args, **kwargs):
              try:
                  self.prevent_timeouts()
                  return func(self, *args, **kwargs)
              finally:
                  self.used()
                  self.handler.finished()
                  self.creating_wallet = False
                  self.msg = None
  
          return wrapped
  
      @staticmethod
      def wrap_methods(cls):
          for method in ['apply_settings', 'change_pin', 'decrypt_message',
                         'get_address', 'get_public_node',
                         'load_device_by_mnemonic', 'load_device_by_xprv',
                         'recovery_device', 'reset_device', 'sign_message',
                         'sign_tx', 'wipe_device']:
              setattr(cls, method, cls.wrapper(getattr(cls, method)))
  