text: #!/usr/bin/env python2
  # -*- mode: python -*-
  #
  # Electrum - lightweight Fujicoin client
  # Copyright (C) 2016  The Electrum developers
  #
  # 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.
  
  from electrum.plugin import BasePlugin, hook
  from electrum.i18n import _
  from electrum.bitcoin import is_address, TYPE_SCRIPT
  from electrum.util import bfh, versiontuple, UserFacingException
  from electrum.transaction import opcodes, TxOutput, Transaction
  
  
  class HW_PluginBase(BasePlugin):
      # Derived classes provide:
      #
      #  class-static variables: client_class, firmware_URL, handler_class,
      #     libraries_available, libraries_URL, minimum_firmware,
      #     wallet_class, ckd_public, types, HidTransport
  
      minimum_library = (0, )
  
      def __init__(self, parent, config, name):
          BasePlugin.__init__(self, parent, config, name)
          self.device = self.keystore_class.device
          self.keystore_class.plugin = self
  
      def is_enabled(self):
          return True
  
      def device_manager(self):
          return self.parent.device_manager
  
      @hook
      def close_wallet(self, wallet):
          for keystore in wallet.get_keystores():
              if isinstance(keystore, self.keystore_class):
                  self.device_manager().unpair_xpub(keystore.xpub)
  
      def setup_device(self, device_info, wizard, purpose):
          """Called when creating a new wallet or when using the device to decrypt
          an existing wallet. Select the device to use.  If the device is
          uninitialized, go through the initialization process.
          """
          raise NotImplementedError()
  
      def show_address(self, wallet, address, keystore=None):
          pass  # implemented in child classes
  
      def show_address_helper(self, wallet, address, keystore=None):
          if keystore is None:
              keystore = wallet.get_keystore()
          if not is_address(address):
              keystore.handler.show_error(_('Invalid Fujicoin Address'))
              return False
          if not wallet.is_mine(address):
              keystore.handler.show_error(_('Address not in wallet.'))
              return False
          if type(keystore) != self.keystore_class:
              return False
          return True
  
      def get_library_version(self) -> str:
          """Returns the version of the 3rd party python library
          for the hw wallet. For example '0.9.0'
  
          Returns 'unknown' if library is found but cannot determine version.
          Raises 'ImportError' if library is not found.
          Raises 'LibraryFoundButUnusable' if found but there was some problem (includes version num).
          """
          raise NotImplementedError()
  
      def check_libraries_available(self) -> bool:
          def version_str(t):
              return ".".join(str(i) for i in t)
  
          try:
              # this might raise ImportError or LibraryFoundButUnusable
              library_version = self.get_library_version()
              # if no exception so far, we might still raise LibraryFoundButUnusable
              if (library_version == 'unknown'
                      or versiontuple(library_version) < self.minimum_library
                      or hasattr(self, "maximum_library") and versiontuple(library_version) >= self.maximum_library):
                  raise LibraryFoundButUnusable(library_version=library_version)
          except ImportError:
              return False
          except LibraryFoundButUnusable as e:
              library_version = e.library_version
              max_version_str = version_str(self.maximum_library) if hasattr(self, "maximum_library") else "inf"
              self.libraries_available_message = (
                      _("Library version for '{}' is incompatible.").format(self.name)
                      + '\nInstalled: {}, Needed: {} <= x < {}'
                      .format(library_version, version_str(self.minimum_library), max_version_str))
              self.print_stderr(self.libraries_available_message)
              return False
  
          return True
  
      def get_library_not_available_message(self) -> str:
          if hasattr(self, 'libraries_available_message'):
              message = self.libraries_available_message
          else:
              message = _("Missing libraries for {}.").format(self.name)
          message += '\n' + _("Make sure you install it with python3")
          return message
  
  
  def is_any_tx_output_on_change_branch(tx: Transaction):
      if not tx.output_info:
          return False
      for o in tx.outputs():
          info = tx.output_info.get(o.address)
          if info is not None:
              if info.address_index[0] == 1:
                  return True
      return False
  
  
  def trezor_validate_op_return_output_and_get_data(output: TxOutput) -> bytes:
      if output.type != TYPE_SCRIPT:
          raise Exception("Unexpected output type: {}".format(output.type))
      script = bfh(output.address)
      if not (script[0] == opcodes.OP_RETURN and
              script[1] == len(script) - 2 and script[1] <= 75):
          raise UserFacingException(_("Only OP_RETURN scripts, with one constant push, are supported."))
      if output.value != 0:
          raise UserFacingException(_("Amount for OP_RETURN output must be zero."))
      return script[2:]
  
  
  def only_hook_if_libraries_available(func):
      # note: this decorator must wrap @hook, not the other way around,
      # as 'hook' uses the name of the function it wraps
      def wrapper(self, *args, **kwargs):
          if not self.libraries_available: return None
          return func(self, *args, **kwargs)
      return wrapper
  
  
  class LibraryFoundButUnusable(Exception):
      def __init__(self, library_version='unknown'):
          self.library_version = library_version
  