# Protocol Buffers - Google's data interchange format
# Copyright 2008 Google Inc.  All rights reserved.
# http://code.google.com/p/protobuf/
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
#     * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
#     * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# Keep it Python2.5 compatible for GAE.
#
# Copyright 2007 Google Inc. All Rights Reserved.
#
# This code is meant to work on Python 2.4 and above only.
#
# TODO(robinson): Helpers for verbose, common checks like seeing if a
# descriptor's cpp_type is CPPTYPE_MESSAGE.

"""Contains a metaclass and helper functions used to create
protocol message classes from Descriptor objects at runtime.

Recall that a metaclass is the "type" of a class.
(A class is to a metaclass what an instance is to a class.)

In this case, we use the GeneratedProtocolMessageType metaclass
to inject all the useful functionality into the classes
output by the protocol compiler at compile-time.

The upshot of all this is that the real implementation
details for ALL pure-Python protocol buffers are *here in
this file*.
"""

__author__ = 'robinson@google.com (Will Robinson)'

import sys
if sys.version_info[0] < 3:
  try:
    from io import StringIO as BytesIO
  except ImportError:
    from io import StringIO as BytesIO
  import copyreg as copyreg
else:
  from io import BytesIO
  import copyreg
import struct
import weakref

# We use "as" to avoid name collisions with variables.
from google.protobuf.internal import containers
from google.protobuf.internal import decoder
from google.protobuf.internal import encoder
from google.protobuf.internal import enum_type_wrapper
from google.protobuf.internal import message_listener as message_listener_mod
from google.protobuf.internal import type_checkers
from google.protobuf.internal import wire_format
from google.protobuf import descriptor as descriptor_mod
from google.protobuf import message as message_mod
from google.protobuf import text_format

_FieldDescriptor = descriptor_mod.FieldDescriptor


def NewMessage(bases, descriptor, dictionary):
  _AddClassAttributesForNestedExtensions(descriptor, dictionary)
  _AddSlots(descriptor, dictionary)
  return bases


def InitMessage(descriptor, cls):
  cls._decoders_by_tag = {}
  cls._extensions_by_name = {}
  cls._extensions_by_number = {}
  if (descriptor.has_options and
      descriptor.GetOptions().message_set_wire_format):
    cls._decoders_by_tag[decoder.MESSAGE_SET_ITEM_TAG] = (
        decoder.MessageSetItemDecoder(cls._extensions_by_number))

  # Attach stuff to each FieldDescriptor for quick lookup later on.
  for field in descriptor.fields:
    _AttachFieldHelpers(cls, field)

  _AddEnumValues(descriptor, cls)
  _AddInitMethod(descriptor, cls)
  _AddPropertiesForFields(descriptor, cls)
  _AddPropertiesForExtensions(descriptor, cls)
  _AddStaticMethods(cls)
  _AddMessageMethods(descriptor, cls)
  _AddPrivateHelperMethods(descriptor, cls)
  copyreg.pickle(cls, lambda obj: (cls, (), obj.__getstate__()))


# Stateless helpers for GeneratedProtocolMessageType below.
# Outside clients should not access these directly.
#
# I opted not to make any of these methods on the metaclass, to make it more
# clear that I'm not really using any state there and to keep clients from
# thinking that they have direct access to these construction helpers.


def _PropertyName(proto_field_name):
  """Returns the name of the public property attribute which
  clients can use to get and (in some cases) set the value
  of a protocol message field.

  Args:
    proto_field_name: The protocol message field name, exactly
      as it appears (or would appear) in a .proto file.
  """
  # TODO(robinson): Escape Python keywords (e.g., yield), and test this support.
  # nnorwitz makes my day by writing:
  # """
  # FYI.  See the keyword module in the stdlib. This could be as simple as:
  #
  # if keyword.iskeyword(proto_field_name):
  #   return proto_field_name + "_"
  # return proto_field_name
  # """
  # Kenton says:  The above is a BAD IDEA.  People rely on being able to use
  #   getattr() and setattr() to reflectively manipulate field values.  If we
  #   rename the properties, then every such user has to also make sure to apply
  #   the same transformation.  Note that currently if you name a field "yield",
  #   you can still access it just fine using getattr/setattr -- it's not even
  #   that cumbersome to do so.
  # TODO(kenton):  Remove this method entirely if/when everyone agrees with my
  #   position.
  return proto_field_name


def _VerifyExtensionHandle(message, extension_handle):
  """Verify that the given extension handle is valid."""

  if not isinstance(extension_handle, _FieldDescriptor):
    raise KeyError('HasExtension() expects an extension handle, got: %s' %
                   extension_handle)

  if not extension_handle.is_extension:
    raise KeyError('"%s" is not an extension.' % extension_handle.full_name)

  if not extension_handle.containing_type:
    raise KeyError('"%s" is missing a containing_type.'
                   % extension_handle.full_name)

  if extension_handle.containing_type is not message.DESCRIPTOR:
    raise KeyError('Extension "%s" extends message type "%s", but this '
                   'message is of type "%s".' %
                   (extension_handle.full_name,
                    extension_handle.containing_type.full_name,
                    message.DESCRIPTOR.full_name))


def _AddSlots(message_descriptor, dictionary):
  """Adds a __slots__ entry to dictionary, containing the names of all valid
  attributes for this message type.

  Args:
    message_descriptor: A Descriptor instance describing this message type.
    dictionary: Class dictionary to which we'll add a '__slots__' entry.
  """
  dictionary['__slots__'] = ['_cached_byte_size',
                             '_cached_byte_size_dirty',
                             '_fields',
                             '_unknown_fields',
                             '_is_present_in_parent',
                             '_listener',
                             '_listener_for_children',
                             '__weakref__',
                             '_oneofs']


def _IsMessageSetExtension(field):
  return (field.is_extension and
          field.containing_type.has_options and
          field.containing_type.GetOptions().message_set_wire_format and
          field.type == _FieldDescriptor.TYPE_MESSAGE and
          field.message_type == field.extension_scope and
          field.label == _FieldDescriptor.LABEL_OPTIONAL)


def _AttachFieldHelpers(cls, field_descriptor):
  is_repeated = (field_descriptor.label == _FieldDescriptor.LABEL_REPEATED)
  is_packed = (field_descriptor.has_options and
               field_descriptor.GetOptions().packed)

  if _IsMessageSetExtension(field_descriptor):
    field_encoder = encoder.MessageSetItemEncoder(field_descriptor.number)
    sizer = encoder.MessageSetItemSizer(field_descriptor.number)
  else:
    field_encoder = type_checkers.TYPE_TO_ENCODER[field_descriptor.type](
        field_descriptor.number, is_repeated, is_packed)
    sizer = type_checkers.TYPE_TO_SIZER[field_descriptor.type](
        field_descriptor.number, is_repeated, is_packed)

  field_descriptor._encoder = field_encoder
  field_descriptor._sizer = sizer
  field_descriptor._default_constructor = _DefaultValueConstructorForField(
      field_descriptor)

  def AddDecoder(wiretype, is_packed):
    tag_bytes = encoder.TagBytes(field_descriptor.number, wiretype)
    cls._decoders_by_tag[tag_bytes] = (
        type_checkers.TYPE_TO_DECODER[field_descriptor.type](
            field_descriptor.number, is_repeated, is_packed,
            field_descriptor, field_descriptor._default_constructor))

  AddDecoder(type_checkers.FIELD_TYPE_TO_WIRE_TYPE[field_descriptor.type],
             False)

  if is_repeated and wire_format.IsTypePackable(field_descriptor.type):
    # To support wire compatibility of adding packed = true, add a decoder for
    # packed values regardless of the field's options.
    AddDecoder(wire_format.WIRETYPE_LENGTH_DELIMITED, True)


def _AddClassAttributesForNestedExtensions(descriptor, dictionary):
  extension_dict = descriptor.extensions_by_name
  for extension_name, extension_field in list(extension_dict.items()):
    assert extension_name not in dictionary
    dictionary[extension_name] = extension_field


def _AddEnumValues(descriptor, cls):
  """Sets class-level attributes for all enum fields defined in this message.

  Also exporting a class-level object that can name enum values.

  Args:
    descriptor: Descriptor object for this message type.
    cls: Class we're constructing for this message type.
  """
  for enum_type in descriptor.enum_types:
    setattr(cls, enum_type.name, enum_type_wrapper.EnumTypeWrapper(enum_type))
    for enum_value in enum_type.values:
      setattr(cls, enum_value.name, enum_value.number)


def _DefaultValueConstructorForField(field):
  """Returns a function which returns a default value for a field.

  Args:
    field: FieldDescriptor object for this field.

  The returned function has one argument:
    message: Message instance containing this field, or a weakref proxy
      of same.

  That function in turn returns a default value for this field.  The default
    value may refer back to |message| via a weak reference.
  """

  if field.label == _FieldDescriptor.LABEL_REPEATED:
    if field.has_default_value and field.default_value != []:
      raise ValueError('Repeated field default value not empty list: %s' % (
          field.default_value))
    if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
      # We can't look at _concrete_class yet since it might not have
      # been set.  (Depends on order in which we initialize the classes).
      message_type = field.message_type
      def MakeRepeatedMessageDefault(message):
        return containers.RepeatedCompositeFieldContainer(
            message._listener_for_children, field.message_type)
      return MakeRepeatedMessageDefault
    else:
      type_checker = type_checkers.GetTypeChecker(field)
      def MakeRepeatedScalarDefault(message):
        return containers.RepeatedScalarFieldContainer(
            message._listener_for_children, type_checker)
      return MakeRepeatedScalarDefault

  if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
    # _concrete_class may not yet be initialized.
    message_type = field.message_type
    def MakeSubMessageDefault(message):
      result = message_type._concrete_class()
      result._SetListener(message._listener_for_children)
      return result
    return MakeSubMessageDefault

  def MakeScalarDefault(message):
    # TODO(protobuf-team): This may be broken since there may not be
    # default_value.  Combine with has_default_value somehow.
    return field.default_value
  return MakeScalarDefault


def _AddInitMethod(message_descriptor, cls):
  """Adds an __init__ method to cls."""
  fields = message_descriptor.fields
  def init(self, **kwargs):
    self._cached_byte_size = 0
    self._cached_byte_size_dirty = len(kwargs) > 0
    self._fields = {}
    # Contains a mapping from oneof field descriptors to the descriptor
    # of the currently set field in that oneof field.
    self._oneofs = {}

    # _unknown_fields is () when empty for efficiency, and will be turned into
    # a list if fields are added.
    self._unknown_fields = ()
    self._is_present_in_parent = False
    self._listener = message_listener_mod.NullMessageListener()
    self._listener_for_children = _Listener(self)
    for field_name, field_value in list(kwargs.items()):
      field = _GetFieldByName(message_descriptor, field_name)
      if field is None:
        raise TypeError("%s() got an unexpected keyword argument '%s'" %
                        (message_descriptor.name, field_name))
      if field.label == _FieldDescriptor.LABEL_REPEATED:
        copy = field._default_constructor(self)
        if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:  # Composite
          for val in field_value:
            copy.add().MergeFrom(val)
        else:  # Scalar
          copy.extend(field_value)
        self._fields[field] = copy
      elif field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
        copy = field._default_constructor(self)
        copy.MergeFrom(field_value)
        self._fields[field] = copy
      else:
        setattr(self, field_name, field_value)

  init.__module__ = None
  init.__doc__ = None
  cls.__init__ = init


def _GetFieldByName(message_descriptor, field_name):
  """Returns a field descriptor by field name.

  Args:
    message_descriptor: A Descriptor describing all fields in message.
    field_name: The name of the field to retrieve.
  Returns:
    The field descriptor associated with the field name.