# Protocol Buffers - Google's data interchange format
# Copyright 2008 Google Inc.  All rights reserved.
# https://developers.google.com/protocol-buffers/
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"""Contains _ExtensionDict class to represent extensions.
"""

from lark_oapi.ws.pb.google.protobuf.internal import type_checkers
from lark_oapi.ws.pb.google.protobuf.descriptor import FieldDescriptor


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))


# TODO(robinson): Unify error handling of "unknown extension" crap.
# TODO(robinson): Support iteritems()-style iteration over all
# extensions with the "has" bits turned on?
class _ExtensionDict(object):
    """Dict-like container for Extension fields on proto instances.

    Note that in all cases we expect extension handles to be
    FieldDescriptors.
    """

    def __init__(self, extended_message):
        """
        Args:
          extended_message: Message instance for which we are the Extensions dict.
        """
        self._extended_message = extended_message

    def __getitem__(self, extension_handle):
        """Returns the current value of the given extension handle."""

        _VerifyExtensionHandle(self._extended_message, extension_handle)

        result = self._extended_message._fields.get(extension_handle)
        if result is not None:
            return result

        if extension_handle.label == FieldDescriptor.LABEL_REPEATED:
            result = extension_handle._default_constructor(self._extended_message)
        elif extension_handle.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE:
            message_type = extension_handle.message_type
            if not hasattr(message_type, '_concrete_class'):
                # pylint: disable=protected-access
                self._extended_message._FACTORY.GetPrototype(message_type)
            assert getattr(extension_handle.message_type, '_concrete_class', None), (
                    'Uninitialized concrete class found for field %r (message type %r)'
                    % (extension_handle.full_name,
                       extension_handle.message_type.full_name))
            result = extension_handle.message_type._concrete_class()
            try:
                result._SetListener(self._extended_message._listener_for_children)
            except ReferenceError:
                pass
        else:
            # Singular scalar -- just return the default without inserting into the
            # dict.
            return extension_handle.default_value

        # Atomically check if another thread has preempted us and, if not, swap
        # in the new object we just created.  If someone has preempted us, we
        # take that object and discard ours.
        # WARNING:  We are relying on setdefault() being atomic.  This is true
        #   in CPython but we haven't investigated others.  This warning appears
        #   in several other locations in this file.
        result = self._extended_message._fields.setdefault(
            extension_handle, result)

        return result

    def __eq__(self, other):
        if not isinstance(other, self.__class__):
            return False

        my_fields = self._extended_message.ListFields()
        other_fields = other._extended_message.ListFields()

        # Get rid of non-extension fields.
        my_fields = [field for field in my_fields if field.is_extension]
        other_fields = [field for field in other_fields if field.is_extension]

        return my_fields == other_fields

    def __ne__(self, other):
        return not self == other

    def __len__(self):
        fields = self._extended_message.ListFields()
        # Get rid of non-extension fields.
        extension_fields = [field for field in fields if field[0].is_extension]
        return len(extension_fields)

    def __hash__(self):
        raise TypeError('unhashable object')

    # Note that this is only meaningful for non-repeated, scalar extension
    # fields.  Note also that we may have to call _Modified() when we do
    # successfully set a field this way, to set any necessary "has" bits in the
    # ancestors of the extended message.
    def __setitem__(self, extension_handle, value):
        """If extension_handle specifies a non-repeated, scalar extension
        field, sets the value of that field.
        """

        _VerifyExtensionHandle(self._extended_message, extension_handle)

        if (extension_handle.label == FieldDescriptor.LABEL_REPEATED or
                extension_handle.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE):
            raise TypeError(
                'Cannot assign to extension "%s" because it is a repeated or '
                'composite type.' % extension_handle.full_name)

        # It's slightly wasteful to lookup the type checker each time,
        # but we expect this to be a vanishingly uncommon case anyway.
        type_checker = type_checkers.GetTypeChecker(extension_handle)
        # pylint: disable=protected-access
        self._extended_message._fields[extension_handle] = (
            type_checker.CheckValue(value))
        self._extended_message._Modified()

    def __delitem__(self, extension_handle):
        self._extended_message.ClearExtension(extension_handle)

    def _FindExtensionByName(self, name):
        """Tries to find a known extension with the specified name.

        Args:
          name: Extension full name.

        Returns:
          Extension field descriptor.
        """
        return self._extended_message._extensions_by_name.get(name, None)

    def _FindExtensionByNumber(self, number):
        """Tries to find a known extension with the field number.

        Args:
          number: Extension field number.

        Returns:
          Extension field descriptor.
        """
        return self._extended_message._extensions_by_number.get(number, None)

    def __iter__(self):
        # Return a generator over the populated extension fields
        return (f[0] for f in self._extended_message.ListFields()
                if f[0].is_extension)

    def __contains__(self, extension_handle):
        _VerifyExtensionHandle(self._extended_message, extension_handle)

        if extension_handle not in self._extended_message._fields:
            return False

        if extension_handle.label == FieldDescriptor.LABEL_REPEATED:
            return bool(self._extended_message._fields.get(extension_handle))

        if extension_handle.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE:
            value = self._extended_message._fields.get(extension_handle)
            # pylint: disable=protected-access
            return value is not None and value._is_present_in_parent

        return True