# Copyright 2010-present Basho Technologies, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from riak.datatypes.datatype import Datatype
from riak.datatypes import TYPES


class Flag(Datatype):
    """
    A convergent datatype that represents a boolean value that can be
    enabled or disabled, and may only be embedded in :class:`Map`
    instances.
    """

    type_name = 'flag'
    _type_error_msg = "Flags can only be booleans"

    def _post_init(self):
        self._op = None

    def _default_value(self):
        return False

    @Datatype.modified.getter
    def modified(self):
        """
        Whether this flag has staged toggles.
        """
        return self._op is not None

    def enable(self):
        """
        Turns the flag on, effectively setting its value to ``True``.
        """
        self._op = 'enable'

    def disable(self):
        """
        Turns the flag off, effectively setting its value to ``False``.
        """
        self._require_context()
        self._op = 'disable'

    def to_op(self):
        """
        Extracts the mutation operation from the flag.

        :rtype: bool, None
        """
        return self._op

    def _check_type(self, new_value):
        return isinstance(new_value, bool)


TYPES['flag'] = Flag
