#    Copyright 2013 IBM Corp.
#
#    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.
#
# Copyright (c) 2018 Wind River Systems, Inc.
#
# SPDX-License-Identifier: Apache-2.0
#

from oslo_versionedobjects import base as object_base
from oslo_versionedobjects import fields as object_fields


class FmObject(object_base.VersionedObject):
    """Base class and object factory.

    This forms the base of all objects that can be remoted or instantiated
    via RPC. Simply defining a class that inherits from this base class
    will make it remotely instantiatable. Objects should implement the
    necessary "get" classmethod routines as well as "save" object methods
    as appropriate.
    """

    OBJ_SERIAL_NAMESPACE = 'fm_object'
    OBJ_PROJECT_NAMESPACE = 'fm'

    fields = {
        'created_at': object_fields.DateTimeField(nullable=True),
        'updated_at': object_fields.DateTimeField(nullable=True),
    }

    def __getitem__(self, name):
        return getattr(self, name)

    def __setitem__(self, name, value):
        setattr(self, name, value)

    def as_dict(self):
        return dict((k, getattr(self, k))
                    for k in self.fields
                    if hasattr(self, k))

    def obj_refresh(self, loaded_object):
        """Applies updates for objects that inherit from base.FmObject.

        Checks for updated attributes in an object. Updates are applied from
        the loaded object column by column in comparison with the current
        object.
        """
        for field in self.fields:
            if (self.obj_attr_is_set(field) and
                    self[field] != loaded_object[field]):
                self[field] = loaded_object[field]

    @staticmethod
    def _from_db_object(obj, db_object):
        """Converts a database entity to a formal object.

        :param obj: An object of the class.
        :param db_object: A DB model of the object
        :return: The object of the class with the database entity added
        """

        for field in obj.fields:
            obj[field] = db_object[field]

        obj.obj_reset_changes()
        return obj

    @classmethod
    def from_db_object(cls, db_obj):
        return cls._from_db_object(cls(), db_obj)


class FmObjectSerializer(object_base.VersionedObjectSerializer):
    # Base class to use for object hydration
    OBJ_BASE_CLASS = FmObject