# Copyright 2017 MDSLAB - University of Messina
# All Rights Reserved.
#
#    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 iotronic.common import exception
from iotronic.db import api as dbapi
from iotronic.objects import base
from iotronic.objects import utils as obj_utils
from oslo_utils import strutils
from oslo_utils import uuidutils


class SessionWP(base.IotronicObject):
    VERSION = '1.0'

    dbapi = dbapi.get_instance()

    fields = {
        'id': int,
        'board_uuid': obj_utils.str_or_none,
        'session_id': obj_utils.str_or_none,
        'board_id': obj_utils.int_or_none,
        'valid': bool,
    }

    @staticmethod
    def _from_db_object(session, db_session):
        """Converts a database entity to a formal object."""
        for field in session.fields:
            session[field] = db_session[field]

        session.obj_reset_changes()
        return session

    @base.remotable_classmethod
    def get(cls, context, session_or_board_uuid):
        """Find a session based on its id or uuid and return a SessionWP object.

        :param session_id: the id *or* uuid of a session.
        :returns: a :class:`SessionWP` object.
        """
        if strutils.is_int_like(session_or_board_uuid):
            return cls.get_by_id(context, session_or_board_uuid)
        elif uuidutils.is_uuid_like(session_or_board_uuid):
            return cls.get_by_uuid(context, session_or_board_uuid)
        else:
            raise exception.InvalidIdentity(identity=session_or_board_uuid)

    @base.remotable_classmethod
    def get_by_id(cls, context, ses_id):
        """Find a session based on its integer id and return a SessionWP object.

        :param ses_id: the id of a session.
        :returns: a :class:`SessionWP` object.
        """
        db_session = cls.dbapi.get_session_by_id(ses_id)
        session = SessionWP._from_db_object(cls(context), db_session)
        return session

    @base.remotable_classmethod
    def get_session_by_board_uuid(cls, context, board_uuid, valid=True):
        """Find a session based on uuid and return a :class:`SessionWP` object.

        :param board_uuid: the uuid of a board.
        :param context: Security context
        :returns: a :class:`SessionWP` object.
        """

        db_session = cls.dbapi.get_session_by_board_uuid(board_uuid, valid)
        session = SessionWP._from_db_object(cls(context), db_session)
        return session

    @base.remotable_classmethod
    def valid_list(cls, context):
        """Return a list of SessionWP objects.

        :returns: a list of valid session_id

        """

        db_list = cls.dbapi.get_valid_wpsessions_list()
        return [SessionWP._from_db_object(cls(context), x) for x in db_list]

    @base.remotable
    def create(self, context=None):
        """Create a SessionWP record in the DB.

        :param context: Security context. NOTE: This should only
                        be used internally by the indirection_api.
                        Unfortunately, RPC requires context as the first
                        argument, even though we don't use it.
                        A context should be set when instantiating the
                        object, e.g.: SessionWP(context)

        """
        values = self.obj_get_changes()
        db_session = self.dbapi.create_session(values)
        self._from_db_object(self, db_session)

    @base.remotable
    def destroy(self, context=None):
        """Delete the SessionWP from the DB.

        :param context: Security context. NOTE: This should only
                        be used internally by the indirection_api.
                        Unfortunately, RPC requires context as the first
                        argument, even though we don't use it.
                        A context should be set when instantiating the
                        object, e.g.: SessionWP(context)
        """
        self.dbapi.destroy_session(self.uuid)
        self.obj_reset_changes()

    @base.remotable
    def save(self, context=None):
        """Save updates to this SessionWP.

        Updates will be made column by column based on the result
        of self.what_changed().

        :param context: Security context. NOTE: This should only
                        be used internally by the indirection_api.
                        Unfortunately, RPC requires context as the first
                        argument, even though we don't use it.
                        A context should be set when instantiating the
                        object, e.g.: SessionWP(context)
        """
        updates = self.obj_get_changes()
        self.dbapi.update_session(self.id, updates)

        self.obj_reset_changes()

    @base.remotable
    def refresh(self, context=None):
        """Loads updates for this SessionWP.

        Loads a session with the same uuid from the database and
        checks for updated attributes. Updates are applied from
        the loaded session column by column, if there are any updates.

        :param context: Security context. NOTE: This should only
                        be used internally by the indirection_api.
                        Unfortunately, RPC requires context as the first
                        argument, even though we don't use it.
                        A context should be set when instantiating the
                        object, e.g.: SessionWP(context)
        """
        current = self.__class__.get_by_uuid(self._context, uuid=self.uuid)
        for field in self.fields:
            if (hasattr(
                    self, base.get_attrname(field))
                    and self[field] != current[field]):
                        self[field] = current[field]