# Copyright 2018 TrilioData Inc.
# All Rights Reserved.

from sqlalchemy.orm import joinedload

from dmapi.db.sqlalchemy import api as db_api
from dmapi.db.sqlalchemy import api_models
from dmapi import exception
from dmapi import objects
from dmapi.objects import base
from dmapi.objects import cell_mapping
from dmapi.objects import fields


@base.ContegoObjectRegistry.register
class InstanceMapping(base.ContegoObject):

    fields = {
        'id': fields.IntegerField(read_only=True),
        'instance_uuid': fields.UUIDField(),
        'cell_mapping': fields.ObjectField('CellMapping', nullable=True),
        'project_id': fields.StringField(),
        }

    @staticmethod
    def _from_db_object(context, instance_mapping, db_instance_mapping):
        for key in instance_mapping.fields:
            db_value = db_instance_mapping.get(key)
            if key == 'cell_mapping':
                # cell_mapping can be None indicating that the instance has
                # not been scheduled yet.
                if db_value:
                    db_value = cell_mapping.CellMapping._from_db_object(
                        context, cell_mapping.CellMapping(), db_value)
            setattr(instance_mapping, key, db_value)
        instance_mapping.obj_reset_changes()
        instance_mapping._context = context
        return instance_mapping

    @staticmethod
    @db_api.api_context_manager.reader
    def _get_by_instance_uuid_from_db(context, instance_uuid):
        db_mapping = (context.session.query(api_models.InstanceMapping)
                        .options(joinedload('cell_mapping'))
                        .filter(
                            api_models.InstanceMapping.instance_uuid
                            == instance_uuid)).first()
        if not db_mapping:
            raise exception.InstanceMappingNotFound(uuid=instance_uuid)

        return db_mapping

    @base.remotable_classmethod
    def get_by_instance_uuid(cls, context, instance_uuid):
        db_mapping = cls._get_by_instance_uuid_from_db(context, instance_uuid)
        return cls._from_db_object(context, cls(), db_mapping)