#    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.

from oslo_db import exception as db_exc
from oslo_log import log as logging
from oslo_utils import uuidutils
from oslo_utils import versionutils

from nova.db.main import api as db
from nova import exception
from nova.i18n import _
from nova import objects
from nova.objects import base
from nova.objects import fields


LOG = logging.getLogger(__name__)

__all__ = [
    'Migration',
    'MigrationList',
    'determine_migration_type',
]


def determine_migration_type(migration):
    if isinstance(migration, dict):
        old_instance_type_id = migration['old_instance_type_id']
        new_instance_type_id = migration['new_instance_type_id']
    else:
        old_instance_type_id = migration.old_instance_type_id
        new_instance_type_id = migration.new_instance_type_id

    if old_instance_type_id != new_instance_type_id:
        return 'resize'

    return 'migration'


@base.NovaObjectRegistry.register
class Migration(base.NovaPersistentObject, base.NovaObject):
    # Version 1.0: Initial version
    # Version 1.1: String attributes updated to support unicode
    # Version 1.2: Added migration_type and hidden
    # Version 1.3: Added get_by_id_and_instance()
    # Version 1.4: Added migration progress detail
    # Version 1.5: Added uuid
    # Version 1.6: Added cross_cell_move and get_by_uuid().
    # Version 1.7: Added user_id and project_id
    # Version 1.8: Added dest_compute_id
    VERSION = '1.8'

    fields = {
        'id': fields.IntegerField(),
        'uuid': fields.UUIDField(),
        'source_compute': fields.StringField(nullable=True),  # source hostname
        'dest_compute': fields.StringField(nullable=True),    # dest hostname
        'source_node': fields.StringField(nullable=True),     # source nodename
        'dest_node': fields.StringField(nullable=True),       # dest nodename
        # ID of ComputeNode matching dest_node
        'dest_compute_id': fields.IntegerField(nullable=True),
        'dest_host': fields.StringField(nullable=True),       # dest host IP
        # TODO(stephenfin): Rename these to old_flavor_id, new_flavor_id in
        # v2.0
        'old_instance_type_id': fields.IntegerField(nullable=True),
        'new_instance_type_id': fields.IntegerField(nullable=True),
        'instance_uuid': fields.StringField(nullable=True),
        'status': fields.StringField(nullable=True),
        'migration_type': fields.MigrationTypeField(nullable=False),
        'hidden': fields.BooleanField(nullable=False, default=False),
        'memory_total': fields.IntegerField(nullable=True),
        'memory_processed': fields.IntegerField(nullable=True),
        'memory_remaining': fields.IntegerField(nullable=True),
        'disk_total': fields.IntegerField(nullable=True),
        'disk_processed': fields.IntegerField(nullable=True),
        'disk_remaining': fields.IntegerField(nullable=True),
        'cross_cell_move': fields.BooleanField(default=False),
        # request context user id
        'user_id': fields.StringField(nullable=True),
        # request context project id
        'project_id': fields.StringField(nullable=True),
        }

    @staticmethod
    def _from_db_object(context, migration, db_migration):
        for key in migration.fields:
            value = db_migration[key]
            if key == 'migration_type' and value is None:
                value = determine_migration_type(db_migration)
            elif key == 'uuid' and value is None:
                continue
            setattr(migration, key, value)

        migration._context = context
        migration.obj_reset_changes()
        migration._ensure_uuid()
        return migration

    def obj_make_compatible(self, primitive, target_version):
        super(Migration, self).obj_make_compatible(primitive, target_version)
        target_version = versionutils.convert_version_to_tuple(target_version)
        if target_version < (1, 2):
            if 'migration_type' in primitive:
                del primitive['migration_type']
                del primitive['hidden']
        if target_version < (1, 4):
            if 'memory_total' in primitive:
                del primitive['memory_total']
                del primitive['memory_processed']
                del primitive['memory_remaining']
                del primitive['disk_total']
                del primitive['disk_processed']
                del primitive['disk_remaining']
        if target_version < (1, 5):
            if 'uuid' in primitive:
                del primitive['uuid']
        if target_version < (1, 6) and 'cross_cell_move' in primitive:
            del primitive['cross_cell_move']
        if target_version < (1, 7):
            if 'user_id' in primitive:
                del primitive['user_id']
            if 'project_id' in primitive:
                del primitive['project_id']
        if target_version < (1, 8):
            primitive.pop('dest_compute_id', None)

    @base.lazy_load_counter
    def obj_load_attr(self, attrname):
        if attrname == 'migration_type':
            # NOTE(danms): The only reason we'd need to load this is if
            # some older node sent us one. So, guess the type.
            self.migration_type = determine_migration_type(self)
        elif attrname in ['hidden', 'cross_cell_move']:
            self.obj_set_defaults(attrname)
        else:
            super(Migration, self).obj_load_attr(attrname)

    def _ensure_uuid(self):
        if 'uuid' in self:
            return

        self.uuid = uuidutils.generate_uuid()
        try:
            self.save()
        except db_exc.DBDuplicateEntry:
            # NOTE(danms) We raced to generate a uuid for this,
            # so fetch the winner and use that uuid
            fresh = self.__class__.get_by_id(self.context, self.id)
            self.uuid = fresh.uuid

    @base.remotable_classmethod
    def get_by_uuid(cls, context, migration_uuid):
        db_migration = db.migration_get_by_uuid(context, migration_uuid)
        return cls._from_db_object(context, cls(), db_migration)

    @base.remotable_classmethod
    def get_by_id(cls, context, migration_id):
        db_migration = db.migration_get(context, migration_id)
        return cls._from_db_object(context, cls(), db_migration)

    @base.remotable_classmethod
    def get_by_id_and_instance(cls, context, migration_id, instance_uuid):
        db_migration = db.migration_get_by_id_and_instance(
            context, migration_id, instance_uuid)
        return cls._from_db_object(context, cls(), db_migration)

    @base.remotable_classmethod
    def get_by_instance_and_status(cls, context, instance_uuid, status):
        db_migration = db.migration_get_by_instance_and_status(
            context, instance_uuid, status)
        return cls._from_db_object(context, cls(), db_migration)

    @base.remotable
    def create(self):
        if self.obj_attr_is_set('id'):
            raise exception.ObjectActionError(action='create',
                                              reason='already created')
        if 'uuid' not in self:
            self.uuid = uuidutils.generate_uuid()
        # Record who is initiating the migration which is
        # not necessarily the owner of the instance.
        if 'user_id' not in self:
            self.user_id = self._context.user_id
        if 'project_id' not in self:
            self.project_id = self._context.project_id
        updates = self.obj_get_changes()
        if 'migration_type' not in updates:
            raise exception.ObjectActionError(
                action="create",
                reason=_("cannot create a Migration object without a "
                         "migration_type set"))
        version = versionutils.convert_version_to_tuple(self.VERSION)
        if 'dest_node' in updates and 'dest_compute_id' not in updates:
            # NOTE(danms): This is not really the best idea, as we should try
            # not to have different behavior based on the version of the
            # object. However, this exception helps us find cases in testing
            # where these may not be updated together. We can remove this
            # later.
            if version >= (1, 8):
                raise exception.ObjectActionError(
                    action='create',
                    reason=_('cannot create a Migration object with a '
                             'dest_node but no dest_compute_id'))
            else:
                LOG.warning('Migration is being created for %s but no '
                            'compute_id is set', self.dest_node)
        db_migration = db.migration_create(self._context, updates)
        self._from_db_object(self._context, self, db_migration)

    @base.remotable
    def save(self):
        updates = self.obj_get_changes()
        updates.pop('id', None)
        db_migration = db.migration_update(self._context, self.id, updates)
        self._from_db_object(self._context, self, db_migration)
        self.obj_reset_changes()

    @property
    def instance(self):
        if not hasattr(self, '_cached_instance'):
            self._cached_instance = objects.Instance.get_by_uuid(
                self._context, self.instance_uuid,
                expected_attrs=['migration_context', 'flavor'])
        return self._cached_instance

    @instance.setter
    def instance(self, instance):
        self._cached_instance = instance

    @property
    def is_live_migration(self):
        return self.migration_type == fields.MigrationType.LIVE_MIGRATION

    @property
    def is_resize(self):
        return self.migration_type == fields.MigrationType.RESIZE

    @property
    def is_same_host_resize(self):
        return self.is_resize and self.source_node == self.dest_node

    def get_dest_compute_id(self):
        """Try to determine the ComputeNode id this migration targets.

        This should be just the dest_compute_id field, but for migrations
        created by older compute nodes, we may not have that set. If not,
        look up the compute the old way for compatibility.

        :raises:ComputeHostNotFound if the destination compute is missing
        """
        if 'dest_compute_id' not in self:
            self.dest_compute_id = (
                objects.ComputeNode.get_by_host_and_nodename(
                    self._context,
                    self.dest_compute,
                    self.dest_node).id)
        return self.dest_compute_id


@base.NovaObjectRegistry.register
class MigrationList(base.ObjectListBase, base.NovaObject):
    # Version 1.0: Initial version
    #              Migration <= 1.1
    # Version 1.1: Added use_slave to get_unconfirmed_by_dest_compute
    # Version 1.2: Migration version 1.2
    # Version 1.3: Added a new function to get in progress migrations
    #              for an instance.
    # Version 1.4: Added sort_keys, sort_dirs, limit, marker kwargs to
    #              get_by_filters for migrations pagination support.
    # Version 1.5: Added a new function to get in progress migrations
    #              and error migrations for a given host + node.
    VERSION = '1.5'

    fields = {
        'objects': fields.ListOfObjectsField('Migration'),
        }

    @staticmethod
    @db.select_db_reader_mode
    def _db_migration_get_unconfirmed_by_dest_compute(
            context, confirm_window, dest_compute, use_slave=False):
        return db.migration_get_unconfirmed_by_dest_compute(
            context, confirm_window, dest_compute)

    @base.remotable_classmethod
    def get_unconfirmed_by_dest_compute(cls, context, confirm_window,
                                        dest_compute, use_slave=False):
        db_migrations = cls._db_migration_get_unconfirmed_by_dest_compute(
            context, confirm_window, dest_compute, use_slave=use_slave)
        return base.obj_make_list(context, cls(context), objects.Migration,
                                  db_migrations)

    @base.remotable_classmethod
    def get_in_progress_by_host_and_node(cls, context, host, node):
        db_migrations = db.migration_get_in_progress_by_host_and_node(
            context, host, node)
        return base.obj_make_list(context, cls(context), objects.Migration,
                                  db_migrations)

    @base.remotable_classmethod
    def get_by_filters(cls, context, filters, sort_keys=None, sort_dirs=None,
                       limit=None, marker=None):
        db_migrations = db.migration_get_all_by_filters(
            context, filters, sort_keys=sort_keys, sort_dirs=sort_dirs,
            limit=limit, marker=marker)
        return base.obj_make_list(context, cls(context), objects.Migration,
                                  db_migrations)

    @base.remotable_classmethod
    def get_in_progress_by_instance(cls, context, instance_uuid,
                                    migration_type=None):
        db_migrations = db.migration_get_in_progress_by_instance(
            context, instance_uuid, migration_type)
        return base.obj_make_list(context, cls(context), objects.Migration,
                                  db_migrations)

    @base.remotable_classmethod
    def get_in_progress_and_error(cls, context, host, node):
        db_migrations = \
            db.migration_get_in_progress_and_error_by_host_and_node(
                context, host, node)
        return base.obj_make_list(context, cls(context), objects.Migration,
                                  db_migrations)
