#    Copyright 2012 OpenStack Foundation
#
#    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.
import datetime

from oslo_log import log as logging

from trove.common import cfg
from trove.common import exception
from trove.common import remote
from trove.common import utils
from trove.extensions.mysql import models as mysql_models
from trove.instance import models as imodels
from trove.instance import models as instance_models
from trove.instance.models import load_instance, InstanceServiceStatus
from trove import rpc

LOG = logging.getLogger(__name__)
CONF = cfg.CONF


def load_mgmt_instances(context, deleted=None, client=None,
                        include_clustered=None):
    if not client:
        client = remote.create_nova_client(context)
    try:
        mgmt_servers = client.rdservers.list()
    except AttributeError:
        mgmt_servers = client.servers.list(search_opts={'all_tenants': 1})
    LOG.info("Found %d servers in Nova" %
             len(mgmt_servers if mgmt_servers else []))
    args = {}
    if deleted is not None:
        args['deleted'] = deleted
    if not include_clustered:
        args['cluster_id'] = None
    db_infos = instance_models.DBInstance.find_all(**args)

    instances = MgmtInstances.load_status_from_existing(context, db_infos,
                                                        mgmt_servers)
    return instances


def load_mgmt_instance(cls, context, id, include_deleted):
    try:
        instance = load_instance(cls, context, id, needs_server=True,
                                 include_deleted=include_deleted)
        client = remote.create_nova_client(context)
        try:
            server = client.rdservers.get(instance.server_id)
        except AttributeError:
            server = client.servers.get(instance.server_id)
        if hasattr(server, 'host'):
            instance.server.host = server.host
        elif hasattr(server, 'hostId'):
            instance.server.host = server.hostId
        if hasattr(server, 'deleted'):
            instance.server.deleted = server.deleted
        if hasattr(server, 'deleted_at'):
            instance.server.deleted_at = server.deleted_at
        if hasattr(server, 'local_id'):
            instance.server.local_id = server.local_id
        assert instance.server is not None
    except Exception as e:
        LOG.error(e)
        instance = load_instance(cls, context, id, needs_server=False,
                                 include_deleted=include_deleted)
    return instance


class SimpleMgmtInstance(imodels.BaseInstance):
    def __init__(self, context, db_info, server, datastore_status):
        super(SimpleMgmtInstance, self).__init__(context, db_info, server,
                                                 datastore_status)

    @property
    def status(self):
        if self.deleted:
            return imodels.InstanceStatus.SHUTDOWN
        return super(SimpleMgmtInstance, self).status

    @property
    def deleted(self):
        return self.db_info.deleted

    @property
    def deleted_at(self):
        return self.db_info.deleted_at

    @classmethod
    def load(cls, context, id, include_deleted=False):
        return load_mgmt_instance(cls, context, id, include_deleted)

    @property
    def task_description(self):
        return self.db_info.task_description


class DetailedMgmtInstance(SimpleMgmtInstance):
    def __init__(self, *args, **kwargs):
        super(DetailedMgmtInstance, self).__init__(*args, **kwargs)
        self.volume = None
        self.volume_used = None
        self.volume_total = None
        self.root_history = None

    @classmethod
    def load(cls, context, id, include_deleted=False):
        instance = load_mgmt_instance(cls, context, id, include_deleted)
        client = remote.create_cinder_client(context)
        try:
            instance.volume = client.volumes.get(instance.volume_id)
        except Exception:
            instance.volume = None
            # Populate the volume_used attribute from the guest agent.
        instance_models.load_guest_info(instance, context, id)
        instance.root_history = mysql_models.RootHistory.load(context=context,
                                                              instance_id=id)
        return instance


class MgmtInstance(imodels.Instance):
    def get_diagnostics(self):
        return self.get_guest().get_diagnostics()

    def stop_db(self):
        return self.get_guest().stop_db()

    def get_hwinfo(self):
        return self.get_guest().get_hwinfo()

    def rpc_ping(self):
        return self.get_guest().rpc_ping()


class MgmtInstances(imodels.Instances):
    @staticmethod
    def load_status_from_existing(context, db_infos, servers):
        def load_instance(context, db, status, server=None):
            return SimpleMgmtInstance(context, db, server, status)

        if context is None:
            raise TypeError("Argument context not defined.")
        find_server = imodels.create_server_list_matcher(servers)
        instances = imodels.Instances._load_servers_status(load_instance,
                                                           context,
                                                           db_infos,
                                                           find_server)
        _load_servers(instances, find_server)
        return instances


def _load_servers(instances, find_server):
    for instance in instances:
        db = instance.db_info
        instance.server = None
        try:
            server = find_server(db.id, db.compute_instance_id)
            instance.server = server
        except Exception as ex:
            LOG.error(ex)
    return instances


def publish_exist_events(transformer, admin_context):
    notifier = rpc.get_notifier("taskmanager")
    notifications = transformer()
    # clear out admin_context.auth_token so it does not get logged
    admin_context.auth_token = None
    for notification in notifications:
        notifier.info(admin_context, "trove.instance.exists", notification)


class NotificationTransformer(object):
    def __init__(self, **kwargs):
        pass

    @staticmethod
    def _get_audit_period():
        now = datetime.datetime.now()
        audit_start = utils.isotime(now, subsecond=True)
        audit_end = utils.isotime(
            now + datetime.timedelta(
                seconds=CONF.exists_notification_interval),
            subsecond=True)
        return audit_start, audit_end

    def _get_service_id(self, datastore_manager, id_map):
        if datastore_manager in id_map:
            datastore_manager_id = id_map[datastore_manager]
        else:
            datastore_manager_id = cfg.UNKNOWN_SERVICE_ID
            LOG.error("Datastore ID for Manager (%s) is not configured"
                      % datastore_manager)
        return datastore_manager_id

    def transform_instance(self, instance, audit_start, audit_end):
        payload = {
            'audit_period_beginning': audit_start,
            'audit_period_ending': audit_end,
            'created_at': instance.created,
            'display_name': instance.name,
            'instance_id': instance.id,
            'instance_name': instance.name,
            'instance_type_id': instance.flavor_id,
            'launched_at': instance.created,
            'nova_instance_id': instance.server_id,
            'region': CONF.region,
            'state_description': instance.status.lower(),
            'state': instance.status.lower(),
            'tenant_id': instance.tenant_id
        }
        payload['service_id'] = self._get_service_id(
            instance.datastore_version.manager, CONF.notification_service_id)
        return payload

    def __call__(self):
        audit_start, audit_end = NotificationTransformer._get_audit_period()
        messages = []
        db_infos = instance_models.DBInstance.find_all(deleted=False)
        for db_info in db_infos:
            try:
                service_status = InstanceServiceStatus.find_by(
                    instance_id=db_info.id)
            except exception.ModelNotFoundError:
                # There is a small window of opportunity during when the db
                # resource for an instance exists, but no InstanceServiceStatus
                # for it has yet been created. We skip sending the notification
                # message for all such instances. These instance are too new
                # and will get picked up the next round of notifications.
                LOG.debug("InstanceServiceStatus not found for %s. "
                          "Will wait to send notification." % db_info.id)
                continue
            instance = SimpleMgmtInstance(None, db_info, None, service_status)
            message = self.transform_instance(instance, audit_start, audit_end)
            messages.append(message)
        return messages


class NovaNotificationTransformer(NotificationTransformer):
    def __init__(self, **kwargs):
        super(NovaNotificationTransformer, self).__init__(**kwargs)
        self.context = kwargs['context']
        self.nova_client = remote.create_admin_nova_client(self.context)
        self._flavor_cache = {}

    def _lookup_flavor(self, flavor_id):
        if flavor_id in self._flavor_cache:
            LOG.debug("Flavor cache hit for %s" % flavor_id)
            return self._flavor_cache[flavor_id]
        # fetch flavor resource from nova
        LOG.info("Flavor cache miss for %s" % flavor_id)
        flavor = self.nova_client.flavors.get(flavor_id)
        self._flavor_cache[flavor_id] = flavor.name if flavor else 'unknown'
        return self._flavor_cache[flavor_id]

    def __call__(self):
        audit_start, audit_end = NotificationTransformer._get_audit_period()
        instances = load_mgmt_instances(self.context, deleted=False,
                                        client=self.nova_client)
        messages = []
        for instance in filter(
                lambda inst: inst.status != 'SHUTDOWN' and inst.server,
                instances):
            message = {
                'instance_type': self._lookup_flavor(instance.flavor_id),
                'user_id': instance.server.user_id
            }
            message.update(self.transform_instance(instance,
                                                   audit_start,
                                                   audit_end))
            messages.append(message)
        return messages
