# Copyright 2013 Red Hat, Inc.
#
#    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 functools

from oslo_log import log as logging
import oslo_messaging as messaging
from oslo_messaging.rpc import dispatcher
from oslo_serialization import jsonutils
from oslo_service import periodic_task
from oslo_utils import importutils

import nova.conf
import nova.context
import nova.exception
from nova.i18n import _

__all__ = [
    'init',
    'cleanup',
    'set_defaults',
    'add_extra_exmods',
    'clear_extra_exmods',
    'get_allowed_exmods',
    'RequestContextSerializer',
    'get_client',
    'get_server',
    'get_notifier',
]

profiler = importutils.try_import("osprofiler.profiler")


CONF = nova.conf.CONF

LOG = logging.getLogger(__name__)

# TODO(stephenfin): These should be private
TRANSPORT = None
LEGACY_NOTIFIER = None
NOTIFICATION_TRANSPORT = None
NOTIFIER = None

# NOTE(danms): If rpc_response_timeout is over this value (per-call or
# globally), we will enable heartbeating
HEARTBEAT_THRESHOLD = 60

ALLOWED_EXMODS = [
    nova.exception.__name__,
]
EXTRA_EXMODS = []


def init(conf):
    global TRANSPORT, NOTIFICATION_TRANSPORT, LEGACY_NOTIFIER, NOTIFIER
    exmods = get_allowed_exmods()
    TRANSPORT = create_transport(get_transport_url())
    NOTIFICATION_TRANSPORT = messaging.get_notification_transport(
        conf, allowed_remote_exmods=exmods)
    serializer = RequestContextSerializer(JsonPayloadSerializer())
    if conf.notifications.notification_format == 'unversioned':
        LEGACY_NOTIFIER = messaging.Notifier(NOTIFICATION_TRANSPORT,
                                             serializer=serializer)
        NOTIFIER = messaging.Notifier(NOTIFICATION_TRANSPORT,
                                      serializer=serializer, driver='noop')
    elif conf.notifications.notification_format == 'both':
        LEGACY_NOTIFIER = messaging.Notifier(NOTIFICATION_TRANSPORT,
                                             serializer=serializer)
        NOTIFIER = messaging.Notifier(
            NOTIFICATION_TRANSPORT,
            serializer=serializer,
            topics=conf.notifications.versioned_notifications_topics)
    else:
        LEGACY_NOTIFIER = messaging.Notifier(NOTIFICATION_TRANSPORT,
                                             serializer=serializer,
                                             driver='noop')
        NOTIFIER = messaging.Notifier(
            NOTIFICATION_TRANSPORT,
            serializer=serializer,
            topics=conf.notifications.versioned_notifications_topics)


def cleanup():
    global TRANSPORT, NOTIFICATION_TRANSPORT, LEGACY_NOTIFIER, NOTIFIER
    assert TRANSPORT is not None
    assert NOTIFICATION_TRANSPORT is not None
    assert LEGACY_NOTIFIER is not None
    assert NOTIFIER is not None
    TRANSPORT.cleanup()
    NOTIFICATION_TRANSPORT.cleanup()
    TRANSPORT = NOTIFICATION_TRANSPORT = LEGACY_NOTIFIER = NOTIFIER = None


def set_defaults(control_exchange):
    messaging.set_transport_defaults(control_exchange)


def add_extra_exmods(*args):
    EXTRA_EXMODS.extend(args)


def clear_extra_exmods():
    del EXTRA_EXMODS[:]


def get_allowed_exmods():
    return ALLOWED_EXMODS + EXTRA_EXMODS


class JsonPayloadSerializer(messaging.NoOpSerializer):

    @staticmethod
    def fallback(obj):
        """Serializer fallback

        This method is used to serialize an object which jsonutils.to_primitive
        does not otherwise know how to handle.

        This is mostly only needed in tests because of the use of the nova
        CheatingSerializer fixture which keeps some non-serializable fields
        on the RequestContext, like db_connection.
        """
        if isinstance(obj, nova.context.RequestContext):
            # This matches RequestContextSerializer.serialize_context().
            return obj.to_dict()
        # The default fallback in jsonutils.to_primitive() is str.
        return str(obj)

    def serialize_entity(self, context, entity):
        return jsonutils.to_primitive(entity, convert_instances=True,
                                      fallback=self.fallback)


class RequestContextSerializer(messaging.Serializer):

    def __init__(self, base):
        self._base = base

    def serialize_entity(self, context, entity):
        if not self._base:
            return entity
        return self._base.serialize_entity(context, entity)

    def deserialize_entity(self, context, entity):
        if not self._base:
            return entity
        return self._base.deserialize_entity(context, entity)

    def serialize_context(self, context):
        return context.to_dict()

    def deserialize_context(self, context):
        return nova.context.RequestContext.from_dict(context)


class ProfilerRequestContextSerializer(RequestContextSerializer):
    def serialize_context(self, context):
        _context = super(ProfilerRequestContextSerializer,
                         self).serialize_context(context)

        prof = profiler.get()
        if prof:
            # FIXME(DinaBelova): we'll add profiler.get_info() method
            # to extract this info -> we'll need to update these lines
            trace_info = {
                "hmac_key": prof.hmac_key,
                "base_id": prof.get_base_id(),
                "parent_id": prof.get_id()
            }
            _context.update({"trace_info": trace_info})

        return _context

    def deserialize_context(self, context):
        trace_info = context.pop("trace_info", None)
        if trace_info:
            profiler.init(**trace_info)

        return super(ProfilerRequestContextSerializer,
                     self).deserialize_context(context)


def get_transport_url(url_str=None):
    return messaging.TransportURL.parse(CONF, url_str)


def get_client(target, version_cap=None, serializer=None,
               call_monitor_timeout=None):
    assert TRANSPORT is not None

    if profiler:
        serializer = ProfilerRequestContextSerializer(serializer)
    else:
        serializer = RequestContextSerializer(serializer)

    return messaging.get_rpc_client(TRANSPORT, target,
        version_cap=version_cap, serializer=serializer,
        call_monitor_timeout=call_monitor_timeout)


def get_server(target, endpoints, serializer=None):
    assert TRANSPORT is not None

    if profiler:
        serializer = ProfilerRequestContextSerializer(serializer)
    else:
        serializer = RequestContextSerializer(serializer)
    access_policy = dispatcher.DefaultRPCAccessPolicy
    return messaging.get_rpc_server(TRANSPORT,
                                    target,
                                    endpoints,
                                    executor='eventlet',
                                    serializer=serializer,
                                    access_policy=access_policy)


def get_notifier(service, host=None):
    assert LEGACY_NOTIFIER is not None
    publisher_id = '%s.%s' % (service, host or CONF.host)
    return LegacyValidatingNotifier(
        LEGACY_NOTIFIER.prepare(publisher_id=publisher_id))


def get_versioned_notifier(publisher_id):
    assert NOTIFIER is not None
    return NOTIFIER.prepare(publisher_id=publisher_id)


def if_notifications_enabled(f):
    """Calls decorated method only if versioned notifications are enabled."""
    @functools.wraps(f)
    def wrapped(*args, **kwargs):
        if (NOTIFIER.is_enabled() and
                CONF.notifications.notification_format in ('both',
                                                           'versioned')):
            return f(*args, **kwargs)
        else:
            return None
    return wrapped


def create_transport(url):
    exmods = get_allowed_exmods()
    return messaging.get_rpc_transport(CONF,
                                       url=url,
                                       allowed_remote_exmods=exmods)


class LegacyValidatingNotifier(object):
    """Wraps an oslo.messaging Notifier and checks for allowed event_types."""

    # If true an exception is thrown if the event_type is not allowed, if false
    # then only a WARNING is logged
    fatal = False

    # This list contains the already existing therefore allowed legacy
    # notification event_types. New items shall not be added to the list as
    # Nova does not allow new legacy notifications any more. This list will be
    # removed when all the notification is transformed to versioned
    # notifications.
    allowed_legacy_notification_event_types = [
        'aggregate.addhost.end',
        'aggregate.addhost.start',
        'aggregate.create.end',
        'aggregate.create.start',
        'aggregate.delete.end',
        'aggregate.delete.start',
        'aggregate.removehost.end',
        'aggregate.removehost.start',
        'aggregate.updatemetadata.end',
        'aggregate.updatemetadata.start',
        'aggregate.updateprop.end',
        'aggregate.updateprop.start',
        'compute.instance.create.end',
        'compute.instance.create.error',
        'compute.instance.create_ip.end',
        'compute.instance.create_ip.start',
        'compute.instance.create.start',
        'compute.instance.delete.end',
        'compute.instance.delete_ip.end',
        'compute.instance.delete_ip.start',
        'compute.instance.delete.start',
        'compute.instance.evacuate',
        'compute.instance.exists',
        'compute.instance.finish_resize.end',
        'compute.instance.finish_resize.start',
        'compute.instance.live.migration.abort.start',
        'compute.instance.live.migration.abort.end',
        'compute.instance.live.migration.force.complete.start',
        'compute.instance.live.migration.force.complete.end',
        'compute.instance.live_migration.post.dest.end',
        'compute.instance.live_migration.post.dest.start',
        'compute.instance.live_migration._post.end',
        'compute.instance.live_migration._post.start',
        'compute.instance.live_migration.pre.end',
        'compute.instance.live_migration.pre.start',
        'compute.instance.live_migration.rollback.dest.end',
        'compute.instance.live_migration.rollback.dest.start',
        'compute.instance.live_migration._rollback.end',
        'compute.instance.live_migration._rollback.start',
        'compute.instance.pause.end',
        'compute.instance.pause.start',
        'compute.instance.power_off.end',
        'compute.instance.power_off.start',
        'compute.instance.power_on.end',
        'compute.instance.power_on.start',
        'compute.instance.reboot.end',
        'compute.instance.reboot.error',
        'compute.instance.reboot.start',
        'compute.instance.rebuild.end',
        'compute.instance.rebuild.error',
        'compute.instance.rebuild.scheduled',
        'compute.instance.rebuild.start',
        'compute.instance.rescue.end',
        'compute.instance.rescue.start',
        'compute.instance.resize.confirm.end',
        'compute.instance.resize.confirm.start',
        'compute.instance.resize.end',
        'compute.instance.resize.error',
        'compute.instance.resize.prep.end',
        'compute.instance.resize.prep.start',
        'compute.instance.resize.revert.end',
        'compute.instance.resize.revert.start',
        'compute.instance.resize.start',
        'compute.instance.restore.end',
        'compute.instance.restore.start',
        'compute.instance.resume.end',
        'compute.instance.resume.start',
        'compute.instance.shelve.end',
        'compute.instance.shelve_offload.end',
        'compute.instance.shelve_offload.start',
        'compute.instance.shelve.start',
        'compute.instance.shutdown.end',
        'compute.instance.shutdown.start',
        'compute.instance.snapshot.end',
        'compute.instance.snapshot.start',
        'compute.instance.soft_delete.end',
        'compute.instance.soft_delete.start',
        'compute.instance.suspend.end',
        'compute.instance.suspend.start',
        'compute.instance.trigger_crash_dump.end',
        'compute.instance.trigger_crash_dump.start',
        'compute.instance.unpause.end',
        'compute.instance.unpause.start',
        'compute.instance.unrescue.end',
        'compute.instance.unrescue.start',
        'compute.instance.unshelve.start',
        'compute.instance.unshelve.end',
        'compute.instance.update',
        'compute.instance.volume.attach',
        'compute.instance.volume.detach',
        'compute.libvirt.error',
        'compute.metrics.update',
        'compute_task.build_instances',
        'compute_task.migrate_server',
        'compute_task.rebuild_server',
        'HostAPI.power_action.end',
        'HostAPI.power_action.start',
        'HostAPI.set_enabled.end',
        'HostAPI.set_enabled.start',
        'HostAPI.set_maintenance.end',
        'HostAPI.set_maintenance.start',
        'keypair.create.start',
        'keypair.create.end',
        'keypair.delete.start',
        'keypair.delete.end',
        'keypair.import.start',
        'keypair.import.end',
        'network.floating_ip.allocate',
        'network.floating_ip.associate',
        'network.floating_ip.deallocate',
        'network.floating_ip.disassociate',
        'scheduler.select_destinations.end',
        'scheduler.select_destinations.start',
        'servergroup.addmember',
        'servergroup.create',
        'servergroup.delete',
        'volume.usage',
    ]

    message = _('%(event_type)s is not a versioned notification and not '
                'whitelisted. See ./doc/source/reference/notifications.rst')

    def __init__(self, notifier):
        self.notifier = notifier
        for priority in ['debug', 'info', 'warn', 'error', 'critical']:
            setattr(self, priority,
                    functools.partial(self._notify, priority))

    def _is_wrap_exception_notification(self, payload):
        # nova.exception_wrapper.wrap_exception decorator emits notification
        # where the event_type is the name of the decorated function. This
        # is used in many places but it will be converted to versioned
        # notification in one run by updating the decorator so it is pointless
        # to white list all the function names here we white list the
        # notification itself detected by the special payload keys.
        return {'exception', 'args'} == set(payload.keys())

    def _notify(self, priority, ctxt, event_type, payload):
        if (event_type not in self.allowed_legacy_notification_event_types and
                not self._is_wrap_exception_notification(payload)):
            if self.fatal:
                raise AssertionError(self.message % {'event_type': event_type})
            else:
                LOG.warning(self.message, {'event_type': event_type})

        getattr(self.notifier, priority)(ctxt, event_type, payload)


class ClientRouter(periodic_task.PeriodicTasks):
    """Creates RPC clients that honor the context's RPC transport
    or provides a default.
    """

    def __init__(self, default_client):
        super(ClientRouter, self).__init__(CONF)
        self.default_client = default_client
        self.target = default_client.target
        self.version_cap = default_client.version_cap
        self.serializer = default_client.serializer

    def client(self, context):
        transport = context.mq_connection
        if transport:
            cmt = self.default_client.call_monitor_timeout
            return messaging.get_rpc_client(transport, self.target,
                version_cap=self.version_cap,
                serializer=self.serializer,
                call_monitor_timeout=cmt)
        else:
            return self.default_client
