# Copyright 2011 OpenStack LLC.
# 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.

import uuid

from nova import exception
from nova import flags
from nova import log as logging
from nova.openstack.common import cfg
from nova.openstack.common import importutils
from nova.openstack.common import jsonutils
from nova import utils


LOG = logging.getLogger(__name__)

notifier_opts = [
    cfg.StrOpt('default_notification_level',
               default='INFO',
               help='Default notification level for outgoing notifications'),
    cfg.StrOpt('default_publisher_id',
               default='$host',
               help='Default publisher_id for outgoing notifications'),
    ]

FLAGS = flags.FLAGS
FLAGS.register_opts(notifier_opts)

WARN = 'WARN'
INFO = 'INFO'
ERROR = 'ERROR'
CRITICAL = 'CRITICAL'
DEBUG = 'DEBUG'

log_levels = (DEBUG, WARN, INFO, ERROR, CRITICAL)


class BadPriorityException(Exception):
    pass


def notify_decorator(name, fn):
    """ decorator for notify which is used from utils.monkey_patch()

        :param name: name of the function
        :param function: - object of the function
        :returns: function -- decorated function

    """
    def wrapped_func(*args, **kwarg):
        body = {}
        body['args'] = []
        body['kwarg'] = {}
        for arg in args:
            body['args'].append(arg)
        for key in kwarg:
            body['kwarg'][key] = kwarg[key]

        context = exception.get_context_from_function_and_args(fn, args, kwarg)
        notify(context,
               FLAGS.default_publisher_id,
               name,
               FLAGS.default_notification_level,
               body)
        return fn(*args, **kwarg)
    return wrapped_func


def publisher_id(service, host=None):
    if not host:
        host = FLAGS.host
    return "%s.%s" % (service, host)


def notify(context, publisher_id, event_type, priority, payload):
    """Sends a notification using the specified driver

    :param publisher_id: the source worker_type.host of the message
    :param event_type:   the literal type of event (ex. Instance Creation)
    :param priority:     patterned after the enumeration of Python logging
                         levels in the set (DEBUG, WARN, INFO, ERROR, CRITICAL)
    :param payload:       A python dictionary of attributes

    Outgoing message format includes the above parameters, and appends the
    following:

    message_id
      a UUID representing the id for this notification

    timestamp
      the GMT timestamp the notification was sent at

    The composite message will be constructed as a dictionary of the above
    attributes, which will then be sent via the transport mechanism defined
    by the driver.

    Message example::

        {'message_id': str(uuid.uuid4()),
         'publisher_id': 'compute.host1',
         'timestamp': utils.utcnow(),
         'priority': 'WARN',
         'event_type': 'compute.create_instance',
         'payload': {'instance_id': 12, ... }}

    """
    if priority not in log_levels:
        raise BadPriorityException(
                 _('%s not in valid priorities') % priority)

    # Ensure everything is JSON serializable.
    payload = jsonutils.to_primitive(payload, convert_instances=True)

    driver = importutils.import_module(FLAGS.notification_driver)
    msg = dict(message_id=str(uuid.uuid4()),
                   publisher_id=publisher_id,
                   event_type=event_type,
                   priority=priority,
                   payload=payload,
                   timestamp=str(utils.utcnow()))
    try:
        driver.notify(context, msg)
    except Exception, e:
        LOG.exception(_("Problem '%(e)s' attempting to "
                        "send to notification system. Payload=%(payload)s") %
                        locals())