# -*- encoding: utf-8 -*-
#
# Copyright © 2012 New Dream Network, LLC (DreamHost)
#
# Author: Doug Hellmann <doug.hellmann@dreamhost.com>
#
# 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.
"""Publish a sample using the preferred RPC mechanism.
"""


import itertools
import operator
import six.moves.urllib.parse as urlparse

from oslo.config import cfg

from ceilometer.openstack.common.gettextutils import _  # noqa
from ceilometer.openstack.common import log
from ceilometer.openstack.common import rpc
from ceilometer import publisher
from ceilometer.publisher import utils


LOG = log.getLogger(__name__)

METER_PUBLISH_OPTS = [
    cfg.StrOpt('metering_topic',
               default='metering',
               help='The topic that ceilometer uses for metering messages.',
               deprecated_group="DEFAULT",
               ),
]


def register_opts(config):
    """Register the options for publishing metering messages.
    """
    config.register_opts(METER_PUBLISH_OPTS, group="publisher_rpc")


register_opts(cfg.CONF)


def import_backend_retry_config():
    """Import the retry config option native to the configured
       rpc backend (if such a native config option exists).
    """
    cfg.CONF.import_opt('rpc_backend',
                        'ceilometer.openstack.common.rpc')
    kombu = 'ceilometer.openstack.common.rpc.impl_kombu'
    if cfg.CONF.rpc_backend == kombu:
        try:
            cfg.CONF.import_opt('rabbit_max_retries', kombu)
        except ImportError:
            pass


import_backend_retry_config()


def override_backend_retry_config(value):
    """Override the retry config option native to the configured
       rpc backend (if such a native config option exists).

       :param value: the value to override
    """
    # TODO(eglynn): ultimately we should add to olso a more generic concept
    # of retry config (i.e. not specific to an individual AMQP provider)
    # see: https://bugs.launchpad.net/ceilometer/+bug/1244698
    kombu = 'ceilometer.openstack.common.rpc.impl_kombu'
    if cfg.CONF.rpc_backend == kombu:
        if 'rabbit_max_retries' in cfg.CONF:
            cfg.CONF.set_override('rabbit_max_retries', value)


class RPCPublisher(publisher.PublisherBase):

    def __init__(self, parsed_url):
        options = urlparse.parse_qs(parsed_url.query)
        # the values of the option is a list of url params values
        # only take care of the latest one if the option
        # is provided more than once
        self.per_meter_topic = bool(int(
            options.get('per_meter_topic', [0])[-1]))

        self.target = options.get('target', ['record_metering_data'])[0]

        self.policy = options.get('policy', ['default'])[-1]
        self.max_queue_length = int(options.get(
            'max_queue_length', [1024])[-1])

        self.local_queue = []

        if self.policy in ['queue', 'drop']:
            LOG.info(_('Publishing policy set to %s, '
                       'override backend retry config to 1') % self.policy)
            override_backend_retry_config(1)

        elif self.policy == 'default':
            LOG.info(_('Publishing policy set to %s') % self.policy)
        else:
            LOG.warn(_('Publishing policy is unknown (%s) force to default')
                     % self.policy)
            self.policy = 'default'

    def publish_samples(self, context, samples):
        """Publish samples on RPC.

        :param context: Execution context from the service or RPC call.
        :param samples: Samples from pipeline after transformation.

        """

        meters = [
            utils.meter_message_from_counter(
                sample,
                cfg.CONF.publisher.metering_secret)
            for sample in samples
        ]

        topic = cfg.CONF.publisher_rpc.metering_topic
        msg = {
            'method': self.target,
            'version': '1.0',
            'args': {'data': meters},
        }
        self.local_queue.append((context, topic, msg))

        if self.per_meter_topic:
            for meter_name, meter_list in itertools.groupby(
                    sorted(meters, key=operator.itemgetter('counter_name')),
                    operator.itemgetter('counter_name')):
                msg = {
                    'method': self.target,
                    'version': '1.0',
                    'args': {'data': list(meter_list)},
                }
                topic_name = topic + '.' + meter_name
                LOG.audit(_('Publishing %(m)d samples on %(n)s') % (
                          {'m': len(msg['args']['data']), 'n': topic_name}))
                self.local_queue.append((context, topic_name, msg))

        self.flush()

    def flush(self):
        #note(sileht):
        # IO of the rpc stuff in handled by eventlet,
        # this is why the self.local_queue, is emptied before processing the
        # queue and the remaining messages in the queue are added to
        # self.local_queue after in case of a other call have already added
        # something in the self.local_queue
        queue = self.local_queue
        self.local_queue = []
        self.local_queue = self._process_queue(queue, self.policy) + \
            self.local_queue
        if self.policy == 'queue':
            self._check_queue_length()

    def _check_queue_length(self):
        queue_length = len(self.local_queue)
        if queue_length > self.max_queue_length > 0:
            count = queue_length - self.max_queue_length
            self.local_queue = self.local_queue[count:]
            LOG.warn(_("Publisher max local_queue length is exceeded, "
                     "dropping %d oldest samples") % count)

    @staticmethod
    def _process_queue(queue, policy):
        #note(sileht):
        # the behavior of rpc.cast call depends of rabbit_max_retries
        # if rabbit_max_retries <= 0:
        #   it returns only if the msg has been sent on the amqp queue
        # if rabbit_max_retries > 0:
        #   it raises a exception if rabbitmq is unreachable
        #
        # Ugly, but actually the oslo.rpc do a sys.exit(1) instead of a
        # RPCException, so we catch both until a correct behavior is
        # implemented in oslo
        #
        # the default policy just respect the rabbitmq configuration
        # nothing special is done if rabbit_max_retries <= 0
        # and exception is reraised if rabbit_max_retries > 0
        while queue:
            context, topic, msg = queue[0]
            try:
                rpc.cast(context, topic, msg)
            except (SystemExit, rpc.common.RPCException):
                samples = sum([len(m['args']['data']) for n, n, m in queue])
                if policy == 'queue':
                    LOG.warn(_("Failed to publish %d samples, queue them"),
                             samples)
                    return queue
                elif policy == 'drop':
                    LOG.warn(_("Failed to publish %d samples, dropping them"),
                             samples)
                    return []
                # default, occur only if rabbit_max_retries > 0
                raise
            else:
                queue.pop(0)
        return []
