# -*- 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.
"""Storage backend management
"""

from stevedore import driver
from datetime import datetime

from ceilometer.openstack.common import log
from ceilometer.openstack.common import cfg
from ceilometer.openstack.common import timeutils

from urlparse import urlparse

LOG = log.getLogger(__name__)

STORAGE_ENGINE_NAMESPACE = 'ceilometer.storage'

STORAGE_OPTS = [
    cfg.StrOpt('database_connection',
               default='mongodb://localhost:27017/ceilometer',
               help='Database connection string',
               ),
    ]


cfg.CONF.register_opts(STORAGE_OPTS)


def register_opts(conf):
    """Register any options for the storage system.
    """
    p = get_engine(conf)
    p.register_opts(conf)


def get_engine(conf):
    """Load the configured engine and return an instance.
    """
    engine_name = urlparse(conf.database_connection).scheme
    LOG.debug('looking for %r driver in %r',
              engine_name, STORAGE_ENGINE_NAMESPACE)
    mgr = driver.DriverManager(STORAGE_ENGINE_NAMESPACE,
                               engine_name,
                               invoke_on_load=True)
    return mgr.driver


def get_connection(conf):
    """Return an open connection to the database.
    """
    engine = get_engine(conf)
    engine.register_opts(conf)
    db = engine.get_connection(conf)
    return db


class EventFilter(object):
    """Holds the properties for building a query to filter events.

    :param user: The event owner.
    :param project: The event owner.
    :param start: Earliest timestamp to include.
    :param end: Only include events with timestamp less than this.
    :param resource: Optional filter for resource id.
    :param meter: Optional filter for meter type using the meter name.
    :param source: Optional source filter.
    """
    def __init__(self, user=None, project=None, start=None, end=None,
                 resource=None, meter=None, source=None):
        self.user = user
        self.project = project
        self.start = self._sanitize_timestamp(start)
        self.end = self._sanitize_timestamp(end)
        self.resource = resource
        self.meter = meter
        self.source = source

    def _sanitize_timestamp(self, timestamp):
        """Return a naive utc datetime object"""
        if not timestamp:
            return timestamp
        if not isinstance(timestamp, datetime):
            timestamp = timeutils.parse_isotime(timestamp)
        return timeutils.normalize_time(timestamp)