# Copyright 2011 VMware, Inc
# 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 logging as std_logging

from oslo_config import cfg

from tacker.common import config
from tacker.openstack.common import excutils
from tacker.openstack.common import log as logging
from tacker import wsgi


service_opts = [
    cfg.IntOpt('periodic_interval',
               default=40,
               help=_('Seconds between running periodic tasks')),
    cfg.IntOpt('api_workers',
               default=0,
               help=_('Number of separate worker processes for service')),
    cfg.IntOpt('periodic_fuzzy_delay',
               default=5,
               help=_('Range of seconds to randomly delay when starting the '
                      'periodic task scheduler to reduce stampeding. '
                      '(Disable by setting to 0)')),
]
CONF = cfg.CONF
CONF.register_opts(service_opts)

LOG = logging.getLogger(__name__)


class WsgiService(object):
    """Base class for WSGI based services.

    For each api you define, you must also define these flags:
    :<api>_listen: The address on which to listen
    :<api>_listen_port: The port on which to listen

    """

    def __init__(self, app_name):
        self.app_name = app_name
        self.wsgi_app = None

    def start(self):
        self.wsgi_app = _run_wsgi(self.app_name)

    def wait(self):
        self.wsgi_app.wait()


class TackerApiService(WsgiService):
    """Class for tacker-api service."""

    @classmethod
    def create(cls, app_name='tacker'):

        # Setup logging early, supplying both the CLI options and the
        # configuration mapping from the config file
        # We only update the conf dict for the verbose and debug
        # flags. Everything else must be set up in the conf file...
        # Log the options used when starting if we're in debug mode...

        config.setup_logging(cfg.CONF)
        # Dump the initial option values
        cfg.CONF.log_opt_values(LOG, std_logging.DEBUG)
        service = cls(app_name)
        return service


def serve_wsgi(cls):

    try:
        service = cls.create()
        service.start()
    except Exception:
        with excutils.save_and_reraise_exception():
            LOG.exception(_('Unrecoverable error: please check log '
                            'for details.'))

    return service


def _run_wsgi(app_name):
    app = config.load_paste_app(app_name)
    if not app:
        LOG.error(_('No known API applications configured.'))
        return
    server = wsgi.Server("Tacker")
    server.start(app, cfg.CONF.bind_port, cfg.CONF.bind_host,
                 workers=cfg.CONF.api_workers)
    # Dump all option values here after all options are parsed
    cfg.CONF.log_opt_values(LOG, std_logging.DEBUG)
    LOG.info(_("Tacker service started, listening on %(host)s:%(port)s"),
             {'host': cfg.CONF.bind_host,
              'port': cfg.CONF.bind_port})
    return server