# Copyright 2018 TrilioData Inc.
# All Rights Reserved.

"""Generic Node base class for all workers that run on hosts."""

import os
import random
import sys

import oslo_i18n
import oslo_messaging as messaging
from oslo_concurrency import processutils
from oslo_config import cfg
from oslo_db import options as db_options
from oslo_log import log as logging
from oslo_policy import opts as policy_opts
from oslo_service import service
from oslo_utils import importutils

import dmapi.conf
from dmapi import (
    baserpc, context, debugger, exception,
    profiler, rpc, utils, version, wsgi
)
from dmapi.conf import defaults
from dmapi.i18n import _, _LE, _LI, _LW

profiler_opts = importutils.try_import('osprofiler.opts')
osprofiler = importutils.try_import("osprofiler")
osprofiler_initializer = importutils.try_import("osprofiler.initializer")

LOG = logging.getLogger(__name__)

CONF = dmapi.conf.CONF

SERVICE_MANAGERS = {
}

OPTS = [
    cfg.IntOpt('http_timeout',
               default=600,
               help='Timeout seconds for HTTP requests. Set it to None to '
                    'disable timeout.'),
    cfg.IntOpt('evaluation_interval',
               default=60,
               help='Period of evaluation cycle, should'
               ' be >= than configured pipeline interval for'
               ' collection of underlying meters.'),
]


def _create_service_ref(this_service, context):
    service = objects.Service(context)
    service.host = this_service.host
    service.binary = this_service.binary
    service.topic = this_service.topic
    service.report_count = 0
    service.create()
    return service


def _update_service_ref(service):
    if service.version != service_obj.SERVICE_VERSION:
        LOG.info(_LI('Updating service version for %(binary)s on '
                     '%(host)s from %(old)i to %(new)i'),
                 {'binary': service.binary,
                  'host': service.host,
                  'old': service.version,
                  'new': service_obj.SERVICE_VERSION})
        service.version = service_obj.SERVICE_VERSION
        service.save()


def setup_profiler(binary, host):
    if osprofiler and CONF.profiler.enabled:
        osprofiler.initializer.init_from_conf(
            conf=CONF,
            context=context.get_admin_context().to_dict(),
            project="dmapi",
            service=binary,
            host=host)
        LOG.info(_LI("OSProfiler is enabled."))


def assert_eventlet_uses_monotonic_clock():
    import eventlet.hubs as hubs
    import monotonic

    hub = hubs.get_hub()
    if hub.clock is not monotonic.monotonic:
        raise RuntimeError(
            'eventlet hub is not using a monotonic clock - '
            'periodic tasks will be affected by drifts of system time.')


class Service(service.Service):
    """Service object for binaries running on hosts.

    A service takes a manager and enables rpc by listening to queues based
    on topic. It also periodically runs tasks on the manager and reports
    its state to the database services table.
    """

    def __init__(self, host, binary, topic, manager, report_interval=None,
                 periodic_enable=None, periodic_fuzzy_delay=None,
                 periodic_interval_max=None, *args, **kwargs):
        super(Service, self).__init__()
        self.host = host
        self.binary = binary
        self.topic = topic
        self.manager_class_name = manager
        self.servicegroup_api = servicegroup.API()
        manager_class = importutils.import_class(self.manager_class_name)
        self.manager = manager_class(host=self.host, *args, **kwargs)
        self.rpcserver = None
        self.report_interval = report_interval
        self.periodic_enable = periodic_enable
        self.periodic_fuzzy_delay = periodic_fuzzy_delay
        self.periodic_interval_max = periodic_interval_max
        self.saved_args, self.saved_kwargs = args, kwargs
        self.backdoor_port = None
        if objects_base.NovaObject.indirection_api:
            conductor_api = conductor.API()
            conductor_api.wait_until_ready(context.get_admin_context())
        setup_profiler(binary, self.host)

    def __repr__(self):
        return "<%(cls_name)s: host=%(host)s, binary=%(binary)s, " \
               "manager_class_name=%(manager)s>" % {
                 'cls_name': self.__class__.__name__,
                 'host': self.host,
                 'binary': self.binary,
                 'manager': self.manager_class_name
                }

    def start(self):
        """Start the service.

        This includes starting an RPC service, initializing
        periodic tasks, etc.
        """
        assert_eventlet_uses_monotonic_clock()

        verstr = version.version_string_with_package()
        LOG.info(_LI('Starting %(topic)s node (version %(version)s)'),
                  {'topic': self.topic, 'version': verstr})
        self.basic_config_check()
        self.manager.init_host()
        self.model_disconnected = False
        ctxt = context.get_admin_context()
        self.service_ref = objects.Service.get_by_host_and_binary(
            ctxt, self.host, self.binary)
        if self.service_ref:
            _update_service_ref(self.service_ref)

        else:
            try:
                self.service_ref = _create_service_ref(self, ctxt)
            except (exception.ServiceTopicExists,
                    exception.ServiceBinaryExists):
                # NOTE(danms): If we race to create a record with a sibling
                # worker, don't fail here.
                self.service_ref = objects.Service.get_by_host_and_binary(
                    ctxt, self.host, self.binary)

        self.manager.pre_start_hook()

        if self.backdoor_port is not None:
            self.manager.backdoor_port = self.backdoor_port

        LOG.debug("Creating RPC server for service %s", self.topic)

        target = messaging.Target(topic=self.topic, server=self.host)

        endpoints = [
            self.manager,
            baserpc.BaseRPCAPI(self.manager.service_name, self.backdoor_port)
        ]
        endpoints.extend(self.manager.additional_endpoints)

        serializer = objects_base.NovaObjectSerializer()

        self.rpcserver = rpc.get_server(target, endpoints, serializer)
        self.rpcserver.start()

        self.manager.post_start_hook()

        LOG.debug("Join ServiceGroup membership for this service %s",
                  self.topic)
        # Add service to the ServiceGroup membership group.
        self.servicegroup_api.join(self.host, self.topic, self)

        if self.periodic_enable:
            if self.periodic_fuzzy_delay:
                initial_delay = random.SystemRandom().randint(0,
                        self.periodic_fuzzy_delay)
            else:
                initial_delay = None

            self.tg.add_dynamic_timer(self.periodic_tasks,
                                     initial_delay=initial_delay,
                                     periodic_interval_max=
                                        self.periodic_interval_max)


    def __getattr__(self, key):
        manager = self.__dict__.get('manager', None)
        return getattr(manager, key)

    @classmethod
    def create(cls, host=None, binary=None, topic=None, manager=None,
               report_interval=None, periodic_enable=None,
               periodic_fuzzy_delay=None, periodic_interval_max=None):
        """Instantiates class and passes back application object.

        :param host: defaults to CONF.host
        :param binary: defaults to basename of executable
        :param topic: defaults to bin_name - 'dmapi-' part
        :param manager: defaults to CONF.<topic>_manager
        :param report_interval: defaults to CONF.report_interval
        :param periodic_enable: defaults to CONF.periodic_enable
        :param periodic_fuzzy_delay: defaults to CONF.periodic_fuzzy_delay
        :param periodic_interval_max: if set, the max time to wait between runs

        """
        if not host:
            host = CONF.host
        if not binary:
            binary = os.path.basename(sys.argv[0])
        if not topic:
            topic = binary.rpartition('dmapi-')[2]
        if not manager:
            manager = SERVICE_MANAGERS.get(binary)
        if report_interval is None:
            report_interval = CONF.report_interval
        if periodic_enable is None:
            periodic_enable = CONF.periodic_enable
        if periodic_fuzzy_delay is None:
            periodic_fuzzy_delay = CONF.periodic_fuzzy_delay

        debugger.init()

        service_obj = cls(host, binary, topic, manager,
                          report_interval=report_interval,
                          periodic_enable=periodic_enable,
                          periodic_fuzzy_delay=periodic_fuzzy_delay,
                          periodic_interval_max=periodic_interval_max)

        return service_obj

    def kill(self):
        """Destroy the service object in the datastore.

        NOTE: Although this method is not used anywhere else than tests, it is
        convenient to have it here, so the tests might easily and in clean way
        stop and remove the service_ref.

        """
        self.stop()
        try:
            self.service_ref.destroy()
        except exception.NotFound:
            LOG.warning(_LW('Service killed that has no database entry'))

    def stop(self):
        """stop the service and clean up."""
        try:
            self.rpcserver.stop()
            self.rpcserver.wait()
        except Exception as ex:
            LOG.exception(_LE(ex))
            pass

        try:
            self.manager.cleanup_host()
        except Exception:
            LOG.exception(_LE('Service error occurred during cleanup_host'))
            pass

        super(Service, self).stop()

    def periodic_tasks(self, raise_on_error=False):
        """Tasks to be run at a periodic interval."""
        ctxt = context.get_admin_context()
        return self.manager.periodic_tasks(ctxt, raise_on_error=raise_on_error)

    def basic_config_check(self):
        """Perform basic config checks before starting processing."""
        # Make sure the tempdir exists and is writable
        try:
            with utils.tempdir():
                pass
        except Exception as e:
            LOG.error(_LE('Temporary directory is invalid: %s'), e)
            sys.exit(1)

    def reset(self):
        """reset the service."""
        self.manager.reset()


class WSGIService(service.Service):
    """Provides ability to launch API from a 'paste' configuration."""

    def __init__(self, name, loader=None, use_ssl=False, max_url_len=None):
        """Initialize, but do not start the WSGI server.

        :param name: The name of the WSGI server given to the loader.
        :param loader: Loads the WSGI application using the given name.
        :returns: None

        """
        self.name = name
        self.binary = 'dmapi-%s' % name
        self.topic = None
        self.manager = self._get_manager()
        self.loader = loader or wsgi.Loader()
        self.app = self.loader.load_app(name)
        wname = name
        self.host = getattr(CONF, '%s_listen' % name, "0.0.0.0")
        self.port = getattr(CONF, '%s_listen_port' % name, 0)
        self.workers = (getattr(CONF, '%s_workers' % wname, None) or
                        processutils.get_worker_count())
        if self.workers and self.workers < 1:
            worker_name = '%s_workers' % name
            msg = (_("%(worker_name)s value of %(workers)s is invalid, "
                     "must be greater than 0") %
                   {'worker_name': worker_name,
                    'workers': str(self.workers)})
            raise exception.InvalidInput(msg)
        self.use_ssl = use_ssl
        self.server = wsgi.Server(name,
                                  self.app,
                                  host=self.host,
                                  port=self.port,
                                  use_ssl=self.use_ssl,
                                  max_url_len=max_url_len)
        # Pull back actual port used
        self.port = self.server.port
        self.backdoor_port = None
        setup_profiler(name, self.host)

    def reset(self):
        """Reset server greenpool size to default and service version cache.

        :returns: None

        """
        self.server.reset()
        service_obj.Service.clear_min_version_cache()

    def _get_manager(self):
        """Initialize a Manager object appropriate for this service.

        Use the service name to look up a Manager subclass from the
        configuration and initialize an instance. If no class name
        is configured, just return None.

        :returns: a Manager instance, or None.

        """
        manager = SERVICE_MANAGERS.get(self.binary)
        if manager is None:
            return None

        manager_class = importutils.import_class(manager)
        return manager_class()

    def start(self):
        """Start serving this service using loaded configuration.

        Also, retrieve updated port number in case '0' was passed in, which
        indicates a random port should be used.

        :returns: None

        """
        self.server.start()

    def stop(self):
        """Stop serving this API.

        :returns: None

        """
        self.server.stop()

    def wait(self):
        """Wait for the service to stop serving this API.

        :returns: None

        """
        self.server.wait()


def process_launcher():
    return service.ProcessLauncher(CONF, restart_method='mutate')


# NOTE(vish): the global launcher is to maintain the existing
#             functionality of calling service.serve +
#             service.wait
_launcher = None


def serve(server, workers=None):
    global _launcher
    if _launcher:
        raise RuntimeError(_('serve() can only be called once'))

    _launcher = service.launch(CONF, server, workers=1,
                               restart_method='mutate')


def wait():
    _launcher.wait()


def prepare_service(argv=None, config_files=None):
    conf = cfg.ConfigOpts()
    oslo_i18n.enable_lazy()
    logging.register_options(conf)
    log_levels = (
        conf.default_log_levels +
        [
            'futurist=INFO',
            'keystoneclient=INFO',
            'oslo_db.sqlalchemy=WARN',
            'cotyledon=INFO'
        ]
    )
    logging.set_defaults(default_log_levels=log_levels)
    defaults.set_cors_middleware_defaults()
    db_options.set_defaults(conf)
    if profiler_opts:
        profiler_opts.set_defaults(conf)

    policy_opts.set_defaults(conf, policy_file=os.path.abspath(
        os.path.join(os.path.dirname(__file__), "api", "policy.json")))
    from dmapi import opts
    # Register our own Aodh options
    for group, options in opts.list_opts():
        conf.register_opts(list(options),
                           group=None if group == "DEFAULT" else group)

    conf(argv, project='dmapi', validate_default_values=True,
         default_config_files=config_files)

    logging.setup(conf, 'dmapi')
    profiler.setup(conf)
    messaging.set_transport_defaults('dmapi')
    return conf