# Copyright 2020 TrilioData Inc.
# All Rights Reserved.

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

import os
import random
import sys
import inspect

from oslo_concurrency import processutils
from oslo_log import log as logging
import oslo_messaging as messaging
from oslo_service import service
from oslo_utils import importutils

from contego import baserpc
import contego.conf
from contego import context
from contego import debugger
from contego import exception
from contego.i18n import _, _LE, _LI, _LW
from contego import rpc
from contego import utils
from contego import version
from contego.objects import base as objects_base
from contego.objects import service as service_obj
from contego import objects
from contego import db
from contego.nova.extension.driver.loopingcall import FixedIntervalLoopingCall

osprofiler = importutils.try_import("osprofiler")
osprofiler_initializer = importutils.try_import("osprofiler.initializer")


LOG = logging.getLogger(__name__)

CONF = contego.conf.CONF

SERVICE_MANAGERS = {
}

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="tvault-contego",
            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
        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
        self.timers = []
        self.verstr = version.version_string_with_package()
        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()

        LOG.info(_LI('Starting %(topic)s node (version %(version)s)'),
                  {'topic': self.topic, 'version': self.verstr})
        self.basic_config_check()
        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:
            self._update_service_ref(self.service_ref)
        else:
            try:
                self.service_ref = self._create_service_ref(ctxt)
            except (exception.ServiceTopicExists,
                    exception.ServiceBinaryExists):
                self.service_ref = objects.Service.get_by_host_and_binary(
                    ctxt, self.host, self.binary)

        self.service_id = self.service_ref['id']
        if len(inspect.getfullargspec(self.manager.pre_start_hook).args) > 1:
            self.manager.pre_start_hook(self.service_ref)
        else:
            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.ContegoObjectSerializer()

        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.report_interval:
            pulse = FixedIntervalLoopingCall(self.report_state)
            pulse.start(interval=self.report_interval,
                        initial_delay=self.report_interval)
            self.timers.append(pulse)

        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 _create_service_ref(self, context):
        service = objects.Service(context)
        service.host = self.host
        service.binary = self.binary
        service.topic = self.topic
        service.version = self.verstr
        service.report_count = 0
        service.create()

        self.service_id = service['id']
        return service



    def _update_service_ref(self, 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 report_state(self):
        """Update the state of this service in the datastore."""
        ctxt = context.get_admin_context()
        state_catalog = {}
        try:
            try:
                service_ref = db.service_get(ctxt, self.service_id)
            except exception.NotFound:
                LOG.debug(_('The service database object disappeared, '
                            'Recreating it.'))
                self._create_service_ref(ctxt)
                service_ref = db.service_get(ctxt, self.service_id)

            state_catalog['report_count'] = service_ref['report_count'] + 1

            db.service_update(ctxt,
                              self.service_id, state_catalog)

            if getattr(self, 'model_disconnected', False):
                self.model_disconnected = False
                LOG.error(_('Recovered model server connection!'))

        except Exception:
            if not getattr(self, 'model_disconnected', False):
                self.model_disconnected = True
                LOG.exception(_('model server went away'))



    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 - 'tvault-' 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('tvault-')[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

        for x in self.timers:
            try:
                x.stop()
            except Exception as ex:
                LOG.exception(_LE(ex))
                pass
        self.timers = []

        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()

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()