# Copyright (c) 2013 Mirantis Inc.
#
# 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 functools
import random

from oslo_config import cfg
from oslo_log import log
from oslo_service import periodic_task
from oslo_service import threadgroup
from oslo_utils import timeutils
import six

from sahara import conductor as c
from sahara import context
from sahara.i18n import _LW
from sahara.service import api
from sahara.service import coordinator
from sahara.service.edp import job_manager
from sahara.service.health import verification_base as vb
from sahara.service import trusts
from sahara.utils import cluster as c_u
from sahara.utils import edp
from sahara.utils import proxy as p


LOG = log.getLogger(__name__)

periodic_opts = [
    cfg.BoolOpt('periodic_enable',
                default=True,
                help='Enable periodic tasks.'),
    cfg.IntOpt('periodic_fuzzy_delay',
               default=60,
               help='Range in seconds to randomly delay when starting the'
                    ' periodic task scheduler to reduce stampeding.'
                    ' (Disable by setting to 0).'),
    cfg.IntOpt('periodic_interval_max',
               default=60,
               help='Max interval size between periodic tasks execution in '
                    'seconds.'),
    cfg.IntOpt('min_transient_cluster_active_time',
               default=30,
               help='Minimal "lifetime" in seconds for a transient cluster. '
                    'Cluster is guaranteed to be "alive" within this time '
                    'period.'),
    cfg.IntOpt('cleanup_time_for_incomplete_clusters',
               default=0,
               help='Maximal time (in hours) for clusters allowed to be in '
                    'states other than "Active", "Deleting" or "Error". If a '
                    'cluster is not in "Active", "Deleting" or "Error" state '
                    'and last update of it was longer than '
                    '"cleanup_time_for_incomplete_clusters" hours ago then it '
                    'will be deleted automatically. (0 value means that '
                    'automatic clean up is disabled).'),
    cfg.StrOpt('periodic_coordinator_backend_url',
               help='The backend URL to use for distributed periodic tasks '
                    'coordination.'),
    cfg.IntOpt('periodic_workers_number',
               default=1,
               help='Number of threads to run periodic tasks.'),
]

CONF = cfg.CONF
CONF.register_opts(periodic_opts)

conductor = c.API


def get_time_since_last_update(cluster):
    cluster_updated_at = timeutils.normalize_time(
        timeutils.parse_isotime(cluster.updated_at))
    current_time = timeutils.utcnow()
    spacing = timeutils.delta_seconds(cluster_updated_at,
                                      current_time)
    return spacing


def terminate_cluster(ctx, cluster, description):
    if CONF.use_identity_api_v3 and cluster.trust_id:
        trusts.use_os_admin_auth_token(cluster)
        context.set_current_cluster_id(cluster.id)

        LOG.debug('Terminating {description} cluster '
                  'in "{status}" state'.format(status=cluster.status,
                                               description=description))

        try:
            api.terminate_cluster(cluster.id)
        except Exception as e:
            LOG.warning(_LW(
                'Failed to terminate {description} cluster in "{status}" '
                'state: {error}.').format(error=six.text_type(e),
                                          status=cluster.status,
                                          description=description))

    else:
        if (cluster.status !=
                c_u.CLUSTER_STATUS_AWAITINGTERMINATION):
            conductor.cluster_update(
                ctx, cluster,
                {'status': c_u.CLUSTER_STATUS_AWAITINGTERMINATION})


def set_context(func):
    @functools.wraps(func)
    def handler(self, ctx):
        ctx = context.get_admin_context()
        context.set_ctx(ctx)
        func(self, ctx)
        context.set_ctx(None)
    return handler


def _make_periodic_tasks():
    '''Return the periodic tasks object

    This function creates the periodic tasks class object, it is wrapped in
    this manner to allow easier control of enabling and disabling tasks.

    '''
    zombie_task_spacing = 300 if CONF.use_domain_for_proxy_users else -1
    heartbeat_interval = (CONF.coordinator_heartbeat_interval if
                          CONF.periodic_coordinator_backend_url else -1)

    class SaharaPeriodicTasks(periodic_task.PeriodicTasks):
        hr = coordinator.HashRing(
            CONF.periodic_coordinator_backend_url, 'sahara-periodic-tasks')

        def __init__(self):
            super(SaharaPeriodicTasks, self).__init__(CONF)

        @periodic_task.periodic_task(
            spacing=heartbeat_interval, run_immediately=True)
        @set_context
        def heartbeat(self, ctx):
            self.hr.heartbeat()

        @periodic_task.periodic_task(spacing=45)
        @set_context
        def update_job_statuses(self, ctx):
            LOG.debug('Updating job statuses')
            all_je = conductor.job_execution_get_all(ctx, end_time=None)
            je_to_manage = self.hr.get_subset(all_je)
            for job in je_to_manage:
                job_manager.update_job_status(job.id)

        @periodic_task.periodic_task(spacing=90)
        @set_context
        def terminate_unneeded_transient_clusters(self, ctx):
            LOG.debug('Terminating unneeded transient clusters')
            all_clusters = conductor.cluster_get_all(
                ctx, status=c_u.CLUSTER_STATUS_ACTIVE, is_transient=True)
            clusters_to_manage = self.hr.get_subset(all_clusters)

            for cluster in clusters_to_manage:
                jc = conductor.job_execution_count(ctx,
                                                   end_time=None,
                                                   cluster_id=cluster.id)

                if jc > 0:
                    continue

                spacing = get_time_since_last_update(cluster)
                if spacing < CONF.min_transient_cluster_active_time:
                    continue

                terminate_cluster(ctx, cluster, description='transient')
                # Add event log info cleanup
                context.ctx().current_instance_info = context.InstanceInfo()

        @periodic_task.periodic_task(spacing=zombie_task_spacing)
        @set_context
        def check_for_zombie_proxy_users(self, ctx):
            all_users = p.proxy_domain_users_list()
            users_to_manage = self.hr.get_subset(all_users)
            for user in users_to_manage:
                if user.name.startswith('job_'):
                    je_id = user.name[4:]
                    je = conductor.job_execution_get(ctx, je_id)
                    if je is None or (je.info['status'] in
                                      edp.JOB_STATUSES_TERMINATED):
                        LOG.debug('Found zombie proxy user {username}'.format(
                            username=user.name))
                        p.proxy_user_delete(user_id=user.id)

        @periodic_task.periodic_task(spacing=3600)
        @set_context
        def terminate_incomplete_clusters(self, ctx):
            if CONF.cleanup_time_for_incomplete_clusters <= 0:
                return

            LOG.debug('Terminating old clusters in non-final state')

            # NOTE(alazarev) Retrieving all clusters once in hour for now.
            # Criteria support need to be implemented in sahara db API to
            # have SQL filtering.
            all_clusters = [
                cluster for cluster in conductor.cluster_get_all(ctx) if
                (cluster.status not in [
                    c_u.CLUSTER_STATUS_ACTIVE, c_u.CLUSTER_STATUS_ERROR,
                    c_u.CLUSTER_STATUS_DELETING])
                ]
            clusters_to_manage = self.hr.get_subset(all_clusters)

            for cluster in clusters_to_manage:

                spacing = get_time_since_last_update(cluster)
                if spacing < CONF.cleanup_time_for_incomplete_clusters * 3600:
                    continue

                terminate_cluster(ctx, cluster, description='incomplete')
                # Add event log info cleanup
                context.ctx().current_instance_info = context.InstanceInfo()

        @periodic_task.periodic_task(
            spacing=vb.get_verification_periodic_interval())
        @set_context
        def run_verifications(self, ctx):
            LOG.debug("Executing health checks for the clusters")
            start_dict = {'verification': {'status': 'START'}}
            all_clusters = conductor.cluster_get_all(
                ctx, status=c_u.CLUSTER_STATUS_ACTIVE)
            clusters_to_manage = self.hr.get_subset(all_clusters)

            for cluster in clusters_to_manage:
                try:
                    vb.validate_verification_start(cluster)
                    api.update_cluster(cluster.id, start_dict)
                except vb.CannotVerifyError:
                    LOG.debug("Skipping running verification "
                              "on the cluster %s" % cluster.name)

    return SaharaPeriodicTasks()


def setup():
    if CONF.periodic_enable:
        if CONF.periodic_fuzzy_delay:
            initial_delay = random.randint(0, CONF.periodic_fuzzy_delay)
            LOG.debug("Starting periodic tasks with initial delay {seconds} "
                      "seconds".format(seconds=initial_delay))
        else:
            initial_delay = None

        tg = threadgroup.ThreadGroup()
        workers_number = (CONF.periodic_workers_number
                          if CONF.periodic_coordinator_backend_url else 1)

        for t in range(workers_number):
            pt = _make_periodic_tasks()
            tg.add_dynamic_timer(
                pt.run_periodic_tasks,
                initial_delay=initial_delay,
                periodic_interval_max=CONF.periodic_interval_max,
                context=None)
