# Copyright 2015 Hewlett-Packard Development Company, L.P.
#
# 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.

from concurrent import futures
import datetime

from oslo_config import cfg
from oslo_log import log as logging
from sqlalchemy.orm import exc as sqlalchemy_exceptions

from octavia.common import constants
from octavia.controller.worker import controller_worker as cw
from octavia.db import api as db_api
from octavia.db import repositories as repo

LOG = logging.getLogger(__name__)
CONF = cfg.CONF


class SpareAmphora(object):
    def __init__(self):
        self.amp_repo = repo.AmphoraRepository()
        self.cw = cw.ControllerWorker()

    def spare_check(self):
        """Checks the DB for the Spare amphora count.

        If it's less than the requirement, starts new amphora.
        """
        session = db_api.get_session()
        conf_spare_cnt = CONF.house_keeping.spare_amphora_pool_size
        curr_spare_cnt = self.amp_repo.get_spare_amphora_count(session)
        LOG.debug("Required Spare Amphora count : %d", conf_spare_cnt)
        LOG.debug("Current Spare Amphora count : %d", curr_spare_cnt)
        diff_count = conf_spare_cnt - curr_spare_cnt

        # When the current spare amphora is less than required
        if diff_count > 0:
            LOG.info("Initiating creation of %d spare amphora.", diff_count)

            # Call Amphora Create Flow diff_count times
            with futures.ThreadPoolExecutor(
                    max_workers=CONF.house_keeping.spare_amphora_pool_size
            ) as executor:
                for i in range(1, diff_count + 1):
                    LOG.debug("Starting amphorae number %d ...", i)
                    executor.submit(self.cw.create_amphora)
        else:
            LOG.debug("Current spare amphora count satisfies the requirement")


class DatabaseCleanup(object):
    def __init__(self):
        self.amp_repo = repo.AmphoraRepository()
        self.amp_health_repo = repo.AmphoraHealthRepository()
        self.lb_repo = repo.LoadBalancerRepository()

    def delete_old_amphorae(self):
        """Checks the DB for old amphora and deletes them based on its age."""
        exp_age = datetime.timedelta(
            seconds=CONF.house_keeping.amphora_expiry_age)

        session = db_api.get_session()
        expiring_amphora = self.amp_repo.get_all_deleted_expiring_amphora(
            session, exp_age=exp_age)

        for amp in expiring_amphora:
            # If we're here, we already think the amp is expiring according to
            # the amphora table. Now check it is expired in the health table.
            # In this way, we ensure that amps aren't deleted unless they are
            # both expired AND no longer receiving zombie heartbeats.
            if self.amp_health_repo.check_amphora_health_expired(
                    session, amp.id, exp_age):
                LOG.debug('Attempting to purge db record for Amphora ID: %s',
                          amp.id)
                self.amp_repo.delete(session, id=amp.id)
                try:
                    self.amp_health_repo.delete(session, amphora_id=amp.id)
                except sqlalchemy_exceptions.NoResultFound:
                    pass  # Best effort delete, this record might not exist
                LOG.info('Purged db record for Amphora ID: %s', amp.id)

    def cleanup_load_balancers(self):
        """Checks the DB for old load balancers and triggers their removal."""
        exp_age = datetime.timedelta(
            seconds=CONF.house_keeping.load_balancer_expiry_age)

        session = db_api.get_session()
        load_balancers, _ = self.lb_repo.get_all(
            session, provisioning_status=constants.DELETED)

        for lb in load_balancers:
            if self.lb_repo.check_load_balancer_expired(session, lb.id,
                                                        exp_age):
                LOG.info('Attempting to delete load balancer id : %s', lb.id)
                self.lb_repo.delete(session, id=lb.id)
                LOG.info('Deleted load balancer id : %s', lb.id)


class CertRotation(object):
    def __init__(self):
        self.threads = CONF.house_keeping.cert_rotate_threads
        self.cw = cw.ControllerWorker()

    def rotate(self):
        """Check the amphora db table for expiring auth certs."""
        amp_repo = repo.AmphoraRepository()

        with futures.ThreadPoolExecutor(max_workers=self.threads) as executor:
            session = db_api.get_session()
            rotation_count = 0
            while True:
                amp = amp_repo.get_cert_expiring_amphora(session)
                if not amp:
                    break
                rotation_count += 1
                LOG.debug("Cert expired amphora's id is: %s", amp.id)
                executor.submit(self.cw.amphora_cert_rotation, amp.id)
            if rotation_count > 0:
                LOG.info("Rotated certificates for %s amphora", rotation_count)
