#
#    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 datetime

from heat.common import exception
from heat.common.i18n import _
from heat.engine import resource
from oslo_log import log as logging
from oslo_utils import timeutils
import six

LOG = logging.getLogger(__name__)


class CooldownMixin(object):
    """Utility class to encapsulate Cooldown related logic.

    This logic includes both cooldown timestamp comparing and scaling in
    progress checking.
    """
    def _sanitize_cooldown(self, cooldown):
        if cooldown is None:
            return 0
        return max(0, cooldown)

    def _check_scaling_allowed(self, cooldown):
        metadata = self.metadata_get()
        if metadata.get('scaling_in_progress'):
            LOG.info("Can not perform scaling action: resource %s "
                     "is already in scaling.", self.name)
            reason = _('due to scaling activity')
            raise resource.NoActionRequired(res_name=self.name,
                                            reason=reason)
        cooldown = self._sanitize_cooldown(cooldown)
        # if both cooldown and cooldown_end not in metadata
        if all(k not in metadata for k in ('cooldown', 'cooldown_end')):
            # Note: this is for supporting old version cooldown checking
            metadata.pop('scaling_in_progress', None)
            if metadata and cooldown != 0:
                last_adjust = next(six.iterkeys(metadata))
                if not timeutils.is_older_than(last_adjust, cooldown):
                    self._log_and_raise_no_action(cooldown)

        elif 'cooldown_end' in metadata:
            cooldown_end = next(six.iterkeys(metadata['cooldown_end']))
            now = timeutils.utcnow().isoformat()
            if now < cooldown_end:
                self._log_and_raise_no_action(cooldown)

        elif cooldown != 0:
            # Note: this is also for supporting old version cooldown checking
            last_adjust = next(six.iterkeys(metadata['cooldown']))
            if not timeutils.is_older_than(last_adjust, cooldown):
                self._log_and_raise_no_action(cooldown)

        # Assumes _finished_scaling is called
        # after the scaling operation completes
        metadata['scaling_in_progress'] = True
        self.metadata_set(metadata)

    def _log_and_raise_no_action(self, cooldown):
        LOG.info("Can not perform scaling action: "
                 "resource %(name)s is in cooldown (%(cooldown)s).",
                 {'name': self.name,
                  'cooldown': cooldown})
        reason = _('due to cooldown, '
                   'cooldown %s') % cooldown
        raise resource.NoActionRequired(
            res_name=self.name, reason=reason)

    def _finished_scaling(self, cooldown,
                          cooldown_reason, size_changed=True):
        # If we wanted to implement the AutoScaling API like AWS does,
        # we could maintain event history here, but since we only need
        # the latest event for cooldown, just store that for now
        metadata = self.metadata_get()
        if size_changed:
            cooldown = self._sanitize_cooldown(cooldown)
            cooldown_end = (timeutils.utcnow() + datetime.timedelta(
                seconds=cooldown)).isoformat()
            if 'cooldown_end' in metadata:
                cooldown_end = max(
                    next(six.iterkeys(metadata['cooldown_end'])),
                    cooldown_end)
            metadata['cooldown_end'] = {cooldown_end: cooldown_reason}
        metadata['scaling_in_progress'] = False
        try:
            self.metadata_set(metadata)
        except exception.NotFound:
            pass

    def handle_metadata_reset(self):
        metadata = self.metadata_get()
        if 'scaling_in_progress' in metadata:
            metadata['scaling_in_progress'] = False
            self.metadata_set(metadata)