#
#    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 oslo_log import log as logging
from oslo_utils import excutils
import six

from heat.common import exception
from heat.common import grouputils
from heat.common.i18n import _
from heat.engine import attributes
from heat.engine import constraints
from heat.engine import function
from heat.engine.notification import autoscaling as notification
from heat.engine import properties
from heat.engine import resource
from heat.engine.resources.openstack.heat import instance_group as instgrp
from heat.engine import rsrc_defn
from heat.engine import support
from heat.scaling import cooldown
from heat.scaling import scalingutil as sc_util

LOG = logging.getLogger(__name__)


class AutoScalingGroup(cooldown.CooldownMixin, instgrp.InstanceGroup):

    support_status = support.SupportStatus(version='2014.1')

    PROPERTIES = (
        AVAILABILITY_ZONES, LAUNCH_CONFIGURATION_NAME, MAX_SIZE, MIN_SIZE,
        COOLDOWN, DESIRED_CAPACITY, HEALTH_CHECK_GRACE_PERIOD,
        HEALTH_CHECK_TYPE, LOAD_BALANCER_NAMES, VPCZONE_IDENTIFIER, TAGS,
        INSTANCE_ID,
    ) = (
        'AvailabilityZones', 'LaunchConfigurationName', 'MaxSize', 'MinSize',
        'Cooldown', 'DesiredCapacity', 'HealthCheckGracePeriod',
        'HealthCheckType', 'LoadBalancerNames', 'VPCZoneIdentifier', 'Tags',
        'InstanceId',
    )

    _TAG_KEYS = (
        TAG_KEY, TAG_VALUE,
    ) = (
        'Key', 'Value',
    )

    _UPDATE_POLICY_SCHEMA_KEYS = (
        ROLLING_UPDATE
    ) = (
        'AutoScalingRollingUpdate'
    )

    _ROLLING_UPDATE_SCHEMA_KEYS = (
        MIN_INSTANCES_IN_SERVICE, MAX_BATCH_SIZE, PAUSE_TIME
    ) = (
        'MinInstancesInService', 'MaxBatchSize', 'PauseTime'
    )

    ATTRIBUTES = (
        INSTANCE_LIST,
    ) = (
        'InstanceList',
    )

    properties_schema = {
        AVAILABILITY_ZONES: properties.Schema(
            properties.Schema.LIST,
            _('Not Implemented.'),
            required=True
        ),
        LAUNCH_CONFIGURATION_NAME: properties.Schema(
            properties.Schema.STRING,
            _('The reference to a LaunchConfiguration resource.'),
            update_allowed=True
        ),
        INSTANCE_ID: properties.Schema(
            properties.Schema.STRING,
            _('The ID of an existing instance to use to '
              'create the Auto Scaling group. If specify this property, '
              'will create the group use an existing instance instead of '
              'a launch configuration.'),
            constraints=[
                constraints.CustomConstraint("nova.server")
            ]
        ),
        MAX_SIZE: properties.Schema(
            properties.Schema.INTEGER,
            _('Maximum number of instances in the group.'),
            required=True,
            update_allowed=True
        ),
        MIN_SIZE: properties.Schema(
            properties.Schema.INTEGER,
            _('Minimum number of instances in the group.'),
            required=True,
            update_allowed=True
        ),
        COOLDOWN: properties.Schema(
            properties.Schema.INTEGER,
            _('Cooldown period, in seconds.'),
            update_allowed=True
        ),
        DESIRED_CAPACITY: properties.Schema(
            properties.Schema.INTEGER,
            _('Desired initial number of instances.'),
            update_allowed=True
        ),
        HEALTH_CHECK_GRACE_PERIOD: properties.Schema(
            properties.Schema.INTEGER,
            _('Not Implemented.'),
            implemented=False
        ),
        HEALTH_CHECK_TYPE: properties.Schema(
            properties.Schema.STRING,
            _('Not Implemented.'),
            constraints=[
                constraints.AllowedValues(['EC2', 'ELB']),
            ],
            implemented=False
        ),
        LOAD_BALANCER_NAMES: properties.Schema(
            properties.Schema.LIST,
            _('List of LoadBalancer resources.')
        ),
        VPCZONE_IDENTIFIER: properties.Schema(
            properties.Schema.LIST,
            _('Use only with Neutron, to list the internal subnet to '
              'which the instance will be attached; '
              'needed only if multiple exist; '
              'list length must be exactly 1.'),
            schema=properties.Schema(
                properties.Schema.STRING,
                _('UUID of the internal subnet to which the instance '
                  'will be attached.')
            )
        ),
        TAGS: properties.Schema(
            properties.Schema.LIST,
            _('Tags to attach to this group.'),
            schema=properties.Schema(
                properties.Schema.MAP,
                schema={
                    TAG_KEY: properties.Schema(
                        properties.Schema.STRING,
                        required=True
                    ),
                    TAG_VALUE: properties.Schema(
                        properties.Schema.STRING,
                        required=True
                    ),
                },
            )
        ),
    }

    attributes_schema = {
        INSTANCE_LIST: attributes.Schema(
            _("A comma-delimited list of server ip addresses. "
              "(Heat extension)."),
            type=attributes.Schema.STRING
        ),
    }

    rolling_update_schema = {
        MIN_INSTANCES_IN_SERVICE: properties.Schema(properties.Schema.INTEGER,
                                                    default=0),
        MAX_BATCH_SIZE: properties.Schema(properties.Schema.INTEGER,
                                          default=1),
        PAUSE_TIME: properties.Schema(properties.Schema.STRING,
                                      default='PT0S')
    }

    update_policy_schema = {
        ROLLING_UPDATE: properties.Schema(properties.Schema.MAP,
                                          schema=rolling_update_schema)
    }

    def handle_create(self):
        return self.create_with_template(self.child_template())

    def _make_launch_config_resource(self, name, props):
        lc_res_type = 'AWS::AutoScaling::LaunchConfiguration'
        lc_res_def = rsrc_defn.ResourceDefinition(name,
                                                  lc_res_type,
                                                  props)
        lc_res = resource.Resource(name, lc_res_def, self.stack)
        return lc_res

    def _get_conf_properties(self):
        instance_id = self.properties.get(self.INSTANCE_ID)
        if instance_id:
            server = self.client_plugin('nova').get_server(instance_id)
            instance_props = {
                'ImageId': server.image['id'],
                'InstanceType': server.flavor['id'],
                'KeyName': server.key_name,
                'SecurityGroups': [sg['name']
                                   for sg in server.security_groups]
            }
            conf = self._make_launch_config_resource(self.name,
                                                     instance_props)
            props = function.resolve(conf.properties.data)
        else:
            conf, props = super(AutoScalingGroup, self)._get_conf_properties()

        vpc_zone_ids = self.properties.get(self.VPCZONE_IDENTIFIER)
        if vpc_zone_ids:
            props['SubnetId'] = vpc_zone_ids[0]

        return conf, props

    def check_create_complete(self, task):
        """Update cooldown timestamp after create succeeds."""
        done = super(AutoScalingGroup, self).check_create_complete(task)
        cooldown = self.properties[self.COOLDOWN]
        if done:
            self._finished_scaling(cooldown,
                                   "%s : %s" % (sc_util.CFN_EXACT_CAPACITY,
                                                grouputils.get_size(self)))
        return done

    def check_update_complete(self, cookie):
        """Update the cooldown timestamp after update succeeds."""
        done = super(AutoScalingGroup, self).check_update_complete(cookie)
        cooldown = self.properties[self.COOLDOWN]
        if done:
            self._finished_scaling(cooldown,
                                   "%s : %s" % (sc_util.CFN_EXACT_CAPACITY,
                                                grouputils.get_size(self)))
        return done

    def _get_new_capacity(self, capacity,
                          adjustment,
                          adjustment_type=sc_util.CFN_EXACT_CAPACITY,
                          min_adjustment_step=None):
        lower = self.properties[self.MIN_SIZE]
        upper = self.properties[self.MAX_SIZE]
        return sc_util.calculate_new_capacity(capacity, adjustment,
                                              adjustment_type,
                                              min_adjustment_step,
                                              lower, upper)

    def resize(self, capacity):
        try:
            super(AutoScalingGroup, self).resize(capacity)
        finally:
            # allow InstanceList to be re-resolved
            self.clear_stored_attributes()

    def handle_update(self, json_snippet, tmpl_diff, prop_diff):
        """Updates self.properties, if Properties has changed.

        If Properties has changed, update self.properties, so we get the new
        values during any subsequent adjustment.
        """
        if tmpl_diff:
            # parse update policy
            if tmpl_diff.update_policy_changed():
                up = json_snippet.update_policy(self.update_policy_schema,
                                                self.context)
                self.update_policy = up

        self.properties = json_snippet.properties(self.properties_schema,
                                                  self.context)
        if prop_diff:
            # Replace instances first if launch configuration has changed
            self._try_rolling_update(prop_diff)

        # Update will happen irrespective of whether auto-scaling
        # is in progress or not.
        capacity = grouputils.get_size(self)
        desired_capacity = self.properties[self.DESIRED_CAPACITY] or capacity
        new_capacity = self._get_new_capacity(capacity, desired_capacity)
        self.resize(new_capacity)

    def adjust(self, adjustment,
               adjustment_type=sc_util.CFN_CHANGE_IN_CAPACITY,
               min_adjustment_step=None, cooldown=None):
        """Adjust the size of the scaling group if the cooldown permits."""
        if self.status != self.COMPLETE:
            LOG.info("%s NOT performing scaling adjustment, "
                     "when status is not COMPLETE", self.name)
            raise resource.NoActionRequired

        capacity = grouputils.get_size(self)
        new_capacity = self._get_new_capacity(capacity, adjustment,
                                              adjustment_type,
                                              min_adjustment_step)
        if new_capacity == capacity:
            LOG.info("%s NOT performing scaling adjustment, "
                     "as there is no change in capacity.", self.name)
            raise resource.NoActionRequired

        if cooldown is None:
            cooldown = self.properties[self.COOLDOWN]

        self._check_scaling_allowed(cooldown)

        # send a notification before, on-error and on-success.
        notif = {
            'stack': self.stack,
            'adjustment': adjustment,
            'adjustment_type': adjustment_type,
            'capacity': capacity,
            'groupname': self.FnGetRefId(),
            'message': _("Start resizing the group %(group)s") % {
                'group': self.FnGetRefId()},
            'suffix': 'start',
        }
        size_changed = False
        try:
            notification.send(**notif)
            try:
                self.resize(new_capacity)
            except Exception as resize_ex:
                with excutils.save_and_reraise_exception():
                    try:
                        notif.update({'suffix': 'error',
                                      'message': six.text_type(resize_ex),
                                      'capacity': grouputils.get_size(self),
                                      })
                        notification.send(**notif)
                    except Exception:
                        LOG.exception('Failed sending error notification')
            else:
                size_changed = True
                notif.update({
                    'suffix': 'end',
                    'capacity': new_capacity,
                    'message': _("End resizing the group %(group)s") % {
                        'group': notif['groupname']},
                })
                notification.send(**notif)
        except Exception:
            LOG.error("Error in performing scaling adjustment for "
                      "group %s.", self.name)
            raise
        finally:
            self._finished_scaling(cooldown,
                                   "%s : %s" % (adjustment_type, adjustment),
                                   size_changed=size_changed)

    def _tags(self):
        """Add Identifying Tags to all servers in the group.

        This is so the Dimensions received from cfn-push-stats all include
        the groupname and stack id.
        Note: the group name must match what is returned from FnGetRefId
        """
        autoscaling_tag = [{self.TAG_KEY: 'metering.AutoScalingGroupName',
                            self.TAG_VALUE: self.FnGetRefId()}]
        return super(AutoScalingGroup, self)._tags() + autoscaling_tag

    def validate(self):
        # check validity of group size
        min_size = self.properties[self.MIN_SIZE]
        max_size = self.properties[self.MAX_SIZE]

        if max_size < min_size:
            msg = _("MinSize can not be greater than MaxSize")
            raise exception.StackValidationFailed(message=msg)

        if min_size < 0:
            msg = _("The size of AutoScalingGroup can not be less than zero")
            raise exception.StackValidationFailed(message=msg)

        if self.properties[self.DESIRED_CAPACITY] is not None:
            desired_capacity = self.properties[self.DESIRED_CAPACITY]
            if desired_capacity < min_size or desired_capacity > max_size:
                msg = _("DesiredCapacity must be between MinSize and MaxSize")
                raise exception.StackValidationFailed(message=msg)

        # TODO(pasquier-s): once Neutron is able to assign subnets to
        # availability zones, it will be possible to specify multiple subnets.
        # For now, only one subnet can be specified. The bug #1096017 tracks
        # this issue.
        if (self.properties.get(self.VPCZONE_IDENTIFIER) and
                len(self.properties[self.VPCZONE_IDENTIFIER]) != 1):
            raise exception.NotSupported(feature=_("Anything other than one "
                                         "VPCZoneIdentifier"))
        # validate properties InstanceId and LaunchConfigurationName
        # for aws auto scaling group.
        # should provide just only one of
        if self.type() == 'AWS::AutoScaling::AutoScalingGroup':
            instanceId = self.properties.get(self.INSTANCE_ID)
            launch_config = self.properties.get(
                self.LAUNCH_CONFIGURATION_NAME)
            if bool(instanceId) == bool(launch_config):
                msg = _("Either 'InstanceId' or 'LaunchConfigurationName' "
                        "must be provided.")
                raise exception.StackValidationFailed(message=msg)

        super(AutoScalingGroup, self).validate()

    def child_template(self):
        if self.properties[self.DESIRED_CAPACITY]:
            num_instances = self.properties[self.DESIRED_CAPACITY]
        else:
            num_instances = self.properties[self.MIN_SIZE]
        return self._create_template(num_instances)


def resource_mapping():
    return {
        'AWS::AutoScaling::AutoScalingGroup': AutoScalingGroup,
    }