#
#    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 math

from oslo.utils import excutils
from oslo_log import log as logging
import six

from heat.common import exception
from heat.common import grouputils
from heat.common.i18n import _
from heat.common.i18n import _LE
from heat.common.i18n import _LI
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 import instance_group as instgrp
from heat.engine import rsrc_defn
from heat.engine import support
from heat.scaling import cooldown

LOG = logging.getLogger(__name__)


(EXACT_CAPACITY, CHANGE_IN_CAPACITY, PERCENT_CHANGE_IN_CAPACITY) = (
    'ExactCapacity', 'ChangeInCapacity', 'PercentChangeInCapacity')


def _calculate_new_capacity(current, adjustment, adjustment_type,
                            minimum, maximum):
    """
    Given the current capacity, calculates the new capacity which results
    from applying the given adjustment of the given adjustment-type.  The
    new capacity will be kept within the maximum and minimum bounds.
    """
    if adjustment_type == CHANGE_IN_CAPACITY:
        new_capacity = current + adjustment
    elif adjustment_type == EXACT_CAPACITY:
        new_capacity = adjustment
    else:
        # PercentChangeInCapacity
        delta = current * adjustment / 100.0
        if math.fabs(delta) < 1.0:
            rounded = int(math.ceil(delta) if delta > 0.0
                          else math.floor(delta))
        else:
            rounded = int(math.floor(delta) if delta > 0.0
                          else math.ceil(delta))
        new_capacity = current + rounded

    if new_capacity > maximum:
        LOG.debug('truncating growth to %s' % maximum)
        return maximum

    if new_capacity < minimum:
        LOG.debug('truncating shrinkage to %s' % minimum)
        return minimum

    return new_capacity


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

    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.NUMBER,
            _('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).")
        ),
    }

    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):
        self.validate_launchconfig()
        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):
        """Invoke the cooldown after creation succeeds."""
        done = super(AutoScalingGroup, self).check_create_complete(task)
        if done:
            self._cooldown_timestamp(
                "%s : %s" % (EXACT_CAPACITY, grouputils.get_size(self)))
        return done

    def handle_update(self, json_snippet, tmpl_diff, prop_diff):
        """
        If Properties has changed, update self.properties, so we get the new
        values during any subsequent adjustment.
        """
        if tmpl_diff:
            # parse update policy
            if 'UpdatePolicy' in tmpl_diff:
                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)

        if self.properties[self.DESIRED_CAPACITY] is not None:
            self.adjust(self.properties[self.DESIRED_CAPACITY],
                        adjustment_type=EXACT_CAPACITY)
        else:
            current_capacity = grouputils.get_size(self)
            self.adjust(current_capacity, adjustment_type=EXACT_CAPACITY)

    def adjust(self, adjustment, adjustment_type=CHANGE_IN_CAPACITY):
        """
        Adjust the size of the scaling group if the cooldown permits.
        """
        if self._cooldown_inprogress():
            LOG.info(_LI("%(name)s NOT performing scaling adjustment, "
                         "cooldown %(cooldown)s"),
                     {'name': self.name,
                      'cooldown': self.properties[self.COOLDOWN]})
            return

        capacity = grouputils.get_size(self)
        lower = self.properties[self.MIN_SIZE]
        upper = self.properties[self.MAX_SIZE]

        new_capacity = _calculate_new_capacity(capacity, adjustment,
                                               adjustment_type, lower, upper)
        total = grouputils.get_size(self, include_failed=True)
        # if there are failed resources in nested_stack, has to change
        if new_capacity == total:
            LOG.debug('no change in capacity %d' % capacity)
            return

        # 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',
        }
        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),
                                  })
                    notification.send(**notif)
                except Exception:
                    LOG.exception(_LE('Failed sending error notification'))
        else:
            notif.update({
                'suffix': 'end',
                'capacity': new_capacity,
                'message': _("End resizing the group %(group)s") % {
                    'group': notif['groupname']},
            })
            notification.send(**notif)

        self._cooldown_timestamp("%s : %s" % (adjustment_type, adjustment))

    def _tags(self):
        """Add Identifing 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 _resolve_attribute(self, name):
        '''
        heat extension: "InstanceList" returns comma delimited list of server
        ip addresses.
        '''
        if name == self.INSTANCE_LIST:
            return u','.join(inst.FnGetAtt('PublicIp')
                             for inst in grouputils.get_members(self)) or None

    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,
    }