#
# Copyright 2015 eNovance
#
# 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 json
import threading

import cachetools
from gnocchiclient import client
from gnocchiclient import exceptions
from keystoneauth1 import exceptions as ka_exceptions
from oslo_config import cfg
from oslo_log import log
import pecan
import wsme
from wsme import types as wtypes

from aodh.api.controllers.v2 import base
from aodh.api.controllers.v2 import utils as v2_utils
from aodh import keystone_client

LOG = log.getLogger(__name__)

GNOCCHI_OPTS = [
    cfg.StrOpt('gnocchi_external_project_owner',
               default="service",
               help='Project name of resources creator in Gnocchi. '
               '(For example the Ceilometer project name'),
    cfg.StrOpt('gnocchi_external_domain_name',
               default="Default",
               help='Domain name of resources creator in Gnocchi. '
               '(For example, default or service_domain'),
]


class GnocchiUnavailable(Exception):
    code = 503


class AlarmGnocchiThresholdRule(base.AlarmRule):
    comparison_operator = base.AdvEnum('comparison_operator', str,
                                       'lt', 'le', 'eq', 'ne', 'ge', 'gt',
                                       default='eq')
    "The comparison against the alarm threshold"

    threshold = wsme.wsattr(float, mandatory=True)
    "The threshold of the alarm"

    aggregation_method = wsme.wsattr(wtypes.text, mandatory=True)
    "The aggregation_method to compare to the threshold"

    evaluation_periods = wsme.wsattr(wtypes.IntegerType(minimum=1), default=1)
    "The number of historical periods to evaluate the threshold"

    granularity = wsme.wsattr(wtypes.IntegerType(minimum=1), default=60)
    "The time range in seconds over which query"

    cache = cachetools.TTLCache(maxsize=1, ttl=3600)
    lock = threading.RLock()

    @classmethod
    def validate_alarm(cls, alarm):
        alarm_rule = getattr(alarm, "%s_rule" % alarm.type)
        aggregation_method = alarm_rule.aggregation_method
        if aggregation_method not in cls._get_aggregation_methods():
            raise base.ClientSideError(
                'aggregation_method should be in %s not %s' % (
                    cls._get_aggregation_methods(), aggregation_method))

    @staticmethod
    @cachetools.cached(cache, lock=lock)
    def _get_aggregation_methods():
        conf = pecan.request.cfg
        gnocchi_client = client.Client(
            '1', keystone_client.get_session(conf),
            adapter_options={
                'interface': conf.service_credentials.interface,
                'region_name': conf.service_credentials.region_name})
        try:
            return gnocchi_client.capabilities.list().get(
                'aggregation_methods', [])
        except exceptions.ClientException as e:
            raise base.ClientSideError(e.message, status_code=e.code)
        except Exception as e:
            raise GnocchiUnavailable(e)


class MetricOfResourceRule(AlarmGnocchiThresholdRule):
    metric = wsme.wsattr(wtypes.text, mandatory=True)
    "The name of the metric"

    resource_id = wsme.wsattr(wtypes.text, mandatory=True)
    "The id of a resource"

    resource_type = wsme.wsattr(wtypes.text, mandatory=True)
    "The resource type"

    def as_dict(self):
        rule = self.as_dict_from_keys(['granularity', 'comparison_operator',
                                       'threshold', 'aggregation_method',
                                       'evaluation_periods',
                                       'metric',
                                       'resource_id',
                                       'resource_type'])
        return rule


class AggregationMetricByResourcesLookupRule(AlarmGnocchiThresholdRule):
    metric = wsme.wsattr(wtypes.text, mandatory=True)
    "The name of the metric"

    query = wsme.wsattr(wtypes.text, mandatory=True)
    ('The query to filter the metric, Don\'t forget to filter out '
     'deleted resources (example: {"and": [{"=": {"ended_at": null}}, ...]}), '
     'Otherwise Gnocchi will try to create the aggregate against obsolete '
     'resources')

    resource_type = wsme.wsattr(wtypes.text, mandatory=True)
    "The resource type"

    def as_dict(self):
        rule = self.as_dict_from_keys(['granularity', 'comparison_operator',
                                       'threshold', 'aggregation_method',
                                       'evaluation_periods',
                                       'metric',
                                       'query',
                                       'resource_type'])
        return rule

    cache = cachetools.TTLCache(maxsize=1, ttl=3600)
    lock = threading.RLock()

    @staticmethod
    @cachetools.cached(cache, lock=lock)
    def get_external_project_owner():
        kc = keystone_client.get_client(pecan.request.cfg)
        project_name = pecan.request.cfg.api.gnocchi_external_project_owner
        domain_name = pecan.request.cfg.api.gnocchi_external_domain_name
        try:
            domains = kc.domains.list(name=domain_name)
            project = kc.projects.find(
                name=project_name,
                domain_id=domains[0].id)
            return project.id
        except ka_exceptions.NotFound:
            LOG.warning("Unable to get domain or project information. "
                        "domain_name : %(domain_name)s, "
                        "project_name : %(project_name)s",
                        {'domain_name': domain_name,
                         'project_name': project_name})
            return None

    @classmethod
    def validate_alarm(cls, alarm):
        super(AggregationMetricByResourcesLookupRule,
              cls).validate_alarm(alarm)

        rule = alarm.gnocchi_aggregation_by_resources_threshold_rule

        # check the query string is a valid json
        try:
            query = json.loads(rule.query)
        except ValueError:
            raise wsme.exc.InvalidInput('rule/query', rule.query)

        conf = pecan.request.cfg

        # Scope the alarm to the project id if needed
        auth_project = v2_utils.get_auth_project(alarm.project_id)
        if auth_project:

            perms_filter = {"=": {"created_by_project_id": auth_project}}

            external_project_owner = cls.get_external_project_owner()
            if external_project_owner:
                perms_filter = {"or": [
                    perms_filter,
                    {"and": [
                        {"=": {"created_by_project_id":
                               external_project_owner}},
                        {"=": {"project_id": auth_project}}]}
                ]}

            query = {"and": [perms_filter, query]}
            rule.query = json.dumps(query)

        gnocchi_client = client.Client(
            '1', keystone_client.get_session(conf),
            adapter_options={
                'interface': conf.service_credentials.interface,
                'region_name': conf.service_credentials.region_name})
        try:
            gnocchi_client.aggregates.fetch(
                operations=[
                    'aggregate', rule.aggregation_method,
                    [
                        'metric', rule.metric,
                        rule.aggregation_method.lstrip('rate:')
                    ]
                ],
                search=query,
                needed_overlap=0,
                start="-1 day",
                stop="now",
                resource_type=rule.resource_type)
        except exceptions.ClientException as e:
            if e.code == 404:
                # NOTE(sileht): We are fine here, we just want to ensure the
                # 'query' payload is valid for Gnocchi If the metric
                # doesn't exists yet, it doesn't matter
                return
            raise base.ClientSideError(e.message, status_code=e.code)
        except Exception as e:
            raise GnocchiUnavailable(e)


class AggregationMetricsByIdLookupRule(AlarmGnocchiThresholdRule):
    metrics = wsme.wsattr([wtypes.text], mandatory=True)
    "A list of metric Ids"

    def as_dict(self):
        rule = self.as_dict_from_keys(['granularity', 'comparison_operator',
                                       'threshold', 'aggregation_method',
                                       'evaluation_periods',
                                       'metrics'])
        return rule
