# -*- encoding: utf-8 -*-
# Copyright (c) 2015 b<>com
#
# Authors: Jean-Emile DARTOIS <jean-emile.dartois@b-com.com>
#
# 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.
#
"""
*Good server consolidation strategy*

Consolidation of VMs is essential to achieve energy optimization in cloud
environments such as OpenStack. As VMs are spinned up and/or moved over time,
it becomes necessary to migrate VMs among servers to lower the costs. However,
migration of VMs introduces runtime overheads and consumes extra energy, thus
a good server consolidation strategy should carefully plan for migration in
order to both minimize energy consumption and comply to the various SLAs.
"""

from oslo_log import log

from watcher._i18n import _, _LE, _LI, _LW
from watcher.common import exception
from watcher.decision_engine.cluster.history import ceilometer as cch
from watcher.decision_engine.model import element
from watcher.decision_engine.strategy.strategies import base

LOG = log.getLogger(__name__)


class BasicConsolidation(base.ServerConsolidationBaseStrategy):
    """Basic offline consolidation using live migration

    *Description*

    This is server consolidation algorithm which not only minimizes the overall
    number of used servers, but also minimizes the number of migrations.

    *Requirements*

    * You must have at least 2 physical compute nodes to run this strategy.

    *Limitations*

    - It has been developed only for tests.
    - It assumes that the virtual machine and the compute node are on the same
      private network.
    - It assumes that live migrations are possible.

    *Spec URL*

    <None>
    """

    HOST_CPU_USAGE_METRIC_NAME = 'compute.node.cpu.percent'
    INSTANCE_CPU_USAGE_METRIC_NAME = 'cpu_util'

    MIGRATION = "migrate"
    CHANGE_NOVA_SERVICE_STATE = "change_nova_service_state"

    def __init__(self, config, osc=None):
        """Basic offline Consolidation using live migration

        :param config: A mapping containing the configuration of this strategy
        :type config: :py:class:`~.Struct` instance
        :param osc: :py:class:`~.OpenStackClients` instance
        """
        super(BasicConsolidation, self).__init__(config, osc)

        # set default value for the number of released nodes
        self.number_of_released_nodes = 0
        # set default value for the number of migrations
        self.number_of_migrations = 0
        # set default value for number of allowed migration attempts
        self.migration_attempts = 0

        # set default value for the efficacy
        self.efficacy = 100

        self._ceilometer = None

        # TODO(jed): improve threshold overbooking?
        self.threshold_mem = 1
        self.threshold_disk = 1
        self.threshold_cores = 1

        # TODO(jed): target efficacy
        self.target_efficacy = 60

        # TODO(jed): weight
        self.weight_cpu = 1
        self.weight_mem = 1
        self.weight_disk = 1

        # TODO(jed): bound migration attempts (80 %)
        self.bound_migration = 0.80

    @classmethod
    def get_name(cls):
        return "basic"

    @classmethod
    def get_display_name(cls):
        return _("Basic offline consolidation")

    @classmethod
    def get_translatable_display_name(cls):
        return "Basic offline consolidation"

    @property
    def ceilometer(self):
        if self._ceilometer is None:
            self._ceilometer = cch.CeilometerClusterHistory(osc=self.osc)
        return self._ceilometer

    @ceilometer.setter
    def ceilometer(self, ceilometer):
        self._ceilometer = ceilometer

    def compute_attempts(self, size_cluster):
        """Upper bound of the number of migration

        :param size_cluster: The size of the cluster
        """
        self.migration_attempts = size_cluster * self.bound_migration

    def check_migration(self, source_node, destination_node,
                        instance_to_migrate):
        """Check if the migration is possible

        :param source_node: the current node of the virtual machine
        :param destination_node: the destination of the virtual machine
        :param instance_to_migrate: the instance / virtual machine
        :return: True if the there is enough place otherwise false
        """
        if source_node == destination_node:
            return False

        LOG.debug('Migrate instance %s from %s to  %s',
                  instance_to_migrate, source_node, destination_node)

        total_cores = 0
        total_disk = 0
        total_mem = 0
        cpu_capacity = self.compute_model.get_resource_from_id(
            element.ResourceType.cpu_cores)
        disk_capacity = self.compute_model.get_resource_from_id(
            element.ResourceType.disk)
        memory_capacity = self.compute_model.get_resource_from_id(
            element.ResourceType.memory)

        for instance_id in self.compute_model. \
                get_mapping().get_node_instances(destination_node):
            instance = self.compute_model.get_instance_from_id(instance_id)
            total_cores += cpu_capacity.get_capacity(instance)
            total_disk += disk_capacity.get_capacity(instance)
            total_mem += memory_capacity.get_capacity(instance)

        # capacity requested by the compute node
        total_cores += cpu_capacity.get_capacity(instance_to_migrate)
        total_disk += disk_capacity.get_capacity(instance_to_migrate)
        total_mem += memory_capacity.get_capacity(instance_to_migrate)

        return self.check_threshold(destination_node, total_cores, total_disk,
                                    total_mem)

    def check_threshold(self, destination_node, total_cores,
                        total_disk, total_mem):
        """Check threshold

        Check the threshold value defined by the ratio of
        aggregated CPU capacity of VMs on one node to CPU capacity
        of this node must not exceed the threshold value.

        :param destination_node: the destination of the virtual machine
        :param total_cores: total cores of the virtual machine
        :param total_disk: total disk size used by the virtual machine
        :param total_mem: total memory used by the virtual machine
        :return: True if the threshold is not exceed
        """
        cpu_capacity = self.compute_model.get_resource_from_id(
            element.ResourceType.cpu_cores).get_capacity(destination_node)
        disk_capacity = self.compute_model.get_resource_from_id(
            element.ResourceType.disk).get_capacity(destination_node)
        memory_capacity = self.compute_model.get_resource_from_id(
            element.ResourceType.memory).get_capacity(destination_node)

        return (cpu_capacity >= total_cores * self.threshold_cores and
                disk_capacity >= total_disk * self.threshold_disk and
                memory_capacity >= total_mem * self.threshold_mem)

    def get_allowed_migration_attempts(self):
        """Allowed migration

        Maximum allowed number of migrations this allows us to fix
        the upper bound of the number of migrations.

        :return:
        """
        return self.migration_attempts

    def calculate_weight(self, compute_resource, total_cores_used,
                         total_disk_used, total_memory_used):
        """Calculate weight of every resource

        :param compute_resource:
        :param total_cores_used:
        :param total_disk_used:
        :param total_memory_used:
        :return:
        """
        cpu_capacity = self.compute_model.get_resource_from_id(
            element.ResourceType.cpu_cores).get_capacity(compute_resource)

        disk_capacity = self.compute_model.get_resource_from_id(
            element.ResourceType.disk).get_capacity(compute_resource)

        memory_capacity = self.compute_model.get_resource_from_id(
            element.ResourceType.memory).get_capacity(compute_resource)

        score_cores = (1 - (float(cpu_capacity) - float(total_cores_used)) /
                       float(cpu_capacity))

        # It's possible that disk_capacity is 0, e.g., m1.nano.disk = 0
        if disk_capacity == 0:
            score_disk = 0
        else:
            score_disk = (1 - (float(disk_capacity) - float(total_disk_used)) /
                          float(disk_capacity))

        score_memory = (
            1 - (float(memory_capacity) - float(total_memory_used)) /
            float(memory_capacity))
        # TODO(jed): take in account weight
        return (score_cores + score_disk + score_memory) / 3

    def calculate_score_node(self, node):
        """Calculate the score that represent the utilization level

        :param node: :py:class:`~.ComputeNode` instance
        :return: Score for the given compute node
        :rtype: float
        """
        resource_id = "%s_%s" % (node.uuid, node.hostname)
        host_avg_cpu_util = self.ceilometer.statistic_aggregation(
            resource_id=resource_id,
            meter_name=self.HOST_CPU_USAGE_METRIC_NAME,
            period="7200",
            aggregate='avg')

        if host_avg_cpu_util is None:
            LOG.error(
                _LE("No values returned by %(resource_id)s "
                    "for %(metric_name)s") % dict(
                        resource_id=resource_id,
                        metric_name=self.HOST_CPU_USAGE_METRIC_NAME))
            host_avg_cpu_util = 100

        cpu_capacity = self.compute_model.get_resource_from_id(
            element.ResourceType.cpu_cores).get_capacity(node)

        total_cores_used = cpu_capacity * (host_avg_cpu_util / 100.0)

        return self.calculate_weight(node, total_cores_used, 0, 0)

    def calculate_migration_efficacy(self):
        """Calculate migration efficacy

        :return: The efficacy tells us that every VM migration resulted
         in releasing on node
        """
        if self.number_of_migrations > 0:
            return (float(self.number_of_released_nodes) / float(
                self.number_of_migrations)) * 100
        else:
            return 0

    def calculate_score_instance(self, instance):
        """Calculate Score of virtual machine

        :param instance: the virtual machine
        :return: score
        """
        instance_cpu_utilization = self.ceilometer. \
            statistic_aggregation(
                resource_id=instance.uuid,
                meter_name=self.INSTANCE_CPU_USAGE_METRIC_NAME,
                period="7200",
                aggregate='avg'
            )
        if instance_cpu_utilization is None:
            LOG.error(
                _LE("No values returned by %(resource_id)s "
                    "for %(metric_name)s") % dict(
                        resource_id=instance.uuid,
                        metric_name=self.INSTANCE_CPU_USAGE_METRIC_NAME))
            instance_cpu_utilization = 100

        cpu_capacity = self.compute_model.get_resource_from_id(
            element.ResourceType.cpu_cores).get_capacity(instance)

        total_cores_used = cpu_capacity * (instance_cpu_utilization / 100.0)

        return self.calculate_weight(instance, total_cores_used, 0, 0)

    def add_change_service_state(self, resource_id, state):
        parameters = {'state': state}
        self.solution.add_action(action_type=self.CHANGE_NOVA_SERVICE_STATE,
                                 resource_id=resource_id,
                                 input_parameters=parameters)

    def add_migration(self,
                      resource_id,
                      migration_type,
                      source_node,
                      destination_node):
        parameters = {'migration_type': migration_type,
                      'source_node': source_node,
                      'destination_node': destination_node}
        self.solution.add_action(action_type=self.MIGRATION,
                                 resource_id=resource_id,
                                 input_parameters=parameters)

    def score_of_nodes(self, score):
        """Calculate score of nodes based on load by VMs"""
        for node in self.compute_model.get_all_compute_nodes().values():
            count = self.compute_model.mapping.get_node_instances_from_id(
                node.uuid)
            if len(count) > 0:
                result = self.calculate_score_node(node)
            else:
                # The node has not VMs
                result = 0
            if len(count) > 0:
                score.append((node.uuid, result))
        return score

    def node_and_instance_score(self, sorted_score, score):
        """Get List of VMs from node"""
        node_to_release = sorted_score[len(score) - 1][0]
        instances_to_migrate = (
            self.compute_model.mapping.get_node_instances_from_id(
                node_to_release))

        instance_score = []
        for instance_id in instances_to_migrate:
            instance = self.compute_model.get_instance_from_id(instance_id)
            if instance.state == element.InstanceState.ACTIVE.value:
                instance_score.append(
                    (instance_id, self.calculate_score_instance(instance)))

        return node_to_release, instance_score

    def create_migration_instance(self, mig_instance, mig_source_node,
                                  mig_destination_node):
        """Create migration VM"""
        if self.compute_model.migrate_instance(
                mig_instance, mig_source_node, mig_destination_node):
            self.add_migration(mig_instance.uuid, 'live',
                               mig_source_node.uuid,
                               mig_destination_node.uuid)

        if len(self.compute_model.get_mapping().get_node_instances(
                mig_source_node)) == 0:
            self.add_change_service_state(mig_source_node.
                                          uuid,
                                          element.ServiceState.DISABLED.value)
            self.number_of_released_nodes += 1

    def calculate_num_migrations(self, sorted_instances, node_to_release,
                                 sorted_score):
        number_migrations = 0
        for instance in sorted_instances:
            for j in range(0, len(sorted_score)):
                mig_instance = self.compute_model.get_instance_from_id(
                    instance[0])
                mig_source_node = self.compute_model.get_node_from_id(
                    node_to_release)
                mig_destination_node = self.compute_model.get_node_from_id(
                    sorted_score[j][0])

                result = self.check_migration(
                    mig_source_node, mig_destination_node, mig_instance)
                if result:
                    self.create_migration_instance(
                        mig_instance, mig_source_node, mig_destination_node)
                    number_migrations += 1
                    break
        return number_migrations

    def unsuccessful_migration_actualization(self, number_migrations,
                                             unsuccessful_migration):
        if number_migrations > 0:
            self.number_of_migrations += number_migrations
            return 0
        else:
            return unsuccessful_migration + 1

    def pre_execute(self):
        LOG.info(_LI("Initializing Sercon Consolidation"))
        if not self.compute_model:
            raise exception.ClusterStateNotDefined()

    def do_execute(self):
        # todo(jed) clone model
        self.efficacy = 100
        unsuccessful_migration = 0

        first_migration = True
        size_cluster = len(self.compute_model.get_all_compute_nodes())
        if size_cluster == 0:
            raise exception.ClusterEmpty()

        self.compute_attempts(size_cluster)

        for node_uuid, node in self.compute_model.get_all_compute_nodes(
        ).items():
            node_instances = (self.compute_model.mapping
                              .get_node_instances_from_id(node_uuid))
            if node_instances:
                if node.state == element.ServiceState.ENABLED:
                    self.add_change_service_state(
                        node_uuid, element.ServiceState.DISABLED.value)

        while self.get_allowed_migration_attempts() >= unsuccessful_migration:
            if not first_migration:
                self.efficacy = self.calculate_migration_efficacy()
                if self.efficacy < float(self.target_efficacy):
                    break
            first_migration = False
            score = []

            score = self.score_of_nodes(score)

            # Sort compute nodes by Score decreasing
            sorted_score = sorted(score, reverse=True, key=lambda x: (x[1]))
            LOG.debug("Compute node(s) BFD %s", sorted_score)

            # Get Node to be released
            if len(score) == 0:
                LOG.warning(_LW(
                    "The workloads of the compute nodes"
                    " of the cluster is zero"))
                break

            node_to_release, instance_score = self.node_and_instance_score(
                sorted_score, score)

            # Sort instances by Score
            sorted_instances = sorted(
                instance_score, reverse=True, key=lambda x: (x[1]))
            # BFD: Best Fit Decrease
            LOG.debug("VM(s) BFD %s", sorted_instances)

            migrations = self.calculate_num_migrations(
                sorted_instances, node_to_release, sorted_score)

            unsuccessful_migration = self.unsuccessful_migration_actualization(
                migrations, unsuccessful_migration)
        infos = {
            "number_of_migrations": self.number_of_migrations,
            "number_of_nodes_released": self.number_of_released_nodes,
            "efficacy": self.efficacy
        }
        LOG.debug(infos)

    def post_execute(self):
        self.solution.set_efficacy_indicators(
            released_compute_nodes_count=self.number_of_released_nodes,
            instance_migrations_count=self.number_of_migrations,
        )
