# Copyright (c) 2011 OpenStack Foundation
# All Rights Reserved.
#
#    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.

"""The hosts admin extension."""

from oslo_log import log as logging
import webob.exc

from nova.api.openstack import extensions
from nova import compute
from nova import context as nova_context
from nova import exception
from nova.i18n import _
from nova.i18n import _LI
from nova import objects

LOG = logging.getLogger(__name__)
authorize = extensions.extension_authorizer('compute', 'hosts')


class HostController(object):
    """The Hosts API controller for the OpenStack API."""
    def __init__(self):
        self.api = compute.HostAPI()
        super(HostController, self).__init__()

    def index(self, req):
        """Returns a dict in the format:

        |  {'hosts': [{'host_name': 'some.host.name',
        |     'service': 'cells',
        |     'zone': 'internal'},
        |    {'host_name': 'some.other.host.name',
        |     'service': 'cells',
        |     'zone': 'internal'},
        |    {'host_name': 'some.celly.host.name',
        |     'service': 'cells',
        |     'zone': 'internal'},
        |    {'host_name': 'console1.host.com',
        |     'service': 'consoleauth',
        |     'zone': 'internal'},
        |    {'host_name': 'network1.host.com',
        |     'service': 'network',
        |     'zone': 'internal'},
        |    {'host_name': 'netwwork2.host.com',
        |     'service': 'network',
        |     'zone': 'internal'},
        |    {'host_name': 'compute1.host.com',
        |     'service': 'compute',
        |     'zone': 'nova'},
        |    {'host_name': 'compute2.host.com',
        |     'service': 'compute',
        |     'zone': 'nova'},
        |    {'host_name': 'sched1.host.com',
        |     'service': 'scheduler',
        |     'zone': 'internal'},
        |    {'host_name': 'sched2.host.com',
        |     'service': 'scheduler',
        |     'zone': 'internal'},
        |    {'host_name': 'vol1.host.com',
        |     'service': 'volume',
        |     'zone': 'internal'}]}

        """
        context = req.environ['nova.context']
        authorize(context)

        # NOTE(alex_xu): back-compatible with db layer hard-code admin
        # permission checks
        nova_context.require_admin_context(context)

        filters = {'disabled': False}
        zone = req.GET.get('zone', None)
        if zone:
            filters['availability_zone'] = zone
        services = self.api.service_get_all(context, filters=filters,
                                            set_zones=True)
        hosts = []
        for service in services:
            hosts.append({'host_name': service['host'],
                          'service': service['topic'],
                          'zone': service['availability_zone']})
        return {'hosts': hosts}

    def update(self, req, id, body):
        """Updates a specified body.

        :param body: example format {'status': 'enable',
                                     'maintenance_mode': 'enable'}
        """
        def read_enabled(orig_val, msg):
            """Checks a specified orig_val and returns True for 'enabled'
            and False for 'disabled'.

            :param orig_val: A string with either 'enable' or 'disable'. May
                             be surrounded by whitespace, and case doesn't
                             matter
            :param msg: The message to be passed to HTTPBadRequest. A single
                        %s will be replaced with orig_val.
            """
            val = orig_val.strip().lower()
            if val == "enable":
                return True
            elif val == "disable":
                return False
            else:
                raise webob.exc.HTTPBadRequest(explanation=msg % orig_val)
        context = req.environ['nova.context']
        authorize(context)
        # See what the user wants to 'update'
        params = {k.strip().lower(): v for k, v in body.iteritems()}
        orig_status = status = params.pop('status', None)
        orig_maint_mode = maint_mode = params.pop('maintenance_mode', None)
        # Validate the request
        if len(params) > 0:
            # Some extra param was passed. Fail.
            explanation = _("Invalid update setting: '%s'") % params.keys()[0]
            raise webob.exc.HTTPBadRequest(explanation=explanation)
        if orig_status is not None:
            status = read_enabled(orig_status, _("Invalid status: '%s'"))
        if orig_maint_mode is not None:
            maint_mode = read_enabled(orig_maint_mode, _("Invalid mode: '%s'"))
        if status is None and maint_mode is None:
            explanation = _("'status' or 'maintenance_mode' needed for "
                            "host update")
            raise webob.exc.HTTPBadRequest(explanation=explanation)
        # Make the calls and merge the results
        result = {'host': id}
        if status is not None:
            result['status'] = self._set_enabled_status(context, id, status)
        if maint_mode is not None:
            result['maintenance_mode'] = self._set_host_maintenance(context,
                id, maint_mode)
        return result

    def _set_host_maintenance(self, context, host_name, mode=True):
        """Start/Stop host maintenance window. On start, it triggers
        guest VMs evacuation.
        """
        LOG.info(_LI("Putting host %(host_name)s in maintenance mode "
                    "%(mode)s."),
                  {'host_name': host_name, 'mode': mode})
        try:
            result = self.api.set_host_maintenance(context, host_name, mode)
        except NotImplementedError:
            msg = _("Virt driver does not implement host maintenance mode.")
            raise webob.exc.HTTPNotImplemented(explanation=msg)
        except exception.NotFound as e:
            raise webob.exc.HTTPNotFound(explanation=e.format_message())
        except exception.ComputeServiceUnavailable as e:
            raise webob.exc.HTTPBadRequest(explanation=e.format_message())
        if result not in ("on_maintenance", "off_maintenance"):
            raise webob.exc.HTTPBadRequest(explanation=result)
        return result

    def _set_enabled_status(self, context, host_name, enabled):
        """Sets the specified host's ability to accept new instances.

        :param enabled: a boolean - if False no new VMs will be able to start
        on the host
        """
        if enabled:
            LOG.info(_LI("Enabling host %s.") % host_name)
        else:
            LOG.info(_LI("Disabling host %s.") % host_name)
        try:
            result = self.api.set_host_enabled(context, host_name=host_name,
                    enabled=enabled)
        except NotImplementedError:
            msg = _("Virt driver does not implement host disabled status.")
            raise webob.exc.HTTPNotImplemented(explanation=msg)
        except exception.NotFound as e:
            raise webob.exc.HTTPNotFound(explanation=e.format_message())
        except exception.ComputeServiceUnavailable as e:
            raise webob.exc.HTTPBadRequest(explanation=e.format_message())
        if result not in ("enabled", "disabled"):
            raise webob.exc.HTTPBadRequest(explanation=result)
        return result

    def _host_power_action(self, req, host_name, action):
        """Reboots, shuts down or powers up the host."""
        context = req.environ['nova.context']
        authorize(context)
        try:
            result = self.api.host_power_action(context, host_name=host_name,
                    action=action)
        except NotImplementedError:
            msg = _("Virt driver does not implement host power management.")
            raise webob.exc.HTTPNotImplemented(explanation=msg)
        except exception.NotFound as e:
            raise webob.exc.HTTPNotFound(explanation=e.format_message())
        except exception.ComputeServiceUnavailable as e:
            raise webob.exc.HTTPBadRequest(explanation=e.format_message())
        return {"host": host_name, "power_action": result}

    def startup(self, req, id):
        return self._host_power_action(req, host_name=id, action="startup")

    def shutdown(self, req, id):
        return self._host_power_action(req, host_name=id, action="shutdown")

    def reboot(self, req, id):
        return self._host_power_action(req, host_name=id, action="reboot")

    @staticmethod
    def _get_total_resources(host_name, compute_node):
        return {'resource': {'host': host_name,
                             'project': '(total)',
                             'cpu': compute_node['vcpus'],
                             'memory_mb': compute_node['memory_mb'],
                             'disk_gb': compute_node['local_gb']}}

    @staticmethod
    def _get_used_now_resources(host_name, compute_node):
        return {'resource': {'host': host_name,
                             'project': '(used_now)',
                             'cpu': compute_node['vcpus_used'],
                             'memory_mb': compute_node['memory_mb_used'],
                             'disk_gb': compute_node['local_gb_used']}}

    @staticmethod
    def _get_resource_totals_from_instances(host_name, instances):
        cpu_sum = 0
        mem_sum = 0
        hdd_sum = 0
        for instance in instances:
            cpu_sum += instance['vcpus']
            mem_sum += instance['memory_mb']
            hdd_sum += instance['root_gb'] + instance['ephemeral_gb']

        return {'resource': {'host': host_name,
                             'project': '(used_max)',
                             'cpu': cpu_sum,
                             'memory_mb': mem_sum,
                             'disk_gb': hdd_sum}}

    @staticmethod
    def _get_resources_by_project(host_name, instances):
        # Getting usage resource per project
        project_map = {}
        for instance in instances:
            resource = project_map.setdefault(instance['project_id'],
                    {'host': host_name,
                     'project': instance['project_id'],
                     'cpu': 0,
                     'memory_mb': 0,
                     'disk_gb': 0})
            resource['cpu'] += instance['vcpus']
            resource['memory_mb'] += instance['memory_mb']
            resource['disk_gb'] += (instance['root_gb'] +
                                    instance['ephemeral_gb'])
        return project_map

    def show(self, req, id):
        """Shows the physical/usage resource given by hosts.

        :param id: hostname
        :returns: expected to use HostShowTemplate.
            ex.::

                {'host': {'resource':D},..}
                D: {'host': 'hostname','project': 'admin',
                    'cpu': 1, 'memory_mb': 2048, 'disk_gb': 30}
        """
        context = req.environ['nova.context']
        host_name = id
        try:
            compute_node = (
                objects.ComputeNode.get_first_node_by_host_for_old_compat(
                    context, host_name))
        except exception.NotFound as e:
            raise webob.exc.HTTPNotFound(explanation=e.format_message())
        except exception.AdminRequired:
            msg = _("Describe-resource is admin only functionality")
            raise webob.exc.HTTPForbidden(explanation=msg)
        instances = self.api.instance_get_all_by_host(context, host_name)
        resources = [self._get_total_resources(host_name, compute_node)]
        resources.append(self._get_used_now_resources(host_name,
                                                      compute_node))
        resources.append(self._get_resource_totals_from_instances(host_name,
                                                                  instances))
        by_proj_resources = self._get_resources_by_project(host_name,
                                                           instances)
        for resource in by_proj_resources.itervalues():
            resources.append({'resource': resource})
        return {'host': resources}


class Hosts(extensions.ExtensionDescriptor):
    """Admin-only host administration."""

    name = "Hosts"
    alias = "os-hosts"
    namespace = "http://docs.openstack.org/compute/ext/hosts/api/v1.1"
    updated = "2011-06-29T00:00:00Z"

    def get_resources(self):
        resources = [extensions.ResourceExtension('os-hosts',
                HostController(),
                collection_actions={'update': 'PUT'},
                member_actions={"startup": "GET", "shutdown": "GET",
                        "reboot": "GET"})]
        return resources
