# 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 collections import defaultdict
import itertools
import logging

from django.utils.translation import ugettext_lazy as _

from horizon import exceptions
from horizon.utils.memoized import memoized  # noqa

from openstack_dashboard.api import base
from openstack_dashboard.api import cinder
from openstack_dashboard.api import network
from openstack_dashboard.api import neutron
from openstack_dashboard.api import nova


LOG = logging.getLogger(__name__)


NOVA_QUOTA_FIELDS = ("metadata_items",
                     "cores",
                     "instances",
                     "injected_files",
                     "injected_file_content_bytes",
                     "ram",
                     "floating_ips",
                     "fixed_ips",
                     "security_groups",
                     "security_group_rules",)

MISSING_QUOTA_FIELDS = ("key_pairs",
                        "injected_file_path_bytes",)

CINDER_QUOTA_FIELDS = ("volumes",
                       "snapshots",
                       "gigabytes",)

NEUTRON_QUOTA_FIELDS = ("network",
                        "subnet",
                        "port",
                        "router",
                        "floatingip",
                        "security_group",
                        "security_group_rule",
                        )

QUOTA_FIELDS = NOVA_QUOTA_FIELDS + CINDER_QUOTA_FIELDS + NEUTRON_QUOTA_FIELDS


class QuotaUsage(dict):
    """Tracks quota limit, used, and available for a given set of quotas."""

    def __init__(self):
        self.usages = defaultdict(dict)

    def __contains__(self, key):
        return key in self.usages

    def __getitem__(self, key):
        return self.usages[key]

    def __setitem__(self, key, value):
        raise NotImplementedError("Directly setting QuotaUsage values is not "
                                  "supported. Please use the add_quota and "
                                  "tally methods.")

    def __repr__(self):
        return repr(dict(self.usages))

    def get(self, key, default=None):
        return self.usages.get(key, default)

    def add_quota(self, quota):
        """Adds an internal tracking reference for the given quota."""
        if quota.limit is None or quota.limit == -1:
            # Handle "unlimited" quotas.
            self.usages[quota.name]['quota'] = float("inf")
            self.usages[quota.name]['available'] = float("inf")
        else:
            self.usages[quota.name]['quota'] = int(quota.limit)

    def tally(self, name, value):
        """Adds to the "used" metric for the given quota."""
        value = value or 0  # Protection against None.
        # Start at 0 if this is the first value.
        if 'used' not in self.usages[name]:
            self.usages[name]['used'] = 0
        # Increment our usage and update the "available" metric.
        self.usages[name]['used'] += int(value)  # Fail if can't coerce to int.
        self.update_available(name)

    def update_available(self, name):
        """Updates the "available" metric for the given quota."""
        available = self.usages[name]['quota'] - self.usages[name]['used']
        if available < 0:
            available = 0
        self.usages[name]['available'] = available


def _get_quota_data(request, method_name, disabled_quotas=None,
                    tenant_id=None):
    quotasets = []
    if not tenant_id:
        tenant_id = request.user.tenant_id
    quotasets.append(getattr(nova, method_name)(request, tenant_id))
    qs = base.QuotaSet()
    if disabled_quotas is None:
        disabled_quotas = get_disabled_quotas(request)
    if 'volumes' not in disabled_quotas:
        quotasets.append(getattr(cinder, method_name)(request, tenant_id))
    for quota in itertools.chain(*quotasets):
        if quota.name not in disabled_quotas:
            qs[quota.name] = quota.limit
    return qs


def get_default_quota_data(request, disabled_quotas=None, tenant_id=None):
    return _get_quota_data(request,
                           "default_quota_get",
                           disabled_quotas=disabled_quotas,
                           tenant_id=tenant_id)


def get_tenant_quota_data(request, disabled_quotas=None, tenant_id=None):
    qs = _get_quota_data(request,
                         "tenant_quota_get",
                         disabled_quotas=disabled_quotas,
                         tenant_id=tenant_id)

    # TODO(jpichon): There is no API to get the default system quotas
    # in Neutron (cf. LP#1204956), so for now handle tenant quotas here.
    # This should be handled in _get_quota_data() eventually.
    if disabled_quotas and 'floating_ips' in disabled_quotas:
        # Neutron with quota extension disabled
        if 'floatingip' in disabled_quotas:
            qs.add(base.QuotaSet({'floating_ips': -1}))
        # Neutron with quota extension enabled
        else:
            tenant_id = tenant_id or request.user.tenant_id
            neutron_quotas = neutron.tenant_quota_get(request, tenant_id)
            # Rename floatingip to floating_ips since that's how it's
            # expected in some places (e.g. Security & Access' Floating IPs)
            fips_quota = neutron_quotas.get('floatingip').limit
            qs.add(base.QuotaSet({'floating_ips': fips_quota}))

    return qs


def get_disabled_quotas(request):
    disabled_quotas = []

    # Cinder
    if not base.is_service_enabled(request, 'volume'):
        disabled_quotas.extend(CINDER_QUOTA_FIELDS)

    # Neutron
    if not base.is_service_enabled(request, 'network'):
        disabled_quotas.extend(NEUTRON_QUOTA_FIELDS)
    else:
        # Remove the nova network quotas
        disabled_quotas.extend(['floating_ips', 'fixed_ips'])

        if neutron.is_extension_supported(request, 'security-group'):
            # If Neutron security group is supported, disable Nova quotas
            disabled_quotas.extend(['security_groups', 'security_group_rules'])
        else:
            # If Nova security group is used, disable Neutron quotas
            disabled_quotas.extend(['security_group', 'security_group_rule'])

        try:
            if not neutron.is_quotas_extension_supported(request):
                disabled_quotas.extend(NEUTRON_QUOTA_FIELDS)
        except Exception:
            LOG.exception("There was an error checking if the Neutron "
                          "quotas extension is enabled.")

    return disabled_quotas


@memoized
def tenant_quota_usages(request):
    # Get our quotas and construct our usage object.
    disabled_quotas = get_disabled_quotas(request)

    usages = QuotaUsage()
    for quota in get_tenant_quota_data(request,
                                       disabled_quotas=disabled_quotas):
        usages.add_quota(quota)

    # Get our usages.
    floating_ips = network.tenant_floating_ip_list(request)
    flavors = dict([(f.id, f) for f in nova.flavor_list(request)])
    instances, has_more = nova.server_list(request)
    # Fetch deleted flavors if necessary.
    missing_flavors = [instance.flavor['id'] for instance in instances
                       if instance.flavor['id'] not in flavors]
    for missing in missing_flavors:
        if missing not in flavors:
            try:
                flavors[missing] = nova.flavor_get(request, missing)
            except Exception:
                flavors[missing] = {}
                exceptions.handle(request, ignore=True)

    usages.tally('instances', len(instances))
    usages.tally('floating_ips', len(floating_ips))

    if 'volumes' not in disabled_quotas:
        volumes = cinder.volume_list(request)
        snapshots = cinder.volume_snapshot_list(request)
        usages.tally('gigabytes', sum([int(v.size) for v in volumes]))
        usages.tally('volumes', len(volumes))
        usages.tally('snapshots', len(snapshots))

    # Sum our usage based on the flavors of the instances.
    for flavor in [flavors[instance.flavor['id']] for instance in instances]:
        usages.tally('cores', getattr(flavor, 'vcpus', None))
        usages.tally('ram', getattr(flavor, 'ram', None))

    # Initialise the tally if no instances have been launched yet
    if len(instances) == 0:
        usages.tally('cores', 0)
        usages.tally('ram', 0)

    return usages


def tenant_limit_usages(request):
    # TODO(licostan): This method shall be removed from Quota module.
    # ProjectUsage/BaseUsage maybe used instead on volume/image dashboards.
    limits = {}

    try:
        limits.update(nova.tenant_absolute_limits(request))
    except Exception:
        msg = _("Unable to retrieve compute limit information.")
        exceptions.handle(request, msg)

    if base.is_service_enabled(request, 'volume'):
        try:
            limits.update(cinder.tenant_absolute_limits(request))
            volumes = cinder.volume_list(request)
            snapshots = cinder.volume_snapshot_list(request)
            total_size = sum([getattr(volume, 'size', 0) for volume
                              in volumes])
            limits['gigabytesUsed'] = total_size
            limits['volumesUsed'] = len(volumes)
            limits['snapshotsUsed'] = len(snapshots)
        except Exception:
            msg = _("Unable to retrieve volume limit information.")
            exceptions.handle(request, msg)

    return limits