# Copyright (c) 2013 Intel, Inc.
# Copyright (c) 2013 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.

from oslo_serialization import jsonutils

import nova.conf
from nova import exception
from nova.i18n import _
from nova.pci import devspec

CONF = nova.conf.CONF


class Whitelist(object):

    """White list class to represent assignable pci devices.

    Not all devices on a compute node can be assigned to a guest. The
    cloud administrator decides which devices can be assigned
    based on vendor_id or product_id, etc. If no white list is specified,
    no devices will be assignable.
    """

    @staticmethod
    def _parse_white_list_from_config(whitelists):
        """Parse and validate the pci whitelist from the nova config."""
        specs = []
        for jsonspec in whitelists:
            try:
                dev_spec = jsonutils.loads(jsonspec)
            except ValueError:
                raise exception.PciConfigInvalidWhitelist(
                          reason=_("Invalid entry: '%s'") % jsonspec)
            if isinstance(dev_spec, dict):
                dev_spec = [dev_spec]
            elif not isinstance(dev_spec, list):
                raise exception.PciConfigInvalidWhitelist(
                          reason=_("Invalid entry: '%s'; "
                                   "Expecting list or dict") % jsonspec)

            for ds in dev_spec:
                if not isinstance(ds, dict):
                    raise exception.PciConfigInvalidWhitelist(
                              reason=_("Invalid entry: '%s'; "
                                       "Expecting dict") % ds)

                spec = devspec.PciDeviceSpec(ds)
                specs.append(spec)

        return specs

    def __init__(self, whitelist_spec=None):
        """White list constructor

        For example, the following json string specifies that devices whose
        vendor_id is '8086' and product_id is '1520' can be assigned
        to guests.
        '[{"product_id":"1520", "vendor_id":"8086"}]'

        :param whitelist_spec: A json string for a dictionary or list thereof.
                               Each dictionary specifies the pci device
                               properties requirement. See the definition of
                               passthrough_whitelist in nova.conf.pci for
                               details and examples.
        """
        super(Whitelist, self).__init__()
        if whitelist_spec:
            self.specs = self._parse_white_list_from_config(whitelist_spec)
        else:
            self.specs = []

    def device_assignable(self, dev):
        """Check if a device can be assigned to a guest.

        :param dev: A dictionary describing the device properties
        """
        for spec in self.specs:
            if spec.match(dev):
                return True
        return False

    def get_devspec(self, pci_dev):
        for spec in self.specs:
            if spec.match_pci_obj(pci_dev):
                return spec