# Copyright 2014 Hewlett-Packard Development Company, L.P.
# Copyright 2014 Red Hat, Inc.
# 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.
#
"""
Helper classes for Ironic HTTP PATCH creation.
"""

from oslo_serialization import jsonutils


import nova.conf

CONF = nova.conf.CONF


def create(node):
    """Create an instance of the appropriate DriverFields class.

    :param node: a node object returned from openstacksdk
    :returns: A GenericDriverFields instance.
    """
    return GenericDriverFields(node)


class GenericDriverFields(object):

    def __init__(self, node):
        self.node = node

    def get_deploy_patch(self, instance, image_meta, flavor,
                         preserve_ephemeral=None, boot_from_volume=False):
        """Build a patch to add the required fields to deploy a node.

        :param instance: the instance object.
        :param image_meta: the nova.objects.ImageMeta object instance
        :param flavor: the flavor object.
        :param preserve_ephemeral: preserve_ephemeral status (bool) to be
                                   specified during rebuild.
        :param boot_from_volume: True if node boots from volume. Then,
                                 image_source is not passed to ironic.
        :returns: a json-patch with the fields that needs to be updated.

        """
        patch = []
        if not boot_from_volume:
            patch.append({'path': '/instance_info/image_source', 'op': 'add',
                          'value': image_meta.id})
        patch.append({'path': '/instance_info/root_gb', 'op': 'add',
                      'value': str(instance.flavor.root_gb)})
        patch.append({'path': '/instance_info/swap_mb', 'op': 'add',
                      'value': str(flavor['swap'])})
        patch.append({'path': '/instance_info/display_name',
                      'op': 'add', 'value': instance.display_name})
        patch.append({'path': '/instance_info/vcpus', 'op': 'add',
                      'value': str(instance.flavor.vcpus)})
        patch.append({'path': '/instance_info/nova_host_id', 'op': 'add',
                      'value': instance.get('host')})
        patch.append({'path': '/instance_info/memory_mb', 'op': 'add',
                      'value': str(instance.flavor.memory_mb)})
        patch.append({'path': '/instance_info/local_gb', 'op': 'add',
                      'value': str(self.node.properties.get('local_gb', 0))})

        if instance.flavor.ephemeral_gb:
            patch.append({'path': '/instance_info/ephemeral_gb',
                          'op': 'add',
                          'value': str(instance.flavor.ephemeral_gb)})
            if CONF.default_ephemeral_format:
                patch.append({'path': '/instance_info/ephemeral_format',
                              'op': 'add',
                              'value': CONF.default_ephemeral_format})

        if preserve_ephemeral is not None:
            patch.append({'path': '/instance_info/preserve_ephemeral',
                          'op': 'add', 'value': str(preserve_ephemeral)})

        # read the flavor and get the extra_specs value.
        extra_specs = flavor.get('extra_specs')

        # scan through the extra_specs values and ignore the keys
        # not starting with keyword 'capabilities' and 'trait'
        capabilities = {}
        traits = []
        for key, val in extra_specs.items():
            # NOTE(mgoddard): For traits we need to support granular resource
            # request syntax, where the 'trait' prefix may be followed by a
            # numeric suffix: trait$N. For ironic we do not care about the
            # group number.
            if key.startswith('capabilities:') or key.startswith('trait'):
                # get the actual key.
                prefix, parsed_key = key.split(':', 1)
                if prefix == "capabilities":
                    capabilities[parsed_key] = val
                else:
                    # NOTE(mgoddard): Currently, the value must be 'required'.
                    # We do not need to pass the value to ironic. When the
                    # value can be something other than 'required', we may need
                    # to filter out traits not supported by the node.
                    if val == 'required':
                        traits.append(parsed_key)
        traits.extend(image_meta.properties.get('traits_required', []))
        if capabilities:
            patch.append({'path': '/instance_info/capabilities',
                          'op': 'add', 'value': jsonutils.dumps(capabilities)})
        if traits:
            # NOTE(mgoddard): Don't JSON encode the traits list - ironic
            # expects instance_info.traits to be a list.
            patch.append({'path': '/instance_info/traits',
                          'op': 'add', 'value': traits})
        return patch
