# Copyright 2017 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.

import logging

from sushy import exceptions

LOG = logging.getLogger(__name__)


def revert_dictionary(dictionary):
    """Given a dictionary revert it's mapping

    :param dictionary: A dictionary to be reverted
    :returns: A dictionary with the keys and values reverted

    """
    return {v: k for k, v in dictionary.items()}


def get_members_identities(members):
    """Extract and return a tuple of members identities

    :param members: A list of members in JSON format
    :returns: A tuple containing the members paths

    """
    members_list = []
    for member in members:
        path = member.get('@odata.id')
        if not path:
            LOG.warning('Could not find the \'@odata.id\' attribute for '
                        'member %s', member)
            continue
        members_list.append(path.rstrip('/'))

    return tuple(members_list)


def int_or_none(x):
    """Given a value x it cast as int or None

    :param x: The value to transform and return
    :returns: Either None or x cast to an int

    """
    if x is None:
        return None
    return int(x)


def get_sub_resource_path_by(resource, subresource_name):
    """Helper function to find the subresource path

    :param resource: ResourceBase instance on which the name
        gets queried upon.
    :param subresource_name: name of the resource field to
        fetch the '@odata.id' from.
    """
    if not subresource_name:
        raise ValueError('"subresource_name" cannot be empty')

    if not isinstance(subresource_name, list):
        subresource_name = [subresource_name]

    body = resource.json
    for path_item in subresource_name:
        body = body.get(path_item, {})

    if not body:
        raise exceptions.MissingAttributeError(
            attribute='/'.join(subresource_name), resource=resource.path)

    if '@odata.id' not in body:
        raise exceptions.MissingAttributeError(
            attribute='/'.join(subresource_name) + '/@odata.id',
            resource=resource.path)

    return body['@odata.id']


def max_safe(iterable, default=0):
    """Helper wrapper over builtin max() function.

    This function is just a wrapper over builtin max() w/o ``key`` argument.
    The ``default`` argument specifies an object to return if the provided
    ``iterable`` is empty. Also it filters out the None type values.
    :param iterable: an iterable
    :param default: 0 by default
    """

    try:
        return max(x for x in iterable if x is not None)
    except ValueError:
        # TypeError is not caught here as that should be thrown.
        return default