# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2014 IBM Corporation
# Copyright 2015-2016 Lenovo
#
# 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 re

numregex = re.compile('([0-9]+)')


def naturalize_string(key):
    """Analyzes string in a human way to enable natural sort

    :param key: The node name to analyze
    :returns: A structure that can be consumed by 'sorted'
    """
    return [int(text) if text.isdigit() else text.lower()
            for text in re.split(numregex, key)]


def natural_sort(iterable):
    """Return a sort using natural sort if possible

    :param iterable:
    :return:
    """
    try:
        return sorted(iterable, key=naturalize_string)
    except TypeError:
        # The natural sort attempt failed, fallback to ascii sort
        return sorted(iterable)