#    Copyright 2012 OpenStack LLC
#
#    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 os
import re
import sys


class HookableMixin(object):
    """Mixin so classes can register and run hooks."""
    _hooks_map = {}

    @classmethod
    def add_hook(cls, hook_type, hook_func):
        if hook_type not in cls._hooks_map:
            cls._hooks_map[hook_type] = []

        cls._hooks_map[hook_type].append(hook_func)

    @classmethod
    def run_hooks(cls, hook_type, *args, **kwargs):
        hook_funcs = cls._hooks_map.get(hook_type) or []
        for hook_func in hook_funcs:
            hook_func(*args, **kwargs)


def env(*vars, **kwargs):
    """
    returns the first environment variable set
    if none are non-empty, defaults to '' or keyword arg default
    """
    for v in vars:
        value = os.environ.get(v, None)
        if value:
            return value
    return kwargs.get('default', '')


_slugify_strip_re = re.compile(r'[^\w\s-]')
_slugify_hyphenate_re = re.compile(r'[-\s]+')


# http://code.activestate.com/recipes/
#   577257-slugify-make-a-string-usable-in-a-url-or-filename/
def slugify(value):
    """
    Normalizes string, converts to lowercase, removes non-alpha characters,
    and converts spaces to hyphens.

    From Django's "django/template/defaultfilters.py".
    """
    import unicodedata
    if not isinstance(value, unicode):
        value = unicode(value)
    value = unicodedata.normalize('NFKD', value).encode('ascii', 'ignore')
    value = unicode(_slugify_strip_re.sub('', value).strip().lower())
    return _slugify_hyphenate_re.sub('-', value)