import unicodedata, re

from django.utils.encoding import smart_text
from django.core.exceptions import ObjectDoesNotExist

def unique_slug(queryset, slug_field, slug):
    """
    Ensures a slug is unique for the given queryset, appending
    an integer to its end until the slug is unique.
    """
    i = 0
    while True:
        if i > 0:
            if i > 1:
                slug = slug.rsplit("-", 1)[0]
            slug = "%s-%s" % (slug, i)
        try:
            queryset.get(**{slug_field: slug})
        except ObjectDoesNotExist:
            break
        i += 1
    return slug

def slugify(s):
    """
    Replacement for Django's slugify which allows unicode chars in
    slugs, for URLs in Chinese, Russian, etc.
    Adopted from https://github.com/mozilla/unicode-slugify/
    """
    chars = []
    for char in smart_text(s):
        cat = unicodedata.category(char)[0]
        if cat in "LN" or char in "-_~":
            chars.append(char)
        elif cat == "Z":
            chars.append(" ")
    return re.sub("[-\s]+", "-", "".join(chars).strip()).lower()