import re
import unicodedata
from django.middleware.csrf import _sanitize_token, _compare_salted_tokens
from django.conf import settings
from django.core.exceptions import PermissionDenied

SLUG_OK = '-_~'

def slugify(s, ok=SLUG_OK, lower=True, spaces=False):
    # L and N signify letter/number.
    # http://www.unicode.org/reports/tr44/tr44-4.html#GC_Values_Table
    rv = []
    s = re.sub('\s*&\s*', ' and ', s)
    for c in unicodedata.normalize('NFKC', s):
        cat = unicodedata.category(c)[0]
        if cat in 'LN' or c in ok:
            rv.append(c)
        if cat == 'Z':  # space
            rv.append(' ')
    new = ''.join(rv).strip()
    if not spaces:
        new = re.sub('[-\s]+', '-', new)
    return new.lower() if lower else new


def verify_csrf(token_key='csrftoken'):

    def wrap_view(view_func):
        def check_csrf_token(request, *args, **kwargs):
            csrf_token = _sanitize_token(request.GET.get(token_key, ''))
            match = _compare_salted_tokens(csrf_token, request.COOKIES.get(settings.CSRF_COOKIE_NAME, ''))
            if not match:
                raise PermissionDenied
            else:
                return view_func(request, *args, **kwargs)

        return  check_csrf_token
    return wrap_view