from django.http import HttpResponseRedirect
from django.conf import settings
from re import compile
from django.core.urlresolvers import reverse

EXEMPT_URLS = [reverse('login'),reverse('logout')]

if hasattr(settings, 'LOGIN_EXEMPT_URLS'):
    EXEMPT_URLS += settings.LOGIN_EXEMPT_URLS

"""
Middleware that requires a user to be authenticated to view any page other
than LOGIN_URL. Exemptions to this requirement can optionally be specified
in settings via a list of regular expressions in LOGIN_EXEMPT_URLS (which
you can copy from your urls.py).

Requires authentication middleware and template context processors to be
loaded. You'll get an error if they aren't.
"""
class LoginRequiredMiddleware(object):
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        if not request.user or not request.user.is_authenticated():
            path = request.path_info
            if path not in EXEMPT_URLS:
                login_uri = '%s?next=%s' % (settings.LOGIN_URL, request.path_info)
                return HttpResponseRedirect(login_uri)

        return self.get_response(request)