try:

    from functools import update_wrapper

except ImportError:

    from django.utils.functional import update_wrapper  # Python 2.3, 2.4 fallback.

from django.contrib.auth import REDIRECT_FIELD_NAME

from django.http import HttpResponseRedirect

from django.utils.http import urlquote

def user_passes_test(test_func, login_url=None, redirect_field_name=REDIRECT_FIELD_NAME):

    """

    Decorator for views that checks that the user passes the given test,

    redirecting to the log-in page if necessary. The test should be a callable

    that takes the user object and returns True if the user passes.

    """

    def decorate(view_func):

        return _CheckLogin(view_func, test_func, login_url, redirect_field_name)

    return decorate

def login_required(function=None, redirect_field_name=REDIRECT_FIELD_NAME):

    """

    Decorator for views that checks that the user is logged in, redirecting

    to the log-in page if necessary.

    """

    actual_decorator = user_passes_test(

        lambda u: u.is_authenticated(),

        redirect_field_name=redirect_field_name

    )

    if function:

        return actual_decorator(function)

    return actual_decorator

def permission_required(perm, login_url=None):

    """

    Decorator for views that checks whether a user has a particular permission

    enabled, redirecting to the log-in page if necessary.

    """

    return user_passes_test(lambda u: u.has_perm(perm), login_url=login_url)

class _CheckLogin(object):

    """

    Class that checks that the user passes the given test, redirecting to

    the log-in page if necessary. If the test is passed, the view function

    is invoked. The test should be a callable that takes the user object

    and returns True if the user passes.

    We use a class here so that we can define __get__. This way, when a

    _CheckLogin object is used as a method decorator, the view function

    is properly bound to its instance.

    """

    def __init__(self, view_func, test_func, login_url=None, redirect_field_name=REDIRECT_FIELD_NAME):

        if not login_url:

            from django.conf import settings

            login_url = settings.LOGIN_URL

        self.view_func = view_func

        self.test_func = test_func

        self.login_url = login_url

        self.redirect_field_name = redirect_field_name

        # We can't blindly apply update_wrapper because it udpates __dict__ and 

        # if the view function is already a _CheckLogin object then 

        # self.test_func and friends will get stomped. However, we also can't 

        # *not* update the wrapper's dict because then view function attributes

        # don't get updated into the wrapper. So we need to split the

        # difference: don't let update_wrapper update __dict__, but then update

        # the (parts of) __dict__ that we care about ourselves.

        update_wrapper(self, view_func, updated=())

        for k in view_func.__dict__:

            if k not in self.__dict__:

                self.__dict__[k] = view_func.__dict__[k]

    def __get__(self, obj, cls=None):

        view_func = self.view_func.__get__(obj, cls)

        return _CheckLogin(view_func, self.test_func, self.login_url, self.redirect_field_name)

    def __call__(self, request, *args, **kwargs):

        if self.test_func(request.user):

            return self.view_func(request, *args, **kwargs)

        path = urlquote(request.get_full_path())

        tup = self.login_url, self.redirect_field_name, path

        return HttpResponseRedirect('%s?%s=%s' % tup)