from django.contrib.auth import REDIRECT_FIELD_NAME
from django.shortcuts import render_to_response
from django.template import RequestContext

def user_passes_test_with_403(test_func, login_url=None):
    """
    Decorator for views that checks that the user passes the given test.
    
    Anonymous users will be redirected to login_url, while users that fail
    the test will be given a 403 error.
    """
    if not login_url:
        from django.conf import settings
        login_url = settings.LOGIN_URL
    def _dec(view_func):
        def _checklogin(request, *args, **kwargs):
            if test_func(request.user):
                return view_func(request, *args, **kwargs)
            elif not request.user.is_authenticated():
                return HttpResponseRedirect('%s?%s=%s' % (login_url, REDIRECT_FIELD_NAME, quote(request.get_full_path())))
            else:
                resp = render_to_response('403.html', context_instance=RequestContext(request))
                resp.status_code = 403
                return resp
        _checklogin.__doc__ = view_func.__doc__
        _checklogin.__dict__ = view_func.__dict__
        return _checklogin
    return _dec

def permission_required_with_403(perm, login_url=None):
    """
    Decorator for views that checks whether a user has a particular permission
    enabled, redirecting to the log-in page or rendering a 403 as necessary.
    """
    return user_passes_test_with_403(lambda u: u.has_perm(perm), login_url=login_url)