from django.db.models import Manager

from guardian.shortcuts import get_objects_for_user

from ldt.security import get_current_user, get_anonymous_user

class SafeManager(Manager):

    use_for_related_fields = True

    def __init__(self, check_perm=False):

        super(SafeManager, self).__init__()

        self.check_perm = check_perm

    def get_query_set(self):

        if not self.check_perm:

            return super(SafeManager, self).get_query_set()   

        user = get_current_user()            

        if not user:

            raise AttributeError("No user is attached to the current thread.")

        if not user.is_authenticated():

            user = get_anonymous_user()

        perm_name = '%s.view_%s' % (self.model._meta.app_label, self.model.__name__.lower()) 

        user_objects = get_objects_for_user(user, perm_name, klass=self.model.objects) 

        return user_objects