tomi77/django-auth-role

from __future__ import unicode_literals

from django.contrib.auth.backends import ModelBackend
from django.contrib.auth.models import Permission
from django.conf import settings
from django.db.models import Q


class BaseAuthRoleBackend(ModelBackend):
    """
    Base class to authenticates against settings.AUTH_USER_MODEL model
    extended by authrole.Role.
    """
    def fetch_role_permissions(self, user_obj):
        raise NotImplementedError()

    def get_role_permissions(self, user_obj, obj=None):
        """
        Returns a set of permission strings that this user has through his/her
        role.
        """
        if user_obj.is_superuser:
            return set()
        if not hasattr(user_obj, '_role_perm_cache'):
            perms = self.fetch_role_permissions(user_obj) \
                .values_list('content_type__app_label', 'codename') \
                .order_by()
            user_obj._role_perm_cache = set(['%s.%s' % (ct, name)
                                             for ct, name in perms])
        return user_obj._role_perm_cache

    def get_all_permissions(self, user_obj, obj=None):
        if user_obj.is_anonymous() or obj is not None:
            return set()
        user_obj._perm_cache = super(BaseAuthRoleBackend, self) \
            .get_all_permissions(user_obj, obj)
        user_obj._perm_cache.update(self.get_role_permissions(user_obj))
        return user_obj._perm_cache


class ExtendedUserAuthRoleBackend(BaseAuthRoleBackend):
    """
    Authenticates against 'auth.User' model extended by authrole.Role.
    """
    def fetch_role_permissions(self, user_obj):
        return Permission.objects.filter(
            Q(group__roles__users__user=user_obj) |
            Q(roles__users__user=user_obj)
        )


class OverriddenUserAuthRoleBackend(BaseAuthRoleBackend):
    """
    Authenticates against settings.AUTH_USER_MODEL (not 'auth.User') model
    with authrole.Role field.
    """
    def fetch_role_permissions(self, user_obj):
        return Permission.objects.filter(
            Q(group__roles__users=user_obj) | Q(roles__users=user_obj)
        )


if getattr(settings, 'AUTH_USER_MODEL', 'auth.User') == 'auth.User':
    class AuthRoleBackend(ExtendedUserAuthRoleBackend):
        pass
else:
    class AuthRoleBackend(OverriddenUserAuthRoleBackend):
        pass