from django.contrib.auth import get_user_model
from django.contrib.auth.backends import ModelBackend

UserModel = get_user_model()

class OTPBackend(ModelBackend):

    """
    Authenticates against settings.AUTH_USER_MODEL.
    """

    def authenticate(self, request, phone_number=None, otp=None, **kwargs):
        if phone_number is None or otp is None:
            return

        try:
            user = UserModel.objects.get(phone_number=phone_number)
            # user = UserModel._default_manager.get_by_natural_key(phone_number)
        except UserModel.DoesNotExist:
            return

        else:
            if user.check_otp(otp) and self.user_can_authenticate(user):
                return user

    def user_can_authenticate(self, user):
        """
        Reject users with is_active=False. Custom user models that don't have
        that attribute are allowed.
        """
        is_active = getattr(user, 'is_active', None)
        return is_active or is_active is None

    # def _get_user_permissions(self, user_obj):
    #     return user_obj.user_permissions.all()
    #
    # def _get_group_permissions(self, user_obj):
    #     user_groups_field = get_user_model()._meta.get_field('groups')
    #     user_groups_query = 'group__%s' % user_groups_field.related_query_name()
    #     return Permission.objects.filter(**{user_groups_query: user_obj})
    #
    # def _get_permissions(self, user_obj, obj, from_name):
    #     """
    #     Return the permissions of `user_obj` from `from_name`. `from_name` can
    #     be either "group" or "user" to return permissions from
    #     `_get_group_permissions` or `_get_user_permissions` respectively.
    #     """
    #     if not user_obj.is_active or user_obj.is_anonymous or obj is not None:
    #         return set()
    #
    #     perm_cache_name = '_%s_perm_cache' % from_name
    #     if not hasattr(user_obj, perm_cache_name):
    #         if user_obj.is_superuser:
    #             perms = Permission.objects.all()
    #         else:
    #             perms = getattr(self, '_get_%s_permissions' % from_name)(user_obj)
    #         perms = perms.values_list('content_type__app_label', 'codename').order_by()
    #         setattr(user_obj, perm_cache_name, {"%s.%s" % (ct, name) for ct, name in perms})
    #     return getattr(user_obj, perm_cache_name)
    #
    # def get_user_permissions(self, user_obj, obj=None):
    #     """
    #     Return a set of permission strings the user `user_obj` has from their
    #     `user_permissions`.
    #     """
    #     return self._get_permissions(user_obj, obj, 'user')
    #
    # def get_group_permissions(self, user_obj, obj=None):
    #     """
    #     Return a set of permission strings the user `user_obj` has from the
    #     groups they belong.
    #     """
    #     return self._get_permissions(user_obj, obj, 'group')
    #
    # def get_all_permissions(self, user_obj, obj=None):
    #     if not user_obj.is_active or user_obj.is_anonymous or obj is not None:
    #         return set()
    #     if not hasattr(user_obj, '_perm_cache'):
    #         user_obj._perm_cache = super().get_all_permissions(user_obj)
    #     return user_obj._perm_cache
    #
    # def has_perm(self, user_obj, perm, obj=None):
    #     return user_obj.is_active and super().has_perm(user_obj, perm, obj=obj)
    #
    # def has_module_perms(self, user_obj, app_label):
    #     """
    #     Return True if user_obj has any permissions in the given app_label.
    #     """
    #     return user_obj.is_active and any(
    #         perm[:perm.index('.')] == app_label
    #         for perm in self.get_all_permissions(user_obj)
    #     )
    #
    # def with_perm(self, perm, is_active=True, include_superusers=True, obj=None):
    #     """
    #     Return users that have permission "perm". By default, filter out
    #     inactive users and include superusers.
    #     """
    #     if isinstance(perm, str):
    #         try:
    #             app_label, codename = perm.split('.')
    #         except ValueError:
    #             raise ValueError(
    #                 'Permission name should be in the form '
    #                 'app_label.permission_codename.'
    #             )
    #     elif not isinstance(perm, Permission):
    #         raise TypeError(
    #             'The `perm` argument must be a string or a permission instance.'
    #         )
    #
    #     UserModel = get_user_model()
    #     if obj is not None:
    #         return UserModel._default_manager.none()
    #
    #     permission_q = Q(group__user=OuterRef('pk')) | Q(user=OuterRef('pk'))
    #     if isinstance(perm, Permission):
    #         permission_q &= Q(pk=perm.pk)
    #     else:
    #         permission_q &= Q(codename=codename, content_type__app_label=app_label)
    #
    #     user_q = Exists(Permission.objects.filter(permission_q))
    #     if include_superusers:
    #         user_q |= Q(is_superuser=True)
    #     if is_active is not None:
    #         user_q &= Q(is_active=is_active)
    #
    #     return UserModel._default_manager.filter(user_q)
    #
    # def get_user(self, user_id):
    #     try:
    #         user = UserModel._default_manager.get(pk=user_id)
    #     except UserModel.DoesNotExist:
    #         return None
    #     return user if self.user_can_authenticate(user) else None
    #
    #