from django.conf import settings
from django.conf.urls import handler404, handler500, include
from django.contrib.auth import get_user_model
from django.contrib.auth.models import AnonymousUser, Group, Permission

__all__ = [
    'Group',
    'Permission',
    'AnonymousUser',
    'get_user_model',
    'user_model_label',
    'include',
    'handler404',
    'handler500',
]

# Since get_user_model() causes a circular import if called when app models are
# being loaded, the user_model_label should be used when possible, with calls
# to get_user_model deferred to execution time

user_model_label = getattr(settings, 'AUTH_USER_MODEL', 'auth.User')


def get_user_model_path():
    """
    Returns 'app_label.ModelName' for User model. Basically if
    ``AUTH_USER_MODEL`` is set at settings it would be returned, otherwise
    ``auth.User`` is returned.
    """
    return getattr(settings, 'AUTH_USER_MODEL', 'auth.User')


def get_user_permission_full_codename(perm):
    """
    Returns 'app_label.<perm>_<usermodulename>'. If standard ``auth.User`` is
    used, for 'change' perm this would return ``auth.change_user`` and if
    ``myapp.CustomUser`` is used it would return ``myapp.change_customuser``.
    """
    User = get_user_model()
    model_name = User._meta.model_name
    return '{}.{}_{}'.format(User._meta.app_label, perm, model_name)


def get_user_permission_codename(perm):
    """
    Returns '<perm>_<usermodulename>'. If standard ``auth.User`` is
    used, for 'change' perm this would return ``change_user`` and if
    ``myapp.CustomUser`` is used it would return ``change_customuser``.
    """
    return get_user_permission_full_codename(perm).split('.')[1]