from functools import cache

from django.apps import apps as django_apps
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.utils.module_loading import import_string


def get_site_model():
    """
    Returns the configured site model or the default site model `feincms3_sites.Site`.

    A custom site model can be configured in the settings like so
    ```
    FEINCMS3_SITES_SITE_MODEL = 'myapp.CustomSite'
    ```
    """

    model_name = settings.FEINCMS3_SITES_SITE_MODEL
    try:
        return django_apps.get_model(model_name, require_ready=False)
    except ValueError as exc:
        raise ImproperlyConfigured(
            "FEINCMS3_SITES_SITE_MODEL must be of the form 'app_label.model_name'"
        ) from exc
    except LookupError as exc:
        raise ImproperlyConfigured(
            "FEINCMS3_SITES_SITE_MODEL refers to model '%s' that has not been installed"
            % model_name
        ) from exc


@cache
def import_callable(spec):
    return spec if callable(spec) else import_string(spec)