from django.apps import apps

from wagtail.wagtailcore.models import Collection, Page


def get_kfet_root_page():
    """
    Returns the K-Fêt root page, or 'None' if it does not exist.
    """
    from .models import KFetPage
    return KFetPage.objects.first()


def get_kfet_root_collection():
    """
    Returns the K-Fêt root collection, or 'None' if it does not exist.
    """
    return Collection.objects.filter(name='K-Fêt').first()


def get_page_model_names():
    """
    Returns all model names of `Page` subclasses.

    This uses the django apps registry (instead of `ContentType.objects.all()`)
    in order to be usuable even before migrations are applied. E.g. this can be
    used in `Field.__init__`.

    Note these model names are the same in `model` attribute of `ContentType`
    objects.
    """
    return [
        model._meta.model_name
        for model in apps.get_models() if issubclass(model, Page)
    ]