from __future__ import annotations

from functools import lru_cache

from django.db.models.signals import pre_save
from django.dispatch import receiver
from wagtail.models import Page
from wagtail.snippets.models import get_snippet_models

from .validators.multilingual import validate_instance_or_raise


@lru_cache(maxsize=1)
def _snippet_models():
    return tuple(get_snippet_models())


def _is_snippet_instance(instance) -> bool:
    instance_model = instance.__class__
    return any(model == instance_model for model in _snippet_models())


@receiver(pre_save)
def enforce_multilingual_integrity(sender, instance, **kwargs):
    if isinstance(instance, Page) or _is_snippet_instance(instance):
        validate_instance_or_raise(instance)