from django.shortcuts import get_object_or_404

from .models import Event
from .scoping import current_event


class EventContextMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        try:
            return self.get_response(request)
        finally:
            # Not current_event.reset(token): under ASGI, process_view and this
            # finally block can run in different contextvars.Context copies
            # (sync_to_async(thread_sensitive=True) copies the context), and
            # Token.reset() requires the exact Context it was created in.
            # set(None) has no such constraint.
            current_event.set(None)

    def process_view(self, request, view_func, view_args, view_kwargs):
        event_path = view_kwargs.get("event_path")
        if event_path:
            request.event = get_object_or_404(
                Event.objects.available_to(getattr(request, "user", None)),
                path=event_path,
            )
            current_event.set(request.event)
        return None