"""`python manage.py cleanup_stale` -- implements plan.md §7.6.

Permanently deletes submissions that have been stuck in `identifying`
(guest awaiting email confirmation) or `rejected` (auto- or operator-
rejected) for longer than the TTL window (default 24 h). Both the DB row
and any uploaded `.stl` file under `MEDIA_ROOT` are removed -- the
file-on-disk side is handled by the `post_delete` signal in
`apps/submissions/signals.py`.

Designed to be invoked on a loop from a sidecar service (plan.md §10):

    while true; do python manage.py cleanup_stale; sleep 300; done
"""

from __future__ import annotations

from datetime import timedelta

from django.core.management.base import BaseCommand
from django.db.models import Q
from django.utils import timezone

from apps.submissions.models import Submission


class Command(BaseCommand):
    help = (
        "Delete submissions stuck in `identifying` or `rejected` for more "
        "than --ttl-hours. Removes both the DB row and any uploaded STL."
    )

    def add_arguments(self, parser) -> None:
        parser.add_argument(
            "--ttl-hours",
            type=int,
            default=24,
            help="How long a row can sit in `identifying` / `rejected` before "
            "being deleted. Default: 24, matching plan.md §7.6.",
        )
        parser.add_argument(
            "--dry-run",
            action="store_true",
            help="Report what would be deleted but make no changes.",
        )

    def handle(self, *args, ttl_hours: int, dry_run: bool, **opts) -> None:
        cutoff = timezone.now() - timedelta(hours=ttl_hours)
        # `identifying` rows are aged off `created_at` (the row hasn't moved
        # state since it was created). `rejected` rows are aged off
        # `closed_at` (the moment the operator or auto-validator closed them).
        stale = Submission.objects.filter(
            Q(status=Submission.Status.IDENTIFYING, created_at__lt=cutoff)
            | Q(status=Submission.Status.REJECTED, closed_at__lt=cutoff)
        )

        if dry_run:
            count = stale.count()
            self.stdout.write(
                f"DRY RUN: would delete {count} stale submission(s) older than "
                f"{ttl_hours} h."
            )
            for sub in stale:
                self.stdout.write(f"  - {sub.slug} ({sub.status})")
            return

        # `QuerySet.delete()` fires `post_delete` per row, which is how the
        # uploaded `.stl` file gets unlinked from MEDIA_ROOT (see signals.py).
        total, _by_model = stale.delete()
        if total:
            self.stdout.write(
                self.style.SUCCESS(
                    f"Deleted {total} stale submission(s) older than {ttl_hours} h."
                )
            )