"""
Celery задачи для модуля communications
"""

import logging
from datetime import timedelta

from celery import shared_task
from django.db import transaction
from django.utils import timezone

logger = logging.getLogger(__name__)


@shared_task
def cleanup_orphaned_attachments():
    """
    Очистка временных вложений без привязки к сообщению.
    Удаляет MessageAttachment с message=null старше 1 часа.
    """
    from communications.models import MessageAttachment

    cutoff_time = timezone.now() - timedelta(hours=1)

    orphaned = MessageAttachment.objects.filter(
        message__isnull=True, uploaded_at__lt=cutoff_time
    )

    count = 0
    # Candidate IDs are only hints. An upload may be claimed while this task is
    # running, so recheck it under the same row lock used by message edits.
    for attachment_id in orphaned.values_list("pk", flat=True).iterator(chunk_size=200):
        try:
            with transaction.atomic():
                attachment = (
                    MessageAttachment.objects.select_for_update(skip_locked=True)
                    .filter(
                        pk=attachment_id,
                        message__isnull=True,
                        uploaded_at__lt=cutoff_time,
                    )
                    .first()
                )
                if attachment is None:
                    continue
                files = [
                    (file.storage, file.name)
                    for file in (attachment.file, attachment.thumbnail)
                    if file
                ]
                attachment.delete()
                for storage, name in files:
                    transaction.on_commit(
                        lambda storage=storage, name=name: storage.delete(name),
                        robust=True,
                    )
            count += 1
        except Exception as exc:
            logger.exception(
                "Orphaned chat attachment deletion failed",
                extra={
                    "event": "chat.attachment_cleanup.item_failed",
                    "attachment_id": attachment_id,
                    "error_type": type(exc).__name__,
                },
            )

    if count:
        logger.info(
            "Orphaned chat attachment cleanup completed",
            extra={
                "event": "chat.attachment_cleanup.completed",
                "attachment_count": count,
            },
        )

    return count