from celery import shared_task, chain, group, chord
from celery.exceptions import MaxRetriesExceededError
from celery.result import AsyncResult
from django.db import transaction
import logging
 
logger = logging.getLogger(__name__)
 
@shared_task(bind=True, max_retries=3, default_retry_delay=60)
def process_article(self, article_id):
    try:
        article = Article.objects.get(id=article_id)
        article.status = 'processing'
        article.save()
        return {'article_id': article_id, 'status': 'processed'}
    except Article.DoesNotExist:
        raise self.retry(exc=Exception(f'Article {article_id} not found'), countdown=120)
 
@shared_task(bind=True, max_retries=5)
def generate_thumbnail(self, article_data):
    if not article_data.get('has_image'):
        return {'skipped': True, 'reason': 'no_image'}
    # Simulate thumbnail generation
    return {'article_id': article_data['article_id'], 'thumbnail': 'generated'}
 
@shared_task
def notify_subscribers(article_data):
    logger.info(f'Notifying subscribers for article {article_data["article_id"]}')
    return {'notified': True}
 
def article_publishing_workflow(article_id):
    workflow = chain(
        process_article.s(article_id),
        generate_thumbnail.s(),
        notify_subscribers.s()
    )
    result = workflow.apply_async(expires=7200, link_error=notify_failure.s())
    return result.id
 
def bulk_publish_articles(article_ids):
    job = group(
        article_publishing_workflow.si(aid) for aid in article_ids
    )
    return job.apply_async()
 
@shared_task
def notify_failure(request, exc, traceback):
    logger.error(f'Task {request.id} failed: {exc}')
    # Send alert to monitoring system
    return {'task_id': request.id, 'error': str(exc)}