# scraper/tasks/pipeline.py

"""
Build the pipeline for a single chapter:
download → parse → save

This module must NOT import scraping.py or controllers,
otherwise Celery will hit circular imports on worker startup.
Only import task functions here.
"""

from celery import chain

from scraper.tasks.download_tasks import download_chapter
from scraper.tasks.parse_tasks import parse_chapter
from scraper.tasks.save_tasks import save_chapter


def build_chapter_pipeline(
    chapter_number: int, chapter_url: str, base_path: str, meta: dict
):
    """
    Construct a Celery chain for one chapter:
      1. download_chapter
      2. parse_chapter
      3. save_chapter
    """

    return chain(
        # download_chapter needs ALL THREE arguments
        download_chapter.s(chapter_number, chapter_url, base_path),
        # parse_chapter gets the output of download_chapter + meta as extra arg
        parse_chapter.s(meta),
        # save_chapter needs base_path as extra arg
        save_chapter.s(base_path),
    )