from sqlalchemy import select
from sqlalchemy.orm import Session

from app.models.category import Category
from app.models.channel import Channel
from app.models.channel_category import channel_categories
from app.models.download_job import DownloadJob
from app.models.video import Video


def channel_categories_map(db: Session, channel_ids: list[int]) -> dict[int, list[dict]]:
    if not channel_ids:
        return {}
    rows = db.execute(
        select(channel_categories.c.channel_id, Category.id, Category.name)
        .join(Category, Category.id == channel_categories.c.category_id)
        .where(channel_categories.c.channel_id.in_(channel_ids))
    ).all()
    result: dict[int, list[dict]] = {}
    for channel_id, category_id, category_name in rows:
        result.setdefault(channel_id, []).append({"id": category_id, "name": category_name})
    return result


def _serialize_local(job: DownloadJob | None) -> dict:
    if job is None:
        return {"available": False, "status": "not_downloaded", "progress_percent": None, "media_url": None}
    if job.status == "completed":
        return {"available": True, "status": "completed", "progress_percent": 100, "media_url": job.media_url}
    return {
        "available": False,
        "status": job.status,
        "progress_percent": job.progress_percent,
        "media_url": None,
    }


def serialize_video(
    video: Video, channel: Channel, categories: list[dict], download_job: DownloadJob | None = None
) -> dict:
    return {
        "youtube_video_id": video.youtube_video_id,
        "title": video.title,
        "description": video.description,
        "channel": {
            "id": channel.id,
            "youtube_channel_id": channel.youtube_channel_id,
            "title": channel.title,
            "thumbnail_url": channel.thumbnail_url,
        },
        "thumbnail_url": video.thumbnail_url,
        "published_at": video.published_at,
        "duration_seconds": video.duration_seconds,
        "youtube_url": video.youtube_url,
        "categories": categories,
        "local": _serialize_local(download_job),
    }