"""Download captions with yt-dlp, optionally with cookies.  pip install yt-dlp"""
import sys
import yt_dlp

def download_subs(url, cookiefile=None, langs=("en",)):
    opts = {
        "skip_download": True,
        "writesubtitles": True,
        "writeautomaticsub": True,
        "subtitleslangs": list(langs),
        "subtitlesformat": "vtt",
        "outtmpl": "%(id)s.%(ext)s",
        "quiet": True,
    }
    if cookiefile:
        opts["cookiefile"] = cookiefile
    with yt_dlp.YoutubeDL(opts) as ydl:
        return ydl.extract_info(url, download=True)

if __name__ == "__main__":
    try:
        info = download_subs(sys.argv[1], cookiefile=(sys.argv[2] if len(sys.argv) > 2 else None))
        print("saved:", list((info.get("requested_subtitles") or {}).keys()))
    except yt_dlp.utils.DownloadError as e:
        if "not a bot" in str(e):
            print("BLOCKED: YouTube wants sign-in from this IP (bot check)")
        else:
            raise