"""yt-dlp integration: download a single YouTube video (or its audio)."""

from __future__ import annotations

import logging
from pathlib import Path
from typing import Optional

import yt_dlp

log = logging.getLogger(__name__)

_BASE_OPTS = {
    "quiet": True,
    "no_warnings": True,
    "noplaylist": True,
    "ignoreerrors": True,
    "no_color": True,
}

# named presets -> yt-dlp format strings. bestvideo+bestaudio requires ffmpeg
# to mux; the trailing /best fallbacks cover formats without a separate stream.
QUALITY_FORMATS = {
    "best": "bestvideo+bestaudio/best",
    "1080": "bestvideo[height<=1080]+bestaudio/best[height<=1080]",
    "720": "bestvideo[height<=720]+bestaudio/best[height<=720]",
    "480": "bestvideo[height<=480]+bestaudio/best[height<=480]",
    "audio": "bestaudio/best",
}

# suffixes yt-dlp leaves behind while downloading / on interrupted runs
_INCOMPLETE = (".part", ".ytdl", ".tmp")


def cookie_opts(cfg) -> dict:
    """yt-dlp options for browser cookies (bot-check mitigation)."""
    opts: dict = {}
    if cfg.cookies_from_browser:
        opts["cookiesfrombrowser"] = (cfg.cookies_from_browser,)
    elif cfg.cookies_file:
        opts["cookiefile"] = cfg.cookies_file
    return opts


def _select_format(quality: str, format_override: Optional[str]) -> str:
    if format_override:
        return format_override
    return QUALITY_FORMATS.get(quality, QUALITY_FORMATS["best"])


def download_video(
    url: str,
    out_dir: Path,
    quality: str = "best",
    format_override: Optional[str] = None,
    extra_opts: dict | None = None,
) -> Optional[Path]:
    """Download a single video into out_dir. Returns the resulting file path."""
    out_dir = out_dir.expanduser()
    out_dir.mkdir(parents=True, exist_ok=True)
    fmt = _select_format(quality, format_override)
    opts = {
        **_BASE_OPTS,
        **(extra_opts or {}),
        "format": fmt,
        "outtmpl": str(out_dir / "%(title).150B [%(id)s].%(ext)s"),
        "nocheckcertificate": True,
    }
    if quality != "audio" and not format_override:
        opts["merge_output_format"] = "mp4"
    try:
        with yt_dlp.YoutubeDL(opts) as ydl:
            info = ydl.extract_info(url, download=True)
        if info is None:
            return None
        actual_id = info.get("id")
        if not actual_id:
            return None
        marker = f" [{actual_id}]."
        for f in out_dir.iterdir():
            if f.is_file() and marker in f.name and f.suffix.lower() not in _INCOMPLETE:
                return f
    except Exception as exc:  # noqa: BLE001
        log.warning("Download failed for %s: %s", url, exc)
        return None
    return None