"""M3U-Playlist-Generierung für Jellyfin."""

from __future__ import annotations

import logging
from pathlib import Path

from musiksammlung.models import Album
from musiksammlung.organizer import sanitize_filename

logger = logging.getLogger(__name__)


def generate_playlist(album: Album, album_dir: Path) -> Path:
    """Erzeugt eine M3U-Playlist für das gesamte Album.

    Die Playlist liegt im Album-Root und referenziert alle Tracks
    über relative Pfade (CD1/01 Titel.flac, CD2/01 Titel.flac, ...).

    Returns:
        Pfad zur erzeugten Playlist-Datei.
    """
    playlist_name = sanitize_filename(album.album) + ".m3u"
    playlist_path = album_dir / playlist_name
    multi_disc = len(album.discs) > 1

    lines = ["#EXTM3U"]

    for disc in album.discs:
        if multi_disc:
            disc_prefix = f"CD{disc.disc_number}/"
        else:
            disc_prefix = ""

        for track in disc.tracks:
            safe_title = sanitize_filename(track.title)
            # Audiodatei im Zielverzeichnis finden
            pattern = f"{track.track_number:02d}_-_{safe_title}*"
            if multi_disc:
                search_dir = album_dir / f"CD{disc.disc_number}"
            else:
                search_dir = album_dir

            matches = list(search_dir.glob(pattern))
            if matches:
                filename = matches[0].name
            else:
                # Fallback: generischer Name mit .flac
                filename = f"{track.track_number:02d}_-_{safe_title}.flac"
                logger.warning("Datei nicht gefunden, Fallback: %s", filename)

            lines.append(f"#EXTINF:0,{track.title}")
            lines.append(f"{disc_prefix}{filename}")

    playlist_path.write_text("\n".join(lines) + "\n", encoding="utf-8")
    logger.info("Playlist erstellt: %s", playlist_path)
    return playlist_path