"""The four shelves of the music library, and how each one differs.

These are folder names, not configuration. The library has one root and the layout
underneath it is fixed - a section that needed configuring would be a section whose
quirks are not understood yet.
"""

from __future__ import annotations

from dataclasses import dataclass
from typing import Final, Literal, TypeAlias

__all__ = ["SECTIONS", "AlbumKind", "ArtistSource", "Section", "TitleSource", "TrackOrder"]

AlbumKind: TypeAlias = Literal["music", "book"]
TrackOrder: TypeAlias = Literal["filename", "newest_first"]
TitleSource: TypeAlias = Literal["tags", "folder"]
ArtistSource: TypeAlias = Literal["tags", "folder"]
AlbumUnit: TypeAlias = Literal["folder", "episode"]


@dataclass(frozen=True, slots=True)
class Section:
    kind: AlbumKind = "music"
    #: Subfolders are figure folders: their name is the figure name from the config.
    figures: bool = False
    order: TrackOrder = "filename"
    title_from: TitleSource = "tags"
    artist_from: ArtistSource = "tags"
    #: "folder" (default): one album per folder, every audio file a track/chapter of it.
    #: "episode": one album per audio *file* - a show folder groups its episodes rather
    #: than being one giant album itself. `title_from`/`artist_from` are not consulted
    #: for this unit: an episode's title always comes from its own tags (or filename),
    #: and the folder always supplies the artist/series, so episodes of the same show
    #: still group together everywhere the browse view groups by category.
    album_unit: AlbumUnit = "folder"


#: ``Kinderpodcasts`` is the odd one out twice over. Its ``artist`` tag is the full
#: presenter list ("Thomas Welling, Sarah Schultes, ...") and its ``album`` tag is the
#: feed name, so neither groups usefully - the folder name is the show. And its files
#: are named ``YYYYMMDD - Title.mp3``, so reversing filename order puts the newest
#: episode first, which is the one anybody wants.
SECTIONS: Final[dict[str, Section]] = {
    # A figure folder is named after the figure, and its contents are whatever that
    # figure should play - often several albums' worth. The folder name is the honest
    # title; the tags still supply a useful artist.
    "Figuren": Section(figures=True, title_from="folder"),
    "Musik": Section(),
    "Hörbücher": Section(kind="book"),
    "Kinderpodcasts": Section(kind="book", order="newest_first", album_unit="episode"),
}