"""Album repository — adapter over ``AsyncSession``."""

import uuid

from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.domain.entities.album import Album
from app.infrastructure.db.models.album import AlbumModel
from app.infrastructure.db.models.track import TrackModel


def _to_entity(row: AlbumModel) -> Album:
    return Album(
        id=row.id,
        title=row.title,
        artist_id=row.artist_id,
        year=row.year,
        cover_path=row.cover_path,
        musicbrainz_id=row.musicbrainz_id,
        created_at=row.created_at,
        updated_at=row.updated_at,
    )


class SqlAlchemyAlbumRepository:
    def __init__(self, session: AsyncSession) -> None:
        self._session = session

    async def get_or_create(
        self,
        *,
        title: str,
        artist_id: uuid.UUID,
        year: int | None,
        musicbrainz_id: str | None,
    ) -> Album:
        """Resolve an album by ``(title, artist_id)``, creating it if absent.
        Backfills ``year``/``musicbrainz_id`` onto an existing row when it lacks
        them and enrichment now has values (gap-fill, never overwrite)."""
        row = (
            await self._session.execute(
                select(AlbumModel).where(
                    AlbumModel.title == title,
                    AlbumModel.artist_id == artist_id,
                )
            )
        ).scalar_one_or_none()
        if row is None:
            row = AlbumModel(
                title=title,
                artist_id=artist_id,
                year=year,
                musicbrainz_id=musicbrainz_id,
            )
            self._session.add(row)
        else:
            if row.year is None and year is not None:
                row.year = year
            if row.musicbrainz_id is None and musicbrainz_id is not None:
                row.musicbrainz_id = musicbrainz_id
        await self._session.flush()
        await self._session.refresh(row)
        return _to_entity(row)

    async def set_cover_path(self, album_id: uuid.UUID, cover_path: str) -> None:
        row = await self._session.get(AlbumModel, album_id)
        if row is not None:
            row.cover_path = cover_path
            await self._session.flush()

    async def get_by_id(self, album_id: uuid.UUID) -> Album | None:
        row = await self._session.get(AlbumModel, album_id)
        return _to_entity(row) if row is not None else None

    async def get_many(self, ids: list[uuid.UUID]) -> list[Album]:
        if not ids:
            return []
        rows = (
            (await self._session.execute(select(AlbumModel).where(AlbumModel.id.in_(ids))))
            .scalars()
            .all()
        )
        return [_to_entity(r) for r in rows]

    async def count(self, *, artist_id: uuid.UUID | None, q: str | None) -> int:
        stmt = select(func.count()).select_from(AlbumModel)
        if artist_id is not None:
            stmt = stmt.where(AlbumModel.artist_id == artist_id)
        if q:
            stmt = stmt.where(AlbumModel.title.ilike(f"%{q}%"))
        return (await self._session.execute(stmt)).scalar_one()

    async def track_count(self, album_id: uuid.UUID) -> int:
        return (
            await self._session.execute(
                select(func.count()).select_from(TrackModel).where(TrackModel.album_id == album_id)
            )
        ).scalar_one()

    async def track_count_many(self, album_ids: list[uuid.UUID]) -> dict[uuid.UUID, int]:
        if not album_ids:
            return {}
        rows = (
            await self._session.execute(
                select(TrackModel.album_id, func.count(TrackModel.id).label("cnt"))
                .where(TrackModel.album_id.in_(album_ids))
                .group_by(TrackModel.album_id)
            )
        ).all()
        return {row.album_id: row.cnt for row in rows}

    # list must come after methods using list[...] in signatures (builtin name shadowing)
    async def list(
        self,
        *,
        artist_id: uuid.UUID | None,
        q: str | None,
        limit: int,
        offset: int,
        sort_by: str = "title",
        order: str = "asc",
    ) -> list[Album]:
        stmt = select(AlbumModel)
        if artist_id is not None:
            stmt = stmt.where(AlbumModel.artist_id == artist_id)
        if q:
            stmt = stmt.where(AlbumModel.title.ilike(f"%{q}%"))

        if order == "random":
            stmt = stmt.order_by(func.random())
        else:
            col = AlbumModel.created_at if sort_by == "created" else AlbumModel.title
            stmt = stmt.order_by(col.desc() if order == "desc" else col.asc())
        stmt = stmt.limit(limit).offset(offset)
        rows = (await self._session.execute(stmt)).scalars().all()
        return [_to_entity(r) for r in rows]