"""管理端：节目（播放清单）CRUD。"""
from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy import delete, select
from sqlalchemy.orm import Session, selectinload

from ..auth import get_current_user
from ..database import get_db
from ..models import Asset, Playlist, PlaylistItem, ScreenBinding
from ..schemas import PlaylistCreate, PlaylistItemIn, PlaylistOut, PlaylistUpdate

router = APIRouter(prefix="/api/playlists", tags=["playlists"], dependencies=[Depends(get_current_user)])


def _get_playlist_or_404(db: Session, playlist_id: int) -> Playlist:
    playlist = db.get(Playlist, playlist_id, options=[selectinload(Playlist.items).selectinload(PlaylistItem.asset)])
    if not playlist:
        raise HTTPException(status_code=404, detail="节目不存在")
    return playlist


def _replace_items(db: Session, playlist_id: int, items: list[PlaylistItemIn]):
    """全量替换节目项。"""
    asset_ids = {item.asset_id for item in items}
    if asset_ids:
        found = set(db.scalars(select(Asset.id).where(Asset.id.in_(asset_ids))).all())
        missing = asset_ids - found
        if missing:
            raise HTTPException(status_code=400, detail=f"素材不存在: {sorted(missing)}")

    db.execute(delete(PlaylistItem).where(PlaylistItem.playlist_id == playlist_id))
    for idx, item in enumerate(items):
        db.add(
            PlaylistItem(
                playlist_id=playlist_id,
                asset_id=item.asset_id,
                sort_order=idx,
                duration=item.duration,
            )
        )


@router.get("", response_model=list[PlaylistOut])
def list_playlists(db: Session = Depends(get_db)):
    return db.scalars(
        select(Playlist)
        .options(selectinload(Playlist.items).selectinload(PlaylistItem.asset))
        .order_by(Playlist.created_at.desc())
    ).all()


@router.get("/{playlist_id}", response_model=PlaylistOut)
def get_playlist(playlist_id: int, db: Session = Depends(get_db)):
    return _get_playlist_or_404(db, playlist_id)


@router.post("", response_model=PlaylistOut)
def create_playlist(body: PlaylistCreate, db: Session = Depends(get_db)):
    playlist = Playlist(name=body.name, description=body.description)
    db.add(playlist)
    db.flush()
    _replace_items(db, playlist.id, body.items)
    db.commit()
    return _get_playlist_or_404(db, playlist.id)


@router.put("/{playlist_id}", response_model=PlaylistOut)
def update_playlist(playlist_id: int, body: PlaylistUpdate, db: Session = Depends(get_db)):
    playlist = _get_playlist_or_404(db, playlist_id)
    if body.name is not None:
        playlist.name = body.name
    if body.description is not None:
        playlist.description = body.description
    if body.items is not None:
        _replace_items(db, playlist.id, body.items)
    db.commit()
    return _get_playlist_or_404(db, playlist_id)


@router.delete("/{playlist_id}")
def delete_playlist(playlist_id: int, db: Session = Depends(get_db)):
    playlist = _get_playlist_or_404(db, playlist_id)
    has_active_binding = (
        db.scalar(select(ScreenBinding.id).where(ScreenBinding.playlist_id == playlist_id, ScreenBinding.active == True))  # noqa: E712
        is not None
    )
    db.execute(delete(ScreenBinding).where(ScreenBinding.playlist_id == playlist_id))
    db.delete(playlist)
    db.commit()
    return {"ok": True, "unbound_screens": has_active_binding}