from collections.abc import Iterator

from sqlalchemy import create_engine
from sqlalchemy.orm import DeclarativeBase, Session, sessionmaker

from app.config import settings


class Base(DeclarativeBase):
    pass


# Pool sized above the sync-endpoint threadpool (~40) so a burst of short DB sessions can't starve on
# checkout. The image proxies deliberately DON'T hold a connection during their slow external fetch
# (see routes/plex.py), so this headroom is only for the many brief sessions, not long ones.
engine = create_engine(
    settings.database_url,
    pool_pre_ping=True,
    pool_size=20,
    max_overflow=30,
    pool_timeout=30,
    future=True,
)
SessionLocal = sessionmaker(bind=engine, autoflush=False, expire_on_commit=False)


def get_db() -> Iterator[Session]:
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()