from __future__ import annotations

from contextlib import contextmanager
from typing import Iterator

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

from .config import settings


SYNC_DATABASE_URL = settings.sync_database_url or settings.database_url

engine = create_engine(SYNC_DATABASE_URL, future=True)
SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False, expire_on_commit=False)

Base = declarative_base()


def init_db() -> None:
    """Create all tables in the database."""

    Base.metadata.create_all(bind=engine)


@contextmanager
def db_session() -> Iterator[Session]:
    """Provide a transactional scope around a series of operations."""

    session: Session = SessionLocal()
    try:
        yield session
    except Exception:
        session.rollback()
        raise
    finally:
        session.close()