from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, DeclarativeBase
from sqlalchemy.pool import StaticPool


class Base(DeclarativeBase):
    pass


def get_engine(db_url: str):
    if db_url.startswith("sqlite"):
        connect_args = {"check_same_thread": False}
        # In-memory SQLite is per-connection; without a shared StaticPool,
        # each new session would see a fresh, empty database.
        if ":memory:" in db_url:
            return create_engine(
                db_url, connect_args=connect_args, poolclass=StaticPool
            )
        return create_engine(db_url, connect_args=connect_args)
    return create_engine(db_url)


def make_session_factory(engine):
    return sessionmaker(bind=engine, autoflush=False, autocommit=False)


def init_db(engine):
    Base.metadata.create_all(bind=engine)