"""SQLAlchemy engine and session factory."""
from sqlalchemy import create_engine
from sqlalchemy.orm import Session, sessionmaker

from db.models import Base

_engine = None
_SessionLocal = None


def get_engine(database_url: str):
    global _engine
    if _engine is None:
        _engine = create_engine(
            database_url,
            connect_args={"check_same_thread": False} if "sqlite" in database_url else {},
            echo=False,
        )
    return _engine


def get_session_factory(database_url: str) -> sessionmaker[Session]:
    global _SessionLocal
    if _SessionLocal is None:
        engine = get_engine(database_url)
        _SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
    return _SessionLocal


def get_session(database_url: str) -> Session:
    return get_session_factory(database_url)()