from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
from sqlalchemy.orm import DeclarativeBase

from app.config import get_settings

_engine = None
_session_factory = None


class Base(DeclarativeBase):
    pass


def get_engine():
    global _engine
    if _engine is None:
        settings = get_settings()
        _engine = create_async_engine(settings.database_url, echo=False)
    return _engine


def get_session_factory():
    global _session_factory
    if _session_factory is None:
        _session_factory = async_sessionmaker(get_engine(), expire_on_commit=False)
    return _session_factory