# session_factory.py
from collections.abc import AsyncGenerator

from sqlalchemy.ext.asyncio import (
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
    AsyncEngine,
)


class SessionFactory:
    def __init__(self, postgres_url: str):
        self.engine: AsyncEngine = create_async_engine(postgres_url, echo=False)
        self.async_session_maker: async_sessionmaker[AsyncSession] = async_sessionmaker(
            self.engine,
            class_=AsyncSession,
            expire_on_commit=False,
        )

    async def dispose(self) -> None:
        await self.engine.dispose()

    async def __call__(self) -> AsyncGenerator[AsyncSession, None]:
        async with self.async_session_maker() as session:
            yield session

# database.py
from collections.abc import AsyncGenerator

from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import DeclarativeBase
from sqlalchemy import MetaData
import contextlib
from src.session_factory import SessionFactory


class Base(DeclarativeBase):
    metadata = MetaData()


session_factory: SessionFactory | None = None


async def get_async_session() -> AsyncGenerator[AsyncSession, None]:
    if session_factory is None:
        raise RuntimeError("SessionFactory is not initialized")
    async for session in session_factory():
        yield session


async def get_db_stub():
    raise NotImplementedError

# main.py

@asynccontextmanager
async def lifespan(app: FastAPI):
    db.session_factory = SessionFactory(settings.db.url_postgres)
    yield
    await db.session_factory.dispose()