from __future__ import annotations

from collections.abc import AsyncIterator
from contextlib import asynccontextmanager

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

from app.config import Settings
from app.db.base import Base


def create_engine(settings: Settings) -> AsyncEngine:
    return create_async_engine(settings.database_url, future=True, echo=False)


def create_session_factory(engine: AsyncEngine) -> async_sessionmaker[AsyncSession]:
    return async_sessionmaker(engine, expire_on_commit=False, class_=AsyncSession)


async def init_db(engine: AsyncEngine) -> None:
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)


@asynccontextmanager
async def session_scope(factory: async_sessionmaker[AsyncSession]) -> AsyncIterator[AsyncSession]:
    session = factory()
    try:
        yield session
        await session.commit()
    except Exception:
        await session.rollback()
        raise
    finally:
        await session.close()