"""Async SQLAlchemy engine and session factory."""

from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
from sqlalchemy.pool import NullPool

from app.core.config import settings

engine = create_async_engine(
    settings.DATABASE_URL,
    echo=settings.APP_DEBUG,
    poolclass=NullPool,  # SQLite doesn't support connection pooling across threads
)

AsyncSessionFactory = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False,
)


async def get_async_session() -> AsyncSession:
    """Dependency that provides an async database session."""
    async with AsyncSessionFactory() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()