from sqlalchemy.orm import declarative_base

Base = declarative_base()


def get_async_engine():
    """Create async engine on demand to avoid import-time config issues."""
    from sqlalchemy.ext.asyncio import create_async_engine
    from app.config import get_settings

    settings = get_settings()
    database_url = settings.database_url.replace(
        "postgresql://", "postgresql+asyncpg://"
    )
    return create_async_engine(database_url, echo=True)


def get_async_session():
    """Create async session factory."""
    from sqlalchemy.ext.asyncio import AsyncSession
    from sqlalchemy.orm import sessionmaker

    engine = get_async_engine()
    return sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)


async def get_db():
    """Dependency for FastAPI routes."""
    AsyncSessionLocal = get_async_session()
    async with AsyncSessionLocal() as session:
        try:
            yield session
        finally:
            await session.close()