"""SQLAlchemy async engine and session."""

from collections.abc import AsyncGenerator

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

from app.config import settings


class Base(DeclarativeBase):
    """Base class for all SQLAlchemy models."""
    pass


engine = create_async_engine(settings.DATABASE_URL, echo=False, future=True)
async_session = async_sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    """Dependency: yields a database session."""
    async with async_session() as session:
        yield session