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

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

from app.config import settings

engine = create_async_engine(
    settings.DATABASE_URL,
    echo=False,
    connect_args={"check_same_thread": False} if "sqlite" in settings.DATABASE_URL else {},
)

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


class Base(DeclarativeBase):
    pass


async def get_db():
    """FastAPI dependency that yields an async DB session."""
    async with async_session() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise


async def init_db():
    """Create all tables on startup."""
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)