"""Fractafrag API — Database engine and session management."""

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


settings = get_settings()

engine = create_async_engine(
    settings.database_url,
    echo=False,
    pool_size=20,
    max_overflow=10,
    pool_pre_ping=True,
)

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


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


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