"""Database connections and session management."""

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

from app.config import settings

# ── PostgreSQL ────────────────────────────────────────────────────
engine = create_async_engine(settings.DATABASE_URL, echo=settings.DEBUG)
async_session_factory = async_sessionmaker(engine, expire_on_commit=False)


class Base(DeclarativeBase):
    pass


async def get_db() -> AsyncSession:
    """Yield a DB session per request."""
    async with async_session_factory() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()


async def init_db() -> None:
    """Create all tables (use Alembic in production)."""
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)


async def close_db() -> None:
    await engine.dispose()