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


# Create async engine
engine = create_async_engine(
    settings.DATABASE_URL,
    echo=False,
    pool_pre_ping=True,
    pool_size=5,
    max_overflow=10,
)

# Create async session factory
async_session_factory = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False,
)


async def get_db() -> AsyncSession:
    """FastAPI dependency to get database session."""
    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:
    """Initialize database tables."""
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)


async def close_db() -> None:
    """Close database connections."""
    await engine.dispose()