from typing import AsyncGenerator

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

from src.config import settings

# Create async engine
async_engine = create_async_engine(
    settings.database_url,
    echo=settings.debug,
    future=True,
)

# Create async session factory
async_session_maker = async_sessionmaker(
    async_engine,
    class_=AsyncSession,
    expire_on_commit=False,
)


# Declarative base for models
class Base(DeclarativeBase):
    pass


# Dependency for FastAPI
async def get_db_session() -> AsyncGenerator[AsyncSession, None]:
    """Provide database session for FastAPI dependency injection."""
    async with async_session_maker() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()