"""Database connection and session management."""

from typing import AsyncGenerator
from sqlalchemy.ext.asyncio import AsyncEngine, AsyncSession, create_async_engine, async_sessionmaker

from tradingagents.api.config import settings


# Create async engine
engine: AsyncEngine = create_async_engine(
    settings.DATABASE_URL,
    echo=settings.ENVIRONMENT == "development",
    future=True,
    pool_pre_ping=True,
)

# Create async session factory
AsyncSessionLocal = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False,
    autocommit=False,
    autoflush=False,
)


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    """
    Dependency for getting database session.

    Yields:
        AsyncSession: Database session

    Example:
        @app.get("/items")
        async def get_items(db: AsyncSession = Depends(get_db)):
            result = await db.execute(select(Item))
            return result.scalars().all()
    """
    async with AsyncSessionLocal() 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.

    Creates all tables defined in models.
    Use only for development - use Alembic migrations in production.
    """
    from tradingagents.api.models import Base

    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()