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

from collections.abc import AsyncGenerator

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

from app.config import get_settings

settings = get_settings()

engine = create_async_engine(
    settings.DATABASE_URL,
    echo=settings.DEBUG,
    pool_size=20,
    max_overflow=10,
)

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


class Base(DeclarativeBase):
    """SQLAlchemy declarative base."""

    pass


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    """Dependency for getting async database sessions."""
    async with async_session() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise