from __future__ import annotations

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


def _make_engine() -> None:
    pass  # deferred — engine created at import of this module


settings = get_settings()

async_engine = create_async_engine(
    settings.database_url.get_secret_value(),
    pool_size=10,
    max_overflow=20,
    pool_pre_ping=True,
    pool_recycle=3600,
    connect_args={
        "server_settings": {
            "statement_timeout": "30000",  # 30s
            "lock_timeout": "5000",        # 5s
        }
    },
)

AsyncSessionLocal = async_sessionmaker(
    bind=async_engine,
    class_=AsyncSession,
    expire_on_commit=False,
    autoflush=False,
    autocommit=False,
)


class Base(DeclarativeBase):
    pass


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    async with AsyncSessionLocal() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise