"""Async SQLAlchemy engine/session setup.

Works against Postgres (`postgresql+psycopg://...`) or SQLite
(`sqlite+aiosqlite://...`) depending on `DATABASE_URL` - the same models and
repositories run against either, which is what makes the no-Docker local dev
path possible.
"""

from __future__ import annotations

from collections.abc import AsyncGenerator
from functools import lru_cache

from sqlalchemy.ext.asyncio import (
    AsyncEngine,
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
)

from app.core.config import get_settings


@lru_cache
def get_engine() -> AsyncEngine:
    settings = get_settings()
    connect_args = {}
    if settings.database_url.startswith("sqlite"):
        connect_args = {"check_same_thread": False}
    return create_async_engine(
        settings.database_url,
        echo=False,
        pool_pre_ping=True,
        connect_args=connect_args,
    )


@lru_cache
def get_sessionmaker() -> async_sessionmaker[AsyncSession]:
    return async_sessionmaker(bind=get_engine(), expire_on_commit=False)


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