"""Keep synchronous compatibility reads off the Gateway's async connection pool."""

import asyncio
from contextvars import ContextVar

from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
from sqlalchemy.pool import NullPool

_isolated_factory = ContextVar("isolated_db_factory", default=None)


def isolated_session_factory():
    return _isolated_factory.get()


async def run_isolated_db_read(coro):
    from deerflow.persistence.engine import get_engine

    source = get_engine()
    if source is None:
        return await coro
    # Never return a connection created on this temporary loop to the main pool.
    engine = create_async_engine(source.url, poolclass=NullPool)
    token = _isolated_factory.set(async_sessionmaker(engine, expire_on_commit=False))
    try:
        return await asyncio.wait_for(coro, 30)
    finally:
        _isolated_factory.reset(token)
        await engine.dispose()