"""
Lightweight in-process job queue (docs/02). Adequate for single-worker dev; swap
the backend for Redis/Celery at scale without changing callers.
"""
from __future__ import annotations

import asyncio
from typing import Any, Awaitable, Callable

Job = Callable[..., Awaitable[Any]]


class JobQueue:
    def __init__(self) -> None:
        self._q: "asyncio.Queue[tuple[Job, tuple[Any, ...]]]" = asyncio.Queue()

    async def enqueue(self, fn: Job, *args: Any) -> None:
        await self._q.put((fn, args))

    async def worker(self) -> None:
        while True:
            fn, args = await self._q.get()
            try:
                await fn(*args)
            except Exception as e:  # keep the worker alive on a failed job
                print("job failed:", repr(e))
            finally:
                self._q.task_done()


queue = JobQueue()