"""Enqueue helper — submit a job to the arq queue from the request cycle.

A short-lived pool per call keeps things simple (enqueues are rare, admin-driven
actions). Redis being down degrades to a clean 503 rather than a crash
(graceful degradation)."""

from typing import Any

from arq import create_pool
from arq.connections import RedisSettings

from app.core.config import get_settings
from app.domain.errors import DependencyUnavailableError


async def enqueue(function: str, **kwargs: Any) -> str:
    """Enqueue ``function`` by name, returning the job id. Raises
    :class:`DependencyUnavailableError` if the queue can't be reached."""
    settings = get_settings()
    try:
        pool = await create_pool(RedisSettings.from_dsn(str(settings.redis_url)))
    except Exception as exc:
        raise DependencyUnavailableError("Task queue (Redis) is unavailable.") from exc
    try:
        job = await pool.enqueue_job(function, **kwargs)
    finally:
        await pool.aclose()
    if job is None:
        raise DependencyUnavailableError("Could not enqueue job.")
    return str(job.job_id)