import { eventBus } from './events.js';
import type { AgentHubEvent } from './events.js';
import { updateStatus } from '../core/services/statusService.js';

/**
 * Keep `.agenthub/status/latest.md` fresh. Agents are told (golden rule #2) to
 * read the status snapshot, but it was only regenerated on an explicit
 * `status --update` — so it drifted stale and misled agents (e.g. showing an
 * old task list). This subscribes to the in-process event bus and regenerates
 * the snapshot on every entity change, from both the REST and filesystem-watch
 * paths, debounced so a burst collapses to one write.
 *
 * Presence ('agent') events are ephemeral and don't affect status. Writing the
 * snapshot lives in `.agenthub/status/` — outside the watched entity dirs — so
 * it never feeds back into the watcher.
 */
const DEBOUNCE_MS = 300;

export function startStatusAutoRefresh(cwd: string): () => void {
  let timer: NodeJS.Timeout | undefined;

  const onChange = (event: AgentHubEvent) => {
    if (event.type === 'agent') return;
    if (timer) clearTimeout(timer);
    timer = setTimeout(() => {
      timer = undefined;
      try {
        updateStatus(cwd);
      } catch {
        // best-effort — a failed status refresh must never break the server
      }
    }, DEBOUNCE_MS);
  };

  eventBus.on('change', onChange);
  return () => {
    if (timer) clearTimeout(timer);
    eventBus.off('change', onChange);
  };
}