import { describe, expect, it, vi } from 'vitest';
import { createVisibilityAwarePollingFallback } from '../../apps/dashboard/src/features/operations/realtime-fallback.js';

describe('visibility-aware realtime fallback', () => {
  it('polls only while stale and visible, including immediately on returning visible', () => {
    let visible = false;
    let interval: (() => void) | undefined;
    let visibilityListener: (() => void) | undefined;
    const poll = vi.fn();
    const fallback = createVisibilityAwarePollingFallback({
      intervalMs: 5_000,
      poll,
      scheduler: {
        setInterval(callback) { interval = callback; return 'timer'; },
        clearInterval: vi.fn(),
      },
      visibility: {
        isVisible: () => visible,
        subscribe(listener) { visibilityListener = listener; return vi.fn(); },
      },
    });

    fallback.start();
    fallback.setStale(true);
    interval?.();
    expect(poll).not.toHaveBeenCalled();

    visible = true;
    visibilityListener?.();
    expect(poll).toHaveBeenCalledOnce();
    interval?.();
    expect(poll).toHaveBeenCalledTimes(2);

    fallback.setStale(false);
    interval?.();
    expect(poll).toHaveBeenCalledTimes(2);
  });
});