import { render } from '@testing-library/react';
import { describe, expect, it, vi } from 'vitest';

import type { LiveClient } from '../../src/liveClient';
import type { LiveSample } from '../../src/liveBuffer';
import type { MetricQueryRequest } from '../../src/metricClient';
import { useLiveMetric } from '../../src/useLiveMetric';

const request: MetricQueryRequest = {
  metric: 'host.cpu.utilization',
  range: { from: '2026-08-10T06:00:00.000Z', to: '2026-08-10T06:05:00.000Z', stepSeconds: 15 },
  aggregation: 'avg',
};

function sample(timestamp: string, value: number): LiveSample {
  return { series: 'cpu', timestamp, value, freshness: 'fresh' };
}

describe('useLiveMetric lifecycle', () => {
  it('updates historical seed data without recreating an unchanged live subscription', () => {
    const unsubscribe = vi.fn();
    const subscribe = vi.fn(() => ({ key: 'cpu', unsubscribe }));
    const releaseUnused = vi.fn();
    const client = { subscribe, releaseUnused } as unknown as LiveClient;

    function Harness({ initial, query = request }: { initial: LiveSample[]; query?: MetricQueryRequest }) {
      useLiveMetric(client, query, initial);
      return null;
    }

    const view = render(<Harness initial={[sample('2026-08-10T06:00:00.000Z', 10)]} />);
    expect(subscribe).toHaveBeenCalledTimes(1);

    view.rerender(<Harness initial={[
      sample('2026-08-10T06:00:00.000Z', 10),
      sample('2026-08-10T06:00:15.000Z', 11),
    ]} />);

    expect(subscribe).toHaveBeenCalledTimes(1);
    expect(unsubscribe).not.toHaveBeenCalled();

    view.rerender(<Harness
      initial={[sample('2026-08-10T06:00:15.000Z', 11)]}
      query={{ ...request, range: { ...request.range, from: '2026-08-10T06:01:00.000Z', to: '2026-08-10T06:06:00.000Z' } }}
    />);

    expect(subscribe).toHaveBeenCalledTimes(1);
    expect(unsubscribe).not.toHaveBeenCalled();

    view.unmount();
    expect(unsubscribe).toHaveBeenCalledTimes(1);
    expect(releaseUnused).toHaveBeenCalledTimes(1);
  });
});