import { renderHook, act, waitFor } from '@testing-library/react';
import { useSchoolSuggest } from '@/hooks/useSchoolSuggest';

const realFetch = global.fetch;

function mockFetch(rows: unknown[], delayMs = 0) {
  global.fetch = jest.fn(async (_url: unknown, init?: { signal?: AbortSignal }) => {
    if (delayMs) {
      await new Promise((resolve, reject) => {
        const t = setTimeout(resolve, delayMs);
        init?.signal?.addEventListener('abort', () => {
          clearTimeout(t);
          reject(Object.assign(new Error('aborted'), { name: 'AbortError' }));
        });
      });
    }
    return { ok: true, json: async () => ({ suggestions: rows }) };
  }) as unknown as typeof fetch;
}

const ROW = {
  urn: 1, school_name: 'Brecknock Primary School', local_authority: 'Camden',
  postcode: 'NW1 1AA', phase: 'Primary', school_type: 'Community school',
};

describe('useSchoolSuggest', () => {
  beforeEach(() => { jest.useFakeTimers(); });
  afterEach(() => { jest.useRealTimers(); global.fetch = realFetch; });

  it('does not fetch below the minimum query length', () => {
    mockFetch([ROW]);
    renderHook(() => useSchoolSuggest('b', true));
    act(() => { jest.advanceTimersByTime(500); });
    expect(global.fetch).not.toHaveBeenCalled();
  });

  it('does not fetch at all when disabled', () => {
    // The flag being off must mean no request, not a hidden dropdown.
    mockFetch([ROW]);
    renderHook(() => useSchoolSuggest('brecknock', false));
    act(() => { jest.advanceTimersByTime(500); });
    expect(global.fetch).not.toHaveBeenCalled();
  });

  it('debounces rather than firing per keystroke', () => {
    mockFetch([ROW]);
    const { rerender } = renderHook(
      ({ q }) => useSchoolSuggest(q, true), { initialProps: { q: 'br' } });
    rerender({ q: 'bre' });
    rerender({ q: 'brec' });
    act(() => { jest.advanceTimersByTime(199); });
    expect(global.fetch).not.toHaveBeenCalled();
    act(() => { jest.advanceTimersByTime(2); });
    expect(global.fetch).toHaveBeenCalledTimes(1);
  });

  it('opens with results once they arrive', async () => {
    mockFetch([ROW]);
    const { result } = renderHook(() => useSchoolSuggest('brecknock', true));
    act(() => { jest.advanceTimersByTime(200); });
    await waitFor(() => expect(result.current.suggestions).toHaveLength(1));
    expect(result.current.open).toBe(true);
  });

  it('close() hides the list without clearing the query', async () => {
    mockFetch([ROW]);
    const { result } = renderHook(() => useSchoolSuggest('brecknock', true));
    act(() => { jest.advanceTimersByTime(200); });
    await waitFor(() => expect(result.current.open).toBe(true));
    act(() => { result.current.close(); });
    expect(result.current.open).toBe(false);
  });
});