import { beforeEach, describe, expect, it, vi } from 'vitest';

const testState = vi.hoisted(() => ({
  entriesMock: vi.fn(async () => [] as Array<['nsfw' | 'sfw', string]>),
  setItemMock: vi.fn(async () => undefined),
}));

vi.mock('@bitsocial/bitsocial-react-hooks/dist/lib/localforage-lru/index.js', () => ({
  default: {
    createInstance: () => ({
      entries: testState.entriesMock,
      setItem: testState.setItemMock,
    }),
  },
}));

const waitFor = async (predicate: () => boolean) => {
  for (let i = 0; i < 20; i += 1) {
    await Promise.resolve();
    if (predicate()) {
      return;
    }
  }
};

describe('useThemeStore', () => {
  beforeEach(() => {
    vi.resetModules();
    localStorage.clear();
    testState.entriesMock.mockReset();
    testState.entriesMock.mockResolvedValue([]);
    testState.setItemMock.mockReset();
    testState.setItemMock.mockResolvedValue(undefined);
  });

  it('loads stored themes on initialization', async () => {
    testState.entriesMock.mockResolvedValue([
      ['nsfw', 'tomorrow'],
      ['sfw', 'photon'],
    ]);

    const store = (await import('../use-theme-store')).default;
    await waitFor(() => store.getState().themes.nsfw === 'tomorrow');

    expect(store.getState().themes).toEqual({
      nsfw: 'tomorrow',
      sfw: 'photon',
    });
    expect(store.getState().currentTheme).toBeNull();
  });

  it('setTheme persists the updated theme and updates currentTheme', async () => {
    const store = (await import('../use-theme-store')).default;
    await waitFor(() => testState.entriesMock.mock.calls.length > 0);

    await store.getState().setTheme('nsfw', 'photon');

    expect(testState.setItemMock).toHaveBeenCalledWith('nsfw', 'photon');
    expect(store.getState().themes.nsfw).toBe('photon');
    expect(store.getState().currentTheme).toBe('photon');
  });

  it('getTheme can skip updating currentTheme when requested', async () => {
    const store = (await import('../use-theme-store')).default;
    await waitFor(() => testState.entriesMock.mock.calls.length > 0);

    expect(store.getState().getTheme('sfw', false)).toBe('yotsuba-b');
    expect(store.getState().currentTheme).toBeNull();

    expect(store.getState().getTheme('sfw')).toBe('yotsuba-b');
    expect(store.getState().currentTheme).toBe('yotsuba-b');
  });

  it('initializes themes synchronously from localStorage before async load resolves', async () => {
    // Keep the async localForage load pending so it cannot overwrite the synchronous init.
    testState.entriesMock.mockReturnValue(new Promise(() => {}));
    localStorage.setItem('5chan-themes', JSON.stringify({ nsfw: 'tomorrow', sfw: 'photon' }));

    const store = (await import('../use-theme-store')).default;

    // No await for the async load: the first render must already see the saved themes,
    // otherwise the default theme flashes before the saved one loads.
    expect(store.getState().themes).toEqual({ nsfw: 'tomorrow', sfw: 'photon' });
  });

  it('falls back to defaults when localStorage is empty or invalid', async () => {
    testState.entriesMock.mockReturnValue(new Promise(() => {}));
    localStorage.setItem('5chan-themes', 'not-json');

    const store = (await import('../use-theme-store')).default;

    expect(store.getState().themes).toEqual({ nsfw: 'yotsuba', sfw: 'yotsuba-b' });
  });

  it('setTheme mirrors the saved theme into localStorage', async () => {
    // Keep the async load pending so it cannot race and overwrite the localStorage mirror.
    testState.entriesMock.mockReturnValue(new Promise(() => {}));
    const store = (await import('../use-theme-store')).default;

    await store.getState().setTheme('sfw', 'tomorrow');

    expect(testState.setItemMock).toHaveBeenCalledWith('sfw', 'tomorrow');
    expect(JSON.parse(localStorage.getItem('5chan-themes') ?? '{}')).toEqual({
      nsfw: 'yotsuba',
      sfw: 'tomorrow',
    });
  });
});