import { beforeEach, describe, expect, it, vi } from 'vitest';
import { keepOfflineShellFresh, manifestFiles } from './offlineShell';
import { TrekShell } from './trekShell';

vi.mock('./trekShell', () => ({ TrekShell: { refreshOfflineCopy: vi.fn() } }));

const manifest = {
  'index.html': {
    file: 'assets/index-a1b2c3d4.js',
    css: ['assets/index-e5f6a7b8.css'],
    assets: ['assets/poppins-11223344.woff2'],
  },
  'src/pages/AtlasPage.tsx': { file: 'assets/AtlasPage-99887766.js', css: ['assets/index-e5f6a7b8.css'] },
  _shared: { file: 'assets/shared-55443322.js', assets: 'not-a-list' },
  broken: null,
};

beforeEach(() => {
  vi.mocked(TrekShell.refreshOfflineCopy).mockReset().mockResolvedValue({ saved: true });
  window.localStorage.clear();
});

describe('manifestFiles', () => {
  it('collects every chunk, stylesheet and asset once', () => {
    expect(manifestFiles(manifest).sort()).toEqual([
      'assets/AtlasPage-99887766.js',
      'assets/index-a1b2c3d4.js',
      'assets/index-e5f6a7b8.css',
      'assets/poppins-11223344.woff2',
      'assets/shared-55443322.js',
    ]);
  });

  it('returns nothing for something that is not a manifest', () => {
    expect(manifestFiles(null)).toEqual([]);
    expect(manifestFiles('x')).toEqual([]);
  });
});

describe('keepOfflineShellFresh', () => {
  it('refreshes the stored start page and fetches every file of the build', async () => {
    const fetched: string[] = [];
    const fetchImpl = vi.fn(async (input: RequestInfo | URL, init?: RequestInit) => {
      const url = String(input);
      if (url === '/asset-manifest.json') {
        expect(init).toEqual({ cache: 'no-store' });
        return new Response(JSON.stringify(manifest));
      }
      fetched.push(url);
      if (url.includes('shared')) throw new Error('offline for a moment');
      return new Response('x');
    }) as unknown as typeof fetch;

    await keepOfflineShellFresh(fetchImpl);

    expect(TrekShell.refreshOfflineCopy).toHaveBeenCalled();
    expect(fetched.sort()).toEqual([
      '/assets/AtlasPage-99887766.js',
      '/assets/index-a1b2c3d4.js',
      '/assets/index-e5f6a7b8.css',
      '/assets/poppins-11223344.woff2',
      '/assets/shared-55443322.js',
    ]);
  });

  it('stops after the start page when the build has no manifest', async () => {
    const fetchImpl = vi.fn(async () => new Response('', { status: 404 })) as unknown as typeof fetch;
    await keepOfflineShellFresh(fetchImpl);
    expect(fetchImpl).toHaveBeenCalledTimes(1);
  });

  it('fetches at low priority, only the own language, and once per build', async () => {
    const withLocales = {
      ...manifest,
      '../shared/dist/i18n/de/index.mjs': { file: 'assets/de-aaaa1111.js' },
      '../shared/dist/i18n/fr/index.mjs': { file: 'assets/fr-bbbb2222.js' },
      '../shared/dist/i18n/en/index.mjs': { file: 'assets/en-cccc3333.js' },
    };
    const inits: (RequestInit | undefined)[] = [];
    const fetched: string[] = [];
    const fetchImpl = vi.fn(async (input: RequestInfo | URL, init?: RequestInit) => {
      const url = String(input);
      if (url === '/asset-manifest.json') return new Response(JSON.stringify(withLocales));
      fetched.push(url);
      inits.push(init);
      return new Response('x');
    }) as unknown as typeof fetch;

    await keepOfflineShellFresh(fetchImpl, 'de');
    expect(fetched).toContain('/assets/de-aaaa1111.js');
    expect(fetched).toContain('/assets/en-cccc3333.js');
    expect(fetched).not.toContain('/assets/fr-bbbb2222.js');
    expect(inits.every((i) => (i as { priority?: string } | undefined)?.priority === 'low')).toBe(true);

    const before = fetched.length;
    await keepOfflineShellFresh(fetchImpl, 'de');
    expect(fetched.length).toBe(before);

    await keepOfflineShellFresh(fetchImpl, 'fr');
    expect(fetched).toContain('/assets/fr-bbbb2222.js');
  });
});