const fs = require('fs');
const path = require('path');
const request = require('supertest');
const { MongoMemoryServer } = require('mongodb-memory-server');
const mongoose = require('mongoose');

jest.mock('~/server/services/Config', () => ({
  loadCustomConfig: jest.fn(() => Promise.resolve({})),
  getAppConfig: jest.fn().mockResolvedValue({
    paths: {
      uploads: '/tmp',
      dist: '/tmp/dist',
      fonts: '/tmp/fonts',
      assets: '/tmp/assets',
    },
    fileStrategy: 'local',
    imageOutputType: 'PNG',
  }),
  setCachedTools: jest.fn(),
}));

jest.mock('~/app/clients/tools', () => ({
  createOpenAIImageTools: jest.fn(() => []),
  createYouTubeTools: jest.fn(() => []),
  manifestToolMap: {},
  toolkits: [],
}));

jest.mock('~/config', () => ({
  createMCPServersRegistry: jest.fn(),
  createMCPManager: jest.fn().mockResolvedValue({
    getAppToolFunctions: jest.fn().mockResolvedValue({}),
  }),
}));

jest.mock(
  '@librechat/api/telemetry',
  () => ({
    initializeTelemetry: jest.fn(() => ({
      enabled: false,
      status: 'disabled',
      shutdown: jest.fn(),
    })),
    telemetryMiddleware: jest.fn((_req, _res, next) => next()),
    telemetryErrorMiddleware: jest.fn((err, _req, _res, next) => next(err)),
  }),
  { virtual: true },
);

describe('Telemetry wiring', () => {
  const source = fs.readFileSync(path.join(__dirname, 'index.js'), 'utf8');

  it('loads telemetry before other server imports', () => {
    const firstStatement = source
      .split('\n')
      .map((line) => line.trim())
      .find(Boolean);

    expect(firstStatement).toBe("const telemetry = require('./telemetry');");
  });

  it('mounts telemetry middleware after static assets and before routes', () => {
    const telemetryMiddlewareIndex = source.indexOf('app.use(telemetry.telemetryMiddleware);');
    const staticAssetsIndex = source.indexOf('app.use(staticCache(appConfig.paths.assets));');
    const apiRoutesIndex = source.indexOf("app.use('/api/auth'");

    expect(telemetryMiddlewareIndex).toBeGreaterThan(-1);
    expect(staticAssetsIndex).toBeGreaterThan(-1);
    expect(apiRoutesIndex).toBeGreaterThan(-1);
    expect(staticAssetsIndex).toBeLessThan(telemetryMiddlewareIndex);
    expect(telemetryMiddlewareIndex).toBeLessThan(apiRoutesIndex);
  });

  it('mounts telemetry error middleware before ErrorController', () => {
    const telemetryErrorMiddlewareIndex = source.indexOf(
      'app.use(telemetry.telemetryErrorMiddleware);',
    );
    const errorControllerIndex = source.indexOf('app.use(ErrorController);');

    expect(telemetryErrorMiddlewareIndex).toBeGreaterThan(-1);
    expect(errorControllerIndex).toBeGreaterThan(-1);
    expect(telemetryErrorMiddlewareIndex).toBeLessThan(errorControllerIndex);
  });
});

describe('Startup readiness wiring', () => {
  const source = fs.readFileSync(path.join(__dirname, 'index.js'), 'utf8');

  it('configures generation streams before the server accepts requests', () => {
    const streamConfigIndex = source.indexOf('configureGenerationStreams();');
    const listenIndex = source.indexOf('const server = app.listen');
    const postListenMcpIndex = source.indexOf('await initializeMCPs();');

    expect(streamConfigIndex).toBeGreaterThan(-1);
    expect(listenIndex).toBeGreaterThan(-1);
    expect(postListenMcpIndex).toBeGreaterThan(-1);
    expect(streamConfigIndex).toBeLessThan(listenIndex);
    expect(streamConfigIndex).toBeLessThan(postListenMcpIndex);
  });

  it('mounts the chat-start readiness gate before agent routes', () => {
    const readinessGateIndex = source.indexOf(
      "app.use('/api/agents/chat', rejectChatStartsUntilReady);",
    );
    const agentsRouteIndex = source.indexOf("app.use('/api/agents', routes.agents);");

    expect(readinessGateIndex).toBeGreaterThan(-1);
    expect(agentsRouteIndex).toBeGreaterThan(-1);
    expect(readinessGateIndex).toBeLessThan(agentsRouteIndex);
  });
});

describe('Server Configuration', () => {
  // Increase the default timeout to allow for Mongo cleanup
  jest.setTimeout(30_000);

  let mongoServer;
  let app;

  /** Mocked fs.readFileSync for index.html */
  const originalReadFileSync = fs.readFileSync;
  beforeAll(() => {
    fs.readFileSync = function (filepath, options) {
      if (filepath.includes('index.html')) {
        return '<!DOCTYPE html><html><head><title>LibreChat</title></head><body><div id="root"></div></body></html>';
      }
      return originalReadFileSync(filepath, options);
    };
  });

  afterAll(() => {
    // Restore original fs.readFileSync
    fs.readFileSync = originalReadFileSync;
  });

  beforeAll(async () => {
    // Create the required directories and files for the test
    const fs = require('fs');
    const path = require('path');

    const dirs = ['/tmp/dist', '/tmp/fonts', '/tmp/assets'];
    dirs.forEach((dir) => {
      if (!fs.existsSync(dir)) {
        fs.mkdirSync(dir, { recursive: true });
      }
    });

    fs.writeFileSync(
      path.join('/tmp/dist', 'index.html'),
      '<!DOCTYPE html><html><head><title>LibreChat</title></head><body><div id="root"></div></body></html>',
    );

    mongoServer = await MongoMemoryServer.create();
    process.env.MONGO_URI = mongoServer.getUri();
    process.env.PORT = '0'; // Use a random available port
    app = require('~/server');

    // Wait for the app to be healthy
    await healthCheckPoll(app);
  });

  afterAll(async () => {
    await mongoServer.stop();
    await mongoose.disconnect();
  });

  it('should return OK for /health', async () => {
    const response = await request(app).get('/health');
    expect(response.status).toBe(200);
    expect(response.text).toBe('OK');
  });

  it('should not cache index page', async () => {
    const response = await request(app).get('/');
    expect(response.status).toBe(200);
    expect(response.headers['cache-control']).toBe('no-cache, no-store, must-revalidate');
    expect(response.headers['pragma']).toBe('no-cache');
    expect(response.headers['expires']).toBe('0');
  });

  it('should return 404 JSON for undefined API routes', async () => {
    const response = await request(app).get('/api/nonexistent');
    expect(response.status).toBe(404);
    expect(response.body).toEqual({ message: 'Endpoint not found' });
  });

  it('should return 404 JSON for nested undefined API routes', async () => {
    const response = await request(app).get('/api/nonexistent/nested/path');
    expect(response.status).toBe(404);
    expect(response.body).toEqual({ message: 'Endpoint not found' });
  });

  it('should return 404 JSON for non-GET methods on undefined API routes', async () => {
    const post = await request(app).post('/api/nonexistent');
    expect(post.status).toBe(404);
    expect(post.body).toEqual({ message: 'Endpoint not found' });

    const del = await request(app).delete('/api/nonexistent');
    expect(del.status).toBe(404);
    expect(del.body).toEqual({ message: 'Endpoint not found' });
  });

  it('should return 404 JSON for the /api root path', async () => {
    const response = await request(app).get('/api');
    expect(response.status).toBe(404);
    expect(response.body).toEqual({ message: 'Endpoint not found' });
  });

  it('should serve SPA HTML for non-API unmatched routes', async () => {
    const response = await request(app).get('/this/does/not/exist');
    expect(response.status).toBe(200);
    expect(response.headers['content-type']).toMatch(/html/);
  });

  it('should gate React Query Devtools config in SPA HTML by debug header', async () => {
    const defaultResponse = await request(app).get('/this/does/not/exist');
    const debugResponse = await request(app)
      .get('/this/does/not/exist')
      .set('x-librechat-enable-query-devtools', '1');
    const directIndexResponse = await request(app)
      .get('/index.html')
      .set('x-librechat-enable-query-devtools', '1');

    expect(defaultResponse.status).toBe(200);
    expect(defaultResponse.headers.vary).toContain('x-librechat-enable-query-devtools');
    expect(defaultResponse.text).not.toContain('enableQueryDevtools');

    expect(debugResponse.status).toBe(200);
    expect(debugResponse.headers.vary).toContain('x-librechat-enable-query-devtools');
    expect(debugResponse.text).toContain('window.__LIBRECHAT_CONFIG__');
    expect(debugResponse.text).toContain('data-librechat-query-devtools="true"');
    expect(debugResponse.text).toContain('"enableQueryDevtools":true');

    expect(directIndexResponse.status).toBe(200);
    expect(directIndexResponse.headers.vary).toContain('x-librechat-enable-query-devtools');
    expect(directIndexResponse.text).toContain('window.__LIBRECHAT_CONFIG__');
    expect(directIndexResponse.text).toContain('data-librechat-query-devtools="true"');
    expect(directIndexResponse.text).toContain('"enableQueryDevtools":true');
  });

  it('should return 500 for unknown errors via ErrorController', async () => {
    // Testing the error handling here on top of unit tests to ensure the middleware is correctly integrated

    // Mock MongoDB operations to fail
    const originalFindOne = mongoose.models.User.findOne;
    const mockError = new Error('MongoDB operation failed');
    mongoose.models.User.findOne = jest.fn().mockImplementation(() => {
      throw mockError;
    });

    try {
      const response = await request(app).post('/api/auth/login').send({
        email: 'test@example.com',
        password: 'password123',
      });

      expect(response.status).toBe(500);
      expect(response.text).toBe('An unknown error occurred.');
    } finally {
      // Restore original function
      mongoose.models.User.findOne = originalFindOne;
    }
  });
});

// Polls the /health endpoint every 30ms for up to 10 seconds to wait for the server to start completely
async function healthCheckPoll(app, retries = 0) {
  const maxRetries = Math.floor(10000 / 30); // 10 seconds / 30ms
  try {
    const response = await request(app).get('/health');
    if (response.status === 200) {
      return; // App is healthy
    }
  } catch {
    // Ignore connection errors during polling
  }

  if (retries < maxRetries) {
    await new Promise((resolve) => setTimeout(resolve, 30));
    await healthCheckPoll(app, retries + 1);
  } else {
    throw new Error('App did not become healthy within 10 seconds.');
  }
}
