app.js

// app.js
require('dotenv').config();
const setupDNS = require('./config/dns');
// Fix Windows DNS SRV issues for MongoDB Atlas
setupDNS();

const express = require('express');
const cors = require('cors');
const helmet = require('helmet');
const morgan = require('morgan');
const connectDB = require('./config/connectDB');
connectDB();

const app = express();
app.use(cors());

/* -----------------------------
   Middleware
------------------------------ */
app.set('trust proxy', 1);
app.use(helmet({ contentSecurityPolicy: false }));
app.use(cors());
app.use(express.json({ limit: '8mb' }));
if (process.env.NODE_ENV !== 'test') app.use(morgan('dev'));

// -----------------------------
// Swagger (OpenAPI 3) 集成
// -----------------------------
const swaggerUi = require('swagger-ui-express');
const swaggerJSDoc = require('swagger-jsdoc');

const baseUrl = process.env.SWAGGER_SERVER_BASE || '/api'; // 与业务路由前缀一致（如 /api/ai/*）  [1](https://waikatouniversitynz-my.sharepoint.com/personal/jl1132_students_waikato_ac_nz/Documents/Microsoft%20Copilot%20Chat%20Files/app.js)

const swaggerDefinition = {
  openapi: '3.0.3',
  info: {
    title: 'Your Project API',
    version: '1.0.0',
    description: 'API 文档（基于 OpenAPI 3.0 & swagger-jsdoc 自动生成）',
  },
  servers: [
    {
      url: baseUrl,
      description: 'API Base',
    },
  ],
  components: {
    securitySchemes: {
      bearerAuth: {
        type: 'http',
        scheme: 'bearer',
        bearerFormat: 'JWT', // 你的路由使用 authenticate 中间件（Bearer Token）  [2](https://waikatouniversitynz-my.sharepoint.com/personal/jl1132_students_waikato_ac_nz/Documents/Microsoft%20Copilot%20Chat%20Files/ai.routes.js)
      },
    },
    // 如需统一错误/响应模型，可在此定义 schemas 并通过 $ref 引用
    // schemas: { ... }
  },
  security: [{ bearerAuth: [] }],
};

const swaggerOptions = {
  definition: swaggerDefinition,
  apis: [
    './routes/*.js',     // 扫描路由文件中的 @openapi JSDoc 注释
    './controllers/*.js' // 如你在 controller 中补充注释，可一并扫描
  ],
};

const swaggerSpec = swaggerJSDoc(swaggerOptions);

// Swagger UI 与原始 JSON
app.use('/docs', swaggerUi.serve, swaggerUi.setup(swaggerSpec, { explorer: true }));
app.get('/docs.json', (req, res) => {
  res.setHeader('Content-Type', 'application/json');
  res.send(swaggerSpec);
});

// -----------------------------
// Route loader (handles CJS/ESM)
// -----------------------------
function loadRouter(path, name) {
  // Require the module
  const mod = require(path);

  // Support both CJS (module.exports = router) and ESM default exports
  const candidate = typeof mod === 'function'
    ? mod
    : (mod && typeof mod.default === 'function' ? mod.default : mod);

  // Validate it's a Router (Routers are callable middleware and have a .stack array)
  const isRouter =
    typeof candidate === 'function' &&
    (Array.isArray(candidate.stack) || typeof candidate.use === 'function');

  if (!isRouter) {
    // Helpfully show what we actually got
    const type = typeof candidate;
    const keys = candidate && typeof candidate === 'object' ? Object.keys(candidate) : [];
    throw new TypeError(
      `[Route Mount Error] ${name} must export an Express Router function.\n` +
      `Got: ${type}${keys.length ? ` with keys: ${keys.join(', ')}` : ''}\n` +
      `Fix: ensure the route file ends with "module.exports = router" (CommonJS).`
    );
  }

  return candidate;
}

/* -----------------------------
   Import routers with validation
------------------------------ */
const usersRoutes   = loadRouter('./routes/users.routes',   'users.routes');
const promptsRoutes = loadRouter('./routes/prompts.routes', 'prompts.routes');
const storiesRoutes = loadRouter('./routes/stories.routes', 'stories.routes');
const aiRoutes      = loadRouter('./routes/ai.routes',      'ai.routes');

/* -----------------------------
   Routes
------------------------------ */
app.use('/api/users', usersRoutes);
app.use('/api/prompts', promptsRoutes);
app.use('/api/stories', storiesRoutes);
app.use('/api/ai', aiRoutes);

// Health probes
app.get('/health', (_, res) => res.status(200).send('OK'));
app.get('/ready',  (_, res) => res.status(200).json({ status: 'ready' }));

/* -----------------------------
   404 & Error Handling
------------------------------ */
app.use((req, res) => {
  res.status(404).json({
    error: 'NotFound',
    message: 'The requested resource was not found.',
  });
});

app.use((err, req, res, next) => {
  const status = err.status || err.statusCode || 500;
  const isProd = process.env.NODE_ENV === 'production';
  const payload = {
    error: err.name || 'InternalServerError',
    message: isProd ? 'An unexpected error occurred.' : err.message,
  };
  if (!isProd) payload.stack = err.stack;
  console.error('❌', err.message);
  res.status(status).json(payload);
});

module.exports = app;

/* -----------------------------
   Bootstrap (DB before listen)
------------------------------ */
// Start server only if not in test mode
if (require.main === module) {
  const PORT = process.env.PORT || 3000;
  app.listen(PORT, () => console.log(`Server running on port ${PORT}`));
}