index.js

const Koa = require('koa');
const next = require('next');
const Router = require('koa-router');
const LRUCache = require('lru-cache');
const logger = require('koa-logger');
const provider = require('./src/middleware/config/config.js');

const dev = process.env.NODE_ENV !== 'production';
const app = next({ dev });
const handle = app.getRequestHandler();

const mongoose = require('mongoose');

const serviceFactory = require('./src/middleware/services/ServiceFactory.js');

const ssrCache = new LRUCache({
  max: 100,
  maxAge: 1000 * 60 * 60 // 1hour
});

app.prepare()
.then(() => {
  const server = new Koa();
  const router = new Router();
  
  // mongoose.connect('mongodb://localhost/test');
  // const db = mongoose.connection;


  // db.on('error', function(err) {
  //   console.error('error occurs:', JSON.stringify(err));
  //   mongoose.disconnect();
  // });


  // const userService = serviceFactory.create('User');

  // userService.find({name: 'John'}, function(data) {
  //   console.log('user John has been found:', data);
  // });

  // db.once('open', function (callback) {
  //   // yay!
  //   console.log('yay');
  //   //const User = mongoose.model('User');
  //   // const userId = mongoose.Types.ObjectId();
  //   // const john = new User({
  //   //   _id: userId,
  //   //   name: 'John',
  //   //   nickName: 'John Doe',
  //   //   password: 'xxyyzz',
  //   // });

  //   // john.save(function (err, john) {
  //   //   if (err) return console.error(err);
  //   //   console.log('User john has been successfully saved...', john);
  //   // });
  // });

  // page routers
  router.get('/index', function *() {
    let { req, res, query } = this;
    let path = '/index'
    renderAndCache(req, res, path, query)
    this.respond = false
  })

  router.get('/other', function *() {
    let { req, res, query } = this;
    let path = '/other'
    renderAndCache(req, res, path, query)
    this.respond = false
  })

  // interface routers
  router.get('/user/:id', function *(id) {
    let { req, res, params} = this;

    res.send(500, {'error': 'holy shit'});

    res.end(JSON.stringify({
      username: 'John Doe ' + ~~(100 * Math.random()),
      age: 45,
    }))
  })

  router.get('*', function *() {
    handle(this.req, this.res)
    this.respond = false
  })

  server.use(logger())
  server.use(function *(next) {
    // Koa doesn't seems to set the default statusCode.
    // So, this middleware does that
    this.res.statusCode = 200
    yield next
  })

  server.use(router.routes())
  server.listen(3001, (err) => {
    if (err) throw err
    console.log('> Ready on http://localhost:3001')
  })
})

function renderAndCache (req, res, path, query) {
  let html
  let cacheKey = getCacheKey(req)

  if (html = ssrCache.get(cacheKey)) {
    res.setHeader('Content-Type', 'text/html')
    res.setHeader('Content-Length', Buffer.byteLength(html))
    console.log(`Hit cache key ${cacheKey}`)
    res.end(html)
    return
  }

  app.renderToHTML(req, res, path, query)
  .then((html) => {
    console.log(`Miss cache ${path}`);
    res.setHeader('Content-Type', 'text/html')
    res.setHeader('Content-Length', Buffer.byteLength(html))
    ssrCache.set(path, html)
    res.end(html)
  }).catch((e) => {
    console.error(e)
  })
}

function getCacheKey (req) {
  return `${req.url}`
}