// server.js
const express = require('express')
const path = require('path')
const LRU = require('lru-cache')
const microcache = require('route-cache')
const compression = require('compression')
const resolve = file => path.resolve(__dirname, file)
const { createBundleRenderer } = require('vue-server-renderer')

const useMicroCache = process.env.MICRO_CACHE !== 'false'

const serverInfo =
  `express/${require('express/package.json').version} ` +
  `vue-server-renderer/${require('vue-server-renderer/package.json').version}`
  
const app = express()

function createRenderer (bundle, options) {
  // https://github.com/vuejs/vue/blob/dev/packages/vue-server-renderer/README.md#why-use-bundlerenderer
  return createBundleRenderer(bundle, Object.assign(options, {
    // for component caching
    // cache: LRU({
    //   max: 1000,
    //   maxAge: 1000 * 60 * 15
    // }),
    // this is only needed when vue-server-renderer is npm-linked
    basedir: resolve('./dist'),
    // recommended for performance
    runInNewContext: false
  }))
}


let renderer
let readyPromise
const templatePath = resolve('./src/index.template.html')

readyPromise = require('./build/setup-dev-server')(
  app,
  templatePath,
  (bundle, options) => {
    renderer = createRenderer(bundle, options)
  }
)

const serve = (path, cache) => express.static(resolve(path), {
  maxAge: cache ? 1000 * 60 * 60 * 24 * 30 : 0
})

app.use(compression({ threshold: 0 }))
app.use('/dist', serve('./dist', true))
app.use('/public', serve('./public', true))
app.use('/manifest.json', serve('./manifest.json', true))
app.use('/service-worker.js', serve('./dist/service-worker.js'))
app.use(microcache.cacheSeconds(1, req => useMicroCache && req.originalUrl))

function render (req, res) {
  const s = Date.now()

  res.setHeader("Content-Type", "text/html")
  res.setHeader("Server", serverInfo)

  const handleError = err => {
    if (err.url) {
      res.redirect(err.url)
    } else if(err.code === 404) {
      res.status(404).send('404 | Page Not Found')
    } else {
      // Render Error Page or Redirect
      res.status(500).send('500 | Internal Server Error')
      console.error(`error during render : ${req.url}`)
      console.error(err.stack)
    }
  }
  const context = {
    title: 'hsello',
    meta: `
      <meta charset="UTF-8">
      <meta http-equiv="X-UA-Compatible" content="IE=edge">
      <meta name="viewport" content="width=device-width, initial-scale=1.0">
      <meta name="keyword" content="vue,ssr">
      <meta name="description" content="vue srr demo">
    `,
    url: req.url
  }
  console.log(renderer);
  renderer.renderToString(context, (err, html) => {
    if (err) {
      return handleError(err)
    }
    res.send(html)
    console.log(`whole request: ${Date.now() - s}ms`)
  })
}

app.get('*', (req, res) => {
  readyPromise.then(() => render(req, res))
})

const port = process.env.PORT || 8080
app.listen(port, () => {
  console.log(`server started at localhost:${port}`)
})