import ansiHTML from 'ansi-html'
import serialize from 'serialize-javascript'
import generateETag from 'etag'
import fresh from 'fresh'
import { getContext, setAnsiColors, encodeHtml } from './utils'
import Tapable from 'tapable'

const debug = require('debug')('nuxt:render')
debug.color = 4 // Force blue color
setAnsiColors(ansiHTML)

let jsdom = null

export default class Renderer extends Tapable {
  constructor (nuxt) {
    super()
    this.nuxt = nuxt
    this.options = nuxt.options
  }

  async render (req, res) {
    // Wait for nuxt.js to be ready
    await this.nuxt._ready
    // Check if project is built for production
    if (!this.nuxt.builder.renderer && !this.options.dev) {
      console.error('> No build files found, please run `nuxt build` before launching `nuxt start`') // eslint-disable-line no-console
      process.exit(1)
    }
    /* istanbul ignore if */
    if (!this.nuxt.builder.renderer || !this.nuxt.builder.appTemplate) {
      return new Promise((resolve) => {
        setTimeout(() => {
          resolve(this.render(req, res))
        }, 1000)
      })
    }
    // Get context
    const context = getContext(req, res)
    res.statusCode = 200
    try {
      if (this.options.dev) {
        // Call webpack middleware only in development
        await this.nuxt.builder.webpackDevMiddleware(req, res)
        await this.nuxt.builder.webpackHotMiddleware(req, res)
      }
      if (!this.options.dev && this.options.render.gzip) {
        await this.nuxt.gzipMiddleware(req, res)
      }
      // If base in req.url, remove it for the middleware and vue-router
      if (this.options.router.base !== '/' && req.url.indexOf(this.options.router.base) === 0) {
        // Compatibility with base url for dev server
        req.url = req.url.replace(this.options.router.base, '/')
      }
      // Serve static/ files
      await this.nuxt.serveStatic(req, res)
      // Serve .nuxt/dist/ files (only for production)
      if (!this.options.dev && req.url.indexOf(this.options.build.publicPath) === 0) {
        const url = req.url
        req.url = req.url.replace(this.options.build.publicPath, '/')
        await this.nuxt.serveStaticNuxt(req, res)
        /* istanbul ignore next */
        req.url = url
      }
      if (this.options.dev && req.url.indexOf(this.options.build.publicPath) === 0 && req.url.includes('.hot-update.json')) {
        res.statusCode = 404
        return res.end()
      }
      const { html, error, redirected, resourceHints } = await this.renderRoute(req.url, context)
      if (redirected) {
        return html
      }
      if (error) {
        res.statusCode = context.nuxt.error.statusCode || 500
      }
      // ETag header
      if (!error && this.options.render.etag) {
        const etag = generateETag(html, this.options.render.etag)
        if (fresh(req.headers, { etag })) {
          res.statusCode = 304
          res.end()
          return
        }
        res.setHeader('ETag', etag)
      }
      // HTTP2 push headers
      if (!error && this.options.render.http2.push) {
        // Parse resourceHints to extract HTTP.2 prefetch/push headers
        // https://w3c.github.io/preload/#server-push-http-2
        const regex = /link rel="([^"]*)" href="([^"]*)" as="([^"]*)"/g
        const pushAssets = []
        let m
        while (m = regex.exec(resourceHints)) { // eslint-disable-line no-cond-assign
          const [_, rel, href, as] = m // eslint-disable-line no-unused-vars
          if (rel === 'preload') {
            pushAssets.push(`<${href}>; rel=${rel}; as=${as}`)
          }
        }
        // Pass with single Link header
        // https://blog.cloudflare.com/http-2-server-push-with-multiple-assets-per-link-header
        res.setHeader('Link', pushAssets.join(','))
      }
      res.setHeader('Content-Type', 'text/html; charset=utf-8')
      res.setHeader('Content-Length', Buffer.byteLength(html))
      res.end(html, 'utf8')
      return html
    } catch (err) {
      if (context.redirected) {
        console.error(err) // eslint-disable-line no-console
        return err
      }
      const html = this.nuxt.errorTemplate({
        /* istanbul ignore if */
        error: err,
        stack: ansiHTML(encodeHtml(err.stack))
      })
      res.statusCode = 500
      res.setHeader('Content-Type', 'text/html; charset=utf-8')
      res.setHeader('Content-Length', Buffer.byteLength(html))
      res.end(html, 'utf8')
      return err
    }
  }

  async renderRoute (url, context = {}) {
    // Wait for nuxt.js to be ready
    await this.nuxt._ready

    // Log rendered url
    debug(`Rendering url ${url}`)
    // Add url and isSever to the context
    context.url = url
    context.isServer = true
    // Call renderToString from the bundleRenderer and generate the HTML (will update the context as well)
    let APP = await this.nuxt.builder.renderToString(context)
    if (!context.nuxt.serverRendered) {
      APP = '<div id="__nuxt"></div>'
    }
    const m = context.meta.inject()
    let HEAD = m.meta.text() + m.title.text() + m.link.text() + m.style.text() + m.script.text() + m.noscript.text()
    if (this._routerBaseSpecified) {
      HEAD += `<base href="${this.options.router.base}">`
    }
    const resourceHints = context.renderResourceHints()
    HEAD += resourceHints + context.renderStyles()
    APP += `<script type="text/javascript">window.__NUXT__=${serialize(context.nuxt, { isJSON: true })}</script>`
    APP += context.renderScripts()
    const html = this.nuxt.builder.appTemplate({
      HTML_ATTRS: 'data-n-head-ssr ' + m.htmlAttrs.text(),
      BODY_ATTRS: m.bodyAttrs.text(),
      HEAD,
      APP
    })
    return {
      html,
      resourceHints,
      error: context.nuxt.error,
      redirected: context.redirected
    }
  }

  async renderAndGetWindow (url, opts = {}) {
    if (!this.ready) {
      // Wait for nuxt.js to be ready
      await this.nuxt._ready
      this.ready = true
    }

    /* istanbul ignore if */
    if (!jsdom) {
      try {
        jsdom = require('jsdom')
      } catch (e) {
        console.error('Fail when calling nuxt.renderAndGetWindow(url)') // eslint-disable-line no-console
        console.error('jsdom module is not installed') // eslint-disable-line no-console
        console.error('Please install jsdom with: npm install --save-dev jsdom') // eslint-disable-line no-console
        process.exit(1)
      }
    }
    let options = {
      resources: 'usable', // load subresources (https://github.com/tmpvar/jsdom#loading-subresources)
      runScripts: 'dangerously',
      beforeParse (window) {
        // Mock window.scrollTo
        window.scrollTo = () => {
        }
      }
    }
    if (opts.virtualConsole !== false) {
      options.virtualConsole = new jsdom.VirtualConsole().sendTo(console)
    }
    url = url || 'http://localhost:3000'
    const { window } = await jsdom.JSDOM.fromURL(url, options)
    // If Nuxt could not be loaded (error from the server-side)
    const nuxtExists = window.document.body.innerHTML.includes('window.__NUXT__')
    if (!nuxtExists) {
      /* istanbul ignore next */
      let error = new Error('Could not load the nuxt app')
      /* istanbul ignore next */
      error.body = window.document.body.innerHTML
      throw error
    }
    // Used by nuxt.js to say when the components are loaded and the app ready
    await new Promise((resolve) => {
      window._onNuxtLoaded = () => resolve(window)
    })
    // Send back window object
    return window
  }
}