/**

 * Copyright (c) Meta Platforms, Inc. and affiliates.

 *

 * This source code is licensed under the MIT license found in the

 * LICENSE file in the root directory of this source tree.

 *

 */

import {Writable} from 'stream';

import * as React from 'react';

import {renderToPipeableStream} from 'react-dom/server';

import App from '../src/App';

import {ABORT_DELAY} from './delays';

// In a real setup, you'd read it from webpack build stats.

let assets = {

  'main.js': '/main.js',

  'main.css': '/main.css',

};

function HtmlWritable(options) {

  Writable.call(this, options);

  this.chunks = [];

  this.html = '';

}

HtmlWritable.prototype = Object.create(Writable.prototype);

HtmlWritable.prototype.getHtml = function getHtml() {

  return this.html;

};

HtmlWritable.prototype._write = function _write(chunk, encoding, callback) {

  this.chunks.push(chunk);

  callback();

};

HtmlWritable.prototype._final = function _final(callback) {

  this.html = Buffer.concat(this.chunks).toString();

  callback();

};

module.exports = function render(url, res) {

  let writable = new HtmlWritable();

  res.socket.on('error', error => {

    console.error('Fatal', error);

  });

  let didError = false;

  let didFinish = false;

  writable.on('finish', () => {

    // If something errored before we started streaming, we set the error code appropriately.

    res.statusCode = didError ? 500 : 200;

    res.setHeader('Content-type', 'text/html');

    res.send(writable.getHtml());

  });

  const {pipe, abort} = renderToPipeableStream(<App assets={assets} />, {

    bootstrapScripts: [assets['main.js']],

    onAllReady() {

      // Full completion.

      // You can use this for SSG or crawlers.

      didFinish = true;

    },

    onShellReady() {

      // If something errored before we started streaming, we set the error code appropriately.

      pipe(writable);

    },

    onShellError(x) {

      // Something errored before we could complete the shell so we emit an alternative shell.

      res.statusCode = 500;

      res.send('<!doctype><p>Error</p>');

    },

    onError(x) {

      didError = true;

      console.error(x);

    },

  });

  // Abandon and switch to client rendering if enough time passes.

  // Try lowering this to see the client recover.

  setTimeout(() => {

    if (!didFinish) {

      abort();

    }

  }, ABORT_DELAY);

};