mock version of prerender.js support for preact-cli

_internal_entry.js

const { h } = require('preact');
const app = require('preact-cli-entrypoint-prerendering');
const prerender = app && app.default || app;

if (typeof prerender !== 'function') {
  throw Error('prerender module must export a function, but exported '+(typeof prerender));
}

module.exports = function(props) {
  const result = prerender(props);

  // there's no way to get around this wrapping div, and that probably breaks hydration.
  return h('div', {
    id: 'preact_root',
    dangerouslySetInnerHTML: { __html: result.html }
  });
};

preact-cli-plugin-prerender.js

const path = require('path');
const fs = require('fs');

const entries = ['prerender.ts', 'prerender.js']
entries = entries.concat(entries.map(f => f + 'x'));
entries = entries.concat(entries.map(f => 'src/' + f);

module.exports = function(config, env) {
  const cwd = env ? env.cwd : process.cwd();
  const isSsr = !env || env.ssr === true;
  const source = f => existsSync(f = path.resolve(cwd, f)) && f;
  const entry = entries.map(source).find(Boolean);
  if (env) {
    const definePlugin = config.plugins.filter(p => /^DefinePlugin$/.test(p && p.constructor && p.constructor.name))[0];
    if (definePlugin) {
      Object.assign(definePlugin.plugin.definitions, {
        'process.env.SSR': String(env.ssr),
        'process.env.PRERENDER': String(env.ssr),
        PRERENDER: String(env.ssr)
      });
    }
  }
  if (entry) {
    console.log('Using custom prerender entry: ' + path.relative(cwd, entry));
    config.resolve.alias['preact-cli-entrypoint-prerendering'] = entry;
    config.resolve.alias['preact-cli-entrypoint'] = require.resolve('./_internal_entry.js');
  }
  else {
    console.log('Prerendering using default settings.');
  }
}

preact.config.js

const prerender = require('preact-cli-plugin-prerender');

module.exports = function(config, env, helpers) {
  prerender(config, env);
};