/**
 * *** NOTE ON IMPORTING FROM ANGULAR AND NGUNIVERSAL IN THIS FILE ***
 *
 * If your application uses third-party dependencies, you'll need to
 * either use Webpack or the Angular CLI's `bundleDependencies` feature
 * in order to adequately package them for use on the server without a
 * node_modules directory.
 *
 * However, due to the nature of the CLI's `bundleDependencies`, importing
 * Angular in this file will create a different instance of Angular than
 * the version in the compiled application code. This leads to unavoidable
 * conflicts. Therefore, please do not explicitly import from @angular or
 * @nguniversal in this file. You can export any needed resources
 * from your application's main.server.ts file, as seen below with the
 * import for `ngExpressEngine`.
 */

import 'zone.js/dist/zone-node';
import 'reflect-metadata';
import 'rxjs';

import * as fs from 'fs';
import * as pem from 'pem';
import * as https from 'https';
import * as morgan from 'morgan';
import * as express from 'express';
import * as bodyParser from 'body-parser';
import * as compression from 'compression';
import * as cookieParser from 'cookie-parser';
import { join } from 'path';

import { enableProdMode, NgModuleFactory, Type } from '@angular/core';

import { REQUEST, RESPONSE } from '@nguniversal/express-engine/tokens';
import { environment } from './src/environments/environment';

/*
 * Set path for the browser application's dist folder
 */
const DIST_FOLDER = join(process.cwd(), 'dist/browser');

// * NOTE :: leave this as require() since this file is built Dynamically from webpack
const { ServerAppModuleNgFactory, LAZY_MODULE_MAP, ngExpressEngine, provideModuleMap } = require('./dist/server/main');

/*
 * Create a new express application
 */
const app = express();

/*
 * If production mode is enabled in the environment file:
 * - Enable Angular's production mode
 * - Enable compression for response bodies. See [compression](https://github.com/expressjs/compression)
 */
if (environment.production) {
  enableProdMode();
  app.use(compression());
}

/*
 * Enable request logging
 * See [morgan](https://github.com/expressjs/morgan)
 */
app.use(morgan('dev'));

/*
 * Add cookie parser middleware
 * See [morgan](https://github.com/expressjs/cookie-parser)
 */
app.use(cookieParser());

/*
 * Add parser for request bodies
 * See [morgan](https://github.com/expressjs/body-parser)
 */
app.use(bodyParser.json());

/*
 * Render html pages by running angular server side
 */
app.engine('html', (_, options, callback) =>
  ngExpressEngine({
    bootstrap: ServerAppModuleNgFactory,
    providers: [
      {
        provide: REQUEST,
        useValue: (options as any).req,
      },
      {
        provide: RESPONSE,
        useValue: (options as any).req.res,
      },
      provideModuleMap(LAZY_MODULE_MAP)
    ],
  })(_, (options as any), callback)
);

/*
 * Register the view engines for html and ejs
 */
app.set('view engine', 'ejs');
app.set('view engine', 'html');

/*
 * Set views folder path to directory where template files are stored
 */
app.set('views', DIST_FOLDER);

/*
 * Adds a cache control header to the response
 * The cache control value can be configured in the environments file and defaults to max-age=60
 */
function cacheControl(req, res, next) {
  // instruct browser to revalidate
  res.header('Cache-Control', environment.cache.control || 'max-age=60');
  next();
}

/*
 * Serve static resources (images, i18n messages, …)
 */
app.get('*.*', cacheControl, express.static(DIST_FOLDER, { index: false }));

/*
 * The callback function to serve server side angular
 */
function ngApp(req, res) {
  // Object to be set to window.dspace when CSR is used
  // this allows us to pass the info in the original request
  // to the dspace7-angular instance running in the client's browser
  const dspace = {
    originalRequest: {
      headers: req.headers,
      body: req.body,
      method: req.method,
      params: req.params,
      reportProgress: req.reportProgress,
      withCredentials: req.withCredentials,
      responseType: req.responseType,
      urlWithParams: req.urlWithParams
    }
  };

  // callback function for the case when SSR throws an error.
  function onHandleError(parentZoneDelegate, currentZone, targetZone, error) {
    if (!res._headerSent) {
      console.warn('Error in SSR, serving for direct CSR. Error details : ', error);
      res.sendFile('index.csr.ejs', {
        root: DIST_FOLDER,
        scripts: `<script>window.dspace = ${JSON.stringify(dspace)}</script>`
      });
    }
  }

  if (environment.universal.preboot) {
    // If preboot is enabled, create a new zone for SSR, and
    // register the error handler for when it throws an error
    Zone.current.fork({ name: 'CSR fallback', onHandleError }).run(() => {
      res.render(DIST_FOLDER + '/index.html', {
        req,
        res,
        preboot: environment.universal.preboot,
        async: environment.universal.async,
        time: environment.universal.time,
        baseUrl: environment.ui.nameSpace,
        originUrl: environment.ui.baseUrl,
        requestUrl: req.originalUrl
      });
    });
  } else {
    // If preboot is disabled, just serve the client side ejs template and pass it the required
    // variables
    console.log('Universal off, serving for direct CSR');
    res.render('index-csr.ejs', {
      root: DIST_FOLDER,
      scripts: `<script>window.dspace = ${JSON.stringify(dspace)}</script>`
    });
  }
}

// Register the ngApp callback function to handle incoming requests
app.get('*', ngApp);

/*
 * Callback function for when the server has started
 */
function serverStarted() {
  console.log(`[${new Date().toTimeString()}] Listening at ${environment.ui.baseUrl}`);
}

/*
 * Create an HTTPS server with the configured port and host
 * @param keys SSL credentials
 */
function createHttpsServer(keys) {
  https.createServer({
    key: keys.serviceKey,
    cert: keys.certificate
  }, app).listen(environment.ui.port, environment.ui.host, () => {
    serverStarted();
  });
}

/*
 * If SSL is enabled
 * - Read credentials from configuration files
 * - Call script to start an HTTPS server with these credentials
 * When SSL is disabled
 * - Start an HTTP server on the configured port and host
 */
if (environment.ui.ssl) {
  let serviceKey;
  try {
    serviceKey = fs.readFileSync('./config/ssl/key.pem');
  } catch (e) {
    console.warn('Service key not found at ./config/ssl/key.pem');
  }

  let certificate;
  try {
    certificate = fs.readFileSync('./config/ssl/cert.pem');
  } catch (e) {
    console.warn('Certificate not found at ./config/ssl/key.pem');
  }

  if (serviceKey && certificate) {
    createHttpsServer({
      serviceKey: serviceKey,
      certificate: certificate
    });
  } else {

    process.env.NODE_TLS_REJECT_UNAUTHORIZED = '0';

    pem.createCertificate({
      days: 1,
      selfSigned: true
    }, (error, keys) => {
      createHttpsServer(keys);
    });
  }
} else {
  app.listen(environment.ui.port, environment.ui.host, () => {
    serverStarted();
  });
}
