server.js

require("dotenv").config({ path: "/var/www/.env" });
const express = require("express");
const helmet = require("helmet");
const timeout = require("connect-timeout");
const fs = require("fs");

const haltOnTimedout = (req, res, next) => {
  if (!req.timedout) next();
};

const sendCustomizedIndexFile = (filePath, title, description) => {
  return function (req, res, next) {
    fs.readFile(filePath, "utf8", (err, data) => {
      if (err) {
        console.log(err);
        res.sendFile(filePath);
      } else {
        data = data.replace(/%TITLE%/g, title);
        data = data.replace(/%DESCRIPTION%/g, description);
        res.send(data);
      }
    });
  };
};

const app = express();
app.use(timeout("15s"));
app.use(helmet());
app.use(haltOnTimedout);

// process.env is read from the .env file on server
if (process.env.NODE_ENV === "production") {
  //serve up production assests, disable directory indexing
  app.use(express.static("client/build", { index: false }));
  //serve up index.html if route is unrecognizable
  const path = require("path");
  const indexFilePath = path.join(__dirname, "client", "build", "index.html");

  app.get(
    "/",
    sendCustomizedIndexFile(
      indexFilePath,
      "WasedaTime",
      "An unofficial app for Syllabus Searching, Classroom Usage Checking, and Shuttle Bus Arrival Time Checking at Waseda University."
    )
  );

  app.get(
    "/timetable",
    sendCustomizedIndexFile(
      indexFilePath,
      "WasedaTime - TimeTable",
      "Create Your Own TimeTable at Waseda University."
    )
  );

  app.get(
    "/syllabus",
    sendCustomizedIndexFile(
      indexFilePath,
      "WasedaTime - Syllabus",
      "Syllabus Searching at Waseda University."
    )
  );

  app.get(
    "/roomfinder",
    sendCustomizedIndexFile(
      indexFilePath,
      "WasedaTime - Classroom Usage",
      "Classroom Usage Checking at Waseda University."
    )
  );

  app.get(
    "/bus",
    sendCustomizedIndexFile(
      indexFilePath,
      "WasedaTime - Bus",
      "Shuttle Bus Arrival Time Checking at Waseda University."
    )
  );

  app.get(
    "*",
    sendCustomizedIndexFile(
      indexFilePath,
      "WasedaTime",
      "An unofficial app for Syllabus Searching, Classroom Usage Checking, and Shuttle Bus Arrival Time Checking at Waseda University."
    )
  );
}

const PORT = process.env.PORT || 5000;
app.listen(PORT, () => console.log(`App listening on port ${PORT}`));