app.js

// Import our node modules
const express = require("express");
const mongoose = require("mongoose");
const bodyParser = require("body-parser");
const path = require("path");

// Initialize express app
const app = express();

// Connect to mongodb
// connect returns a Promise object - get used to these.
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise
// Due to the asyrnchonous nature of nodeJs, a promise allows us to safely execute code only
// once a certain operation has finished
// For example, in this case the function passed into the .then clause is only
// executed once the .connect(...) call has finished.
// If something fails within the .connnect(...) call then the code passed in to the
// .catch clause is executed instead.
const db = require("./config/database");

mongoose
  .connect(db.mongoURI)
  .then(() => console.log("MongoDB Connected..."))
  .catch(err => console.log(err));

// Initialize the Middleware for our imported node modules
// Middleware is a function(s) that occur before every HTTP request
// so certain modules require us to use their middleware in order
// for them to work
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
app.use(express.static(path.join(__dirname, "public")));

// Set preflight headers to allows cors
app.use("*", (req, res, next) => {
  res.header(
    "Access-Control-Allow-Headers",
    "content-type, page, authorization"
  );
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Methods", "PUT, DELETE");
  next();
});

// Direct the appropriate urls to the respective controller (you may see this referred
// to as routes & routers elsewhere)
// The first parameter passed into app.use(...) directs all urls starting
// with this parameter to the controller passed in to the second paramater.
// Here, every request from the uri ('/examples/<ANYTHING>') will check the exampleController
// for the matching <ANYTHING> route
const exampleController = require("./controllers/exampleController");

app.use("/examples", exampleController);

const channelController = require("./controllers/channelController");

app.use("/channels", channelController);

const userController = require("./controllers/userController");

app.use("/users", userController);

const postController = require("./controllers/postController");

app.use("/posts", postController);

const notificationsController = require("./controllers/notificationsController");

app.use("/notifications", notificationsController);

const adminController = require("./controllers/adminController");

app.use("/admin", adminController);

const analyticsController = require("./controllers/analyticsController");

app.use("/analytics", analyticsController);

// Start the server on port 3000
// Use the port environment variable (needed for heroku) or 300 (dev)
const port = process.env.PORT || 3000;
app.listen(port, () => {
  console.log(`Server started on port ${port}`);
});