app.js

/**
 *  Here, we will sync our database, create our application, and export this 
 *  module so that we can use it in the bin directory, where we will be able to 
 *  establish a server to listen and handle requests and responses
 */

// Load environmental variables from .env file
require("dotenv").config();

var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');
var helmet = require("helmet");
var compression = require("compression");

// Utilities
const createLocalDatabase = require("./utils/createLocalDatabase");
const seedDatabase = require("./utils/seedDatabase");

// Our database instance
const db = require("./database");

// A helper function to sync our database
const syncDatabase = () =>
{
    if(process.env.NODE_ENV === "production")
    {
        db.sync();
    }
    else
    {
        console.log("As a reminder, the forced synchronization option is on");
        db.sync({ force: true })
        .then(() => seedDatabase())
        .catch((err) =>
        {
            if(err.name === "SequelizeConnectionError")
            {
                createLocalDatabase();
                seedDatabase();
            }
            else console.log(err);
        });
    }
};

// Instantiate our express application
const app = express();

// A helper function to create our app with configurations and middleware
const configureApp = () =>
{
    app.use(helmet());
    app.use(logger("dev"));
    
    // Handle request data
    app.use(express.json());
    app.use(express.urlencoded({ extended: false }));
    app.use(compression());
    app.use(cookieParser());

    // Our API router
    const apiRouter = require("./routes/index");

    // Mount our API router
    app.use("/api", apiRouter);

    // Error handling
    app.use((req, res, next) =>
    {
        if(path.extname(req.path).length)
        {
            const err = new Error("Not found");
            err.status = 404;
            next(err);
        }
        else next();
    });

    // More error handling
    app.use((err, req, res, next) =>
    {
        console.error(err);
        console.error(err.stack);
        res.status(err.status || 500).send(err.message || "Internal server error.");
    });
}

// Main function declaration
const bootApp = async () =>
{
    await syncDatabase();
    await configureApp();
};

// Main function invocation
bootApp();

// Export our app, so that it can be imported in the www file
module.exports = app;