server.js

console.log("Server is booting...");

const express = require('express');
const bodyParser = require('body-parser');
const cors = require('cors');
const mqtt = require('mqtt');
const handlebars = require('express-handlebars').create({defaultLayout: 'main'});

// Custom Modules
const documentation = require('./modules/common/documentation');
const temperature = require('./modules/temperature');
const constants = require('./modules/common/constants');

// Initialise ExpressJS
var api = express();
api.use(bodyParser.urlencoded({ extended: true }));
api.use(bodyParser.json());
api.use(express.static('public'));
api.use(cors());

// Initialise Handlebars View handler.
api.engine('handlebars', handlebars.engine);
api.set('view engine', 'handlebars');

// Initialise Constants

const PORT = 8080;
const BASE_URL = "/api/v1";
const DATABASE_CONNECTION = constants.sqlConnection();


const MQTT_CONNECTION = constants.mqttConnection();
console.log(`Connecting to ${MQTT_CONNECTION.url}...`);
const CLIENT = mqtt.connect(MQTT_CONNECTION.url);
console.log(`Connected to ${MQTT_CONNECTION.url}`);

// MQTT Endpoints - (Arduino Circuits ONLY)
CLIENT.on('connect', () => {
    console.log('Setting up MQTT Client Subscriptions...');

    // Temperature
    CLIENT.subscribe(MQTT_CONNECTION.temperature_feed);
    console.log(`Subscribed to ${MQTT_CONNECTION.temperature_feed}`);

    CLIENT.subscribe(MQTT_CONNECTION.servo_feed);
    console.log(`Subscribed to ${MQTT_CONNECTION.servo_feed}`);

    console.log('MQTT Client Subscriptions have been registered');
});

CLIENT.on('message', (topic, message) => {
    switch (topic) {
        case MQTT_CONNECTION.temperature_feed:
            console.log('Current Temperature: %s*C', message);
            temperature.setCurrentTemperature(message);
            break;
        case MQTT_CONNECTION.servo_feed:
            console.log('Current Target: %s*C', message);
            break;
        default:
            console.log('Connected Status %s', message);
            break;
    }
});

// API Endpoints - (Web Application)
api.get(`${BASE_URL}/`, (req, res) => {
    var endpoints = documentation.getDocumentation();
    res.render('documentation', {endpoints: endpoints});
});

api.get(`${BASE_URL}/temperature/settings`, (req, res) => {
    temperature.getTemperatureSettings(DATABASE_CONNECTION, function (err, data){
        if(err){
            res.status(400);
            res.end("Error:" + err)
            return;
        }

        res.status(200);
        res.end(data);
    });
});

api.post(`${BASE_URL}/temperature/settings`, (req, res) => {
    temperature.createTemperatureSetting(DATABASE_CONNECTION, req, function (err, data){
        if(err){
            res.status(400);
            res.end("Error:" + err)
            return;
        }

        res.status(200);
        res.end(data);
    });
});

api.get(`${BASE_URL}/temperature/settings/:uid`, (req, res) => {
    temperature.getTemperatureSetting(DATABASE_CONNECTION, req, function (err, data){
        if(err){
            res.status(400);
            res.end("Error:" + err);
            return;
        }

        res.status(200);
        res.end(data);
    });
});

api.delete(`${BASE_URL}/temperature/settings/:uid`, (req, res) => {
    temperature.deleteTemperatureSetting(DATABASE_CONNECTION, req, function (err, data) {
        if(err){
            res.status(400);
            res.end("Error:" + err);
            return;
        }

        res.status(200);
        res.end(data);
    });
});

api.patch(`${BASE_URL}/temperature/settings/:uid`, (req, res) => {
    temperature.patchTemperatureSetting(DATABASE_CONNECTION, req, function (err, data) {
        if(err){
            res.status(400);
            res.end("Error:" + err);
            return;
        }

        res.status(200);
        res.end(data);
    });
});

api.get(`${BASE_URL}/temperature/dial`, (req, res) => {
    temperature.getTemperatureDial(DATABASE_CONNECTION, function (err, data) {
        if(err){
            res.status(400);
            res.end("Error:" + err);
            return;
        }

        res.status(200);
        res.end(data);
    });
});

api.patch(`${BASE_URL}/temperature/dial`, (req, res) => {
    temperature.updateTemperatureDial(DATABASE_CONNECTION, req, function (err, data) {
        if(err){
            res.status(400);
            res.end("Error:" + err);
            return;
        }

        res.status(200);
        res.end(data);
    });
});

api.get(`${BASE_URL}/temperature/current`, (req, res) => {
    const currentTemperature = temperature.getCurrentTemperature();
    console.log(currentTemperature);
    res.status(200);
    res.end(currentTemperature);
});

api.get(`${BASE_URL}/servo/:targetTemp`, (req, res) => {
    if (!isNaN(req.params.targetTemp)) {
        CLIENT.publish(MQTT_CONNECTION.servo_feed, req.params.targetTemp);
        res.status(201);
        res.end();
    }
    res.status(400);
    res.end();
});

// Set program listener on specific port.
api.listen(PORT, function() {
    console.log("Server is currently listening to port: " + PORT);
});