app.js

'use strict';
var debug = require('debug');
var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');

var routes = require('./routes/index');
var messages = require('./routes/messages');
var connectionString = 'mongodb://localhost:27017/chatbot';

var app = express();

const { DateTime } = require("luxon");

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'pug');

// uncomment after placing your favicon in /public
//app.use(favicon(__dirname + '/public/favicon.ico'));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', routes);
app.use('/messages', messages);

// catch 404 and forward to error handler
app.use(function (req, res, next) {
    var err = new Error('Not Found');
    err.status = 404;
    next(err);
});

// error handlers

// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
    app.use(function (err, req, res, next) {
        res.status(err.status || 500);
        res.render('error', {
            message: err.message,
            error: err
        });
    });
}

// production error handler
// no stacktraces leaked to user
app.use(function (err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
        message: err.message,
        error: {}
    });
});

app.set('port', process.env.PORT || 3000);


const MongoClient = require('mongodb').MongoClient;
var db = null;

function reply(socket, message, messagesCollection) {

    socket.emit('chat message', message);
    messagesCollection.insertOne({ time: new Date(), isBot: 1, message: message });
}

MongoClient.connect(connectionString, (err, client) => {
    if (err) return console.error(err)
    console.log('Connected to Database');
    db = client.db('chatbot');
    app.locals.db = db;

    var server = app.listen(app.get('port'), function () {
        debug('Express server listening on port ' + server.address().port);
    });

    var io = require('socket.io')(server);

    io.on('connection', (socket) => {

        console.log('a user connected');
        const messagesCollection = db.collection('messages')
        reply(socket, 'Hi, what is your first name?', messagesCollection);
    
        socket.on('disconnect', () => {
            console.log('user disconnected');
        });
        socket.on('chat message', (msg) => {

            console.log('message: ' + msg);
            messagesCollection.insertOne({ time: new Date(), isBot: 0, message: msg });

            if (!socket.hasOwnProperty('firstName')) {
                socket.firstName = msg;
                reply(socket, 'hi ' + msg + ', when is your birthday? YYYY-MM-DD', messagesCollection);
            } else {
                if (!socket.hasOwnProperty('birthDay')) {
                    var birthDay = DateTime.fromFormat(msg, 'yyyy-MM-dd');
                    if (birthDay.isValid) {
                        socket.birthDay = birthDay;
                        reply(socket, 'Do you want to know how many days till your next birthday?', messagesCollection);
                    } else {
                        reply(socket, 'Invalid date, retype your birthday again with YYYY-MM-DD format', messagesCollection);
                    }
                } else {
                    var yes = ["yes", "yeah", "yup", "sure", "ya"];
                    var no = ["no", "nope", "nah"];
                    if (yes.some(e1 => msg.includes(e1))) {
                        var nextBirthDay = socket.birthDay;
                        var now = DateTime.local();
                        var yearNow = now.year;
                        nextBirthDay = nextBirthDay.set({ year: yearNow });
                        var diff = nextBirthDay.diffNow('days').toObject().days;
                        if (diff < 0) { //if birthday date in this year already passed
                            nextBirthDay = nextBirthDay.set({ year: yearNow + 1 });
                            diff = nextBirthDay.diffNow('days').toObject().days;
                        }
                        reply(socket, 'There are ' + Math.ceil(diff) + ' days left until your next birthday', messagesCollection);
                    } else if (no.some(e1 => msg.includes(e1))) {
                        reply(socket, 'Goodbye', messagesCollection);
                    } else {
                        reply(socket, 'uhh... is that a yes?', messagesCollection);
                    }
                }
            }
        });
    });
})