A simple rule-based chatbot developed with javascript

app.js

const bot = require("./training");
console.log("Hello I'm Bujo. Let's Talk :)");
bot.converse();

simple-nlp.js

"use strict";

const readline = require("readline");
const chalk = require("chalk");

const prompt = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

// Utilities
function input(self, str = "> ") {
    prompt.question(str, (value) => {
        const result = self.process(value);
        if(result.answer) {
            process.stdout.write(chalk.yellow(result.answer) + "\n");
            if(value.includes("bye")) {
                prompt.close();
                process.exit();
            }
            input(self, str);
        } else {
            process.stdout.write("Sorry please could you rephrase that?" + "\n");
            input(self, str);
        }
    });
    // prompt.close();
}

function randomBetween(min, max) {
    return Math.floor(Math.random() * (max - min + 1) + min);
}

function flattenArray(arr) {
    let result = [];
    arr.forEach(i => {
        if(!Array.isArray(i)) {
            result.push(i);
        } else {
            result.push(...flattenArray(i));
        }
    });
    return result;
};
/** Test
const testArr = [
    [1, 2, 3, 4],
    5, 6, 7,
    [8, 9, 10, [11, 12, [13, 14, 15], 16]],
    ];
 */

// function processData(reg, str, template) {
//     // const m = /hello|hi\s+([^\s]+)/g.exec(str);
//     const m = reg.exec(str);
//     for(let i = 1; i < m.length; i++) {
//         console.log(i);
//         template = template.replace(`%${i}`, m[i]);
//     }
//     return template;
// }

function processData(match, templates) {
    const newTemp = templates.map(template => {
        for(let i = 1; i < match.length; i++) {
            template = template.replace(`%${i}`, match[i]);
        }
        return template;
    });
    return newTemp;
}

/**
 *  @description A simple example of nlp functions for building chatbots
 *
 */


class Simple_Nlp {
    constructor() {
        this.__Markers = Object.create(null);
        this.__Rules = Object.create(null);
        this.__Answers = Object.create(null);

        // Bind methods
        this.addRule = this.addRule.bind(this);
        this.addAnswer = this.addAnswer.bind(this);
        this.train = this.train.bind(this);
        this.process = this.process.bind(this);
        this.converse = this.converse.bind(this);
    }

    // Use String.raw to create string using
    addRule(rule, marker) {
        this.__Markers[marker] ? this.__Markers[marker] += `|${rule}` : this.__Markers[marker] = rule;
        if(!this.__Answers[marker]) this.__Answers[marker] = Array();
    }

    addAnswer(marker, answer) {
        if(!this.__Answers[marker]) throw new Error(`Sorry '${marker} does not exist`);
        this.__Answers[marker].push(answer);
    }

    train() {
        for(let marker in this.__Markers) {
            this.__Rules[marker] = new RegExp(this.__Markers[marker], "gim");
        }
    }

    /**
     * @todo    Add formatted output
     */
    process(str) {
        const result = Object.create(null);
        result.utterance = str;
        result.possibleAnswers = Array();
        result.classifications = Object.create(null);
        for(let marker in this.__Rules) {
            // let match = str.match(this.__Rules[marker]);
            let match = this.__Rules[marker].exec(str);
            if(match) {
                result.classifications[marker] = match;
                result.possibleAnswers.push(processData(match, this.__Answers[marker]))
            }
        }
        result.possibleAnswers = flattenArray(result.possibleAnswers);
        result.answer = result.possibleAnswers[randomBetween(0, result.possibleAnswers.length - 1)];
        return result;
    }

    converse() {
        input(this);
    }
}

const nlp = new Simple_Nlp();
module.exports = {
    bot: nlp,
    r: String.raw
};

training.js

const {bot, r} = require("./simple-nlp");
// console.log(r);

// Possible questions
// bot.addRule('hi', "greeting.hi");
bot.addRule("hey", "greeting.hi");
bot.addRule("hello", "greeting.hi");
bot.addRule("how are you", "ask.about");
bot.addRule("whatsup", "ask.about");
bot.addRule("howfar", "ask.about");
bot.addRule("your name", "ask.self");
bot.addRule("sex", "ask.sex");
bot.addRule("bye", "greeting.bye");
bot.addRule("fine", "answer.greeting");
bot.addRule("great", "answer.greeting");
bot.addRule("good", "answer.greeting");
bot.addRule("sorry", "answer.plead");

bot.addRule("order", "business.order");
bot.addRule("purchase", "business.order");
bot.addRule(r`i want ([^\s]+)`, "business.order");
bot.addRule(r`i need ([^\s]+)`, "business.order");
bot.addRule("Menu", "business.menu");
bot.addRule("List", "business.menu");
bot.addRule("Products", "business.menu");

// Answers
bot.addAnswer("greeting.hi", "Hello dear how are you?");
bot.addAnswer("greeting.hi", "How are you?");
bot.addAnswer("greeting.hi", "Hi, how can i help you?");
bot.addAnswer("greeting.bye", "Ok see you around");
bot.addAnswer("greeting.bye", "It was nice talking with you");
bot.addAnswer("ask.about", "I'm doing great, how can I help you?");
bot.addAnswer("ask.self", "I am a bot Created by Spiff");
bot.addAnswer("ask.sex", "😂 Hey I am a bot");
bot.addAnswer("ask.sex", "😂 Ha thats funny, you know i'm not human right?");
bot.addAnswer("answer.greeting", "That's good to know");
bot.addAnswer("answer.greeting", "That's great");
bot.addAnswer("answer.plead", "It's all good.");

bot.addAnswer("business.order", "You want to place an order, Contact +234 701 0990 0405");
bot.addAnswer("business.order", "You want to make a purchase, Contact +234 701 0990 0405");
bot.addAnswer("business.order", "Your order for %1 has been placed. :)")
bot.addAnswer("business.menu", "We sell eggs, milk, chickens, chicken feed, fish, etc");

// Test
bot.addRule(r`my name is ([^\s]+)`, "intro.name");
bot.addAnswer("intro.name", "Hello %1");

// Train bot
bot.train();

module.exports = bot;