app.js

'use strict';

require('dotenv').config();

const port = process.env.PORT || 3000;
const courses = [
    { id: 1, name: 'Software Engineering' },
    { id: 2, name: 'Computer Science' },
    { id: 3, name: 'Robotics' },
    { id: 4, name: 'Artificial intelligence' },
    { id: 5, name: 'Machine Learning' },
    { id: 6, name: 'Theoretical Physics'}
];

const Joi = require('joi'); // Validation package - returns a class Joi
const express = require('express');
const app = express();

// enable parsing of JSON objects in body of request
app.use(express.json());

app.get('/', (req, res) => {
    return res.send('Index');
});

app.get('/api/courses', (req, res) => {
    return res.send(courses);
});

app.get('/api/courses/:id', (req, res) => {
    const course = courses.find(c => c.id === parseInt(req.params.id));
    return !course ? res.status(404).send('404 Not Found!') : res.send(course);
});

app.post('/api/courses', (req, res) => {
    const { error } = validateCourse(req.body);
    if (error) return res.status(400).send(error.details[0].message);

    const course = {
        id: courses.length+1,
        name: req.body.name,
    }
    courses.push(course);
    return res.status(201).send(course);
});

app.put('/api/courses/:id', (req, res) => {
    const course = courses.find(c => c.id === parseInt(req.params.id));
    if (!course) return res.status(404).send('404 Not Found!');

    const { error } = validateCourse(req.body);
    if (error) return res.status(200).send(error.details[0].message);

    course.name = req.body.name;
    return res.send(course);
});

app.delete('/api/courses/:id', (req, res) => {
    const course = courses.find(c => c.id === parseInt(req.params.id));
    if (!course) return res.status(404).send('404 Not Found!'); 

    const index = courses.indexOf(course);
    courses.splice(index, 1);

    return res.status(204).send(course);
});

function validateCourse(course) {
    return Joi.object({
        name: Joi.string().min(3).required(),
    }).validate(course);
}

app.listen(port, (req, res) => {
    console.log(`Listening on port ${port}`);
});