app.js

const express = require('express');
const app = express();
const morgan = require('morgan');
const bodyParser = require('body-parser');
const mongoose = require('mongoose');

const itemRoutes = require('./api/routes/items');
const userRoutes = require('./api/routes/user');
const msgRoutes = require('./api/routes/messages');

//Method to connect the API to an existing MongoDB database
mongoose.connect(
    'mongodb+srv://Caracold:304CEM-resit@cluster0-kbwm8.mongodb.net/test?retryWrites=true&w=majority', { useNewUrlParser: true, useUnifiedTopology: true })

//Setting dependencies for parsing and setting the uploads folder to public to allow access to image files.
app.use(morgan('dev'));
app.use('/uploads', express.static('uploads'));
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

//Middleware setting permissions to avoid browser-related errors
app.use((req, res, next) => {
    res.header('Access-Control-Allow-Origin', '*');
    res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept, Authorization');
    if (req.method === 'OPTIONS') {
        res.header('Access-Control-Allow-Methods', 'GET, POST, PATCH, DELETE');
        return res.status(200).json({});
    }
    next();
});

//Ensuring a browser that reaches the API's homepage is redirected to an existing route
app.get('/', function(req, res) {
    res.redirect('/itemlist');
});

app.use('/itemlist', itemRoutes);
app.use('/user', userRoutes);
app.use('/inbox', msgRoutes);

//Catch inexistent routes with a 404 error
app.use((req, res, next) => {
    const error = new Error('Address not found');
    error.status = 404;
    next(error);
})

app.use((error, req, res, next) => {
    res.status(error.status || 500);
    res.json({
        error: {
            message: error.message
        }
    })
})

module.exports = app;