1import { GetServerSideProps } from 'next';23import dbConnect from '../utils/dbConnect';45import Url from '../models/Url';678// this to handle the URL redirection based on a shortCode parameter.910export const getServerSideProps: GetServerSideProps = async (context) => {11    try {12        await dbConnect();1314        const { shortCode } = context.params;15        console.log('Fetching URL for shortCode:', shortCode);16        const urlEntry = await Url.findOne({ shortCode }).exec();17        console.log('URL Entry:', urlEntry);1819        // use tenary operator that determines the value of the baseUrl variable 20        // based on the environment in which the application is running. Here's a breakdown of what it does:21        if (urlEntry) {22            const originalUrl = urlEntry.originalUrl.startsWith('http')23                ? urlEntry.originalUrl24                : `http://${urlEntry.originalUrl}`;25            console.log('Redirecting to:', originalUrl);2627            return {28                redirect: {29                    destination: originalUrl,30                    permanent: false,31                },32            };33        } else {34            console.log('No URL entry found for shortCode:', shortCode);35            return {36                notFound: true,37            };38        }39    } catch (error) {40        console.error('Error in getServerSideProps:', error);41        return {42            notFound: true,43        };44    }45};4647const RedirectPage = () => {48    return null;49};5051export default RedirectPage;5253**pages/api/shorten.ts - Manages the URL shortening process and database interaction.**5455import { NextApiRequest, NextApiResponse } from 'next';5657import { nanoid } from 'nanoid';5859import QRCode from 'qrcode';6061import dbConnect from '../../utils/dbConnect';6263import Url from '../../models/Url';6465export default async function handler(req: NextApiRequest, res: NextApiResponse) {66    await dbConnect();6768    // The code fetches the original URL from the database6970    if (req.method === 'POST') {71        const { originalUrl, customDomain, customUrl } = req.body;7273        if (!originalUrl || typeof originalUrl !== 'string') {74            return res.status(400).json({ error: 'Invalid URL' });75        }7677        try {7879            // he nanoid library is used to generate a short code. 80            // The base URL is determined by checking if the environment is production8182            let shortCode = customUrl || nanoid(7);83            const baseUrl = process.env.NODE_ENV === 'production'84                ? process.env.NEXTAUTH_URL85                : 'http://localhost:3000';8687            const shortUrl = customDomain88                ? `${customDomain}/${shortCode}`89                : `${baseUrl}/${shortCode}`;9091            // generates a QR code for the shortened URL.9293            const qrCode = await QRCode.toDataURL(shortUrl);9495            const newUrl = new Url({96                originalUrl,97                shortUrl,98                shortCode,99                qrCode,100            });101102            await [newUrl.save](https://newurl.save)();103104            res.status(201).json({ message: 'URL shortened successfully', shortUrl, qrCode });105        } catch (error) {106            console.error('Error saving URL:', error);107            res.status(500).json({ message: 'Internal Server Error' });108        }109    } else {110        res.status(405).json({ message: 'Method not allowed' });111    }112}113114 **utils/dbConnect.ts - Handles the database connection logic** 115116import mongoose from 'mongoose';117118const MONGODB_URI: string = process.env.MONGODB_URI as string;119120if (!MONGODB_URI) {121    throw new Error('Please define the MONGODB_URI environment variable inside .env.local');122}123124let cached = (global as any).mongoose;125126if (!cached) {127    cached = (global as any).mongoose = { conn: null, promise: null };128}129130async function dbConnect() {131    if (cached.conn) {132        return cached.conn;133    }134135    if (!cached.promise) {136        const opts = {137            bufferCommands: false,138        };139140        cached.promise = mongoose.connect(MONGODB_URI, opts).then((mongoose) => mongoose);141    }142    cached.conn = await cached.promise;143    return cached.conn;144}145146export default dbConnect;147148**env.local - Environment variables setup (with sensitive information redacted)**149150  MONGODB_URI=mongodb+srv://user:password@cluster0.mongodb.net/myDatabase?retryWrites=true&w=majority151152  NEXTAUTH_URL=https://shorty-sigma.vercel.app/153154  GOOGLE_CLIENT_ID=[1234567890-abcde1234.apps.googleusercontent.com](https://1234567890-abcde1234.apps.googleusercontent.com)155156  GOOGLE_CLIENT_SECRET=ABCDEF1234567890157158  GITHUB_CLIENT_ID=gh1234567890abcdef159160  GITHUB_CLIENT_SECRET=ghabcdef1234567890161162  EMAIL_USER=myemail@example.com163164  EMAIL_PASS=myemailpassword165166  JWT_SECRET=myjwtsecretkey167168  NEXTAUTH_SECRET=myNextAuthSecretKey169170171**NOTE: the env.local values are generated for demonstration purpose except for NEXTAUTH_URL**172173import mongoose, { Schema, Model, Document } from 'mongoose';174175interface IUrl extends Document {176    originalUrl: string;177    shortUrl: string;178    shortCode: string;179    qrCode: string;180    customUrl?: string;181    customDomain?: string;182    userId: Schema.Types.ObjectId;183    createdAt: Date;184}185186const UrlSchema: Schema = new Schema({187    originalUrl: { type: String, required: true },188    shortUrl: { type: String, required: true, unique: true },189    shortCode: { type: String, required: true, unique: true },190    qrCode: { type: String },191    userId: { type: mongoose.Schema.Types.ObjectId, ref: 'User' },192    customDomain: { type: String },193    customUrl: { type: String },194    createdAt: { type: Date, default: [Date.now](https://date.now) }195196}, { timestamps: true });197const Url: Model = mongoose.models.Url || mongoose.model('Url', UrlSchema);198export default Url