firebase.js

import { initializeApp, getApps, getApp } from 'firebase/app';
import { getAuth, GoogleAuthProvider } from 'firebase/auth';
import { getFirestore } from 'firebase/firestore';

const firebaseConfig = {
    apiKey: process.env.NEXT_PUBLIC_FIREBASE_API_KEY,
    authDomain: process.env.NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN,
    projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID,
    storageBucket: process.env.NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET,
    messagingSenderId: process.env.NEXT_PUBLIC_FIREBASE_MESSAGING_SENDER_ID,
    appId: process.env.NEXT_PUBLIC_FIREBASE_APP_ID,
    measurementId: process.env.NEXT_PUBLIC_FIREBASE_MEASUREMENT_ID
};

// Initialize Firebase
let app;

if (!getApps().length) {
    app = initializeApp(firebaseConfig);
} else {
    app = getApp(); // if already initialized, use that one
}

export const auth = getAuth(app);
export const db = getFirestore(app);
export const googleProvider = new GoogleAuthProvider();
export const firebaseApp = app;