// SPDX-License-Identifier: MIT OR Apache-2.0
// Copyright (c) 2025 Pierre Fitness Intelligence
// ABOUTME: Firebase SDK configuration and authentication utilities
// ABOUTME: Provides Google Sign-In via Firebase for the Pierre frontend
import { initializeApp, type FirebaseApp } from 'firebase/app';
import {
getAuth,
signInWithRedirect,
getRedirectResult,
onAuthStateChanged,
GoogleAuthProvider,
signOut,
type Auth,
type UserCredential,
type User,
} from 'firebase/auth';
// Firebase configuration - all values from environment variables
// Set these in frontend/.env or frontend/.env.local:
// VITE_FIREBASE_API_KEY, VITE_FIREBASE_AUTH_DOMAIN, VITE_FIREBASE_PROJECT_ID,
// VITE_FIREBASE_STORAGE_BUCKET, VITE_FIREBASE_MESSAGING_SENDER_ID, VITE_FIREBASE_APP_ID
const firebaseConfig = {
apiKey: import.meta.env.VITE_FIREBASE_API_KEY,
authDomain: import.meta.env.VITE_FIREBASE_AUTH_DOMAIN,
projectId: import.meta.env.VITE_FIREBASE_PROJECT_ID,
storageBucket: import.meta.env.VITE_FIREBASE_STORAGE_BUCKET,
messagingSenderId: import.meta.env.VITE_FIREBASE_MESSAGING_SENDER_ID,
appId: import.meta.env.VITE_FIREBASE_APP_ID,
};
// Check if Firebase is configured
const isFirebaseConfigured = Boolean(
firebaseConfig.apiKey &&
firebaseConfig.authDomain &&
firebaseConfig.projectId
);
let app: FirebaseApp | null = null;
let auth: Auth | null = null;
/**
* Check if Firebase is properly configured via environment variables
*/
export function isFirebaseEnabled(): boolean {
return isFirebaseConfigured;
}
/**
* Initialize Firebase app (lazy initialization)
* Returns null if Firebase is not configured
*/
export function getFirebaseApp(): FirebaseApp | null {
if (!isFirebaseConfigured) {
return null;
}
if (!app) {
app = initializeApp(firebaseConfig);
}
return app;
}
/**
* Get Firebase Auth instance
* Returns null if Firebase is not configured
*/
export function getFirebaseAuth(): Auth | null {
if (!isFirebaseConfigured) {
return null;
}
if (!auth) {
const firebaseApp = getFirebaseApp();
if (!firebaseApp) {
return null;
}
auth = getAuth(firebaseApp);
}
return auth;
}
/**
* Initiate Google sign-in via redirect flow
* After calling this, the page will redirect to Google's login page.
* On return, call checkGoogleRedirectResult() to get the authentication result.
* Throws if Firebase is not configured.
*/
export async function signInWithGoogle(): Promise<void> {
const firebaseAuth = getFirebaseAuth();
if (!firebaseAuth) {
throw new Error('Google Sign-In is not available. Firebase is not configured.');
}
const provider = new GoogleAuthProvider();
provider.addScope('email');
provider.addScope('profile');
await signInWithRedirect(firebaseAuth, provider);
}
/**
* Check for Google sign-in redirect result on page load
* Returns null if no redirect result is pending or Firebase not configured
*/
export async function checkGoogleRedirectResult(): Promise<{
idToken: string;
email: string;
displayName: string | null;
} | null> {
const firebaseAuth = getFirebaseAuth();
if (!firebaseAuth) {
return null;
}
const result: UserCredential | null = await getRedirectResult(firebaseAuth);
if (!result) {
return null;
}
const idToken = await result.user.getIdToken();
return {
idToken,
email: result.user.email || '',
displayName: result.user.displayName,
};
}
/**
* Sign out from Firebase
* No-op if Firebase is not configured
*/
export async function signOutFromFirebase(): Promise<void> {
const firebaseAuth = getFirebaseAuth();
if (!firebaseAuth) {
return;
}
await signOut(firebaseAuth);
}
/**
* Subscribe to Firebase auth state changes
* Returns an unsubscribe function (no-op if Firebase not configured)
*/
export function subscribeToAuthState(
callback: (user: User | null) => void
): () => void {
const firebaseAuth = getFirebaseAuth();
if (!firebaseAuth) {
// Return no-op unsubscribe if Firebase not configured
return () => {};
}
return onAuthStateChanged(firebaseAuth, callback);
}
/**
* Get the current Firebase user (if signed in)
* Returns null if Firebase not configured
*/
export function getCurrentFirebaseUser(): User | null {
const firebaseAuth = getFirebaseAuth();
if (!firebaseAuth) {
return null;
}
return firebaseAuth.currentUser;
}
/**
* Get ID token for current user
* Returns null if Firebase not configured or no user
*/
export async function getFirebaseIdToken(): Promise<string | null> {
const user = getCurrentFirebaseUser();
if (!user) {
return null;
}
return user.getIdToken();
}
