firebaseConfig.js

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

const firebaseConfig = {
  apiKey: process.env.EXPO_PUBLIC_FIREBASE_API_KEY || 'MISSING_FIREBASE_API_KEY',
  authDomain: process.env.EXPO_PUBLIC_FIREBASE_AUTH_DOMAIN || 'example.firebaseapp.com',
  projectId: process.env.EXPO_PUBLIC_FIREBASE_PROJECT_ID || 'example-project-id',
  storageBucket: process.env.EXPO_PUBLIC_FIREBASE_STORAGE_BUCKET || 'example.appspot.com',
  messagingSenderId: process.env.EXPO_PUBLIC_FIREBASE_MESSAGING_SENDER_ID || '000000000000',
  appId: process.env.EXPO_PUBLIC_FIREBASE_APP_ID || '1:000000000000:web:replace-me',
};

const missingFirebaseConfig = Object.entries(firebaseConfig)
  .filter(([, value]) => value.startsWith('MISSING_') || value.includes('example'))
  .map(([key]) => key);

if (missingFirebaseConfig.length > 0) {
  console.warn(
    `Firebase config placeholders are active. Set ${missingFirebaseConfig.join(', ')} in your Expo environment before using auth features.`
  );
}

const app = getApps().length > 0 ? getApp() : initializeApp(firebaseConfig);

export const auth = getAuth(app);
export default app;