src/lib/firebase.ts

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

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,
}

const requiredFirebaseConfig = [
  ['NEXT_PUBLIC_FIREBASE_API_KEY', firebaseConfig.apiKey],
  ['NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN', firebaseConfig.authDomain],
  ['NEXT_PUBLIC_FIREBASE_PROJECT_ID', firebaseConfig.projectId],
  ['NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET', firebaseConfig.storageBucket],
  ['NEXT_PUBLIC_FIREBASE_MESSAGING_SENDER_ID', firebaseConfig.messagingSenderId],
  ['NEXT_PUBLIC_FIREBASE_APP_ID', firebaseConfig.appId],
] as const

function getMissingFirebaseConfig() {
  return requiredFirebaseConfig
    .filter(([, value]) => !value)
    .map(([key]) => key)
}

function getFirebaseApp() {
  const missingConfig = getMissingFirebaseConfig()
  if (missingConfig.length > 0) {
    throw new Error(`Firebase is not configured. Missing: ${missingConfig.join(', ')}`)
  }

  return getApps().length ? getApp() : initializeApp(firebaseConfig)
}

export function getFirebaseAuth() {
  return getAuth(getFirebaseApp())
}

export function getFirebaseDb() {
  return getFirestore(getFirebaseApp())
}

export function getFirebaseStorage() {
  return getStorage(getFirebaseApp())
}