import 'server-only';
import admin from 'firebase-admin';

interface FirebaseAdminConfig {
  projectId: string;
  clientEmail: string;
  privateKey: string;
}

function formatPrivateKey(key: string) {
  return key.replace(/\\n/g, '\n');
}

export function createFirebaseAdminApp(config: FirebaseAdminConfig) {
  if (admin.apps.length > 0) {
    return admin.app();
  }

  return admin.initializeApp({
    credential: admin.credential.cert({
      projectId: config.projectId,
      clientEmail: config.clientEmail,
      privateKey: formatPrivateKey(config.privateKey),
    }),
  });
}

export function getAdminAuth() {
    // Only initialize if we have credentials, otherwise return null (or throw)
    // This prevents build crashes if env vars are missing
    if (!process.env.FIREBASE_PROJECT_ID || !process.env.FIREBASE_CLIENT_EMAIL || !process.env.FIREBASE_PRIVATE_KEY) {
        console.warn("Firebase Admin credentials missing. Server-side auth will fail.");
        return null;
    }

    const app = createFirebaseAdminApp({
        projectId: process.env.FIREBASE_PROJECT_ID,
        clientEmail: process.env.FIREBASE_CLIENT_EMAIL,
        privateKey: process.env.FIREBASE_PRIVATE_KEY,
    });
    
    return app.auth();
}