const admin = require('firebase-admin');
const { getAuth } = require('firebase-admin/auth');

// Initialize Firebase Admin if not already initialized
try {
  const apps = admin.getApps ? admin.getApps() : (admin.apps || []);
  if (apps.length === 0) {
    admin.initializeApp({
      projectId: process.env.FIREBASE_PROJECT_ID || process.env.GCLOUD_PROJECT || 'motoapp-d22e0'
    });
  }
} catch (e) {
  console.warn('Firebase admin initialization failed:', e.message);
}

/**
 * Express middleware to verify Firebase ID tokens.
 */
async function requireAuth(req, res, next) {
  const authHeader = req.headers.authorization;
  if (!authHeader || !authHeader.startsWith('Bearer ')) {
    return res.status(401).json({
      error: 'authenticationRequired',
      message: 'Missing or malformed Authorization header'
    });
  }

  const idToken = authHeader.split('Bearer ')[1];

  try {
    const auth = typeof admin.auth === 'function' ? admin.auth() : getAuth();
    const decodedToken = await auth.verifyIdToken(idToken);
    req.user = decodedToken;
    next();
  } catch (error) {
    console.error('Error verifying Firebase ID token:', error.message);
    let errorCode = 'invalidToken';
    if (error.code === 'auth/id-token-expired') errorCode = 'expiredToken';

    return res.status(401).json({
      error: errorCode,
      message: 'Invalid or expired Firebase ID token'
    });
  }
}

module.exports = { requireAuth, admin };