const formatFileSize = (bytes) => {
  if (bytes === 0) return '0 Bytes';
  
  const k = 1024;
  const sizes = ['Bytes', 'KB', 'MB', 'GB'];
  const i = Math.floor(Math.log(bytes) / Math.log(k));
  
  return parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + ' ' + sizes[i];
};

const generateInviteCode = () => {
  return Math.random().toString(36).substring(2, 8).toUpperCase();
};

const sanitizeUser = (user) => {
  const userObj = user.toObject ? user.toObject() : user;
  const { password, __v, ...sanitized } = userObj;
  return sanitized;
};

const paginate = (query, page = 1, limit = 20) => {
  const skip = (page - 1) * limit;
  return query.skip(skip).limit(limit);
};

module.exports = {
  formatFileSize,
  generateInviteCode,
  sanitizeUser,
  paginate
};