function validateFile(file) {
  const MAX_SIZE = 50 * 1024 * 1024; // 50MiB
  const filenameRegex = /^(?!\s)(?!.*\s$)[^<>:"/\\|?*\x00-\x1F]+\.(?!\.)[^<>:"/\\|?*\x00-\x1F]{1,4}$|^(?!\s)(?!.*\s$)[^<>:"/\\|?*\x00-\x1F]+$/;

  if (!file) return { valid: false, reason: 'No file provided' };
  if (file.size > MAX_SIZE) return { valid: false, reason: 'The file is too big. (Max is 50MiB)' };
  if (!filenameRegex.test(file.originalname)) return { valid: false, reason: 'Invalid filename.' };

  return { valid: true };
}

module.exports = { validateFile };