const path = require('path');

function isPathInside(parent, child) {
  const relativePath = path.relative(parent, child);
  return relativePath === '' || (!relativePath.startsWith('..') && !path.isAbsolute(relativePath));
}

function normalizeVirtualPath(rawPath) {
  if (typeof rawPath !== 'string') return null;

  let decoded = rawPath;
  try {
    decoded = decodeURIComponent(rawPath);
  } catch {
    // The traversal checks below still apply to malformed encoded input.
  }

  if (decoded.includes('\x00') || decoded.toLowerCase().includes('%00')) return null;

  const unifiedPath = decoded.replace(/\\/g, '/');
  if (/(^|\/)\.\.(\/|$)/.test(unifiedPath)) return null;

  let normalized = path.posix.normalize(unifiedPath);
  if (normalized === '' || normalized === '.') normalized = '/';
  if (!normalized.startsWith('/')) normalized = `/${normalized}`;

  normalized = normalized.replace(/\/+$/g, '');
  return normalized || '/';
}

module.exports = {
  isPathInside,
  normalizeVirtualPath
};