namespace Zcbot.WindowsNode;

internal static class PathGuard
{
    internal static string CombineUnderRoot(string root, params string[] segments)
    {
        var normalizedRoot = Path.TrimEndingDirectorySeparator(Path.GetFullPath(root));
        if (segments.Any(Path.IsPathFullyQualified))
        {
            throw new InvalidDataException("A persisted path segment must be relative.");
        }
        var candidate = Path.GetFullPath(Path.Combine([normalizedRoot, .. segments]));
        var prefix = normalizedRoot + Path.DirectorySeparatorChar;
        if (!candidate.StartsWith(prefix, StringComparison.OrdinalIgnoreCase))
        {
            throw new InvalidDataException("A persisted path escaped its expected root.");
        }
        return candidate;
    }
}