[C#] SharpCompress - get XZ uncompressed size

XzFileInfo.cs

namespace MyProgram {
public class XzFileInfo
    {
        private const int XzHeaderSize = 12;
        public static ulong GetUncompressedSize(string filePath)
        {
            using var file = File.Open(filePath, FileMode.Open);

            // Read the footer from the end. Footer size is 12 bytes according to the spec.
            file.Seek(-XzHeaderSize, SeekOrigin.End);
            var footer = XZFooter.FromStream(file);
            Debug.WriteLine($"BackwardSize: {footer.BackwardSize}");

            // Get xz index offset from BackwardSize and seek to it.
            file.Seek(-(XzHeaderSize + footer.BackwardSize), SeekOrigin.End);
            var index = XZIndex.FromStream(file, false);
            Debug.WriteLine($"Index: number of records - {index.NumberOfRecords}");

            // Calculate total uncompressed size of each block. 
            var size = index.Records.Select(r => r.UncompressedSize).Aggregate((acc, x) => acc + x);
            Debug.WriteLine($"Total size of uncompressed archive: {UnitFormatter.FormatByteSize(size)} ({size} bytes)");
            return size;
        }
    }
}