internal class LargeStreamResult : System.IO.Stream
{
    private long _position = 0;
    private const long _length = 8L * 1024L * 1024L * 1024L; // 8 GB

    public override bool CanRead => true;
    public override bool CanSeek => true;
    public override bool CanWrite => false;
    public override long Length => _length;
    public override long Position { get => _position; set => _position = value; }

    public override void Flush() { }

    public override int Read(byte[] buffer, int offset, int count)
    {
        int bytesToRead = (int)Math.Min(count, _length - _position);
        if (bytesToRead <= 0)
            return 0;

        _position += bytesToRead;
        return bytesToRead;
    }

    public override long Seek(long offset, System.IO.SeekOrigin origin)
    {
        switch (origin)
        {
            case System.IO.SeekOrigin.Begin:
                _position = offset;
                break;
            case System.IO.SeekOrigin.Current:
                _position += offset;
                break;
            case System.IO.SeekOrigin.End:
                _position = _length + offset;
                break;
        }
        return _position;
    }

    public override void SetLength(long value) { }

    public override void Write(byte[] buffer, int offset, int count) { }
}