using System;
using System.IO;
using System.Security.Cryptography;

namespace ScreenConnect;

public class HashingStream : CountingStream
{
	private Stream innerStream;

	private HashAlgorithm hashAlgorithm;

	public HashingStream(Stream innerStream, Func<HashAlgorithm> hashAlgorithmFactory)
	{
		this.innerStream = innerStream;
		hashAlgorithm = hashAlgorithmFactory();
	}

	public override void Write(byte[] buffer, int offset, int count)
	{
		base.Write(buffer, offset, count);
		innerStream.Write(buffer, offset, count);
		hashAlgorithm.TransformBlock(buffer, offset, count, null, 0);
	}

	public override void Flush()
	{
		innerStream.Flush();
	}

	public byte[] FinalizeAndGetHash()
	{
		hashAlgorithm.TransformFinalBlock(new byte[0], 0, 0);
		return hashAlgorithm.Hash;
	}
}