using System;
using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Crypto.Digests;

public class ShakeDigest : KeccakDigest, IXof, IDigest
{
	public override string AlgorithmName => "SHAKE" + fixedOutputLength;

	private static int CheckBitLength(int bitLength)
	{
		if (bitLength == 128 || bitLength == 256)
		{
			return bitLength;
		}
		throw new ArgumentException(bitLength + " not supported for SHAKE", "bitLength");
	}

	public ShakeDigest()
		: this(128)
	{
	}

	public ShakeDigest(int bitLength)
		: base(CheckBitLength(bitLength))
	{
	}

	public ShakeDigest(ShakeDigest source)
		: base(source)
	{
	}

	public override int DoFinal(byte[] output, int outOff)
	{
		return DoFinal(output, outOff, GetDigestSize());
	}

	public virtual int DoFinal(byte[] output, int outOff, int outLen)
	{
		DoOutput(output, outOff, outLen);
		Reset();
		return outLen;
	}

	public virtual int DoOutput(byte[] output, int outOff, int outLen)
	{
		if (!squeezing)
		{
			AbsorbBits(15, 4);
		}
		Squeeze(output, outOff, (long)outLen << 3);
		return outLen;
	}

	protected override int DoFinal(byte[] output, int outOff, byte partialByte, int partialBits)
	{
		return DoFinal(output, outOff, GetDigestSize(), partialByte, partialBits);
	}

	protected virtual int DoFinal(byte[] output, int outOff, int outLen, byte partialByte, int partialBits)
	{
		if (partialBits < 0 || partialBits > 7)
		{
			throw new ArgumentException("must be in the range [0,7]", "partialBits");
		}
		int num = (partialByte & ((1 << partialBits) - 1)) | (15 << partialBits);
		int num2 = partialBits + 4;
		if (num2 >= 8)
		{
			Absorb(new byte[1] { (byte)num }, 0, 1);
			num2 -= 8;
			num >>= 8;
		}
		if (num2 > 0)
		{
			AbsorbBits(num, num2);
		}
		Squeeze(output, outOff, (long)outLen << 3);
		Reset();
		return outLen;
	}

	public override IMemoable Copy()
	{
		return new ShakeDigest(this);
	}
}