using System;
using Org.BouncyCastle.Crypto.Utilities;
using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Crypto.Digests;

public class MD5Digest : GeneralDigest
{
	private const int DigestLength = 16;

	private uint H1;

	private uint H2;

	private uint H3;

	private uint H4;

	private uint[] X = new uint[16];

	private int xOff;

	private static readonly int S11 = 7;

	private static readonly int S12 = 12;

	private static readonly int S13 = 17;

	private static readonly int S14 = 22;

	private static readonly int S21 = 5;

	private static readonly int S22 = 9;

	private static readonly int S23 = 14;

	private static readonly int S24 = 20;

	private static readonly int S31 = 4;

	private static readonly int S32 = 11;

	private static readonly int S33 = 16;

	private static readonly int S34 = 23;

	private static readonly int S41 = 6;

	private static readonly int S42 = 10;

	private static readonly int S43 = 15;

	private static readonly int S44 = 21;

	public override string AlgorithmName => "MD5";

	public MD5Digest()
	{
		Reset();
	}

	public MD5Digest(MD5Digest t)
		: base(t)
	{
		CopyIn(t);
	}

	private void CopyIn(MD5Digest t)
	{
		CopyIn((GeneralDigest)t);
		H1 = t.H1;
		H2 = t.H2;
		H3 = t.H3;
		H4 = t.H4;
		Array.Copy(t.X, 0, X, 0, t.X.Length);
		xOff = t.xOff;
	}

	public override int GetDigestSize()
	{
		return 16;
	}

	internal override void ProcessWord(byte[] input, int inOff)
	{
		X[xOff] = Pack.LE_To_UInt32(input, inOff);
		if (++xOff == 16)
		{
			ProcessBlock();
		}
	}

	internal override void ProcessLength(long bitLength)
	{
		if (xOff > 14)
		{
			if (xOff == 15)
			{
				X[15] = 0u;
			}
			ProcessBlock();
		}
		for (int i = xOff; i < 14; i++)
		{
			X[i] = 0u;
		}
		X[14] = (uint)bitLength;
		X[15] = (uint)((ulong)bitLength >> 32);
	}

	public override int DoFinal(byte[] output, int outOff)
	{
		Finish();
		Pack.UInt32_To_LE(H1, output, outOff);
		Pack.UInt32_To_LE(H2, output, outOff + 4);
		Pack.UInt32_To_LE(H3, output, outOff + 8);
		Pack.UInt32_To_LE(H4, output, outOff + 12);
		Reset();
		return 16;
	}

	public override void Reset()
	{
		base.Reset();
		H1 = 1732584193u;
		H2 = 4023233417u;
		H3 = 2562383102u;
		H4 = 271733878u;
		xOff = 0;
		for (int i = 0; i != X.Length; i++)
		{
			X[i] = 0u;
		}
	}

	private static uint RotateLeft(uint x, int n)
	{
		return (x << n) | (x >> 32 - n);
	}

	private static uint F(uint u, uint v, uint w)
	{
		return (u & v) | (~u & w);
	}

	private static uint G(uint u, uint v, uint w)
	{
		return (u & w) | (v & ~w);
	}

	private static uint H(uint u, uint v, uint w)
	{
		return u ^ v ^ w;
	}

	private static uint K(uint u, uint v, uint w)
	{
		return v ^ (u | ~w);
	}

	internal override void ProcessBlock()
	{
		uint h = H1;
		uint h2 = H2;
		uint h3 = H3;
		uint h4 = H4;
		h = RotateLeft(h + F(h2, h3, h4) + X[0] + 3614090360u, S11) + h2;
		h4 = RotateLeft(h4 + F(h, h2, h3) + X[1] + 3905402710u, S12) + h;
		h3 = RotateLeft(h3 + F(h4, h, h2) + X[2] + 606105819, S13) + h4;
		h2 = RotateLeft(h2 + F(h3, h4, h) + X[3] + 3250441966u, S14) + h3;
		h = RotateLeft(h + F(h2, h3, h4) + X[4] + 4118548399u, S11) + h2;
		h4 = RotateLeft(h4 + F(h, h2, h3) + X[5] + 1200080426, S12) + h;
		h3 = RotateLeft(h3 + F(h4, h, h2) + X[6] + 2821735955u, S13) + h4;
		h2 = RotateLeft(h2 + F(h3, h4, h) + X[7] + 4249261313u, S14) + h3;
		h = RotateLeft(h + F(h2, h3, h4) + X[8] + 1770035416, S11) + h2;
		h4 = RotateLeft(h4 + F(h, h2, h3) + X[9] + 2336552879u, S12) + h;
		h3 = RotateLeft(h3 + F(h4, h, h2) + X[10] + 4294925233u, S13) + h4;
		h2 = RotateLeft(h2 + F(h3, h4, h) + X[11] + 2304563134u, S14) + h3;
		h = RotateLeft(h + F(h2, h3, h4) + X[12] + 1804603682, S11) + h2;
		h4 = RotateLeft(h4 + F(h, h2, h3) + X[13] + 4254626195u, S12) + h;
		h3 = RotateLeft(h3 + F(h4, h, h2) + X[14] + 2792965006u, S13) + h4;
		h2 = RotateLeft(h2 + F(h3, h4, h) + X[15] + 1236535329, S14) + h3;
		h = RotateLeft(h + G(h2, h3, h4) + X[1] + 4129170786u, S21) + h2;
		h4 = RotateLeft(h4 + G(h, h2, h3) + X[6] + 3225465664u, S22) + h;
		h3 = RotateLeft(h3 + G(h4, h, h2) + X[11] + 643717713, S23) + h4;
		h2 = RotateLeft(h2 + G(h3, h4, h) + X[0] + 3921069994u, S24) + h3;
		h = RotateLeft(h + G(h2, h3, h4) + X[5] + 3593408605u, S21) + h2;
		h4 = RotateLeft(h4 + G(h, h2, h3) + X[10] + 38016083, S22) + h;
		h3 = RotateLeft(h3 + G(h4, h, h2) + X[15] + 3634488961u, S23) + h4;
		h2 = RotateLeft(h2 + G(h3, h4, h) + X[4] + 3889429448u, S24) + h3;
		h = RotateLeft(h + G(h2, h3, h4) + X[9] + 568446438, S21) + h2;
		h4 = RotateLeft(h4 + G(h, h2, h3) + X[14] + 3275163606u, S22) + h;
		h3 = RotateLeft(h3 + G(h4, h, h2) + X[3] + 4107603335u, S23) + h4;
		h2 = RotateLeft(h2 + G(h3, h4, h) + X[8] + 1163531501, S24) + h3;
		h = RotateLeft(h + G(h2, h3, h4) + X[13] + 2850285829u, S21) + h2;
		h4 = RotateLeft(h4 + G(h, h2, h3) + X[2] + 4243563512u, S22) + h;
		h3 = RotateLeft(h3 + G(h4, h, h2) + X[7] + 1735328473, S23) + h4;
		h2 = RotateLeft(h2 + G(h3, h4, h) + X[12] + 2368359562u, S24) + h3;
		h = RotateLeft(h + H(h2, h3, h4) + X[5] + 4294588738u, S31) + h2;
		h4 = RotateLeft(h4 + H(h, h2, h3) + X[8] + 2272392833u, S32) + h;
		h3 = RotateLeft(h3 + H(h4, h, h2) + X[11] + 1839030562, S33) + h4;
		h2 = RotateLeft(h2 + H(h3, h4, h) + X[14] + 4259657740u, S34) + h3;
		h = RotateLeft(h + H(h2, h3, h4) + X[1] + 2763975236u, S31) + h2;
		h4 = RotateLeft(h4 + H(h, h2, h3) + X[4] + 1272893353, S32) + h;
		h3 = RotateLeft(h3 + H(h4, h, h2) + X[7] + 4139469664u, S33) + h4;
		h2 = RotateLeft(h2 + H(h3, h4, h) + X[10] + 3200236656u, S34) + h3;
		h = RotateLeft(h + H(h2, h3, h4) + X[13] + 681279174, S31) + h2;
		h4 = RotateLeft(h4 + H(h, h2, h3) + X[0] + 3936430074u, S32) + h;
		h3 = RotateLeft(h3 + H(h4, h, h2) + X[3] + 3572445317u, S33) + h4;
		h2 = RotateLeft(h2 + H(h3, h4, h) + X[6] + 76029189, S34) + h3;
		h = RotateLeft(h + H(h2, h3, h4) + X[9] + 3654602809u, S31) + h2;
		h4 = RotateLeft(h4 + H(h, h2, h3) + X[12] + 3873151461u, S32) + h;
		h3 = RotateLeft(h3 + H(h4, h, h2) + X[15] + 530742520, S33) + h4;
		h2 = RotateLeft(h2 + H(h3, h4, h) + X[2] + 3299628645u, S34) + h3;
		h = RotateLeft(h + K(h2, h3, h4) + X[0] + 4096336452u, S41) + h2;
		h4 = RotateLeft(h4 + K(h, h2, h3) + X[7] + 1126891415, S42) + h;
		h3 = RotateLeft(h3 + K(h4, h, h2) + X[14] + 2878612391u, S43) + h4;
		h2 = RotateLeft(h2 + K(h3, h4, h) + X[5] + 4237533241u, S44) + h3;
		h = RotateLeft(h + K(h2, h3, h4) + X[12] + 1700485571, S41) + h2;
		h4 = RotateLeft(h4 + K(h, h2, h3) + X[3] + 2399980690u, S42) + h;
		h3 = RotateLeft(h3 + K(h4, h, h2) + X[10] + 4293915773u, S43) + h4;
		h2 = RotateLeft(h2 + K(h3, h4, h) + X[1] + 2240044497u, S44) + h3;
		h = RotateLeft(h + K(h2, h3, h4) + X[8] + 1873313359, S41) + h2;
		h4 = RotateLeft(h4 + K(h, h2, h3) + X[15] + 4264355552u, S42) + h;
		h3 = RotateLeft(h3 + K(h4, h, h2) + X[6] + 2734768916u, S43) + h4;
		h2 = RotateLeft(h2 + K(h3, h4, h) + X[13] + 1309151649, S44) + h3;
		h = RotateLeft(h + K(h2, h3, h4) + X[4] + 4149444226u, S41) + h2;
		h4 = RotateLeft(h4 + K(h, h2, h3) + X[11] + 3174756917u, S42) + h;
		h3 = RotateLeft(h3 + K(h4, h, h2) + X[2] + 718787259, S43) + h4;
		h2 = RotateLeft(h2 + K(h3, h4, h) + X[9] + 3951481745u, S44) + h3;
		H1 += h;
		H2 += h2;
		H3 += h3;
		H4 += h4;
		xOff = 0;
	}

	public override IMemoable Copy()
	{
		return new MD5Digest(this);
	}

	public override void Reset(IMemoable other)
	{
		MD5Digest t = (MD5Digest)other;
		CopyIn(t);
	}
}