/*
    * GordianKnot: Security Suite
    * Copyright 2012-2026. Tony Washer
    *
    * Licensed under the Apache License, Version 2.0 (the "License"); you may not
    * use this file except in compliance with the License.  You may obtain a copy
    * of the License at
    *
    *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
   * License for the specific language governing permissions and limitations under
   * the License.
   */
  package io.github.tonywasher.joceanus.gordianknot.impl.ext.digests;
  
  import io.github.tonywasher.joceanus.gordianknot.impl.ext.params.GordianBlake2Parameters;
  import org.bouncycastle.crypto.ExtendedDigest;
  import org.bouncycastle.util.Arrays;
  import org.bouncycastle.util.Memoable;
  
  /**
   * Blake2 Base class.
   */
  @SuppressWarnings("checkstyle:MagicNumber")
  public abstract class GordianBlake2Base
          implements ExtendedDigest, Memoable {
      /**
       * Number of Words.
       */
      static final int NUMWORDS = 8;
  
      /**
       * Maximum Byte value.
       */
      private static final int MAXBYTE = 0xFF;
  
      /**
       * Message word permutations.
       */
      private static final byte[][] SIGMA = {
              {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
              {14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3},
              {11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4},
              {7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8},
              {9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13},
              {2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9},
              {12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11},
              {13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10},
              {6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5},
              {10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13, 0},
      };
  
      /**
       * The number of Rounds.
       */
      private final int theRounds;
  
      /**
       * The maximum xofLen.
       */
      private final long theMaxXofLen;
  
      /**
       * The buffer.
       */
      private final byte[] theBuffer;
  
      /**
       * Position of last inserted byte.
       */
      private int thePos;
  
      /**
       * The digestLength.
       */
      private short theDigestLen;
  
      /**
       * The key.
       */
      private byte[] theKey;
  
      /**
       * The salt.
       */
      private byte[] theSalt;
  
      /**
       * The personalisation.
       */
      private byte[] thePersonal;
  
      /**
       * The fanOut.
       */
      private short theFanOut;
 
     /**
      * The maxDepth.
      */
     private short theMaxDepth;
 
     /**
      * The leafLength.
      */
     private int theLeafLen;
 
     /**
      * The nodeOffSet.
      */
     private int theNodeOffset;
 
     /**
      * The nodeDepth.
      */
     private short theNodeDepth;
 
     /**
      * The xofLength.
      */
     private int theXofLen;
 
     /**
      * The innerLength.
      */
     private short theInnerLen;
 
     /**
      * Is this the final block?
      */
     private boolean isLastBlock;
 
     /**
      * Is this the last node at this depth?
      */
     private boolean isLastNode;
 
     /**
      * Constructor.
      *
      * @param pRounds   the number of rounds.
      * @param pBlockLen the blockLength
      */
     GordianBlake2Base(final int pRounds,
                       final int pBlockLen) {
         /* Store parameters */
         theRounds = pRounds;
         theBuffer = new byte[pBlockLen];
         theFanOut = 1;
         theMaxDepth = 1;
 
         /* Determine maxXofLen */
         theMaxXofLen = isBlake2b() ? 0xFFFFFFFEL : 0xFFFEL;
     }
 
     /**
      * Constructor.
      *
      * @param pSource the source
      */
     GordianBlake2Base(final GordianBlake2Base pSource) {
         /* Store parameters */
         theRounds = pSource.theRounds;
         theBuffer = new byte[pSource.theBuffer.length];
 
         /* Determine maxXofLen */
         theMaxXofLen = pSource.theMaxXofLen;
     }
 
     /**
      * Is the digest a blake2b digest?
      *
      * @return true/false
      */
     public abstract boolean isBlake2b();
 
     /**
      * Set the digestLength.
      *
      * @param pLength the digestLength.
      */
     void setDigestLength(final int pLength) {
         if (pLength < 0 || pLength > theBuffer.length << 2) {
             throw new IllegalArgumentException("DigestLength out of range");
         }
         theDigestLen = (short) pLength;
     }
 
     @Override
     public int getDigestSize() {
         return theDigestLen;
     }
 
     /**
      * Initialise.
      *
      * @param pParams the parameters.
      */
     public void init(final GordianBlake2Parameters pParams) {
         /* Store parameters */
         setKey(pParams.getKey());
         setSalt(pParams.getSalt());
         setPersonalisation(pParams.getPersonalisation());
         setXofLen(pParams.getMaxOutputLength());
         setTreeConfig(pParams.getTreeFanOut(), pParams.getTreeMaxDepth(), pParams.getTreeLeafLen());
 
         /* Reset the cipher */
         reset();
     }
 
     /**
      * Set the key.
      *
      * @param pKey the key.
      */
     void setKey(final byte[] pKey) {
         if (pKey == null || pKey.length == 0) {
             clearKey();
             theKey = null;
         } else {
             if (pKey.length > theBuffer.length >> 1) {
                 throw new IllegalArgumentException("Key too long");
             }
             clearKey();
             theKey = Arrays.copyOf(pKey, pKey.length);
         }
     }
 
     /**
      * Clear the key.
      */
     private void clearKey() {
         if (theKey != null) {
             Arrays.fill(theKey, (byte) 0);
         }
     }
 
     /**
      * Obtain the keyLength.
      *
      * @return the keyLength
      */
     int getKeyLen() {
         return theKey == null ? 0 : theKey.length;
     }
 
     /**
      * Set the salt.
      *
      * @param pSalt the salt.
      */
     void setSalt(final byte[] pSalt) {
         if (pSalt == null || pSalt.length == 0) {
             theSalt = null;
         } else {
             if (pSalt.length != theBuffer.length >> 3) {
                 throw new IllegalArgumentException("Salt incorrect length");
             }
             theSalt = Arrays.copyOf(pSalt, pSalt.length);
         }
     }
 
     /**
      * Obtain the salt.
      *
      * @return the salt
      */
     byte[] getSalt() {
         return theSalt;
     }
 
     /**
      * Set the personalisation.
      *
      * @param pPersonal the personalisation.
      */
     void setPersonalisation(final byte[] pPersonal) {
         if (pPersonal == null || pPersonal.length == 0) {
             thePersonal = null;
         } else {
             if (pPersonal.length != theBuffer.length >> 3) {
                 throw new IllegalArgumentException("Personalisation incorrect length");
             }
             thePersonal = Arrays.copyOf(pPersonal, pPersonal.length);
         }
     }
 
     /**
      * Obtain the personalisation.
      *
      * @return the personalisation
      */
     byte[] getPersonal() {
         return thePersonal;
     }
 
     /**
      * Set the xofLen.
      *
      * @param pXofLen the xofLength.
      */
     void setXofLen(final long pXofLen) {
         if (pXofLen < -1 || pXofLen > theMaxXofLen) {
             throw new IllegalArgumentException("XofLength out of range");
         }
         theXofLen = (int) pXofLen;
     }
 
     /**
      * Obtain the xofLength.
      *
      * @return the xofLength
      */
     int getXofLen() {
         return theXofLen;
     }
 
     /**
      * Set the treeConfig.
      *
      * @param pFanOut   the fanOut.
      * @param pMaxDepth the maxDepth.
      * @param pLeafLen  the leafLength.
      */
     void setTreeConfig(final int pFanOut,
                        final int pMaxDepth,
                        final int pLeafLen) {
         /* Check that fanOut value makes sense */
         if (pFanOut < 0 || pFanOut > MAXBYTE) {
             throw new IllegalArgumentException("FanOut out of range");
         }
         final boolean seqMode = pFanOut == 1;
 
         /* Check that maxDepth value makes sense */
         final boolean xofMode = pMaxDepth == 0;
         if (pMaxDepth < 0 || pMaxDepth > MAXBYTE) {
             throw new IllegalArgumentException("MaxDepth out of range");
         }
         if (seqMode != (pMaxDepth == 1)) {
             throw new IllegalArgumentException("Inconsistent treeConfig for sequentialMode");
         }
 
         /* Check that leaf value makes sense */
         if (pLeafLen < 0) {
             throw new IllegalArgumentException("LeafLength out of range");
         }
         if (seqMode != (pLeafLen == 0)) {
             throw new IllegalArgumentException("Inconsistent treeConfig for LeafLen and fanOut");
         }
         if (xofMode && pFanOut != 0) {
             throw new IllegalArgumentException("Inconsistent treeConfig for xofMode");
         }
 
         /* Record the values */
         theFanOut = (short) pFanOut;
         theMaxDepth = (short) pMaxDepth;
         theLeafLen = pLeafLen;
     }
 
     /**
      * Obtain the fanout.
      *
      * @return the fanout
      */
     short getFanOut() {
         return theFanOut;
     }
 
     /**
      * Obtain the maxDepth.
      *
      * @return the maxDepth
      */
     short getMaxDepth() {
         return theMaxDepth;
     }
 
     /**
      * Obtain the leafLength.
      *
      * @return the leafLength
      */
     int getLeafLen() {
         return theLeafLen;
     }
 
     /**
      * Set the nodePosition.
      *
      * @param pOffset the offset.
      * @param pDepth  the depth.
      */
     void setNodePosition(final int pOffset,
                          final int pDepth) {
         if (pOffset < 0) {
             throw new IllegalArgumentException("NodeOffset out of range");
         }
         theNodeOffset = pOffset;
         if (pDepth < 0 || pDepth > MAXBYTE) {
             throw new IllegalArgumentException("NodeDepth out of range");
         }
         theNodeDepth = (byte) pDepth;
         reset();
     }
 
     /**
      * Obtain the nodeOffset.
      *
      * @return the nodeOffset
      */
     int getNodeOffset() {
         return theNodeOffset;
     }
 
     /**
      * Obtain the nodeDepth.
      *
      * @return the nodeDepth
      */
     short getNodeDepth() {
         return theNodeDepth;
     }
 
     /**
      * is this the last node?
      *
      * @return true/false
      */
     boolean isLastBlock() {
         return isLastBlock;
     }
 
     /**
      * Set the lastNode indicator.
      */
     void setLastNode() {
         isLastNode = true;
     }
 
     /**
      * is this the last node?
      *
      * @return true/false
      */
     boolean isLastNode() {
         return isLastNode;
     }
 
     /**
      * Set the innerLength.
      *
      * @param pInnerLen the innerLength.
      */
     void setInnerLength(final int pInnerLen) {
         if (pInnerLen < 0 || pInnerLen > MAXBYTE) {
             throw new IllegalArgumentException("InnerLength out of range");
         }
         theInnerLen = (short) pInnerLen;
     }
 
     /**
      * Obtain the innerLength.
      *
      * @return the innerLength
      */
     short getInnerLen() {
         return theInnerLen;
     }
 
     @Override
     public void update(final byte b) {
         /* If the buffer is full */
         final int blockLen = theBuffer.length;
         final int remainingLength = blockLen - thePos;
         if (remainingLength == 0) {
             /* Process the buffer */
             adjustCounter(blockLen);
             compressF(theBuffer, 0);
 
             /* Reset the buffer */
             Arrays.fill(theBuffer, (byte) 0);
             thePos = 0;
         }
 
         /* Store the byte */
         theBuffer[thePos] = b;
         thePos++;
     }
 
     @Override
     public void update(final byte[] pMessage,
                        final int pOffset,
                        final int pLen) {
         /* Ignore null operation */
         if (pMessage == null || pLen == 0) {
             return;
         }
 
         /* Process any bytes currently in the buffer */
         final int blockLen = theBuffer.length;
         int remainingLen = 0; // left bytes of buffer
         if (thePos != 0) {
             /* Calculate space remaining in the buffer */
             remainingLen = blockLen - thePos;
 
             /* If there is sufficient space in the buffer */
             if (remainingLen >= pLen) {
                 /* Copy date into byffer and return */
                 System.arraycopy(pMessage, pOffset, theBuffer, thePos, pLen);
                 thePos += pLen;
                 return;
             }
 
             /* Fill the buffer */
             System.arraycopy(pMessage, pOffset, theBuffer, thePos, remainingLen);
 
             /* Adjust bytes count */
             adjustCounter(blockLen);
 
             /* Process the buffer */
             compressF(theBuffer, 0);
 
             /* Reset the buffer */
             thePos = 0;
             Arrays.fill(theBuffer, (byte) 0);
         }
 
         /* process all blocks except the last one */
         int messagePos;
         final int blockWiseLastPos = pOffset + pLen - blockLen;
         for (messagePos = pOffset + remainingLen; messagePos < blockWiseLastPos; messagePos += blockLen) {
             /* Adjust bytes count */
             adjustCounter(blockLen);
 
             /* Process the buffer */
             compressF(pMessage, messagePos);
         }
 
         /* Fill the buffer with the remaining bytes of the message */
         final int len = pLen - messagePos;
         System.arraycopy(pMessage, messagePos, theBuffer, 0, pOffset + len);
         thePos += pOffset + len;
     }
 
     @Override
     public int doFinal(final byte[] pOut,
                        final int pOutOffset) {
         /* Adjust flags and counter */
         isLastBlock = true;
         completeCounter(thePos);
 
         /* Process the buffer */
         compressF(theBuffer, 0);
         Arrays.fill(theBuffer, (byte) 0);
 
         /* Output the digest */
         outputDigest(pOut, pOutOffset);
 
         /* Reset the state */
         reset();
 
         /* Return the digest length */
         return theDigestLen;
     }
 
     @Override
     public void reset() {
         /* Reset flags */
         isLastBlock = false;
         isLastNode = false;
 
         /* Reset the data Buffer */
         thePos = 0;
         Arrays.fill(theBuffer, (byte) 0);
 
         /* Activate */
         activateH();
     }
 
     /**
      * Copy state from source.
      *
      * @param pSource the source
      */
     void reset(final GordianBlake2Base pSource) {
         /* Copy config */
         theDigestLen = pSource.theDigestLen;
         theInnerLen = pSource.theInnerLen;
         theLeafLen = pSource.theLeafLen;
         theXofLen = pSource.theXofLen;
         theFanOut = pSource.theFanOut;
         theMaxDepth = pSource.theMaxDepth;
         theNodeDepth = pSource.theNodeDepth;
         theNodeOffset = pSource.theNodeOffset;
 
         /* Copy flags */
         isLastNode = pSource.isLastNode;
 
         /* Clone arrays */
         theKey = Arrays.clone(pSource.theKey);
         theSalt = Arrays.clone(pSource.theSalt);
         thePersonal = Arrays.clone(pSource.thePersonal);
 
         /* Copy buffer */
         System.arraycopy(pSource.theBuffer, 0, theBuffer, 0, theBuffer.length);
         thePos = pSource.thePos;
     }
 
     /**
      * Adjust Counter.
      *
      * @param pCount bytes processed
      */
     abstract void adjustCounter(int pCount);
 
     /**
      * Complete Counter.
      *
      * @param pCount bytes processed
      */
     abstract void completeCounter(int pCount);
 
     /**
      * Output the digest.
      *
      * @param pOut       the output buffer
      * @param pOutOffset the offset in the output buffer
      */
     abstract void outputDigest(byte[] pOut,
                                int pOutOffset);
 
     /**
      * Init the keyBlock.
      */
     void initKeyBlock() {
         /* If we have a key */
         if (theKey != null) {
             /* Initialise the first data block */
             System.arraycopy(theKey, 0, theBuffer, 0, theKey.length);
             thePos = theBuffer.length;
         }
     }
 
     /**
      * ActivateH.
      */
     abstract void activateH();
 
     /**
      * Obtain the Sigma for the round.
      *
      * @param pRound the round
      * @return the Sigma
      */
     private static byte[] getSigmaForRound(final int pRound) {
         return SIGMA[pRound % SIGMA.length];
     }
 
     /**
      * Compress a message.
      *
      * @param pMessage the message buffer
      * @param pMsgPos  the position within the message buffer
      */
     private void compressF(final byte[] pMessage,
                            final int pMsgPos) {
         /* Initialise the buffers */
         initV();
         initM(pMessage, pMsgPos);
 
         /* Loop through the rounds */
         for (int round = 0; round < theRounds; round++) {
             /* Obtain the relevant SIGMA */
             final byte[] sigma = getSigmaForRound(round);
 
             /* Apply to columns of V */
             mixG(sigma[0], sigma[1], 0, 4, 8, 12);
             mixG(sigma[2], sigma[3], 1, 5, 9, 13);
             mixG(sigma[4], sigma[5], 2, 6, 10, 14);
             mixG(sigma[6], sigma[7], 3, 7, 11, 15);
 
             /* Apply to diagonals of V */
             mixG(sigma[8], sigma[9], 0, 5, 10, 15);
             mixG(sigma[10], sigma[11], 1, 6, 11, 12);
             mixG(sigma[12], sigma[13], 2, 7, 8, 13);
             mixG(sigma[14], sigma[15], 3, 4, 9, 14);
         }
 
         /* Adjust H */
         adjustH();
     }
 
     /**
      * Initialise V.
      */
     abstract void initV();
 
     /**
      * Initialise M.
      *
      * @param pMessage the message buffer
      * @param pMsgPos  the position in the message buffer
      */
     abstract void initM(byte[] pMessage,
                         int pMsgPos);
 
     /**
      * Mix function.
      *
      * @param msgIdx1 the first msgIndex
      * @param msgIdx2 the second msgIndex
      * @param posA    position A
      * @param posB    position B
      * @param posC    position C
      * @param posD    position D
      */
     abstract void mixG(int msgIdx1,
                        int msgIdx2,
                        int posA,
                        int posB,
                        int posC,
                        int posD);
 
     /**
      * Adjust H.
      */
     abstract void adjustH();
 }