/*
    * GordianKnot: Security Suite
    * Copyright 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.bc.sign;
  
  import io.github.tonywasher.joceanus.gordianknot.api.base.GordianException;
  import io.github.tonywasher.joceanus.gordianknot.api.keypair.GordianKeyPair;
  import io.github.tonywasher.joceanus.gordianknot.api.sign.GordianNewSignParams;
  import io.github.tonywasher.joceanus.gordianknot.api.sign.spec.GordianSignatureSpec;
  import io.github.tonywasher.joceanus.gordianknot.impl.bc.keypair.BouncyKeyPair;
  import io.github.tonywasher.joceanus.gordianknot.impl.bc.keypair.BouncyMLDSAKeyPair.BouncyMLDSAPrivateKey;
  import io.github.tonywasher.joceanus.gordianknot.impl.bc.keypair.BouncyMLDSAKeyPair.BouncyMLDSAPublicKey;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.base.GordianBaseFactory;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.exc.GordianCryptoException;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.sign.GordianCoreSignature;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.spec.keypair.GordianCoreKeyPairSpec;
  import org.bouncycastle.crypto.CipherParameters;
  import org.bouncycastle.crypto.CryptoException;
  import org.bouncycastle.crypto.Signer;
  import org.bouncycastle.crypto.params.ParametersWithContext;
  import org.bouncycastle.crypto.params.ParametersWithRandom;
  import org.bouncycastle.crypto.signers.HashMLDSASigner;
  import org.bouncycastle.crypto.signers.MLDSASigner;
  
  /**
   * MLDSA signer.
   */
  public class BouncyMLDSASignature
          extends GordianCoreSignature {
      /**
       * The MLDSA Signer.
       */
      private Signer theSigner;
  
      /**
       * Constructor.
       *
       * @param pFactory the factory
       * @param pSpec    the signatureSpec.
       */
      BouncyMLDSASignature(final GordianBaseFactory pFactory,
                           final GordianSignatureSpec pSpec) {
          /* Initialise underlying class */
          super(pFactory, pSpec);
      }
  
      /**
       * Create the signer according to the keyPair.
       *
       * @param pKeyPair the keyPair
       * @return the signer
       */
      private static Signer createSigner(final GordianKeyPair pKeyPair) {
          /* Determine whether this is a hashSigner */
          final GordianCoreKeyPairSpec myKeySpec = (GordianCoreKeyPairSpec) pKeyPair.getKeyPairSpec();
          final boolean isHash = myKeySpec.getMLDSASpec().isHash();
  
          /* Create the internal digests */
          return isHash
                  ? new HashMLDSASigner()
                  : new MLDSASigner();
      }
  
      @Override
      public void initForSigning(final GordianNewSignParams pParams) throws GordianException {
          /* Initialise detail */
          super.initForSigning(pParams);
          final BouncyKeyPair myPair = getKeyPair();
          final byte[] myContext = getContext();
          BouncyKeyPair.checkKeyPair(myPair);
  
          /* Initialise and set the signer */
          theSigner = createSigner(myPair);
          final BouncyMLDSAPrivateKey myPrivate = (BouncyMLDSAPrivateKey) myPair.getPrivateKey();
          CipherParameters myParms = new ParametersWithRandom(myPrivate.getPrivateKey(), getRandom());
          if (myContext != null) {
              myParms = new ParametersWithContext(myParms, myContext);
          }
          theSigner.init(true, myParms);
      }
  
      @Override
      public void initForVerify(final GordianNewSignParams pParams) throws GordianException {
          /* Initialise detail */
          super.initForVerify(pParams);
         final BouncyKeyPair myPair = getKeyPair();
         final byte[] myContext = getContext();
         BouncyKeyPair.checkKeyPair(myPair);
 
         /* Initialise and set the signer */
         theSigner = createSigner(myPair);
         final BouncyMLDSAPublicKey myPublic = (BouncyMLDSAPublicKey) myPair.getPublicKey();
         CipherParameters myParms = myPublic.getPublicKey();
         if (myContext != null) {
             myParms = new ParametersWithContext(myParms, myContext);
         }
         theSigner.init(false, myParms);
     }
 
     @Override
     public void update(final byte[] pBytes,
                        final int pOffset,
                        final int pLength) {
         theSigner.update(pBytes, pOffset, pLength);
     }
 
     @Override
     public void update(final byte pByte) {
         theSigner.update(pByte);
     }
 
     @Override
     public void update(final byte[] pBytes) {
         theSigner.update(pBytes, 0, pBytes.length);
     }
 
     @Override
     public void reset() {
         theSigner.reset();
     }
 
     @Override
     protected BouncyKeyPair getKeyPair() {
         return (BouncyKeyPair) super.getKeyPair();
     }
 
     @Override
     public byte[] sign() throws GordianException {
         /* Check that we are in signing mode */
         checkMode(GordianSignatureMode.SIGN);
 
         /* Sign the message */
         try {
             return theSigner.generateSignature();
         } catch (CryptoException e) {
             throw new GordianCryptoException("Failed to sign message", e);
         }
     }
 
     @Override
     public boolean verify(final byte[] pSignature) throws GordianException {
         /* Check that we are in verify mode */
         checkMode(GordianSignatureMode.VERIFY);
 
         /* Verify the message */
         return theSigner.verifySignature(pSignature);
     }
 }