/*
    * 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.digest.spec.GordianDigestSpec;
  import io.github.tonywasher.joceanus.gordianknot.api.digest.spec.GordianDigestType;
  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.digest.BouncyDigest;
  import io.github.tonywasher.joceanus.gordianknot.impl.bc.keypair.BouncyEllipticKeyPair.BouncyECPrivateKey;
  import io.github.tonywasher.joceanus.gordianknot.impl.bc.keypair.BouncyEllipticKeyPair.BouncyECPublicKey;
  import io.github.tonywasher.joceanus.gordianknot.impl.bc.keypair.BouncyKeyPair;
  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.sign.GordianCoreSignatureSpec;
  import org.bouncycastle.crypto.CryptoException;
  import org.bouncycastle.crypto.params.ParametersWithRandom;
  import org.bouncycastle.crypto.signers.SM2Signer;
  
  /**
   * SM2 signature.
   */
  public class BouncySM2Signature
          extends GordianCoreSignature {
      /**
       * The Signer.
       */
      private final SM2Signer theSigner;
  
      /**
       * Constructor.
       *
       * @param pFactory the factory
       * @param pSpec    the signatureSpec.
       * @throws GordianException on error
       */
      BouncySM2Signature(final GordianBaseFactory pFactory,
                         final GordianSignatureSpec pSpec) throws GordianException {
          /* Initialise underlying class */
          super(pFactory, pSpec);
  
          /* Create the signer */
          final GordianDigestSpec mySpec = ((GordianCoreSignatureSpec) pSpec).getDigestSpec();
          if (GordianDigestType.SM3.equals(mySpec.getDigestType())) {
              theSigner = new SM2Signer();
          } else {
              final BouncyDigest myDigest = (BouncyDigest) pFactory.getDigestFactory().createDigest(mySpec);
              theSigner = new SM2Signer(myDigest.getDigest());
          }
      }
  
      @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 void initForSigning(final GordianNewSignParams pParams) throws GordianException {
          /* Initialise detail */
          super.initForSigning(pParams);
         final BouncyKeyPair myPair = getKeyPair();
         BouncyKeyPair.checkKeyPair(myPair);
 
         /* Initialise and set the signer */
         final BouncyECPrivateKey myPrivate = (BouncyECPrivateKey) myPair.getPrivateKey();
         final ParametersWithRandom myParms = new ParametersWithRandom(myPrivate.getPrivateKey(), getRandom());
         theSigner.init(true, myParms);
     }
 
     @Override
     public void initForVerify(final GordianNewSignParams pParams) throws GordianException {
         /* Initialise detail */
         super.initForVerify(pParams);
         final BouncyKeyPair myPair = getKeyPair();
         BouncyKeyPair.checkKeyPair(myPair);
 
         /* Initialise and set the signer */
         final BouncyECPublicKey myPublic = (BouncyECPublicKey) myPair.getPublicKey();
         theSigner.init(false, myPublic.getPublicKey());
     }
 
     @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(BouncySignature.ERROR_SIGGEN, 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);
     }
 }