/*
    * 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.jca.agree;
  
  import io.github.tonywasher.joceanus.gordianknot.api.base.GordianException;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.agree.GordianCoreAgreementFactory;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.exc.GordianCryptoException;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.spec.agree.GordianCoreAgreementSpec;
  import io.github.tonywasher.joceanus.gordianknot.impl.jca.agree.JcaAgreement.JcaAgreementBase;
  import io.github.tonywasher.joceanus.gordianknot.impl.jca.keypair.JcaKeyPair.JcaPrivateKey;
  import io.github.tonywasher.joceanus.gordianknot.impl.jca.keypair.JcaKeyPair.JcaPublicKey;
  import org.bouncycastle.jcajce.spec.MQVParameterSpec;
  
  import javax.crypto.KeyAgreement;
  import java.security.InvalidAlgorithmParameterException;
  import java.security.InvalidKeyException;
  
  /**
   * Jca MQV Agreement.
   */
  public class JcaMQVEngine
          extends JcaAgreementBase {
      /**
       * Key Agreement.
       */
      private final KeyAgreement theAgreement;
  
      /**
       * Constructor.
       *
       * @param pFactory   the security factory
       * @param pSpec      the agreementSpec
       * @param pAgreement the agreement
       */
      JcaMQVEngine(final GordianCoreAgreementFactory pFactory,
                   final GordianCoreAgreementSpec pSpec,
                   final KeyAgreement pAgreement) throws GordianException {
          /* Initialize underlying class */
          super(pFactory, pSpec);
  
          /* Store the agreement */
          theAgreement = pAgreement;
      }
  
      @Override
      public void processClientHello() throws GordianException {
          /* Protect against exceptions */
          try {
              /* Access keys */
              final JcaPublicKey myClientPublic = (JcaPublicKey) getPublicKey(getClientKeyPair());
              final JcaPublicKey myClientEphPublic = (JcaPublicKey) getPublicKey(getClientEphemeral());
              final JcaPrivateKey myPrivate = (JcaPrivateKey) getPrivateKey(getServerKeyPair());
              final JcaPublicKey myEphPublic = (JcaPublicKey) getPublicKey(getServerEphemeral());
              final JcaPrivateKey myEphPrivate = (JcaPrivateKey) getPrivateKey(getServerEphemeral());
  
              /* Derive the secret */
              final MQVParameterSpec myParams = new MQVParameterSpec(myEphPublic.getPublicKey(),
                      myEphPrivate.getPrivateKey(), myClientEphPublic.getPublicKey(), getAdditional());
              theAgreement.init(myPrivate.getPrivateKey(), myParams, getRandom());
              theAgreement.doPhase(myClientPublic.getPublicKey(), true);
              storeSecret(theAgreement.generateSecret());
  
          } catch (InvalidKeyException
                   | InvalidAlgorithmParameterException e) {
              throw new GordianCryptoException(JcaAgreement.ERR_AGREEMENT, e);
          }
      }
  
      @Override
      public void processServerHello() throws GordianException {
          /* Protect against exceptions */
          try {
              /* Access keys */
              final JcaPublicKey myServerPublic = (JcaPublicKey) getPublicKey(getServerKeyPair());
              final JcaPublicKey myServerEphPublic = (JcaPublicKey) getPublicKey(getServerEphemeral());
              final JcaPrivateKey myPrivate = (JcaPrivateKey) getPrivateKey(getClientKeyPair());
              final JcaPublicKey myEphPublic = (JcaPublicKey) getPublicKey(getClientEphemeral());
              final JcaPrivateKey myEphPrivate = (JcaPrivateKey) getPrivateKey(getClientEphemeral());
  
              /* Derive the secret */
              final MQVParameterSpec myParams = new MQVParameterSpec(myEphPublic.getPublicKey(),
                      myEphPrivate.getPrivateKey(), myServerEphPublic.getPublicKey(), getAdditional());
              theAgreement.init(myPrivate.getPrivateKey(), myParams);
              theAgreement.doPhase(myServerPublic.getPublicKey(), true);
             storeSecret(theAgreement.generateSecret());
 
         } catch (InvalidKeyException
                  | InvalidAlgorithmParameterException e) {
             throw new GordianCryptoException(JcaAgreement.ERR_AGREEMENT, e);
         }
     }
 }