/*
    * 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.encrypt;
  
  import io.github.tonywasher.joceanus.gordianknot.api.base.GordianException;
  import io.github.tonywasher.joceanus.gordianknot.api.digest.GordianDigestFactory;
  import io.github.tonywasher.joceanus.gordianknot.api.encrypt.spec.GordianSM2EncryptionSpec;
  import io.github.tonywasher.joceanus.gordianknot.api.encrypt.spec.GordianSM2EncryptionType;
  import io.github.tonywasher.joceanus.gordianknot.api.keypair.GordianKeyPair;
  import io.github.tonywasher.joceanus.gordianknot.impl.bc.digest.BouncyDigest;
  import io.github.tonywasher.joceanus.gordianknot.impl.bc.keypair.BouncyKeyPair;
  import io.github.tonywasher.joceanus.gordianknot.impl.bc.keypair.BouncyKeyPair.BouncyPrivateKey;
  import io.github.tonywasher.joceanus.gordianknot.impl.bc.keypair.BouncyKeyPair.BouncyPublicKey;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.base.GordianBaseFactory;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.encrypt.GordianCoreEncryptor;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.exc.GordianCryptoException;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.spec.encrypt.GordianCoreEncryptorSpec;
  import org.bouncycastle.crypto.InvalidCipherTextException;
  import org.bouncycastle.crypto.engines.SM2Engine;
  import org.bouncycastle.crypto.engines.SM2Engine.Mode;
  import org.bouncycastle.crypto.params.ParametersWithRandom;
  
  /**
   * SM2 Encryptor.
   */
  public class BouncySM2Encryptor
          extends GordianCoreEncryptor {
      /**
       * The underlying encryptor.
       */
      private final SM2Engine theEncryptor;
  
      /**
       * Constructor.
       *
       * @param pFactory the factory
       * @param pSpec    the encryptorSpec
       * @throws GordianException on error
       */
      BouncySM2Encryptor(final GordianBaseFactory pFactory,
                         final GordianCoreEncryptorSpec pSpec) throws GordianException {
          /* Initialise underlying cipher */
          super(pFactory, pSpec);
          final GordianDigestFactory myFactory = pFactory.getDigestFactory();
          final GordianSM2EncryptionSpec mySpec = pSpec.getSM2EncryptionSpec();
          final BouncyDigest myDigest = (BouncyDigest) myFactory.createDigest(mySpec.getDigestSpec());
          final Mode mySM2Mode = mySpec.getEncryptionType() == GordianSM2EncryptionType.C1C2C3
                  ? Mode.C1C2C3 : Mode.C1C3C2;
          theEncryptor = new SM2Engine(myDigest.getDigest(), mySM2Mode);
      }
  
      @Override
      protected BouncyPublicKey<?> getPublicKey() {
          return (BouncyPublicKey<?>) super.getPublicKey();
      }
  
      @Override
      protected BouncyPrivateKey<?> getPrivateKey() {
          return (BouncyPrivateKey<?>) super.getPrivateKey();
      }
  
      @Override
      public void initForEncrypt(final GordianKeyPair pKeyPair) throws GordianException {
          /* Initialise underlying cipher */
          BouncyKeyPair.checkKeyPair(pKeyPair);
          super.initForEncrypt(pKeyPair);
  
          /* Initialise for encryption */
          final ParametersWithRandom myParms = new ParametersWithRandom(getPublicKey().getPublicKey(), getRandom());
          theEncryptor.init(true, myParms);
      }
  
      @Override
      public void initForDecrypt(final GordianKeyPair pKeyPair) throws GordianException {
          /* Initialise underlying cipher */
          BouncyKeyPair.checkKeyPair(pKeyPair);
          super.initForDecrypt(pKeyPair);
  
          /* Initialise for decryption */
          theEncryptor.init(false, getPrivateKey().getPrivateKey());
      }
  
      @Override
      public byte[] encrypt(final byte[] pBytes) throws GordianException {
         try {
             /* Check that we are in encryption mode */
             checkMode(GordianEncryptMode.ENCRYPT);
 
             /* Encrypt the message */
             return theEncryptor.processBlock(pBytes, 0, pBytes.length);
         } catch (InvalidCipherTextException e) {
             throw new GordianCryptoException("Failed to encrypt data", e);
         }
     }
 
     @Override
     public byte[] decrypt(final byte[] pBytes) throws GordianException {
         try {
             /* Check that we are in decryption mode */
             checkMode(GordianEncryptMode.DECRYPT);
 
             /* Decrypt the message */
             return theEncryptor.processBlock(pBytes, 0, pBytes.length);
         } catch (InvalidCipherTextException e) {
             throw new GordianCryptoException("Failed to decrypt data", e);
         }
     }
 }