/*
    * 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.jca;
  
  import io.github.tonywasher.joceanus.gordianknot.api.base.GordianException;
  import io.github.tonywasher.joceanus.gordianknot.api.base.GordianKeySpec;
  import io.github.tonywasher.joceanus.gordianknot.api.base.GordianLength;
  import io.github.tonywasher.joceanus.gordianknot.api.cipher.GordianCipherParams;
  import io.github.tonywasher.joceanus.gordianknot.api.cipher.GordianStreamCipher;
  import io.github.tonywasher.joceanus.gordianknot.api.cipher.GordianSymCipher;
  import io.github.tonywasher.joceanus.gordianknot.api.cipher.spec.GordianCipherSpec;
  import io.github.tonywasher.joceanus.gordianknot.api.cipher.spec.GordianStreamCipherSpec;
  import io.github.tonywasher.joceanus.gordianknot.api.cipher.spec.GordianStreamKeySpec;
  import io.github.tonywasher.joceanus.gordianknot.api.cipher.spec.GordianSymCipherSpec;
  import io.github.tonywasher.joceanus.gordianknot.api.cipher.spec.GordianSymKeySpec;
  import io.github.tonywasher.joceanus.gordianknot.api.cipher.spec.GordianSymKeyType;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.base.GordianBaseData;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.base.GordianBaseFactory;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.cipher.GordianCoreCipher;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.exc.GordianCryptoException;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.spec.cipher.GordianCoreSymCipherSpec;
  
  import javax.crypto.BadPaddingException;
  import javax.crypto.Cipher;
  import javax.crypto.IllegalBlockSizeException;
  import javax.crypto.SecretKey;
  import javax.crypto.ShortBufferException;
  import javax.crypto.spec.IvParameterSpec;
  import javax.crypto.spec.RC2ParameterSpec;
  import javax.crypto.spec.RC5ParameterSpec;
  import java.security.InvalidAlgorithmParameterException;
  import java.security.InvalidKeyException;
  import java.security.spec.AlgorithmParameterSpec;
  
  /**
   * Cipher for JCA BouncyCastle Ciphers.
   *
   * @param <T> the key Type
   */
  public abstract class JcaCipher<T extends GordianKeySpec>
          extends GordianCoreCipher<T> {
      /**
       * Cipher.
       */
      private final Cipher theCipher;
  
      /**
       * is the cipher encrypting?
       */
      private boolean isEncrypting;
  
      /**
       * Constructor.
       *
       * @param pFactory    the Security Factory
       * @param pCipherSpec the cipherSpec
       * @param pCipher     the cipher
       */
      JcaCipher(final GordianBaseFactory pFactory,
                final GordianCipherSpec<T> pCipherSpec,
                final Cipher pCipher) {
          super(pFactory, pCipherSpec);
          theCipher = pCipher;
      }
  
      @Override
      public JcaKey<T> getKey() {
          return (JcaKey<T>) super.getKey();
      }
  
      @Override
      public void init(final boolean pEncrypt,
                       final GordianCipherParams pParams) throws GordianException {
          /* Process the parameters and access the key */
          processParameters(pParams);
          final JcaKey<T> myJcaKey = JcaKey.accessKey(getKey());
  
          /* Access details */
          final int myMode = pEncrypt
                  ? Cipher.ENCRYPT_MODE
                  : Cipher.DECRYPT_MODE;
          final SecretKey myKey = myJcaKey.getKey();
          final byte[] myIV = getInitVector();
  
          /* Protect against exceptions */
         try {
             /* Careful of RC5 */
             final T myKeyType = myJcaKey.getKeyType();
             final boolean isRC5 = myKeyType instanceof GordianSymKeySpec mySymKeySpec
                     && GordianSymKeyType.RC5.equals(mySymKeySpec.getSymKeyType());
 
             /* Initialise as required */
             if (myIV != null || isRC5) {
                 final AlgorithmParameterSpec myParms = generateParameters(myJcaKey, myIV);
                 theCipher.init(myMode, myKey, myParms);
             } else {
                 theCipher.init(myMode, myKey);
             }
             isEncrypting = pEncrypt;
         } catch (InvalidKeyException
                  | InvalidAlgorithmParameterException e) {
             throw new GordianCryptoException("Failed to initialise cipher", e);
         }
     }
 
     /**
      * Generate AlgorithmParameters.
      *
      * @param pKey the key
      * @param pIV  the Initialisation vector
      * @return the parameters
      */
     static AlgorithmParameterSpec generateParameters(final JcaKey<?> pKey,
                                                      final byte[] pIV) {
         final Object myKeyType = pKey.getKeyType();
         if (myKeyType instanceof GordianSymKeySpec mySpec) {
             final GordianSymKeyType myType = mySpec.getSymKeyType();
             final GordianLength myLen = mySpec.getBlockLength();
             if (GordianSymKeyType.RC2.equals(myType)) {
                 return new RC2ParameterSpec(pKey.getKeyBytes().length * Byte.SIZE, pIV);
             }
             if (GordianSymKeyType.RC5.equals(myType)) {
                 return pIV == null
                         ? new RC5ParameterSpec(1, GordianBaseData.RC5_ROUNDS, myLen.getLength() >> 1)
                         : new RC5ParameterSpec(1, GordianBaseData.RC5_ROUNDS, myLen.getLength() >> 1, pIV);
             }
         }
         return new IvParameterSpec(pIV);
     }
 
     @Override
     public int getOutputLength(final int pLength) {
         return theCipher.getOutputSize(pLength);
     }
 
     @Override
     public int doUpdate(final byte[] pBytes,
                         final int pOffset,
                         final int pLength,
                         final byte[] pOutput,
                         final int pOutOffset) throws GordianException {
         /* Protect against exceptions */
         try {
             /* Process the bytes */
             return theCipher.update(pBytes, pOffset, pLength, pOutput, pOutOffset);
 
             /* Handle exceptions */
         } catch (ShortBufferException e) {
             throw new GordianCryptoException("Failed to process bytes", e);
         }
     }
 
     @Override
     public int doFinish(final byte[] pOutput,
                         final int pOutOffset) throws GordianException {
         /* Protect against exceptions */
         try {
             /* Finish the operation */
             return theCipher.doFinal(pOutput, pOutOffset);
 
             /* Handle exceptions */
         } catch (ShortBufferException
                  | IllegalBlockSizeException
                  | BadPaddingException e) {
             throw new GordianCryptoException("Failed to finish operation", e);
         }
     }
 
     @Override
     public int getBlockSize() {
         final GordianCipherSpec<T> mySpec = getCipherSpec();
         return (mySpec instanceof GordianCoreSymCipherSpec mySymCipherSpec
                 && mySymCipherSpec.getCoreCipherMode().hasPadding())
                 ? theCipher.getBlockSize() : 0;
     }
 
     /**
      * JcaSymCipher.
      */
     public static class JcaSymCipher
             extends JcaCipher<GordianSymKeySpec>
             implements GordianSymCipher {
         /**
          * Constructor.
          *
          * @param pFactory    the Security Factory
          * @param pCipherSpec the cipherSpec
          * @param pCipher     the cipher
          */
         JcaSymCipher(final GordianBaseFactory pFactory,
                      final GordianSymCipherSpec pCipherSpec,
                      final Cipher pCipher) {
             super(pFactory, pCipherSpec, pCipher);
         }
     }
 
     /**
      * JcaStreamCipher.
      */
     public static class JcaStreamCipher
             extends JcaCipher<GordianStreamKeySpec>
             implements GordianStreamCipher {
         /**
          * Constructor.
          *
          * @param pFactory    the Security Factory
          * @param pCipherSpec the cipherSpec
          * @param pCipher     the cipher
          */
         JcaStreamCipher(final GordianBaseFactory pFactory,
                         final GordianStreamCipherSpec pCipherSpec,
                         final Cipher pCipher) {
             super(pFactory, pCipherSpec, pCipher);
         }
     }
 
     @Override
     public boolean equals(final Object pThat) {
         /* Handle trivial cases */
         if (this == pThat) {
             return true;
         }
         if (pThat == null) {
             return false;
         }
 
         /* Make sure that the classes are the same */
         if (!(pThat instanceof JcaCipher<?> myThat)) {
             return false;
         }
 
         /* Check that the fields are equal */
         return isEncrypting == myThat.isEncrypting
                 && super.equals(myThat);
     }
 
     @Override
     public int hashCode() {
         return super.hashCode()
                 + (isEncrypting ? 1 : 0);
     }
 }