/*
    * The contents of this file are subject to the terms of the Common Development and
    * Distribution License (the License). You may not use this file except in compliance with the
    * License.
    *
    * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
    * specific language governing permission and limitations under the License.
    *
    * When distributing Covered Software, include this CDDL Header Notice in each file and include
   * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
   * Header, with the fields enclosed by brackets [] replaced by your own identifying
   * information: "Portions copyright [year] [name of copyright owner]".
   *
   * Copyright 2013-2015 ForgeRock AS.
   */
  
  package org.forgerock.json.jose.jws.handlers;
  
  import org.forgerock.json.jose.exceptions.JwsSigningException;
  import org.forgerock.json.jose.exceptions.JwsVerifyingException;
  import org.forgerock.json.jose.jws.JwsAlgorithm;
  import org.forgerock.json.jose.jws.JwsAlgorithmType;
  import org.forgerock.json.jose.utils.Utils;
  import org.forgerock.util.Reject;
  import org.forgerock.util.SignatureUtil;
  
  import java.security.InvalidKeyException;
  import java.security.Key;
  import java.security.NoSuchAlgorithmException;
  import java.security.PrivateKey;
  import java.security.PublicKey;
  import java.security.Signature;
  import java.security.SignatureException;
  
  /**
   * An implementation of the SigningHandler which can sign and verify using algorithms from the RSA family.
   *
   * @since 2.0.0
   */
  public class RSASigningHandler implements SigningHandler {
  
      private final SignatureUtil signatureUtil;
      private final Key key;
  
      /**
       * Constructs a new RSASigningHandler, with a SignatureUtil instance to delegate the signing and verifying calls to.
       *
       * @param key The key used to sign and verify the signature.
       * @param signatureUtil An instance of the SignatureUtil.
       */
      public RSASigningHandler(Key key, SignatureUtil signatureUtil) {
          this.key = key;
          this.signatureUtil = signatureUtil;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public byte[] sign(JwsAlgorithm algorithm, String data) {
          validateAlgorithm(algorithm);
          try {
              Reject.ifFalse(key instanceof PrivateKey, "RSA requires private key for signing.");
              return signatureUtil.sign((PrivateKey) key, algorithm.getAlgorithm(), data);
          } catch (SignatureException e) {
              if (e.getCause() != null && e.getCause().getClass().isAssignableFrom(NoSuchAlgorithmException.class)) {
                  throw new JwsSigningException("Unsupported Signing Algorithm, " + algorithm.getAlgorithm(), e);
              }
              throw new JwsSigningException(e);
          }
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public byte[] sign(final JwsAlgorithm algorithm, final byte[] data) {
          validateAlgorithm(algorithm);
          try {
              Reject.ifFalse(key instanceof PrivateKey, "RSA requires private key for signing.");
              Signature signature = Signature.getInstance(algorithm.getAlgorithm());
              signature.initSign((PrivateKey) key);
              signature.update(data);
              return signature.sign();
          } catch (SignatureException | InvalidKeyException e) {
              throw new JwsSigningException(e);
          } catch (NoSuchAlgorithmException e) {
              throw new JwsSigningException("Unsupported Signing Algorithm, " + algorithm.getAlgorithm(), e);
          }
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public boolean verify(JwsAlgorithm algorithm, byte[] data, byte[] signature) {
          validateAlgorithm(algorithm);
          try {
              Reject.ifFalse(key instanceof PublicKey, "RSA requires public key for signature verification.");
             return signatureUtil.verify((PublicKey) key, algorithm.getAlgorithm(),
                     new String(data, Utils.CHARSET), signature);
         } catch (SignatureException e) {
             if (e.getCause() != null && e.getCause().getClass().isAssignableFrom(NoSuchAlgorithmException.class)) {
                 throw new JwsVerifyingException("Unsupported Signing Algorithm, " + algorithm.getAlgorithm(), e);
             }
             throw new JwsVerifyingException(e);
         }
     }
 
     private void validateAlgorithm(JwsAlgorithm algorithm) {
         Reject.ifNull(algorithm, "Algorithm must not be null.");
         Reject.ifTrue(algorithm.getAlgorithmType() != JwsAlgorithmType.RSA, "Not an RSA algorithm.");
     }
 }