/*
    * 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.keypair.GordianKeyPair;
  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.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.exc.GordianCryptoException;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.sign.GordianCoreSignature;
  import io.github.tonywasher.joceanus.gordianknot.impl.core.spec.keypair.GordianCoreKeyPairSpec;
  import org.bouncycastle.crypto.CryptoException;
  import org.bouncycastle.crypto.Signer;
  import org.bouncycastle.crypto.signers.Ed25519Signer;
  import org.bouncycastle.crypto.signers.Ed448Signer;
  
  /**
   * EdDSA signature.
   */
  public class BouncyEdDSASignature
          extends GordianCoreSignature {
      /**
       * The Signer.
       */
      private Signer theSigner;
  
      /**
       * Constructor.
       *
       * @param pFactory the factory
       * @param pSpec    the signatureSpec.
       */
      BouncyEdDSASignature(final GordianBaseFactory pFactory,
                           final GordianSignatureSpec pSpec) {
          /* Initialise underlying class */
          super(pFactory, pSpec);
      }
  
      /**
       * Create the signer according to the keyPair.
       *
       * @param pKeyPair the keyPair
       * @return the signer
       */
      private static Signer createSigner(final GordianKeyPair pKeyPair) {
          /* Determine the EdwardsCurve */
          final GordianCoreKeyPairSpec myKeySpec = (GordianCoreKeyPairSpec) pKeyPair.getKeyPairSpec();
          final boolean is25519 = myKeySpec.getEdwardsSpec().is25519();
          final byte[] myContext = new byte[0];
  
          /* Create the internal digests */
          return is25519
                  ? new Ed25519Signer()
                  : new Ed448Signer(myContext);
      }
  
      @Override
      public void initForSigning(final GordianNewSignParams pParams) throws GordianException {
          /* Initialise detail */
          super.initForSigning(pParams);
          final GordianKeyPair myPair = getKeyPair();
          BouncyKeyPair.checkKeyPair(myPair);
  
          /* Initialise and set the signer */
          theSigner = createSigner(myPair);
          final BouncyPrivateKey<?> myPrivate = getKeyPair().getPrivateKey();
          theSigner.init(true, myPrivate.getPrivateKey());
      }
  
      @Override
      public void initForVerify(final GordianNewSignParams pParams) throws GordianException {
          /* Initialise detail */
          super.initForVerify(pParams);
          final GordianKeyPair myPair = getKeyPair();
          BouncyKeyPair.checkKeyPair(myPair);
  
          /* Initialise and set the signer */
          theSigner = createSigner(myPair);
          final BouncyPublicKey<?> myPublic = getKeyPair().getPublicKey();
          theSigner.init(false, myPublic.getPublicKey());
     }
 
     @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 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);
     }
 }