package org.jboss.resteasy.jose.jws.crypto;

import org.jboss.resteasy.jose.jws.Algorithm;
import org.jboss.resteasy.jose.jws.JWSInput;
import org.jboss.resteasy.jose.jws.util.PemUtils;

import java.nio.charset.StandardCharsets;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.cert.X509Certificate;

/**
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
 * @version $Revision: 1 $
 */
public class RSAProvider implements SignatureProvider {
   public static String getJavaAlgorithm(Algorithm alg) {
      switch (alg) {
         case RS256:
            return "SHA256withRSA";
         case RS384:
            return "SHA384withRSA";
         case RS512:
            return "SHA512withRSA";
         default:
            throw new IllegalArgumentException("Not an RSA Algorithm");
      }
   }

   public static Signature getSignature(Algorithm alg) {
      try {
         return Signature.getInstance(getJavaAlgorithm(alg));
      } catch (Exception e) {
         throw new RuntimeException(e);
      }
   }

   public static byte[] sign(byte[] data, Algorithm algorithm, PrivateKey privateKey) {
      try {
         Signature signature = getSignature(algorithm);
         signature.initSign(privateKey);
         signature.update(data);
         return signature.sign();
      } catch (Exception e) {
         throw new RuntimeException(e);
      }
   }

   public static boolean verifyViaCertificate(JWSInput input, String cert) {
      X509Certificate certificate = null;
      try {
         certificate = PemUtils.decodeCertificate(cert);
      } catch (Exception e) {
         throw new RuntimeException(e);
      }
      return verify(input, certificate.getPublicKey());
   }

   public static boolean verify(JWSInput input, PublicKey publicKey) {
      try {
         Signature verifier = getSignature(input.getHeader().getAlgorithm());
         verifier.initVerify(publicKey);
         verifier.update(input.getEncodedSignatureInput().getBytes(StandardCharsets.UTF_8));
         return verifier.verify(input.getSignature());
      } catch (Exception e) {
         return false;
      }

   }

   @Override
   public boolean verify(JWSInput input, String key) {
      return verifyViaCertificate(input, key);
   }


}
