package won.cryptography.webid;

import org.apache.jena.query.Dataset;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.security.authentication.InternalAuthenticationServiceException;
import org.springframework.security.core.AuthenticationException;
import won.cryptography.rdfsign.WonKeysReaderWriter;
import won.protocol.util.linkeddata.LinkedDataSource;

import java.net.URI;
import java.security.PublicKey;
import java.security.interfaces.ECPublicKey;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;

/**
 * User: ypanchenko
 * Date: 28.07.2015
 */
public class WebIDVerificationAgent
{
  final Logger logger = LoggerFactory.getLogger(getClass());

  private LinkedDataSource linkedDataSource;

  public boolean verify(PublicKey publicKey, URI webId){
    Dataset dataset = null;
    try {
      dataset = linkedDataSource.getDataForResource(webId);
    } catch (Exception e) {
      throw new InternalAuthenticationServiceException("Could not retrieve data for WebID '" + webId + "'", e);
    }


    //TODO for RSA key
    //      if (publicKey instanceof RSAPublicKey) {
    //        RSAPublicKey rsaPublicKey = (RSAPublicKey) publicKey;
    //        BigInteger modulus = WonRdfUtils.SignatureUtils.getRsaPublicKeyModulus(webID, dataset);
    //        BigInteger exponent = WonRdfUtils.SignatureUtils.getRsaPublicKeyExponent(webID, dataset);
    //        if (exponent != null && rsaPublicKey.getPublicExponent().equals(exponent)) {
    //          if (modulus != null && rsaPublicKey.getModulus().equals(modulus)) {
    //            verified.add(webID.toString());
    //          }
    //        }
    //      }
    if (publicKey instanceof ECPublicKey) {
      ECPublicKey ecPublicKey = (ECPublicKey) publicKey;
      WonKeysReaderWriter ecKeyReader = new WonKeysReaderWriter();
      Set<PublicKey> keys = null;
      try {
        keys = ecKeyReader.readFromDataset(dataset, webId.toString());
      } catch (Exception e) {
        throw new InternalAuthenticationServiceException("Could not verify key",e );
      }
      for (PublicKey key: keys) {
        ECPublicKey ecPublicKeyFetched = (ECPublicKey) key;
        //TODO check if equals work
        if (ecPublicKey.getW().getAffineX().equals(ecPublicKeyFetched.getW().getAffineX())) {
          if (ecPublicKey.getW().getAffineY().equals(ecPublicKeyFetched.getW().getAffineY())) {
            return true;
          }
        }
      }
    } else {
      throw new InternalAuthenticationServiceException("Key type " + publicKey.getAlgorithm() + " not supported");
    }
    return false;
  }

  /**
   *
   * @return list of those webIDs that were successfully verified by fetching the webID's url
   * and comparing public key data found there with the provided in constructor public key data
   */
  public List<String> verify(PublicKey publicKey, List<URI> webIDs) throws AuthenticationException {
    List<String> verified = new ArrayList<String>();

    for (URI webID : webIDs) {
      if (verify(publicKey, webID)){
        verified.add(webID.toString());
      }
    }
    return verified;
  }

  public void setLinkedDataSource(final LinkedDataSource linkedDataSource) {
    this.linkedDataSource = linkedDataSource;
  }

}