/*-
 * ============LICENSE_START=======================================================
 *  Copyright (C) 2020 Nordix Foundation.
 * ================================================================================
 * 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.
 *
 * SPDX-License-Identifier: Apache-2.0
 * ============LICENSE_END=========================================================
 */

package org.onap.aaf.certservice.cmpv2client.impl;

import static org.onap.aaf.certservice.cmpv2client.impl.CmpResponseHelper.checkIfCmpResponseContainsError;
import static org.onap.aaf.certservice.cmpv2client.impl.CmpResponseHelper.getCertfromByteArray;
import static org.onap.aaf.certservice.cmpv2client.impl.CmpResponseHelper.verifyAndReturnCertChainAndTrustSTore;

import java.io.IOException;
import java.security.cert.CertificateParsingException;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import org.apache.http.impl.client.CloseableHttpClient;
import org.bouncycastle.asn1.cmp.CMPCertificate;
import org.bouncycastle.asn1.cmp.CertRepMessage;
import org.bouncycastle.asn1.cmp.CertResponse;
import org.bouncycastle.asn1.cmp.PKIBody;
import org.bouncycastle.asn1.cmp.PKIMessage;
import org.onap.aaf.certservice.cmpv2client.exceptions.CmpClientException;
import org.onap.aaf.certservice.cmpv2client.api.CmpClient;
import org.onap.aaf.certservice.cmpv2client.external.CSRMeta;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Implementation of the CmpClient Interface conforming to RFC4210 (Certificate Management Protocol
 * (CMP)) and RFC4211 (Certificate Request Message Format (CRMF)) standards.
 */
public class CmpClientImpl implements CmpClient {

  private final Logger LOG = LoggerFactory.getLogger(CmpClientImpl.class);
  private final CloseableHttpClient httpClient;

  private static final String DEFAULT_PROFILE = "RA";
  private static final String DEFAULT_CA_NAME = "Certification Authority";

  public CmpClientImpl(CloseableHttpClient httpClient) {
    this.httpClient = httpClient;
  }

  @Override
  public List<List<X509Certificate>> createCertificate(
      String caName,
      String profile,
      CSRMeta csrMeta,
      X509Certificate cert,
      Date notBefore,
      Date notAfter)
      throws CmpClientException {
    // Validate inputs for Certificate Request
    validate(csrMeta, cert, caName, profile, httpClient, notBefore, notAfter);

    final CreateCertRequest certRequest =
        CmpMessageBuilder.of(CreateCertRequest::new)
            .with(CreateCertRequest::setIssuerDn, csrMeta.issuerx500Name())
            .with(CreateCertRequest::setSubjectDn, csrMeta.x500Name())
            .with(CreateCertRequest::setSansList, csrMeta.sans())
            .with(CreateCertRequest::setSubjectKeyPair, csrMeta.keyPair())
            .with(CreateCertRequest::setNotBefore, notBefore)
            .with(CreateCertRequest::setNotAfter, notAfter)
            .with(CreateCertRequest::setInitAuthPassword, csrMeta.password())
            .build();

    final PKIMessage pkiMessage = certRequest.generateCertReq();
    Cmpv2HttpClient cmpv2HttpClient = new Cmpv2HttpClient(httpClient);
    return retrieveCertificates(caName, csrMeta, pkiMessage, cmpv2HttpClient);
  }

  @Override
  public List<List<X509Certificate>> createCertificate(
      String caName, String profile, CSRMeta csrMeta, X509Certificate csr)
      throws CmpClientException {
    return createCertificate(caName, profile, csrMeta, csr, null, null);
  }

  private List<List<X509Certificate>> checkCmpCertRepMessage(final PKIMessage respPkiMessage)
      throws CmpClientException {
    final PKIBody pkiBody = respPkiMessage.getBody();
    if (Objects.nonNull(pkiBody) && pkiBody.getContent() instanceof CertRepMessage) {
      final CertRepMessage certRepMessage = (CertRepMessage) pkiBody.getContent();
      if (Objects.nonNull(certRepMessage)) {
        final CertResponse certResponse =
            getCertificateResponseContainingNewCertificate(certRepMessage);
        try {
          return verifyReturnCertChainAndTrustStore(respPkiMessage, certRepMessage, certResponse);
        } catch (IOException | CertificateParsingException ex) {
          CmpClientException cmpClientException =
              new CmpClientException(
                  "Exception occurred while retrieving Certificates from response", ex);
          LOG.error("Exception occurred while retrieving Certificates from response", ex);
          throw cmpClientException;
        }
      } else {
        return new ArrayList<>(Collections.emptyList());
      }
    }
    return new ArrayList<>(Collections.emptyList());
  }

  private List<List<X509Certificate>> verifyReturnCertChainAndTrustStore(
      PKIMessage respPkiMessage, CertRepMessage certRepMessage, CertResponse certResponse)
      throws CertificateParsingException, CmpClientException, IOException {
    LOG.info("Verifying certificates returned as part of CertResponse.");
    final CMPCertificate cmpCertificate =
        certResponse.getCertifiedKeyPair().getCertOrEncCert().getCertificate();
    final Optional<X509Certificate> leafCertificate =
        getCertfromByteArray(cmpCertificate.getEncoded(), X509Certificate.class);
    ArrayList<X509Certificate> certChain = new ArrayList<>();
    ArrayList<X509Certificate> trustStore = new ArrayList<>();
    return verifyAndReturnCertChainAndTrustSTore(
        respPkiMessage, certRepMessage, leafCertificate.get(), certChain, trustStore);
  }

  private CertResponse getCertificateResponseContainingNewCertificate(
      CertRepMessage certRepMessage) {
    return certRepMessage.getResponse()[0];
  }

  /**
   * Validate inputs for Certificate Creation.
   *
   * @param csrMeta CSRMeta Object containing variables for creating a Certificate Request.
   * @param cert Certificate object needed to validate response from CA server.
   * @param incomingCaName Date specifying certificate is not valid before this date.
   * @param incomingProfile Date specifying certificate is not valid after this date.
   * @throws IllegalArgumentException if Before Date is set after the After Date.
   */
  private void validate(
      final CSRMeta csrMeta,
      final X509Certificate cert,
      final String incomingCaName,
      final String incomingProfile,
      final CloseableHttpClient httpClient,
      final Date notBefore,
      final Date notAfter) {

    String caName;
    String caProfile;
    caName = CmpUtil.isNullOrEmpty(incomingCaName) ? incomingCaName : DEFAULT_CA_NAME;
    caProfile = CmpUtil.isNullOrEmpty(incomingProfile) ? incomingProfile : DEFAULT_PROFILE;
    LOG.info(
        "Validate before creating Certificate Request for CA :{} in Mode {} ", caName, caProfile);

    CmpUtil.notNull(csrMeta, "CSRMeta Instance");
    CmpUtil.notNull(csrMeta.x500Name(), "Subject DN");
    CmpUtil.notNull(csrMeta.issuerx500Name(), "Issuer DN");
    CmpUtil.notNull(csrMeta.password(), "IAK/RV Password");
    CmpUtil.notNull(cert, "Certificate Signing Request (CSR)");
    CmpUtil.notNull(csrMeta.caUrl(), "External CA URL");
    CmpUtil.notNull(csrMeta.keypair(), "Subject KeyPair");
    CmpUtil.notNull(httpClient, "Closeable Http Client");

    if (notBefore != null && notAfter != null && notBefore.compareTo(notAfter) > 0) {
      throw new IllegalArgumentException("Before Date is set after the After Date");
    }
  }

  private List<List<X509Certificate>> retrieveCertificates(
      String caName, CSRMeta csrMeta, PKIMessage pkiMessage, Cmpv2HttpClient cmpv2HttpClient)
      throws CmpClientException {
    final byte[] respBytes = cmpv2HttpClient.postRequest(pkiMessage, csrMeta.caUrl(), caName);
    try {
      final PKIMessage respPkiMessage = PKIMessage.getInstance(respBytes);
      LOG.info("Recieved response from Server");
      checkIfCmpResponseContainsError(respPkiMessage);
      return checkCmpCertRepMessage(respPkiMessage);
    } catch (IllegalArgumentException iae) {
      CmpClientException cmpClientException =
          new CmpClientException(
              "Error encountered while processing response from CA server ", iae);
      LOG.error("Error encountered while processing response from CA server ", iae);
      throw cmpClientException;
    }
  }
}