content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 org.apache.cassandra.auth;
  
  import java.security.cert.Certificate;
  import java.security.cert.X509Certificate;
  import java.util.Arrays;
  import java.util.concurrent.TimeUnit;
  
  public final class MutualTlsUtil
  {
      private static final int ONE_DAY_IN_MINUTES = (int) TimeUnit.DAYS.toMinutes(1);
      private static final int ONE_HOUR_IN_MINUTES = (int) TimeUnit.HOURS.toMinutes(1);
  
      /**
       * Filters instances of {@link X509Certificate} certificates and returns the certificate chain as
       * {@link X509Certificate} certificates.
       *
       * @param clientCertificateChain client certificate chain
       * @return an array of certificates that were cast to {@link X509Certificate}
       */
      public static X509Certificate[] castCertsToX509(Certificate[] clientCertificateChain)
      {
          if (clientCertificateChain == null || clientCertificateChain.length == 0)
          {
              return null;
          }
          return Arrays.stream(clientCertificateChain)
                       .filter(certificate -> certificate instanceof X509Certificate)
                       .toArray(X509Certificate[]::new);
      }
  
      public static String toHumanReadableCertificateExpiration(int minutesToExpiration)
      {
          if (minutesToExpiration >= ONE_DAY_IN_MINUTES)
          {
              return formatHelper(minutesToDays(minutesToExpiration), "day")
                     + maybeAppendRemainder(minutesToExpiration % ONE_DAY_IN_MINUTES);
          }
          if (minutesToExpiration >= ONE_HOUR_IN_MINUTES)
          {
              return formatHelper((int) TimeUnit.MINUTES.toHours(minutesToExpiration), "hour")
                     + maybeAppendRemainder(minutesToExpiration % ONE_HOUR_IN_MINUTES);
          }
          return formatHelper(minutesToExpiration, "minute");
      }
  
      public static int minutesToDays(int minutes)
      {
          return (int) TimeUnit.MINUTES.toDays(minutes);
      }
  
      static String formatHelper(int unit, String singularForm)
      {
          if (unit == 1)
              return unit + " " + singularForm;
          // assumes plural form just adds s at the end
          return unit + " " + singularForm + 's';
      }
  
      static String maybeAppendRemainder(int remainderInMinutes)
      {
          if (remainderInMinutes == 0)
              return "";
          return ' ' + toHumanReadableCertificateExpiration(remainderInMinutes);
      }
  }
  