/**
    *
    * 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.hadoop.hbase.security;
  
  import java.nio.charset.StandardCharsets;
  import java.util.Map;
  import java.util.TreeMap;
  
  import javax.security.sasl.Sasl;
  import javax.security.sasl.SaslClient;
  import javax.security.sasl.SaslException;
  
  import org.apache.commons.codec.binary.Base64;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.util.Bytes;
  
  @InterfaceAudience.Private
  public class SaslUtil {
    private static final Log LOG = LogFactory.getLog(SaslUtil.class);
    public static final String SASL_DEFAULT_REALM = "default";
    public static final int SWITCH_TO_SIMPLE_AUTH = -88;
  
    public enum QualityOfProtection {
      AUTHENTICATION("auth"),
      INTEGRITY("auth-int"),
      PRIVACY("auth-conf");
  
      private final String saslQop;
  
      QualityOfProtection(String saslQop) {
        this.saslQop = saslQop;
      }
  
      public String getSaslQop() {
        return saslQop;
      }
  
      public boolean matches(String stringQop) {
        if (saslQop.equals(stringQop)) {
          LOG.warn("Use authentication/integrity/privacy as value for rpc protection "
              + "configurations instead of auth/auth-int/auth-conf.");
          return true;
        }
        return name().equalsIgnoreCase(stringQop);
      }
    }
  
    /** Splitting fully qualified Kerberos name into parts */
    public static String[] splitKerberosName(String fullName) {
      return fullName.split("[/@]");
    }
  
    static String encodeIdentifier(byte[] identifier) {
      return new String(Base64.encodeBase64(identifier), StandardCharsets.UTF_8);
    }
  
    static byte[] decodeIdentifier(String identifier) {
      return Base64.decodeBase64(Bytes.toBytes(identifier));
    }
  
    static char[] encodePassword(byte[] password) {
      return new String(Base64.encodeBase64(password), StandardCharsets.UTF_8).toCharArray();
    }
  
    /**
     * Returns {@link org.apache.hadoop.hbase.security.SaslUtil.QualityOfProtection}
     * corresponding to the given {@code stringQop} value.
     * @throws IllegalArgumentException If stringQop doesn't match any QOP.
     */
    public static QualityOfProtection getQop(String stringQop) {
      for (QualityOfProtection qop : QualityOfProtection.values()) {
        if (qop.matches(stringQop)) {
          return qop;
        }
      }
      throw new IllegalArgumentException("Invalid qop: " +  stringQop
          + ". It must be one of 'authentication', 'integrity', 'privacy'.");
    }
  
    /**
     * @param rpcProtection Value of 'hbase.rpc.protection' configuration.
    * @return Map with values for SASL properties.
    */
   public static Map<String, String> initSaslProperties(String rpcProtection) {
     String saslQop;
     if (rpcProtection.isEmpty()) {
       saslQop = QualityOfProtection.AUTHENTICATION.getSaslQop();
     } else {
       String[] qops = rpcProtection.split(",");
       StringBuilder saslQopBuilder = new StringBuilder();
       for (int i = 0; i < qops.length; ++i) {
         QualityOfProtection qop = getQop(qops[i]);
         saslQopBuilder.append(",").append(qop.getSaslQop());
       }
       saslQop = saslQopBuilder.substring(1);  // remove first ','
     }
     Map<String, String> saslProps = new TreeMap<>();
     saslProps.put(Sasl.QOP, saslQop);
     saslProps.put(Sasl.SERVER_AUTH, "true");
     return saslProps;
   }
 
   static void safeDispose(SaslClient saslClient) {
     try {
       saslClient.dispose();
     } catch (SaslException e) {
       LOG.error("Error disposing of SASL client", e);
     }
   }
 }