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.ambari.server.serveraction.kerberos;
  
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import javax.annotation.Nullable;
  
  /**
   * DeconstructedPrincipal manages the different parts of a principal and can be used to get a
   * normalized principal value
   * <p/>
   * A "normalized" principal has the following forms:
   * <ul>
   * <li>primary/instance@realm</li>
   * <li>primary@realm</li>
   * </ul>
   * <p/>
   * This class will create a DeconstructedPrincipal from a String containing a principal using
   * {@link DeconstructedPrincipal#valueOf(String, String)}
   */
  public class DeconstructedPrincipal {
    /**
     * Regular expression to parse the different principal formats:
     * <ul>
     * <li>primary/instance@REALM</li>
     * <li>primary@REALM</li>
     * <li>primary/instance</li>
     * <li>primary</li>
     * </ul>
     */
    private static Pattern PATTERN_PRINCIPAL = Pattern.compile("^([^ /@]+)(?:/([^ /@]+))?(?:@(.+)?)?$");
  
    /**
     * A String containing the "primary" component of a principal
     */
    private final String primary;
  
    /**
     * A String containing the "instance" component of a principal
     */
    private final String instance;
  
    /**
     * A String containing the "realm" component of a principal
     */
    private final String realm;
  
    /**
     * A String containing the principal name portion of the principal.
     * The principal name is the combination of the primary and instance components.
     * This value is generated using the primary, instance, and realm components.
     */
    private final String principalName;
  
    /**
     * A String containing the complete normalized principal
     * The normalized principal is the combination of the primary, instance, and realm components.
     * This value is generated using the primary, instance, and realm components.
     */
    private final String normalizedPrincipal;
  
    /**
     * Given a principal and a default realm, creates a new DeconstructedPrincipal
     * <p/>
     * If the supplied principal does not have a realm component, the default realm (supplied) will be
     * used.
     *
     * @param principal    a String containing the principal to deconstruct
     * @param defaultRealm a String containing the default realm
     * @return a new DeconstructedPrincipal
     */
    public static DeconstructedPrincipal valueOf(String principal, @Nullable String defaultRealm) {
      if (principal == null) {
        throw new IllegalArgumentException("The principal may not be null");
      }
  
      Matcher matcher = PATTERN_PRINCIPAL.matcher(principal);
  
      if (matcher.matches()) {
        String primary = matcher.group(1);
        String instance = matcher.group(2);
        String realm = matcher.group(3);
  
        if ((realm == null) || realm.isEmpty()) {
          realm = defaultRealm;
        }
  
        return new DeconstructedPrincipal(primary, instance, realm);
      } else {
        throw new IllegalArgumentException(String.format("Invalid principal value: %s", principal));
      }
    }
  
  
    /**
     * Constructs a new DeconstructedPrincipal
     *
     * @param primary  a String containing the "primary" component of the principal
     * @param instance a String containing the "instance" component of the principal
     * @param realm    a String containing the "realm" component of the principal
     */
    protected DeconstructedPrincipal(String primary, String instance, String realm) {
      this.primary = primary;
      this.instance = instance;
      this.realm = realm;
  
      StringBuilder builder = new StringBuilder();
  
      if (this.primary != null) {
        builder.append(primary);
      }
  
      if (this.instance != null) {
        builder.append('/');
        builder.append(this.instance);
      }
  
      this.principalName = builder.toString();
  
      if (this.realm != null) {
        builder.append('@');
        builder.append(this.realm);
      }
  
      this.normalizedPrincipal = builder.toString();
    }
  
    /**
     * Gets the primary component of this DeconstructedPrincipal
     *
     * @return a String containing the "primary" component of this DeconstructedPrincipal
     */
    public String getPrimary() {
      return primary;
    }
  
    /**
     * Gets the instance component of this DeconstructedPrincipal
     *
     * @return a String containing the "instance" component of this DeconstructedPrincipal
     */
    public String getInstance() {
      return instance;
    }
  
    /**
     * Gets the realm component of this DeconstructedPrincipal
     *
     * @return a String containing the "realm" component of this DeconstructedPrincipal
     */
    public String getRealm() {
      return realm;
    }
  
    /**
     * Gets the constructed principal name for this DeconstructedPrincipal
     * <p/>
     * The principal name is the combination of the primary and instance components:
     * <ul>
     * <li>primary/instance</li>
     * <li>primary</li>
     * </ul>
     *
     * @return a String containing the "realm" component of this DeconstructedPrincipal
     */
    public String getPrincipalName() {
      return principalName;
    }
  
    /**
     * Gets the constructed normalized  principal for this DeconstructedPrincipal
     * <p/>
     * The normalized principal is the combination of the primary, instance, and realm components:
     * <ul>
     * <li>primary/instance@realm</li>
     * <li>primary@realm</li>
     * </ul>
     *
     * @return a String containing the "realm" component of this DeconstructedPrincipal
     */
    public String getNormalizedPrincipal() {
      return normalizedPrincipal;
    }
  }
  