/*
    *   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.directory.ldap.client.api.callback;
  
  
  import java.io.IOException;
  import java.text.MessageFormat;
  
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.CallbackHandler;
  import javax.security.auth.callback.NameCallback;
  import javax.security.auth.callback.PasswordCallback;
  import javax.security.auth.callback.UnsupportedCallbackException;
  import javax.security.sasl.RealmCallback;
  import javax.security.sasl.RealmChoiceCallback;
  
  import org.apache.directory.api.util.Strings;
  import org.apache.directory.ldap.client.api.SaslRequest;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * The CallbackHandler implementation used by the LdapConnection during SASL mechanism based bind operations.
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class SaslCallbackHandler implements CallbackHandler
  {
      /** The sasl request. */
      private SaslRequest saslReq;
  
      /** The logger. */
      private static final Logger LOG = LoggerFactory.getLogger( SaslCallbackHandler.class );
  
  
      /**
       * Instantiates a new SASL callback handler.
       *
       * @param saslReq the SASL request
       */
      public SaslCallbackHandler( SaslRequest saslReq )
      {
          this.saslReq = saslReq;
      }
  
  
      /**
       * {@inheritDoc}
       */
      public void handle( Callback[] callbacks ) throws IOException, UnsupportedCallbackException
      {
          for ( Callback cb : callbacks )
          {
              if ( cb instanceof NameCallback )
              {
                  NameCallback ncb = ( NameCallback ) cb;
  
                  String name = saslReq.getUsername();
                  LOG.debug( "sending name {} in the NameCallback", name );
                  ncb.setName( name );
              }
              else if ( cb instanceof PasswordCallback )
              {
                  PasswordCallback pcb = ( PasswordCallback ) cb;
  
                  LOG.debug( "sending credentials in the PasswordCallback" );
                  pcb.setPassword( Strings.utf8ToString( saslReq.getCredentials() ).toCharArray() );
              }
              else if ( cb instanceof RealmCallback )
              {
                  RealmCallback rcb = ( RealmCallback ) cb;
  
                  if ( saslReq.getRealmName() != null )
                  {
                      LOG.debug( "sending the user specified realm value {} in the RealmCallback", saslReq.getRealmName() );
                      rcb.setText( saslReq.getRealmName() );
                  }
                  else
                  {
                      LOG.debug(
                         "No user specified relam value, sending the default realm value {} in the RealmCallback",
                         rcb.getDefaultText() );
                     rcb.setText( rcb.getDefaultText() );
                 }
             }
             else if ( cb instanceof RealmChoiceCallback )
             {
                 RealmChoiceCallback rccb = ( RealmChoiceCallback ) cb;
 
                 boolean foundRealmName = false;
 
                 String[] realmNames = rccb.getChoices();
                 for ( int i = 0; i < realmNames.length; i++ )
                 {
                     String realmName = realmNames[i];
                     if ( realmName.equals( saslReq.getRealmName() ) )
                     {
                         foundRealmName = true;
 
                         LOG.debug( "sending the user specified realm value {} in the RealmChoiceCallback", realmName );
                         rccb.setSelectedIndex( i );
                         break;
                     }
                 }
 
                 if ( !foundRealmName )
                 {
                     throw new IOException(
                         MessageFormat
                             .format(
                                 "Cannot match ''java.naming.security.sasl.realm'' property value ''{0}'' with choices ''{1}'' in RealmChoiceCallback.",
                                 saslReq.getRealmName(), getRealmNamesAsString( realmNames ) ) );
                 }
             }
         }
     }
 
 
     /**
      * Gets the realm names as a string.
      *
      * @param realmNames the array of realm names
      * @return  the realm names as a string
      */
     private String getRealmNamesAsString( String[] realmNames )
     {
         StringBuilder sb = new StringBuilder();
 
         if ( ( realmNames != null ) && ( realmNames.length > 0 ) )
         {
             for ( String realmName : realmNames )
             {
                 sb.append( realmName );
                 sb.append( ',' );
             }
             sb.deleteCharAt( sb.length() - 1 );
         }
 
         return sb.toString();
     }
 }