/*
    *  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.server.ldap.handlers.sasl.digestMD5;
  
  
  import java.util.HashMap;
  import java.util.Map;
  
  import javax.security.auth.callback.CallbackHandler;
  import javax.security.sasl.Sasl;
  import javax.security.sasl.SaslServer;
  
  import org.apache.directory.api.ldap.model.constants.SupportedSaslMechanisms;
  import org.apache.directory.api.ldap.model.message.BindRequest;
  import org.apache.directory.server.core.api.CoreSession;
  import org.apache.directory.server.ldap.LdapServer;
  import org.apache.directory.server.ldap.LdapSession;
  import org.apache.directory.server.ldap.handlers.sasl.AbstractMechanismHandler;
  import org.apache.directory.server.ldap.handlers.sasl.SaslConstants;
  
  
  /**
   * The DIGEST-MD5 mechanism handler.
   * 
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class DigestMd5MechanismHandler extends AbstractMechanismHandler
  {
      /**
       * Create a list of all the configured realms.
       * 
       * @param ldapServer the LdapServer for which we want to get the realms
       * @return a list of realms, separated by spaces
       */
      private String getActiveRealms( LdapServer ldapServer )
      {
          StringBuilder realms = new StringBuilder();
          boolean isFirst = true;
  
          for ( String realm : ldapServer.getSaslRealms() )
          {
              if ( isFirst )
              {
                  isFirst = false;
              }
              else
              {
                  realms.append( ' ' );
              }
  
              realms.append( realm );
          }
  
          return realms.toString();
      }
  
  
      public SaslServer handleMechanism( LdapSession ldapSession, BindRequest bindRequest ) throws Exception
      {
          SaslServer ss = ( SaslServer ) ldapSession.getSaslProperty( SaslConstants.SASL_SERVER );
  
          if ( ss == null )
          {
              CoreSession adminSession = ldapSession.getLdapServer().getDirectoryService().getAdminSession();
  
              CallbackHandler callbackHandler = new DigestMd5CallbackHandler( ldapSession, adminSession, bindRequest );
  
              ss = Sasl.createSaslServer(
                  SupportedSaslMechanisms.DIGEST_MD5,
                  SaslConstants.LDAP_PROTOCOL,
                  ( String ) ldapSession.getSaslProperty( SaslConstants.SASL_HOST ),
                  ( Map<String, String> ) ldapSession.getSaslProperty( SaslConstants.SASL_PROPS ),
                  callbackHandler );
              ldapSession.putSaslProperty( SaslConstants.SASL_SERVER, ss );
          }
  
          return ss;
      }
  
  
      /**
       * {@inheritDoc}
      */
     public void init( LdapSession ldapSession )
     {
         // Store the host in the ldap session
         String saslHost = ldapSession.getLdapServer().getSaslHost();
         String userBaseDn = ldapSession.getLdapServer().getSearchBaseDn();
 
         ldapSession.putSaslProperty( SaslConstants.SASL_HOST, saslHost );
         ldapSession.putSaslProperty( SaslConstants.SASL_USER_BASE_DN, userBaseDn );
 
         Map<String, String> saslProps = new HashMap<>();
         saslProps.put( Sasl.QOP, ldapSession.getLdapServer().getSaslQopString() );
         saslProps.put( "com.sun.security.sasl.digest.realm", getActiveRealms( ldapSession.getLdapServer() ) );
         ldapSession.putSaslProperty( SaslConstants.SASL_PROPS, saslProps );
     }
 
 
     /**
      * Remove the Host, UserBaseDn, props and Mechanism property.
      * 
      * @param ldapSession the LdapSession instance
      */
     public void cleanup( LdapSession ldapSession )
     {
         // Inject the Sasl Filter
         insertSaslFilter( ldapSession );
 
         // and cleanup the useless informations
         ldapSession.removeSaslProperty( SaslConstants.SASL_HOST );
         ldapSession.removeSaslProperty( SaslConstants.SASL_USER_BASE_DN );
         ldapSession.removeSaslProperty( SaslConstants.SASL_MECH );
         ldapSession.removeSaslProperty( SaslConstants.SASL_PROPS );
         ldapSession.removeSaslProperty( SaslConstants.SASL_AUTHENT_USER );
     }
 }