/**
    * 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.wss4j.dom.processor;
  
  import org.apache.wss4j.dom.WSConstants;
  import org.apache.wss4j.dom.engine.WSSecurityEngineResult;
  import org.apache.wss4j.common.ext.WSPasswordCallback;
  import org.apache.wss4j.common.ext.WSSecurityException;
  import org.apache.wss4j.common.util.XMLUtils;
  import org.apache.wss4j.dom.handler.RequestData;
  import org.apache.wss4j.dom.message.token.SecurityContextToken;
  import org.apache.wss4j.dom.validate.Credential;
  import org.apache.wss4j.dom.validate.Validator;
  import org.w3c.dom.Element;
  
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.CallbackHandler;
  import javax.security.auth.callback.UnsupportedCallbackException;
  import javax.xml.namespace.QName;
  
  import java.util.List;
  import java.io.IOException;
  
  /**
   * The processor to process <code>wsc:SecurityContextToken</code>.
   */
  public class SecurityContextTokenProcessor implements Processor {
  
      public List<WSSecurityEngineResult> handleToken(
          Element elem,
          RequestData data
      ) throws WSSecurityException {
          SecurityContextToken sct = new SecurityContextToken(elem);
  
          Validator validator =
              data.getValidator(new QName(elem.getNamespaceURI(), elem.getLocalName()));
  
          WSSecurityEngineResult result =
              new WSSecurityEngineResult(WSConstants.SCT, sct);
          if (validator != null) {
              // Hook to allow the user to validate the SecurityContextToken
              Credential credential = new Credential();
              credential.setSecurityContextToken(sct);
  
              Credential returnedCredential = validator.validate(credential, data);
              result.put(WSSecurityEngineResult.TAG_VALIDATED_TOKEN, Boolean.TRUE);
              String tokenId = sct.getID();
              if (tokenId.length() != 0) {
                  result.put(WSSecurityEngineResult.TAG_ID, tokenId);
              }
              result.put(WSSecurityEngineResult.TAG_SECRET, returnedCredential.getSecretKey());
          } else {
              String id = sct.getID();
              id = XMLUtils.getIDFromReference(id);
  
              byte[] secret = null;
              try {
                  secret = getSecret(data.getCallbackHandler(), sct.getIdentifier());
              } catch (WSSecurityException ex) {
                  secret = getSecret(data.getCallbackHandler(), id);
              }
              if (secret == null || secret.length == 0) {
                  secret = getSecret(data.getCallbackHandler(), id);
              }
              result.put(WSSecurityEngineResult.TAG_ID, sct.getID());
              result.put(WSSecurityEngineResult.TAG_SECRET, secret);
          }
  
          data.getWsDocInfo().addTokenElement(elem);
          data.getWsDocInfo().addResult(result);
          return java.util.Collections.singletonList(result);
      }
  
      /**
       * Get the secret from the provided callback handler and return it.
       *
       * @param cb
       * @param identifier
       * @return The key collected using the callback handler
       */
      private byte[] getSecret(CallbackHandler cb, String identifier)
          throws WSSecurityException {
 
         if (cb == null) {
             throw new WSSecurityException(WSSecurityException.ErrorCode.FAILURE, "noCallback");
         }
 
         WSPasswordCallback callback =
             new WSPasswordCallback(identifier, WSPasswordCallback.SECURITY_CONTEXT_TOKEN);
         try {
             Callback[] callbacks = new Callback[]{callback};
             cb.handle(callbacks);
         } catch (IOException | UnsupportedCallbackException e) {
             throw new WSSecurityException(
                 WSSecurityException.ErrorCode.FAILURE, e,
                 "noKey",
                 new Object[] {identifier});
         }
 
         return callback.getKey();
     }
 
 }