/**
    * 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.common;
  
  import org.apache.wss4j.common.ext.WSPasswordCallback;
  import org.apache.wss4j.common.ext.WSSecurityException;
  import org.apache.wss4j.common.util.KeyUtils;
  import org.apache.xml.security.utils.XMLUtils;
  
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.CallbackHandler;
  import javax.security.auth.callback.UnsupportedCallbackException;
  
  import java.io.IOException;
  import java.util.HashMap;
  import java.util.Map;
  
  /**
   * A Callback Handler implementation for the case of storing a secret key.
   */
  public class SecretKeyCallbackHandler implements CallbackHandler {
  
      private Map<String, byte[]> secrets = new HashMap<>();
      private byte[] outboundSecret;
  
      public void handle(Callback[] callbacks)
          throws IOException, UnsupportedCallbackException {
          for (Callback callback : callbacks) {
              if (callback instanceof WSPasswordCallback) {
                  WSPasswordCallback pc = (WSPasswordCallback) callback;
                  if (pc.getUsage() == WSPasswordCallback.SECRET_KEY
                      || pc.getUsage() == WSPasswordCallback.SECURITY_CONTEXT_TOKEN) {
                      byte[] secret = this.secrets.get(pc.getIdentifier());
                      if (secret == null) {
                          secret = outboundSecret;
                      }
                      pc.setKey(secret);
                      break;
                  }
              } else {
                  throw new UnsupportedCallbackException(callback, "Unrecognized Callback");
              }
          }
      }
  
      public void addSecretKey(String identifier, byte[] secretKey) {
          secrets.put(identifier, secretKey);
      }
  
      public void setOutboundSecret(byte[] secret) throws WSSecurityException {
          outboundSecret = secret;
          byte[] encodedBytes = KeyUtils.generateDigest(outboundSecret);
          String identifier = XMLUtils.encodeToString(encodedBytes);
          addSecretKey(identifier, outboundSecret);
      }
  }