/**
    * 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.message;
  
  import javax.security.auth.callback.Callback;
  import javax.security.auth.callback.CallbackHandler;
  import javax.security.auth.callback.UnsupportedCallbackException;
  
  import org.apache.wss4j.common.ext.Attachment;
  import org.apache.wss4j.common.ext.AttachmentRequestCallback;
  import org.apache.wss4j.common.ext.AttachmentResultCallback;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  /**
   * A Callback Handler implementation for the case of signing/encrypting Attachments via the SwA
   * (SOAP with Attachments) specification or when using xop:Include in the case of MTOM.
   */
  public class AttachmentCallbackHandler implements CallbackHandler {
  
      private final List<Attachment> originalRequestAttachments;
      private Map<String, Attachment> attachmentMap = new HashMap<>();
      private List<Attachment> responseAttachments = new ArrayList<>();
  
      public AttachmentCallbackHandler() {
          originalRequestAttachments = Collections.emptyList();
      }
  
      public AttachmentCallbackHandler(List<Attachment> attachments) {
          originalRequestAttachments = attachments;
          if (attachments != null) {
              for (Attachment attachment : attachments) {
                  attachmentMap.put(attachment.getId(), attachment);
              }
          }
      }
  
      public void handle(Callback[] callbacks)
          throws IOException, UnsupportedCallbackException {
          for (Callback callback : callbacks) {
              if (callback instanceof AttachmentRequestCallback) {
                  AttachmentRequestCallback attachmentRequestCallback =
                      (AttachmentRequestCallback) callback;
  
                  List<Attachment> attachments =
                      getAttachmentsToAdd(attachmentRequestCallback.getAttachmentId());
                  if (attachments.isEmpty()) {
                      throw new RuntimeException("wrong attachment requested");
                  }
  
                  attachmentRequestCallback.setAttachments(attachments);
              } else if (callback instanceof AttachmentResultCallback) {
                  AttachmentResultCallback attachmentResultCallback =
                      (AttachmentResultCallback) callback;
                  responseAttachments.add(attachmentResultCallback.getAttachment());
                  attachmentMap.put(attachmentResultCallback.getAttachment().getId(),
                                    attachmentResultCallback.getAttachment());
              } else {
                  throw new UnsupportedCallbackException(callback, "Unrecognized Callback");
              }
          }
      }
  
      public List<Attachment> getResponseAttachments() {
          return responseAttachments;
      }
  
      // Try to match the Attachment Id. Otherwise, add all Attachments.
      private List<Attachment> getAttachmentsToAdd(String id) {
          List<Attachment> attachments = new ArrayList<>();
          if (attachmentMap.containsKey(id)) {
              attachments.add(attachmentMap.get(id));
          } else {
              if (originalRequestAttachments != null) {
                  attachments.addAll(originalRequestAttachments);
              }
          }
 
         return attachments;
     }
 
 }