/*
    * Copyright 2010 the original author or authors.
    * 
    * Licensed 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.openehealth.ipf.platform.camel.ihe.ws;
  
  import java.util.HashMap;
  import java.util.Map;
  import javax.xml.ws.handler.MessageContext;
  
  import org.apache.camel.Exchange;
  import org.apache.camel.ExchangePattern;
  import org.apache.cxf.jaxws.context.WebServiceContextImpl;
  import org.apache.cxf.ws.addressing.AddressingProperties;
  import org.apache.cxf.ws.addressing.JAXWSAConstants;
  import org.openehealth.ipf.commons.ihe.ws.correlation.AsynchronyCorrelator;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Base class for receivers of asynchronous responses for Web Service-based IHE transactions.
   * @author Dmytro Rud
   */
  abstract public class AbstractAsyncResponseWebService extends AbstractWebService {
      private static final transient Logger LOG = LoggerFactory.getLogger(AbstractAsyncResponseWebService.class);
  
      /**
       * Determines whether correlation items related to the given message can be dropped.
       * <p>
       * Per default, always returns <code>true</code>.
       * @param response
       *      response message.
       * @return
       *      <code>true</code> when correlation items related
       *      to the given message can be dropped.
       */
      protected boolean canDropCorrelation(Object response) {
          return true;
      }
  
  
      /**
       * Before calling the base method, determines correlation key  
       * and stores it into message headers. 
       */
      @SuppressWarnings("unchecked")
      @Override
      protected Exchange process(
              Object body, 
              Map<String, Object> headers,
              ExchangePattern exchangePattern) 
      {
          final AsynchronyCorrelator correlator = getConsumer().getEndpoint().getCorrelator();
  
          MessageContext messageContext = new WebServiceContextImpl().getMessageContext();
          AddressingProperties apropos = (AddressingProperties) messageContext.get(JAXWSAConstants.ADDRESSING_PROPERTIES_INBOUND);
          String messageId = ((apropos != null) && (apropos.getRelatesTo() != null))
                  ? apropos.getRelatesTo().getValue()
                  : null;
  
          // when no ReplyTo header found -- try alternative keys
          if (messageId == null) {
              String[] alternativeKeys = getAlternativeResponseKeys(body);
              if (alternativeKeys != null) {
                  for (String key : alternativeKeys) {
                      messageId = correlator.getMessageId(key);
                      if (messageId != null) {
                          break;
                      }
                  }
              }
          }
  
          if (messageId != null) {
              // expose user-defined correlation key as message header
              String correlationKey = correlator.getCorrelationKey(messageId);
              if (correlationKey != null) {
                  if (headers == null) {
                      // NB: it shouldn't be a non-modifiable singleton map...
                      headers = new HashMap<>();
                  }
                  headers.put(AbstractWsEndpoint.CORRELATION_KEY_HEADER_NAME, correlationKey);
              }
  
              // drop correlation data when appropriate
              if (canDropCorrelation(body)) {
                  correlator.delete(messageId);
              }
         } else {
             LOG.error("Cannot retrieve WSA RelatesTo header, message correlation not possible");
         }
 
         return super.process(body, headers, exchangePattern);
     }
 
 
     /**
      * Determines the set of correlation keys for the given response message,
      * which are alternative to the WS-Addressing message ID referenced in the
      * &lt;ReplyTo&gt; header.
      * An example of alternative key is the query ID in HL7v3-based transactions.
      * <p>
      * Per default, this method returns <code>null</code>.
      *
      * @param response
      *      response message.
      * @return
      *      A non-empty collection of non-<code>null</code> alternative keys,
      *      or <code>null</code>, when no keys could have been extracted.
      */
     protected String[] getAlternativeResponseKeys(Object response) {
         return null;
     }
 }