/*
    * Copyright 2009 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.hl7v2.intercept.consumer;
  
  import ca.uhn.hl7v2.AcknowledgmentCode;
  import ca.uhn.hl7v2.HL7Exception;
  import ca.uhn.hl7v2.model.Message;
  import org.apache.camel.Exchange;
  import org.apache.commons.lang3.ClassUtils;
  import org.openehealth.ipf.commons.ihe.hl7v2.Constants;
  import org.openehealth.ipf.platform.camel.core.util.Exchanges;
  import org.openehealth.ipf.platform.camel.ihe.core.InterceptorSupport;
  import org.openehealth.ipf.platform.camel.ihe.hl7v2.HL7v2Endpoint;
  import org.openehealth.ipf.platform.camel.ihe.hl7v2.Hl7v2AdaptingException;
  import org.openehealth.ipf.platform.camel.ihe.hl7v2.Hl7v2MarshalUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  
  import static org.openehealth.ipf.platform.camel.core.util.Exchanges.resultMessage;
  
  
  /**
   * Consumer-side Camel interceptor which creates a {@link Message}
   * from various possible response types.
   *
   * @author Dmytro Rud
   */
  public class ConsumerAdaptingInterceptor extends InterceptorSupport<HL7v2Endpoint> {
      private static final transient Logger LOG = LoggerFactory.getLogger(ConsumerAdaptingInterceptor.class);
      public static final String ACK_TYPE_CODE_HEADER = "ipf.hl7v2.AckTypeCode";
  
      private final String charsetName;
  
  
      /**
       * Constructor which enforces the use of a particular character set.
       * The given value will be propagated to the Camel exchange property
       * {@link Exchange#CHARSET_NAME}, rewriting its old content.
       *
       * @param charsetName
       *      character set to use in all data transformations.
       */
      public ConsumerAdaptingInterceptor(String charsetName) {
          super();
          this.charsetName = charsetName;
      }
  
  
      /**
       * Constructor which does not enforce the use of a particular character set.
       * When the Camel exchange does not contain property {@link Exchange#CHARSET_NAME},
       * the default system character set will be used.
       */
      public ConsumerAdaptingInterceptor() {
          this(null);
      }
  
      
      /**
       * Converts response to a {@link Message}, throws
       * a {@link org.openehealth.ipf.platform.camel.ihe.hl7v2.Hl7v2AdaptingException} on failure.
       */
      @Override
      public void process(Exchange exchange) throws Exception {
          Message originalMessage = exchange.getIn().getHeader(Constants.ORIGINAL_MESSAGE_ADAPTER_HEADER_NAME, Message.class);
  
          // run the route
          try {
              getWrappedProcessor().process(exchange);
              Exception exception = Exchanges.extractException(exchange);
              if (exception != null) {
                  throw exception;
              }
          } catch (Exception e) {
              LOG.warn("Message processing failed", e);
              resultMessage(exchange).setBody(getEndpoint().getNakFactory().createNak(originalMessage, e));
          }
  
          org.apache.camel.Message m = Exchanges.resultMessage(exchange);
          Object body = m.getBody();
  
          // try to convert route response from a known type
          if (charsetName != null) {
              exchange.setProperty(Exchange.CHARSET_NAME, charsetName);
         }
         Message msg = Hl7v2MarshalUtils.extractHapiMessage(
                 m,
                 characterSet(exchange),
                 getEndpoint().getHl7v2TransactionConfiguration().getParser());
         
         // additionally: an Exception in the body?
         if((msg == null) && (body instanceof Throwable)) {
            msg = getEndpoint().getNakFactory().createNak(originalMessage, (Throwable) body);
         }
         
         // no known data type --> determine user's intention on the basis of a header 
         if(msg == null) {
             msg = analyseMagicHeader(m, originalMessage);
         }
 
         // unable to create a Message :-(
         if(msg == null) {
             throw new Hl7v2AdaptingException("Cannot create HL7v2 message from " +
                     ClassUtils.getSimpleName(body, "<null>") +
                     " returned from the route");
         }
         
         m.setBody(msg);
     }
 
 
     /**
      * Considers a specific header to determine whether the route author want us to generate
      * an automatic acknowledgment, and generates the latter when the author really does.   
      */
     @SuppressWarnings("rawtypes")
     private Message analyseMagicHeader(org.apache.camel.Message m, Message originalMessage) throws HL7Exception, IOException {
         Object header = m.getHeader(ACK_TYPE_CODE_HEADER);
         if ((header == null) || ! (header instanceof AcknowledgmentCode)) {
             return null;
         }
 
         Message ack;
         if ((header == AcknowledgmentCode.AA) || (header == AcknowledgmentCode.CA)) {
             ack = getEndpoint().getNakFactory().createAck(
                     originalMessage);
         } else {
             HL7Exception exception = new HL7Exception(
                     "HL7v2 processing failed",
                     getEndpoint().getHl7v2TransactionConfiguration().getResponseErrorDefaultErrorCode());
             ack = getEndpoint().getNakFactory().createNak(
                     originalMessage,
                     exception, 
                     (AcknowledgmentCode) header);
         }
         return ack;
     }
 
 }