/*
    * Copyright 2011 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.hl7v2ws;
  
  import java.io.IOException;
  
  import ca.uhn.hl7v2.AcknowledgmentCode;
  import ca.uhn.hl7v2.HL7Exception;
  import ca.uhn.hl7v2.model.Message;
  import org.apache.camel.Exchange;
  import org.openehealth.ipf.commons.ihe.hl7v2.Hl7v2TransactionConfiguration;
  import org.openehealth.ipf.commons.ihe.hl7v2.NakFactory;
  import org.openehealth.ipf.modules.hl7.message.MessageUtils;
  import org.openehealth.ipf.platform.camel.core.util.Exchanges;
  import org.openehealth.ipf.platform.camel.ihe.hl7v2.Hl7v2ConfigurationHolder;
  import org.openehealth.ipf.platform.camel.ihe.hl7v2.Hl7v2MarshalUtils;
  import org.openehealth.ipf.platform.camel.ihe.ws.AbstractWebService;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static org.apache.commons.lang3.StringUtils.trimToEmpty;
  import static org.openehealth.ipf.commons.ihe.hl7v2ws.Utils.render;
  import static org.openehealth.ipf.platform.camel.core.util.Exchanges.resultMessage;
  
  /**
   * Generic implementation of an HL7v2-based Web Service.
   * 
   * @author Dmytro Rud
   * @author Mitko Kolev
   * @author Stefan Ivanov
   */
  public abstract class AbstractHl7v2WebService extends AbstractWebService {
      private static final Logger LOG = LoggerFactory.getLogger(AbstractHl7v2WebService.class);
  
      private Hl7v2TransactionConfiguration config = null;
      private NakFactory nakFactory = null;
  
  
      /**
       * Configures HL7v2-related parameters of this Web Service.
       * This method is supposed to be called only once, directly after
       * an instance of this class has been created.  In other words,
       * this is a kind of "post-constructor".
       *
       * @param configurationHolder
       *      source of HL7v2-related configuration parameters.
       */
      void setHl7v2Configuration(Hl7v2ConfigurationHolder configurationHolder) {
          if ((this.config != null) || (this.nakFactory != null)) {
              throw new IllegalStateException("multiple calls to this method are not allowed");
          }
  
          this.config = configurationHolder.getHl7v2TransactionConfiguration();
          this.nakFactory = configurationHolder.getNakFactory();
      }
  
  
      protected String doProcess(String request) {
          // parse request
          Message msg;
          try {
              msg = config.getParser().parse(trimToEmpty(request).replaceAll("\n", "\r\n"));
              config.checkRequestAcceptance(msg);
          } catch (HL7Exception e) {
              LOG.error(formatErrMsg("Request not acceptable"), e);
              return render(nakFactory.createDefaultNak(e));
          }
  
          Message originalRequest = MessageUtils.copy(msg);
  
          // play the route, handle its outcomes and check response acceptance
          try {
              Exchange exchange = super.process(msg);
              Exception exception = Exchanges.extractException(exchange);
              if (exception != null) {
                  throw exception;
              }
  
              // check response existence and acceptance
              if ((msg = Hl7v2MarshalUtils.extractHapiMessage(
                      resultMessage(exchange),
                      exchange.getProperty(Exchange.CHARSET_NAME, String.class),
                      config.getParser())) != null) {
                  config.checkResponseAcceptance(msg);
                  return render(msg);
              } else {
                 throw new Exception("Could not extract HAPI message object from exchange");
             }
 
         } catch (Exception e) {
             LOG.error(formatErrMsg("Message processing failed, response missing or not acceptable"), e);
             try {
                 return render(nakFactory.createNak(originalRequest, e));
             } catch (HL7Exception e1) {
                 return render(MessageUtils.defaultNak(e1, AcknowledgmentCode.AE, msg.getVersion()));
             } catch (IOException e2) {
                 return render(MessageUtils.defaultNak(new HL7Exception(e2), AcknowledgmentCode.AE, msg.getVersion()));
             }
         }
     }
 
 
     /**
      * Creates a message from the input <code>text</code >with prefix the sending
      * application in the transaction configuration.
      * 
      * @param text
      *            input text used for logging
      * @return a String with prefix the sending application
      */
     protected String formatErrMsg(String text) {
         return config.getSendingApplication() + ": " + text;
     }
     
 }