/*
    * Copyright 2014 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.hl7.adapter;
  
  import ca.uhn.hl7v2.HL7Exception;
  import ca.uhn.hl7v2.HapiContext;
  import ca.uhn.hl7v2.model.Message;
  import ca.uhn.hl7v2.parser.GenericParser;
  import ca.uhn.hl7v2.parser.Parser;
  import org.apache.camel.Exchange;
  import org.openehealth.ipf.platform.camel.core.adapter.ProcessorAdapter;
  import org.openehealth.ipf.platform.camel.core.util.Exchanges;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   *
   */
  public abstract class HapiAdapter extends ProcessorAdapter {
  
      private static final Parser FALLBACK = new GenericParser();
  
      @Override
      protected void doProcess(Exchange exchange, Object inputData, Object... inputParams) throws Exception {
          Message message = toMessage(inputData, exchange);
          Message result = doProcessMessage(
                  message,
                  exchange.getProperty(Exchange.EXCEPTION_CAUGHT, Throwable.class),
                  inputParams);
          Exchanges.prepareResult(exchange).setBody(result);
      }
  
      protected abstract Message doProcessMessage(Message message, Throwable t, Object... inputParams);
  
      private static Message toMessage(Object inputData, Exchange exchange) throws HL7Exception {
          Message message;
          if (inputData instanceof Message) {
              message = (Message)inputData;
          } else if (inputData instanceof String) {
              HapiContext context = exchange.getIn().getHeader("CamelHL7Context", HapiContext.class);
              Parser parser = context != null ? context.getGenericParser() : FALLBACK;
              message = parser.parse((String)inputData);
          } else {
              // try type conversion
              message = exchange.getIn().getBody(Message.class);
          }
          requireNonNull(message, "Exchange does not contain or can be converted to the required 'ca.uhn.hl7v2.model.Message' type");
          return message;
      }
  }