/*
    * Copyright 2016 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.fhir.datamodel;
  
  import ca.uhn.fhir.context.FhirContext;
  import ca.uhn.fhir.parser.IParser;
  import org.apache.camel.Exchange;
  import org.apache.camel.spi.DataFormat;
  import org.apache.camel.util.ExchangeHelper;
  import org.hl7.fhir.instance.model.api.IBaseResource;
  import org.openehealth.ipf.commons.ihe.fhir.Constants;
  
  import java.io.*;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  
  /**
   *
   */
  abstract class FhirDataFormat implements DataFormat {
  
      private FhirContext defaultFhirContext = FhirContext.forDstu3();
      private Charset defaultCharset = StandardCharsets.UTF_8;
  
      public void setDefaultFhirContext(FhirContext context) {
          defaultFhirContext = context;
      }
  
      public void setDefaultCharset(String charset) {
          defaultCharset = Charset.forName(charset);
      }
  
      @Override
      public void marshal(Exchange exchange, Object body, OutputStream stream) throws Exception {
          IBaseResource resource = ExchangeHelper.convertToMandatoryType(exchange, IBaseResource.class, body);
          Writer writer = new OutputStreamWriter(stream, getCharset(exchange));
          getParser(getFhirContext(exchange))
                  .setPrettyPrint(true)
                  .encodeResourceToWriter(resource, writer);
      }
  
      @Override
      public Object unmarshal(Exchange exchange, InputStream stream) throws Exception {
          Reader reader = new InputStreamReader(stream, getCharset(exchange));
          return getParser(getFhirContext(exchange)).parseResource(reader);
      }
  
      protected FhirContext getFhirContext(Exchange exchange) {
          FhirContext context = exchange.getIn().getHeader(Constants.FHIR_CONTEXT, FhirContext.class);
          if (context == null) context = defaultFhirContext;
          return context;
      }
  
      protected Charset getCharset(Exchange exchange) {
          Charset charset = defaultCharset;
          String charsetName = exchange.getProperty(Exchange.CHARSET_NAME, String.class);
          if (charsetName != null) charset = Charset.forName(charsetName);
          return charset;
      }
  
      protected abstract IParser getParser(FhirContext context);
  }