package won.protocol.rest;

import org.apache.jena.query.Dataset;
import org.apache.jena.riot.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.util.StopWatch;
import won.protocol.util.RdfUtils;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

/**
 * User: fsalcher
 * Date: 15.09.2014
 */
public class RdfDatasetConverter extends AbstractHttpMessageConverter<Dataset>
{
  private static final Logger logger = LoggerFactory.getLogger(RdfDatasetConverter.class);

  private static final MediaType[] supportedMediaTypes =  {
    RDFMediaType.APPLICATION_TRIG,
    RDFMediaType.APPLICATION_JSONLD,
    RDFMediaType.APPLICATION_NQUADS
  };

  public RdfDatasetConverter() {
    this(supportedMediaTypes);
  }

  public RdfDatasetConverter(MediaType supportedMediaType) {
    super(supportedMediaType);
  }

  public RdfDatasetConverter(MediaType... supportedMediaTypes) {
    super(supportedMediaTypes);
  }

  @Override
  protected boolean supports(Class<?> clazz) {
    return Dataset.class.isAssignableFrom(clazz);
  }

  @Override
  protected Dataset readInternal(Class<? extends Dataset> aClass, HttpInputMessage httpInputMessage) throws IOException,
    HttpMessageNotReadableException {
    Lang rdfLanguage = mimeTypeToJenaLanguage(httpInputMessage.getHeaders().getContentType(), Lang.TRIG);

    return RdfUtils.toDataset(httpInputMessage.getBody(), new RDFFormat(rdfLanguage));
  }

  @Override
  protected void writeInternal(Dataset dataset, HttpOutputMessage httpOutputMessage) throws IOException,
    HttpMessageNotWritableException {
    StopWatch stopWatch = new StopWatch();
    stopWatch.start();
    MediaType contentType = httpOutputMessage.getHeaders().getContentType();
    Lang rdfLanguage = mimeTypeToJenaLanguage(contentType, Lang.TRIG);
    WonEtagHelper.setMediaTypeForEtagHeaderIfPresent(contentType, httpOutputMessage.getHeaders());
    RDFDataMgr.write(httpOutputMessage.getBody(), dataset, rdfLanguage);
    //append content type to ETAG header to avoid confusing different representations of the same resource
    httpOutputMessage.getBody().flush();
    stopWatch.stop();
    logger.debug("writing dataset took " + stopWatch.getLastTaskTimeMillis() + " millls");
  }

  private static Lang mimeTypeToJenaLanguage(MediaType mediaType, Lang defaultLanguage) {
    Lang lang = RDFLanguages.contentTypeToLang(mediaType.toString());
    if (lang == null) return defaultLanguage;
    return lang;
  }

  public List<MediaType> getSupportedMediaTypes(){
      return Arrays.asList(supportedMediaTypes);
  }
}