package yarfraw.io;

 import java.io.File;

 import java.io.FileNotFoundException;

 import java.io.FileOutputStream;

 import java.io.OutputStream;

 import java.net.URI;

 import javax.xml.bind.JAXBContext;

 import javax.xml.bind.JAXBException;

 import javax.xml.bind.Marshaller;

 import javax.xml.bind.ValidationEventHandler;

 import org.apache.commons.io.IOUtils;

 import yarfraw.core.datamodel.ChannelFeed;

 import yarfraw.core.datamodel.FeedFormat;

 import yarfraw.core.datamodel.YarfrawException;

 import yarfraw.generated.rss20.elements.ObjectFactory;

 import yarfraw.generated.rss20.elements.TRss;

 import yarfraw.mapping.forward.impl.ToAtom10ChannelImpl;

 import yarfraw.mapping.forward.impl.ToRss10ChannelImpl;

 import yarfraw.mapping.forward.impl.ToRss20ChannelImpl;

 import yarfraw.utils.JAXBUtils;

 /**

  * Provides a set of function to facilitate writing to a feed.

  * <br/>

  * *Note* This class is not thread safe.

  * @author jliang

  *

  */

 public class FeedWriter extends AbstractBaseIO{

   private static final ObjectFactory RSS20_FACTORY = new ObjectFactory();

   public FeedWriter(File file, FeedFormat format){

     super(file, format);

   }

   public FeedWriter(String pathName, FeedFormat format){

     super(new File(pathName), format);

   }

   public FeedWriter(URI uri, FeedFormat format){

     super(new File(uri), format);

   }  

   public FeedWriter(File file){

     super(file);

   }

   public FeedWriter(String pathName){

     this(new File(pathName));

   }

   public FeedWriter(URI uri){

     this(new File(uri));

   }

   /**

    * Writes a channel to the feed file with a custom {@link ValidationEventHandler}

    * @param channel  a valid {@link yarfraw.core.datamodel.ChannelFeed}

    * @throws YarfrawException if write operation failed.

    */

   public void writeChannel(ChannelFeed channel) throws YarfrawException{

     writeChannel(channel, null);

   }

   /**

    * Writes a channel to the feed file with a custom {@link ValidationEventHandler}.

    *

    * @param format any valid {@link yarfraw.core.datamodel.FeedFormat}

    * @param channel  a valid {@link yarfraw.core.datamodel.ChannelFeed}

    * @param outputStream an {@link java.io.OutputStream}

    * @throws YarfrawException if write operation failed.

    */

   public static void writeChannel(FeedFormat format, ChannelFeed channel, OutputStream outputStream) throws YarfrawException{

     if(format == null || channel == null ||outputStream==null){

       throw new YarfrawException("format, channel, or outputStream is null");

     }

     try {

       Marshaller m = getMarshaller(format);

       m.marshal(getJaxbElementFromFormat(format, channel), outputStream);

     } catch (JAXBException e) {

       throw new YarfrawException("Unable to write channel", e);

     }

   }

    /**

    * Writes a channel to the feed file with a custom {@link ValidationEventHandler}.

    *

    * @param channel  a valid {@link yarfraw.core.datamodel.ChannelFeed}

    * @param validationEventHandler a custom {@link javax.xml.bind.ValidationEventHandler}

    * @throws YarfrawException if write operation failed.

    */

   public void writeChannel(ChannelFeed channel, ValidationEventHandler validationEventHandler) throws YarfrawException{

     FileOutputStream out = null;

     try {

       Marshaller m = getMarshaller(_format);

       if(validationEventHandler != null){

         m.setEventHandler(validationEventHandler);

       }

       out = new FileOutputStream(_file);

       m.marshal(getJaxbElementFromFormat(_format, channel), out);

     } catch (JAXBException e) {

       throw new YarfrawException("Unable to write channel", e);

     }

     catch (FileNotFoundException e) {

       throw new YarfrawException("Unable to write channel", e);

     }finally{

       IOUtils.closeQuietly(out);

     }

   }

   private static Object getJaxbElementFromFormat(FeedFormat format, ChannelFeed channel) throws YarfrawException{

     if(format == FeedFormat.RSS20){

       TRss rss = RSS20_FACTORY.createTRss();

       rss.setVersion(2.0d);

       rss.setChannel(ToRss20ChannelImpl.getInstance().execute(channel).getValue());

       return RSS20_FACTORY.createRss(rss);

     }else if(format == FeedFormat.RSS10){

       return ToRss10ChannelImpl.getInstance().execute(channel);

     }else if(format == FeedFormat.ATOM10){

       return ToAtom10ChannelImpl.getInstance().execute(channel);

     }else if(format == FeedFormat.ATOM03){

       throw new UnsupportedOperationException("Yarfraw does not support writting to Atom 0.3 format, use Atom 1.0 instead.");

     }else{

       throw new UnsupportedOperationException("Unknown Feed Format");

     }

   }

   private static Marshaller getMarshaller(FeedFormat format) throws JAXBException{

     JAXBContext context = JAXBUtils.getContext(format);

     Marshaller m = context.createMarshaller();

     m.setProperty(JAXBUtils.PREFIX_MAPPER_PROPERTY_NAME, JAXBUtils.getNamespacePrefixMapper(format));

     return m;

   }

 }