package com.c2kernel.utils;

//Java
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.net.URL;
import java.util.HashSet;
import java.util.StringTokenizer;

import org.exolab.castor.mapping.Mapping;
import org.exolab.castor.mapping.MappingException;
import org.exolab.castor.xml.MarshalException;
import org.exolab.castor.xml.Marshaller;
import org.exolab.castor.xml.Unmarshaller;
import org.exolab.castor.xml.ValidationException;

import com.c2kernel.common.InvalidDataException;
import com.c2kernel.persistency.outcome.Outcome;


/**************************************************************************
 * Loads all mapfiles, and wraps marshalling/unmarshalling
 *
 * @author $Author: abranson $ $Date: 2004/10/20 14:10:21 $
 * @version $Revision: 1.12 $
 **************************************************************************/
public class CastorXMLUtility
{
    private final Mapping mMapping     = new Mapping();
    private final HashSet<URL> mMappingKeys = new HashSet<URL>();
    
    /**
     * Looks for a file called 'index.xml' at the given URL, and loads every file
     * listed in there by relative path
     *
     * @param mapURL - map root
     */    
    public CastorXMLUtility(URL mapURL) throws InvalidDataException {
        // load index
        Logger.msg(3, "Loading maps from "+mapURL);
        String index;
        try {
            index = FileStringUtility.url2String( new URL(mapURL, "index") );
        } catch (Exception e) {
            Logger.warning("Could not load map index from "+mapURL.toString());
            return;
        }

        StringTokenizer sTokenizer = new StringTokenizer(index);
        while( sTokenizer.hasMoreTokens() ) {
            String thisMap = sTokenizer.nextToken();
            try {
                addMapping( new URL(mapURL, thisMap));
            } catch (Exception e) {
                Logger.error(e);
                throw new InvalidDataException("Error loading map '"+thisMap+"'", "");
            }
        }
        
        // Test the maps now, instead of on first use.
        
        try {
        	new Unmarshaller( mMapping );
        } catch (MappingException e) {
        	Logger.error(e);
        	throw new InvalidDataException("Castor mapfiles are not valid", "");
        }
        Logger.msg(1, "Loaded all maps from "+mapURL.toString());
    }


   /**************************************************************************
    * Updates a mapping referenced by the mapID.
    * The same mapping cannot be loaded many times as it generates an exception.
    * That is the reason for this method as it maintains the HashSet of MappingKeys.
    **************************************************************************/
    private void addMapping( URL mapID )
        throws IOException,
               MappingException,
               MarshalException,
               ValidationException
    {

        if( !mMappingKeys.contains(mapID) )
        {
            Logger.msg(7, "Added mapping file:"+mapID);

            mMapping.loadMapping( mapID );
            mMappingKeys.add( mapID );
        }
        else
        {
            Logger.msg(1, "Map file already loaded:"+mapID);
        }
    }

   /**************************************************************************
    * Marshalls a mapped object to string. The mapping must be loaded before.
    * See updateMapping().
    **************************************************************************/
    public String marshall( Object obj )
        throws IOException,
               MappingException,
               MarshalException,
               ValidationException
    {
        if (obj == null) return "<NULL/>";
        if (obj instanceof Outcome)
            return ((Outcome)obj).getData();
        StringWriter sWriter    = new StringWriter();
        Marshaller   marshaller = new Marshaller( sWriter );

        marshaller.setMapping( mMapping );
        marshaller.setMarshalAsDocument( false );
        marshaller.marshal( obj );

        return sWriter.toString();
    }

   /**************************************************************************
    * Unmarshalls a mapped object from string. The mapping must be loaded before.
    * See updateMapping().
    **************************************************************************/
    public Object unmarshall( String data )
        throws IOException,
               MappingException,
               MarshalException,
               ValidationException
    {
        StringReader sReader      = new StringReader( data );
        Unmarshaller unmarshaller = new Unmarshaller( mMapping );
        if (data.equals("<NULL/>")) return null;
        return unmarshaller.unmarshal( sReader );
    }
}