/*****************************************************************
 *   Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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.apache.cayenne.modeler.util;

import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.Serializable;
import java.io.StringWriter;
import java.util.List;

import org.apache.cayenne.util.XMLEncoder;
import org.apache.cayenne.util.XMLSerializable;

/**
 * CayenneTransferable is a data holder of Cayenne object(s), like
 * Entities, Attributes, Relationships etc.
 */
public class CayenneTransferable implements Transferable {
    /**
     * Flavor used for copy-paste between Cayenne Modeler applications
     */
    public static final DataFlavor CAYENNE_FLAVOR = new DataFlavor(Serializable.class, "Cayenne Object");
    
    /**
     * Supported flavors
     */
    private static final DataFlavor[] FLAVORS = new DataFlavor[] { CAYENNE_FLAVOR, DataFlavor.stringFlavor };
    
    /**
     * Data in the buffer
     */
    private Object data;
    
    public CayenneTransferable(Object data) {
        this.data = data;
    }

    public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException,
            IOException {
        
        if (flavor == CAYENNE_FLAVOR) {
            return data;
        }
        else {
            StringWriter out = new StringWriter();
            XMLEncoder encoder = new XMLEncoder(new PrintWriter(out), "\t");
            encoder.println("<?xml version=\"1.0\" encoding=\"utf-8\"?>");
            
            if (data instanceof XMLSerializable) {
                ((XMLSerializable) data).encodeAsXML(encoder);
            }
            else if (data instanceof List) {
                for (Object o : (List) data) {
                    ((XMLSerializable) o).encodeAsXML(encoder);
                }
            }
            
            return out.toString();
        }
        
    }

    public DataFlavor[] getTransferDataFlavors() {
        return FLAVORS;
    }

    public boolean isDataFlavorSupported(DataFlavor flavor) {
        return flavor == CAYENNE_FLAVOR || flavor == DataFlavor.stringFlavor;
    }

}