EDIT

/**

* Copyright (C) 2007 EDIT

* European Distributed Institute of Taxonomy 

* http://www.e-taxonomy.eu

* 

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.taxeditor.editor;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.DataInputStream;

import java.io.DataOutputStream;

import java.io.EOFException;

import java.io.IOException;

import java.util.ArrayList;

import java.util.List;

import java.util.UUID;

import org.apache.log4j.Logger;

import org.eclipse.swt.dnd.ByteArrayTransfer;

import org.eclipse.swt.dnd.TransferData;

import eu.etaxonomy.cdm.api.service.ITaxonService;

import eu.etaxonomy.cdm.model.common.ICdmBase;

import eu.etaxonomy.cdm.model.taxon.Synonym;

import eu.etaxonomy.cdm.model.taxon.Taxon;

import eu.etaxonomy.taxeditor.store.CdmStore;

/**

 * <p>CdmDataTransfer class.</p>

 *

 * @author n.hoffmann

 * @created Jun 18, 2010

 * @version 1.0

 */

public class CdmDataTransfer extends ByteArrayTransfer {

	private static final Logger logger = Logger

			.getLogger(CdmDataTransfer.class);

	private static int SEPARATOR = -10;

	private static int EOF = -20;

	private static final String TYPE_NAME = "cdmdata-transfer-format"; //$NON-NLS-1$

	private static final int TYPE_ID = registerType (TYPE_NAME);		

	private static final CdmDataTransfer instance = new CdmDataTransfer();

	/**

	 * <p>Getter for the field <code>instance</code>.</p>

	 *

	 * @return a {@link eu.etaxonomy.taxeditor.editor.CdmDataTransfer} object.

	 */

	public static synchronized CdmDataTransfer getInstance() {

		return instance;

	}

	private ICdmBase cdmBase;

	/* (non-Javadoc)

	 * @see org.eclipse.swt.dnd.Transfer#getTypeIds()

	 */

	/** {@inheritDoc} */

	@Override

	protected int[] getTypeIds() {

		return new int[] { TYPE_ID }; 

	}

	/* (non-Javadoc)

	 * @see org.eclipse.swt.dnd.Transfer#getTypeNames()

	 */

	/** {@inheritDoc} */

	@Override

	protected String[] getTypeNames() {

		return new String[]{ TYPE_NAME };

	}

	/** {@inheritDoc} */

	@Override

	protected void javaToNative(Object object, TransferData transferData) {

		byte[] bytes = toByteArray((ICdmBase[]) object);

		if (bytes != null)

			super.javaToNative(bytes, transferData);

	}

	/** {@inheritDoc} */

	@Override

	protected Object nativeToJava(TransferData transferData) {

		byte[] bytes = (byte[]) super.nativeToJava(transferData);

		return fromByteArray(bytes);

	}

	private byte[] toByteArray(ICdmBase[] cdmBaseObjects) {

		/**

		 * Transfer data is an array of gadgets. Serialized version is: (int)

		 * number of gadgets (Gadget) gadget 1 (Gadget) gadget 2 ... repeat for

		 * each subsequent gadget see writeGadget for the (Gadget) format.

		 */

		ByteArrayOutputStream byteOut = new ByteArrayOutputStream();

		DataOutputStream out = new DataOutputStream(byteOut);

		byte[] bytes = null;

		try {

			for(ICdmBase cdmBaseObject : cdmBaseObjects){

				writeCdmBaseObject(cdmBaseObject, out);

			}

			out.close();

			bytes = byteOut.toByteArray();

		} catch (IOException e) {

			// when in doubt send nothing

		}

		return bytes;

	}

	private ICdmBase[] fromByteArray(byte[] bytes) {

		DataInputStream in = new DataInputStream(new ByteArrayInputStream(bytes));

		try {

			List<ICdmBase> cdmBaseObjects = new ArrayList<ICdmBase>();

			try{

				while(true){

					cdmBaseObjects.add(readCdmBaseObject(in));

				}

			}catch(EOFException e){

				return cdmBaseObjects.toArray(new ICdmBase[]{});

			}

		} catch (IOException e) {

			return null;

		}

	}

	private ICdmBase readCdmBaseObject(DataInputStream in) throws IOException{

		String className = in.readUTF();

		in.readInt();

		String idString = in.readUTF();

		in.readInt();

		if(className.equals(Synonym.class.getName()) || className.equals(Taxon.class.getName())){

			ICdmBase object = CdmStore.getService(ITaxonService.class).load(UUID.fromString(idString));

			if(object == null){

				return cdmBase;

			}

			return object;

		}

		return null;

	}

	private void writeCdmBaseObject(ICdmBase cdmBase, DataOutputStream out) throws IOException{

		/**

		 * CdmBase object serialization:

		 * 

		 */

		out.writeUTF(cdmBase.getClass().getName());

		out.writeInt(SEPARATOR);

		out.writeUTF(cdmBase.getUuid().toString());

		out.writeInt(EOF);

		if(cdmBase.getId() == 0){

			// fallback for unsaved instances

			this.cdmBase = cdmBase;

		}

	}

}