/*******************************************************************************
 * Copyright (c) 2004 Peter Nehrer and Composent, Inc.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     Peter Nehrer - initial API and implementation
 *******************************************************************************/
package org.eclipse.ecf.sdo.emf;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

import org.eclipse.ecf.core.util.ECFException;
import org.eclipse.ecf.sdo.ISharedDataGraph;
import org.eclipse.ecf.sdo.IUpdateProvider;
import org.eclipse.ecf.sdo.SDOPlugin;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.sdo.EChangeSummary;
import org.eclipse.emf.ecore.sdo.EDataGraph;
import org.eclipse.emf.ecore.sdo.util.SDOUtil;

import commonj.sdo.DataGraph;

/**
 * Update provider capable of handling EMF-based SDO data graphs.
 * 
 * @author pnehrer
 */
public class EMFUpdateProvider implements IUpdateProvider {

    public static final String TRACE_TAG = "EMFUpdateProvider";

    private EDataGraph clone(EDataGraph source) throws IOException {
        ByteArrayOutputStream buf = new ByteArrayOutputStream();
        source.getDataGraphResource().save(buf, null);
        return SDOUtil.loadDataGraph(
                new ByteArrayInputStream(buf.toByteArray()), null);
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.eclipse.ecf.sdo.IUpdateProvider#createUpdate(org.eclipse.ecf.sdo.ISharedDataGraph)
     */
    public byte[] createUpdate(ISharedDataGraph graph) throws ECFException {
        EDataGraph clone;
        try {
            clone = clone((EDataGraph) graph.getDataGraph());
        } catch (IOException e) {
            throw new ECFException(e);
        }

        EChangeSummary changes = (EChangeSummary) clone.getChangeSummary();
        changes.applyAndReverse();

        ByteArrayOutputStream buf = new ByteArrayOutputStream();
        try {
            changes.eResource().save(buf, null);
            if (SDOPlugin.isTracing(TRACE_TAG)) {
                SDOPlugin.getTraceLog().println("commit:");
                changes.eResource().save(SDOPlugin.getTraceLog(), null);
            }
        } catch (IOException e) {
            throw new ECFException(e);
        }

        return buf.toByteArray();
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.eclipse.ecf.sdo.IUpdateProvider#applyUpdate(org.eclipse.ecf.sdo.ISharedDataGraph,
     *      byte[])
     */
    public void applyUpdate(ISharedDataGraph graph, Object data)
            throws ECFException {
        EDataGraph dataGraph = (EDataGraph) graph.getDataGraph();
        EChangeSummary changeSummary = (EChangeSummary) dataGraph
                .getChangeSummary();
        changeSummary.endLogging();
        // throw away any local changes
        changeSummary.apply();

        Resource res = changeSummary.eResource();
        res.unload();

        // apply changes from the event
        try {
            res.load(new ByteArrayInputStream((byte[]) data), null);
            if (SDOPlugin.isTracing(TRACE_TAG)) {
                SDOPlugin.getTraceLog().println("processUpdate:");
                res.save(SDOPlugin.getTraceLog(), null);
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        changeSummary = (EChangeSummary) res.getContents().get(0);
        dataGraph.setEChangeSummary(changeSummary);
        // leave a change summary showing what has changed
        changeSummary.applyAndReverse();
        changeSummary.resumeLogging();
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.eclipse.ecf.sdo.IUpdateProvider#serializeDataGraph(commonj.sdo.DataGraph)
     */
    public Object serializeDataGraph(DataGraph dataGraph) throws IOException {
        EDataGraph clone = clone((EDataGraph) dataGraph);
        EChangeSummary changeSummary = clone.getEChangeSummary();
        if (changeSummary != null)
            changeSummary.apply();

        ByteArrayOutputStream buf = new ByteArrayOutputStream();
        clone.getDataGraphResource().save(buf, null);
        return buf.toByteArray();
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.eclipse.ecf.sdo.IUpdateProvider#deserializeDataGraph(Object)
     */
    public DataGraph deserializeDataGraph(Object data) throws IOException,
            ClassNotFoundException {
        return SDOUtil.loadDataGraph(new ByteArrayInputStream((byte[]) data),
                null);
    }
}