org.eclipse.osbp.runtime.memento/src/org/eclipse/osbp/runtime/memento/MementoManager.java

/**
 *                                                                            
 *  Copyright (c) 2011, 2016 - Loetz GmbH&Co.KG (69115 Heidelberg, Germany) 
 *                                                                            
 *  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:                                                      
 * 	   Christophe Loetz (Loetz GmbH&Co.KG) - initial implementation
 * 
 */
 package org.eclipse.osbp.runtime.memento;

import java.io.File;
import java.io.IOException;
import java.nio.file.Path;
import java.util.ArrayList;

import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.ecore.resource.impl.ResourceSetImpl;
import org.eclipse.osbp.runtime.common.memento.IMementoManager;
import org.eclipse.osbp.runtime.common.validation.IStatus;
import org.eclipse.osbp.runtime.common.validation.Status;
import org.osgi.service.component.ComponentContext;
import org.osgi.service.component.annotations.Activate;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Deactivate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Component(immediate = true)
public class MementoManager implements IMementoManager {

	private static final Logger LOGGER = LoggerFactory
			.getLogger(MementoManager.class);

	private ResourceSet rs;
	private Path basePath;

	@Override
	public Object loadMemento(String userId, String mementoId) {

		URI uri = createURI(userId, mementoId);
		File file = new File(uri.toFileString());
		if (!file.exists()) {
			LOGGER.debug("Memento does not exists: " + uri.toFileString());
			return null;
		}

		Resource resource = rs.getResource(createURI(userId, mementoId), true);
		return resource.getContents().size() > 0 ? resource.getContents()
				.get(0) : null;
	}

	@Override
	public IStatus saveMemento(String userId, String mementoId, Object memento) {
		try {
			URI uri = createURI(userId, mementoId);

			Resource resource = null;
			try {
				resource = rs.getResource(uri, true);
			} catch (Exception ex) {
				LOGGER.debug("Resource not available yet. A new one is created. URI = "
						+ uri);
			}

			if (resource == null) {
				resource = rs.getResource(uri, false);
			}

			resource.getContents().clear();
			resource.getContents().add((EObject) memento);
			resource.save(null);
		} catch (IOException e) {
			return Status.createErrorStatus(e);
		}

		return IStatus.OK;
	}

	protected URI createURI(String userId, String mementoId) {
		URI result = URI.createFileURI(basePath.toString());
		result = result.appendSegment(userId);
		result = result.appendSegment(mementoId);
		result = result.appendFileExtension("memento");
		return result;
	}

	@Activate
	protected void activate(ComponentContext context) {
		rs = new ResourceSetImpl();

		File baseFolder = context.getBundleContext().getDataFile("");
		basePath = baseFolder.toPath();
	}

	@Deactivate
	protected void deactivate() {

		// unload all resources
		for (Resource resource : new ArrayList<Resource>(rs.getResources())) {
			resource.unload();
		}

		rs = null;
		basePath = null;
	}

}