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/**
 * #-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=#
 *   This file is part of the LDP4j Project:
 *     http://www.ldp4j.org/
 *
 *   Center for Open Middleware
 *     http://www.centeropenmiddleware.com/
 * #-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=#
 *   Copyright (C) 2014 Center for Open Middleware.
 * #-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=#
 *   Licensed 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.
 * #-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=#
 *   Artifact    : org.ldp4j.framework:ldp4j-application-examples:0.2.0
 *   Bundle      : ldp4j-application-examples-0.2.0.jar
 * #-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=#
 */
package org.ldp4j.example;

import java.net.URI;
import java.util.Date;

import org.ldp4j.application.ApplicationContext;
import org.ldp4j.application.data.DataSet;
import org.ldp4j.application.data.Individual;
import org.ldp4j.application.data.Literals;
import org.ldp4j.application.data.ManagedIndividualId;
import org.ldp4j.application.data.Name;
import org.ldp4j.application.session.ResourceSnapshot;
import org.ldp4j.application.session.WriteSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Utility class that demonstrates how to update a resource at runtime.
 */
final class DynamicResourceUpdater implements Runnable {

	static final URI REFRESHED_ON = URI.create("http://www.ldp4j.org/ns#refreshedOn");

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

	private DynamicResourceHandler handler;
	private Name name;

	/**
	 * Create a new instance with a handler and a resource name.
	 *
	 * @param handler
	 *            the handler that holds the resource to be updated.
	 * @param name
	 *            the name of the resource to be updated.
	 */
	public DynamicResourceUpdater(DynamicResourceHandler handler, Name name) {
		this.handler = handler;
		this.name = name;
	}

	/**
	 * Update the resource representation adding a temporal timestamp of when
	 * the resource was last updated.
	 */
	@Override
	public void run() {
		ApplicationContext ctx = ApplicationContext.getInstance();
		Date date = new Date();
		LOGGER.debug("Starting update process on {}...",date);
		try(WriteSession session = ctx.createSession()) {
			ResourceSnapshot snapshot = session.find(ResourceSnapshot.class,this.name,DynamicResourceHandler.class);
			DataSet dataSet = this.handler.get(snapshot);
			Individual individual =
				dataSet.
					individualOfId(
						ManagedIndividualId.
							createId(this.name, DynamicResourceHandler.ID));
			individual.
				addValue(
					REFRESHED_ON,
					Literals.of(date).dateTime());
			this.handler.update(this.name, dataSet);
			session.modify(snapshot);
			session.saveChanges();
		} catch (Exception e) {
			LOGGER.error("Could not update resource",e);
		} finally {
			LOGGER.debug("Finalized update process");
		}
	}

}