/*******************************************************************************
 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
 * in Industry THTH ry.
 * 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:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.db.common.primitiverequest;

import java.util.Collection;

import org.simantics.db.AsyncReadGraph;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.common.request.ResourceRead2;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.procedure.AsyncMultiProcedure;
import org.simantics.db.service.CollectionSupport;
import org.simantics.utils.DataContainer;

final public class ForEachAssertedObject extends ResourceRead2<Collection<Resource>> {

    public ForEachAssertedObject(Resource subject, Resource relation) {
        super(subject, relation);
    }

	@Override
	public Collection<Resource> perform(ReadGraph graph) throws DatabaseException {
		CollectionSupport cs = graph.getService(CollectionSupport.class);
		Collection<Resource> result = cs.createSet();
		DataContainer<Throwable> throwable = new DataContainer<Throwable>(null);
		graph.forEachAssertedObject(resource, resource2, new AsyncMultiProcedure<Resource>() {
			
			@Override
			public void finished(AsyncReadGraph graph) {
			}
			
			@Override
			public void execute(AsyncReadGraph graph, Resource r) {
				result.add(r);
			}
			
			@Override
			public void exception(AsyncReadGraph graph, Throwable t) {
				throwable.set(t);
			}
		});
		Throwable t = throwable.get();
		if(t != null)
			if(t instanceof DatabaseException)
				throw (DatabaseException)t;
			else throw new DatabaseException(t);
		return result;
	}

}