/*******************************************************************************
 * 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.layer0.utils.binaryPredicates;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;

import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.Statement;
import org.simantics.db.WriteGraph;
import org.simantics.db.common.utils.OrderedSetUtils;
import org.simantics.db.exception.DatabaseException;
import org.simantics.layer0.Layer0;
import org.simantics.utils.datastructures.Pair;

public class OrderedSetElementsPredicate extends BinaryPredicate {

	public static final OrderedSetElementsPredicate INSTANCE = 
		new OrderedSetElementsPredicate(); 
	
	@Override
	public Collection<Resource> getObjects(ReadGraph g, Resource subject) throws DatabaseException {
		Layer0 l0 = Layer0.getInstance(g);
		if(g.isInstanceOf(subject, l0.OrderedSet))
			return OrderedSetUtils.toList(g, subject);
		else
			return Collections.emptyList();
	}

	@Override
	public Collection<Pair<Resource, Resource>> getStatements(ReadGraph g) {
		throw new UnsupportedOperationException();
	}

	@Override
	public Collection<Resource> getSubjects(ReadGraph g, Resource object) throws DatabaseException {
		Collection<Resource> result = new ArrayList<Resource>(1);
		Layer0 l0 = Layer0.getInstance(g);
		for(Statement stat : g.getStatements(object, l0.IsWeaklyRelatedTo)) {
			Resource pred = stat.getPredicate();
			if(g.isInstanceOf(pred, l0.OrderedSet) && !pred.equals(object))
				result.add(pred);
		}
		return result;
	}

	@Override
	public boolean has(ReadGraph g, Resource subject, Resource object) throws DatabaseException {
		return OrderedSetUtils.contains(g, subject, object) &&
			g.isInstanceOf(subject, Layer0.getInstance(g).OrderedSet);
	}

	@Override
	public boolean supportsGetObjects() {
		return true;
	}

	@Override
	public boolean supportsGetStatements() {		
		return false;
	}

	@Override
	public boolean supportsGetSubjects() {
		return true;
	}

	@Override
	public void add(WriteGraph g, Resource subject, Resource object) throws DatabaseException {
		OrderedSetUtils.add(g, subject, object);
	}

	@Override
	public void remove(WriteGraph g, Resource subject, Resource object) throws DatabaseException {
		OrderedSetUtils.remove(g, subject, object);
	}

	@Override
	public boolean supportsAdditions() {
		return true;
	}

	@Override
	public boolean supportsRemovals() {
		return true;
	}
	
}