package org.simantics.district.selection;

import java.util.List;
import java.util.UUID;

import org.simantics.Simantics;
import org.simantics.databoard.Bindings;
import org.simantics.db.RequestProcessor;
import org.simantics.db.Resource;
import org.simantics.db.WriteGraph;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.QueryIndexUtils;
import org.simantics.db.layer0.request.PossibleActiveModel;
import org.simantics.db.request.WriteResult;
import org.simantics.layer0.Layer0;

public class ElementSelectionUtils {
	public static Resource ensureSelectionLibrary(RequestProcessor graph) throws DatabaseException {
		return graph.syncRequest(new WriteResult<Resource>() {
			@Override
			public Resource perform(WriteGraph graph) throws DatabaseException {
				ElementSelectionResource ES = ElementSelectionResource.getInstance(graph);
				
				Resource model = graph.sync(new PossibleActiveModel(Simantics.getProjectResource()));
				if (model == null) return null;
				
				List<Resource> libs = QueryIndexUtils.searchByTypeShallow(graph, model, ES.SelectionLibrary);
				if (libs.isEmpty()) {
					Resource lib = graph.newResource();
					Layer0 L0 = Layer0.getInstance(graph);
					graph.claim(lib, L0.InstanceOf, ES.SelectionLibrary);
					graph.claim(model, L0.ConsistsOf, lib);
					graph.claimLiteral(lib, L0.HasName, L0.String, UUID.randomUUID().toString(), Bindings.STRING);
					return lib;
				}
				else {
					return libs.get(0);
				}
			}
		});
	}

}