package org.simantics.selectionview;

import java.util.List;

import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.variable.Variable;
import org.simantics.db.layer0.variable.Variables;
import org.simantics.db.layer0.variable.Variables.Role;
import org.simantics.scl.runtime.SCLContext;
import org.simantics.scl.runtime.function.Function1;

public class SelectionViewUtils {

	public static Variable getSpecialCategory(ReadGraph graph, Resource rule, Variable info) throws DatabaseException {
        
		SelectionViewResources SEL = SelectionViewResources.getInstance(graph);
		//Resource categoryResource = info.getPossibleRepresents(graph);
		
		//if(SEL.CategoryHidden.equals(categoryResource)) {
			
			Variable property = info.getParent(graph);
			Variable parent = property.getParent(graph);
			if(Role.PROPERTY.equals(parent.getPossibleRole(graph))) return null;
			
			Resource predicate = property.getPossiblePredicateResource(graph);
			Variable ruleVariable = Variables.getVariable(graph, rule);

			Function1<Object,List<?>> getSpecialCategory = ruleVariable.getPossiblePropertyValue(graph, SEL.getSpecialCategory);
			if(getSpecialCategory == null) return null;

			SCLContext sclContext = SCLContext.getCurrent();
	        Object oldGraph = sclContext.get("graph");
			try {
				sclContext.put("graph", graph);
				Resource cat = (Resource)getSpecialCategory.apply(predicate);
				if(cat != null) return Variables.getVariable(graph, cat);
			} catch (Throwable t) {
				throw new DatabaseException(t);
			} finally {
	            sclContext.put("graph", oldGraph);
			}
		//}
		
		return null;

	}

}