package org.simantics.modeling.adapters;

import java.util.Collection;
import java.util.Collections;
import java.util.List;

import org.simantics.browsing.ui.model.children.ChildRule;
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.modeling.ModelingResources;
import org.simantics.scl.runtime.SCLContext;
import org.simantics.scl.runtime.function.Function1;

public class SCLChildRule implements ChildRule {

    private Resource rule;
    
    public SCLChildRule(ReadGraph graph, Resource rule) {
        this.rule = rule;
    }
    
    @Override
    public boolean isCompatible(Class<?> contentType) {
        return contentType.equals(Resource.class) || contentType.equals(Variable.class);
    }

    @Override
    public Collection<Resource> getChildren(ReadGraph graph, Object parent) throws DatabaseException {
        Resource parentResource;
        
        if (parent instanceof Variable) {
            parentResource = ((Variable)parent).getRepresents(graph);
        } else {
            parentResource = (Resource)parent;
        }
        
        ModelingResources MOD = ModelingResources.getInstance(graph);
        
        Variable ruleVariable = Variables.getVariable(graph, rule);

        Function1<Object,List<Resource>> getChildren = ruleVariable.getPossiblePropertyValue(graph, MOD.SCLChildRule_getChildren);
        if(getChildren == null) return Collections.emptyList();

        SCLContext sclContext = SCLContext.getCurrent();
        Object oldGraph = sclContext.get("graph");
        try {
            sclContext.put("graph", graph);
            return getChildren.apply(parentResource);
        } catch (Throwable t) {
        	throw new DatabaseException(t);
        } finally {
            sclContext.put("graph", oldGraph);
        }

    }

    @Override
    public Collection<?> getParents(ReadGraph graph, Object child) throws DatabaseException {
        return null;
    }

}