package org.simantics.document.server.request;

import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

import org.simantics.db.ReadGraph;
import org.simantics.db.common.request.UnaryRead;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.request.VariableChildren;
import org.simantics.db.layer0.request.VariableRead;
import org.simantics.db.layer0.variable.Variable;
import org.simantics.structural.stubs.StructuralResource2;

public class NodesRequest extends VariableRead<Set<Variable>> {

    public NodesRequest(Variable var) {
        super(var);
    }

    static class CollectNodesRequest2 extends UnaryRead<Collection<Variable>, Set<Variable>> {

        public CollectNodesRequest2(Collection<Variable> nodes) {
            super(nodes);
        }

        @Override
        public Set<Variable> perform(ReadGraph graph) throws DatabaseException {
            HashSet<Variable> rs = new HashSet<>(); // result
            for(Variable child : parameter) {
                Set<Variable> childNodes = graph.syncRequest(new NodesRequest2(child));
                rs.addAll(childNodes);
            }
            return rs;
        }

    }

    @Override
    public Set<Variable> perform(ReadGraph graph) throws DatabaseException {

        long s = System.nanoTime();

        StructuralResource2.getInstance(graph);
        if(variable == null)
            return Collections.emptySet();

        Collection<Variable> children = graph.syncRequest(new VariableChildren(variable));

        Set<Variable> nodes = graph.syncRequest(new CollectNodesRequest2(children));

        if(DocumentRequest.PROFILE) {
            long dura = System.nanoTime()-s;
            System.err.println("NodesRequest " + System.identityHashCode(this) + " in " + 1e-6*dura + "ms. " + variable.getURI(graph));
        }

        return nodes;

    }

}