package org.simantics.document.server.request;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.simantics.db.ReadGraph;
import org.simantics.db.common.procedure.adapter.TransientCacheAsyncListener;
import org.simantics.db.common.request.UnaryRead;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.request.VariableRead;
import org.simantics.db.layer0.variable.Variable;
import org.simantics.document.server.JSONObject;

public class DocumentRequest extends VariableRead<List<JSONObject>> {

    public static boolean PROFILE = false;
    // Thresholds in microseconds
    public static int PROFILE_THRESHOLD_NODEREQUEST = 2000;
    public static int PROFILE_THRESHOLD_VALUEREQUEST = 500;

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

    static class CollectNodesRequest extends UnaryRead<Collection<Variable>, Collection<JSONObject>> {

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

        @Override
        public Collection<JSONObject> perform(ReadGraph graph) throws DatabaseException {
            HashSet<JSONObject> rs = new HashSet<>(); // result
            for(Variable node : parameter) {
                rs.add(graph.syncRequest(new NodeRequest(node)));
            }
            return rs;
        }

    }

    private static final Comparator<JSONObject> JSON_COMPARATOR = (o1, o2) -> o1.id.compareTo(o2.id);

    @Override
    public List<JSONObject> perform(ReadGraph graph) throws DatabaseException {

        long s = System.nanoTime();

        Set<Variable> nodes = graph.syncRequest(new NodesRequest(variable), TransientCacheAsyncListener.<Set<Variable>>instance());
        if(nodes.isEmpty()) {
            return Collections.emptyList();
        }

        Collection<JSONObject> rs = graph.syncRequest(new CollectNodesRequest(nodes));

        ArrayList<JSONObject> result = new ArrayList<>(rs);
        Collections.sort(result, JSON_COMPARATOR);

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

        return result;

    }

}