/*******************************************************************************
 * Copyright (c) 2007, 2011 Association for Decentralized Information Management in
 * Industry THTH ry.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.issues.common;

import java.util.Collection;
import java.util.Collections;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;

import org.simantics.db.AsyncReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.common.request.TernaryAsyncRead;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.procedure.AsyncProcedure;
import org.simantics.issues.Severity;

/**
 * @author Tuukka Lehtonen
 */
public class ChildMaxIssueSeverity extends TernaryAsyncRead<Resource, Resource, Set<Resource>, Severity> {

    static class AsyncReadResult<T> {
        private AtomicReference<T> resultRef;
        private Throwable throwable;
        private AtomicInteger counter = new AtomicInteger(1);
        private AsyncProcedure<T> procedure;
        AsyncReadResult(AsyncProcedure<T> procedure, AtomicReference<T> resultRef) {
            this.procedure = procedure;
            this.resultRef = resultRef;
        }
        void except(AsyncReadGraph graph, Throwable throwable) {
            this.throwable = throwable;
            dec(graph);
        }
        void set(AsyncReadGraph graph, T result) {
            resultRef.set(result);
            dec(graph);
        }
        void inc() {
            counter.incrementAndGet();
        }
        void dec(AsyncReadGraph graph) {
            if(counter.decrementAndGet() == 0) {
                if(throwable != null)
                    procedure.exception(graph, throwable);
                else
                    procedure.execute(graph, resultRef.get());
            }
        }
        
    }
    
    public ChildMaxIssueSeverity(Resource resource, Resource childRelation, Set<Resource> typesToRecurse) {
        super(resource, childRelation, typesToRecurse);
    }

    @Override
    public void perform(AsyncReadGraph graph, final AsyncProcedure<Severity> procedure) {
        
        try {
            Set<Resource> types = graph.getTypes(parameter);
            if (!Collections.disjoint(parameter3, types)) {
                checkChildren(graph, procedure);
            } else {
                procedure.execute(graph, null);
            }
        } catch (DatabaseException e) {
            procedure.exception(graph, e);
        }
        
    }

    protected void checkChildren(AsyncReadGraph graph, final AsyncProcedure<Severity> procedure) {
        
        AsyncReadResult<Severity> maxSeverity = new AsyncReadResult<Severity>(procedure, new AtomicReference<Severity>());
        
        try {
            Collection<Resource> children = graph.getObjects(parameter, parameter2);
            for(Resource child : children) {
                maxSeverity.inc();
                graph.asyncRequest(new MaxIssueSeverityRecursive(child, parameter2, parameter3), new AsyncProcedure<Severity>() {
                    @Override
                    public void execute(AsyncReadGraph graph, Severity severity) {
                        if (severity != null) {
                            synchronized (maxSeverity) {
                                maxSeverity.set(graph, Severity.moreSevere(maxSeverity.resultRef.get(), severity));
                            }
                        } else {
                            maxSeverity.dec(graph);
                        }
                    }
                    @Override
                    public void exception(AsyncReadGraph graph, Throwable throwable) {
                        maxSeverity.except(graph, throwable);
                    }
                });
            }
            maxSeverity.dec(graph);
        } catch (DatabaseException e) {
            maxSeverity.except(graph, e);
            return;
        }
        
    }

}