/*******************************************************************************
 * Copyright (c) 2007, 2010 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.db.impl.query;

import java.util.concurrent.atomic.AtomicInteger;

import org.simantics.db.common.exception.DebugException;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.impl.graph.ReadGraphImpl;

final public class OrderedSet extends CollectionUnaryQuery {
	
	public OrderedSet(final int r) {
        super(r);
    }

 	@Override
 	final public void removeEntry(QueryProcessor provider) {
        provider.cache.remove(this);
 	}

 	private static int nextElement(ReadGraphImpl graph, int current, int orderedSet, OrderedSet parent, final IntProcedure procedure) throws DatabaseException {
 	    
 		QueryProcessor processor = graph.processor;
 		
 		processor.querySupport.ensureLoaded(graph, current);
 		
 		AtomicInteger res = new AtomicInteger(0);
 		
 		processor.querySupport.getObjects(graph, current, orderedSet, new IntProcedure() {

 			@Override
 			public void execute(ReadGraphImpl graph, int i) throws DatabaseException {
 				if(i != orderedSet) {
 					procedure.execute(graph, i);
 				}
 				res.set(i);
 			}

 			@Override
 			public void exception(ReadGraphImpl graph, Throwable t) throws DatabaseException {
 				if(DebugException.DEBUG) new DebugException(t).printStackTrace();
 				procedure.exception(graph, t);
 			}

 			@Override
 			public void finished(ReadGraphImpl graph) {
 			}

 		});

 		if(res.get() == orderedSet) {
 			procedure.finished(graph);
 		}
 		
 		return res.get();

 	}
 	
    @Override
    public void compute(ReadGraphImpl graph, final IntProcedure procedure) throws DatabaseException {
        computeForEach(graph, id, this, procedure);
    }

    static void computeForEach(ReadGraphImpl graph, int orderedSet, final OrderedSet entry, final IntProcedure procedure_) throws DatabaseException {
        
        IntProcedure procedure = entry != null ? entry : procedure_;

    	int current = nextElement(graph, orderedSet, orderedSet, entry, procedure);
    	while(current != orderedSet) {
    		current = nextElement(graph, current, orderedSet, entry, procedure);
    	}

    	if(entry != null) entry.performFromCache(graph, procedure_);
    	
    }
    
    @Override
    public String toString() {
    	return "OrderedSet[" + id + "]";
    }
    
}