/*******************************************************************************
 * 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;
import org.simantics.db.impl.procedure.IntProcedureAdapter;
import org.simantics.db.impl.procedure.InternalProcedure;
import org.simantics.db.procedure.ListenerBase;

final public class OrderedSet extends CollectionUnaryQuery<IntProcedure> {
	
	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 entry, final IntProcedure procedure) throws DatabaseException {
 	    
 		QueryProcessor processor = graph.processor;
 		
 		processor.querySupport.ensureLoaded(graph, current);
 		
 		AtomicInteger res = new AtomicInteger(0);
 		
 		boolean found = processor.querySupport.getObjects(graph, current, orderedSet, new IntProcedure() {

 			@Override
 			public void execute(ReadGraphImpl graph, int i) throws DatabaseException {
 				if(i != orderedSet) {
 					if(entry != null) entry.addOrSet(i);
 					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) {
 			if(entry != null) entry.finish(graph, processor);
 			procedure.finished(graph);
 		}
 		
 		return res.get();

 	}
 	
    @Override
    public void clearResult(QuerySupport support) {
        setResult(new IntArray());
    }
 	
    //@Override
    public Object compute(ReadGraphImpl graph, final IntProcedure procedure) throws DatabaseException {
    	computeForEach(graph, id, this, procedure);
        return getResult();
    }

    static void computeForEach(ReadGraphImpl graph, int orderedSet, final OrderedSet entry, final IntProcedure procedure) throws DatabaseException {

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

    }
    
    @Override
    public String toString() {
    	return "OrderedSet[" + id + "]";
    }

    final private void finish(ReadGraphImpl graph, QueryProcessor provider) {
        
    	assert(isPending());

        synchronized(this) {
        	setReady();
        }
        
    }

    final public void addOrSet(int add) {
        
        assert(isPending());
        
        IntArray value = (IntArray)getResult();
        value.add(add);
        
    }

    @Override
    public Object performFromCache(ReadGraphImpl graph, final IntProcedure procedure) throws DatabaseException {
    	
    	assert(isReady());

    	if(handleException(graph, procedure)) return EXCEPTED;
    	
        final IntArray value = (IntArray)getResult();
        if(value.data == null) {
            if(value.sizeOrData != IntArray.NO_DATA) procedure.execute(graph, value.sizeOrData);
        } else {
            for(int i = 0;i < value.sizeOrData ; i++) procedure.execute(graph, value.data[i]);
        }

        procedure.finished(graph);
        
        return value;
        
    }
    
    @Override
    public void recompute(ReadGraphImpl graph) throws DatabaseException {
        
        compute(graph, new IntProcedureAdapter() {

            @Override
            public void finished(ReadGraphImpl graph) {
            }
			
			@Override
			public void exception(ReadGraphImpl graph, Throwable t) {
				throw new Error("Error in recompute.", t);
            }

        });
        
    }
    
}