/*******************************************************************************
 * 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 org.simantics.db.exception.DatabaseException;
import org.simantics.db.impl.graph.ReadGraphImpl;
import org.simantics.db.impl.procedure.InternalProcedure;

final public class ValueQuery extends UnaryQuery<InternalProcedure<byte[]>> {
    
    ValueQuery(final int resource) {
        super(resource);
    }

 	@Override
 	final public void removeEntry(QueryProcessor provider) {
 		provider.cache.remove(this);
 	}
 		
	public static byte[] computeForEach(ReadGraphImpl graph, final int r, final ValueQuery entry, final InternalProcedure<byte[]> procedure) throws DatabaseException {

 		graph.ensureLoaded(r);
 		
 		byte[] value = graph.getValue(r);
 		if(entry != null) {
 			entry.setResult(value);
 			entry.setReady();
 		}
 		if(procedure != null) {
 			procedure.execute(graph, value);
 		}
 		
 		return value;
 		
 	}

    public static byte[] computeForEach(ReadGraphImpl graph, final int r) {

        graph.ensureLoaded(r);
        
        return graph.getValue(r);
        
    }
	
 	@Override
 	public Object compute(ReadGraphImpl graph, final InternalProcedure<byte[]> procedure) throws DatabaseException {
 		return computeForEach(graph, id, this, procedure);
    }
    
    @Override
    public String toString() {
    	return "Value[" + id + "]";
    }

    @Override
    public Object performFromCache(ReadGraphImpl graph, InternalProcedure<byte[]> procedure) throws DatabaseException {
    	return compute(graph, procedure);
    }
    
    @Override
    public void recompute(ReadGraphImpl graph) throws DatabaseException {
    	
        compute(graph,  new InternalProcedure<byte[]>() {

            @Override
            public void execute(ReadGraphImpl graph, byte[] result) {
            }
			
			@Override
			public void exception(ReadGraphImpl graph, Throwable t) {
				throw new Error("Error in recompute.", t);
            }

        });
        
    }
    
    @Override
    boolean isImmutable(ReadGraphImpl graph) {
    	return graph.processor.isImmutable(id);
    }
    
}