/* 
 * This file is part of the HyperGraphDB source distribution. This is copyrighted 
 * software. For permitted uses, licensing options and redistribution, please see  
 * the LicensingInformation file at the root level of the distribution.  
 * 
 * Copyright (c) 2005-2010 Kobrix Software, Inc.  All rights reserved. 
 */
package org.hypergraphdb.type.javaprimitive;

import org.hypergraphdb.HGException;

import org.hypergraphdb.HGHandle;
import org.hypergraphdb.HGPersistentHandle;
import org.hypergraphdb.IncidenceSetRef;
import org.hypergraphdb.LazyRef;
import org.hypergraphdb.type.HGAtomType;
import org.hypergraphdb.type.HGAtomTypeBase;

/**
 * 
 * <p>
 * Manages instances of <code>EnumType</code>. Each <code>EnumType</code> manages
 * a concrete Java <code>Enum</code>.
 * </p>
 *
 * <p>
 * To allow for cross-platform interoperability of enums, the list of symbolic 
 * constants is also recorded along with the fully-qualified Java class name 
 * of the enum. The Java HyperGraph implementation will only use the latter, though.
 * </p>
 * 
 * @author Borislav Iordanov
 *
 */
public class EnumTypeConstructor extends HGAtomTypeBase
{
//    public static final HGPersistentHandle HGHANDLE =
//        HGHandleFactory.makeHandle("4e3c44ec-da21-11db-84d5-cf67a5f089dc");
 
    @SuppressWarnings("unchecked")
	public Object make(HGPersistentHandle handle, LazyRef<HGHandle[]> targetSet, IncidenceSetRef incidenceSet)
	{
		EnumType result = new EnumType();
		result.setHyperGraph(graph);
		
		// We are pretty sure that this is an atom, so we can find its handle with the by value
		// index. And we use that to get Java class of the enum, instead of the stored one
		// so we can gracefully handle class name changes.
		HGPersistentHandle typeHandle = (HGPersistentHandle)graph.getIndexManager().getIndexByValue().findFirst(handle);
		Class<Enum<?>> cl = (Class<Enum<?>>)graph.getTypeSystem().getClassForType(typeHandle);
		result.setEnumType(cl);		
//		HGPersistentHandle [] layout = graph.getStore().getLink(handle);		
//		HGAtomType stringType = graph.getTypeSystem().getAtomType(String.class);		
//		String classname = (String)stringType.make(layout[0], null, null);
//		try
//		{
//			cl = HGUtils.loadClass(getHyperGraph(), classname);
//			result.setEnumType(cl);
//		}
//		catch (ClassNotFoundException ex)
//		{
//			throw new HGException("Unable to load enum class " + classname, ex);
//		}
		return result;
	}

	public HGPersistentHandle store(Object instance)
	{
		EnumType et = (EnumType)instance;
		if (!et.getEnumType().isEnum())
			throw new HGException("Attempting to store non Enum class " + 
								  et.getEnumType().getClass() + " as an enum.");		
		HGPersistentHandle [] layout = new HGPersistentHandle[1 + et.getEnumType().getEnumConstants().length];
		HGAtomType stringType = graph.getTypeSystem().getAtomType(String.class);
		layout[0] = stringType.store(et.getEnumType().getName());
		Enum<?> [] constants =(Enum[])et.getEnumType().getEnumConstants(); 
		for (int i = 0; i < constants.length; i++ )
		{
			layout[i + 1] = stringType.store(constants[i].name());
		}
		return graph.getStore().store(layout);
	}

	public void release(HGPersistentHandle handle)
	{
		HGPersistentHandle [] layout = graph.getStore().getLink(handle);
		HGAtomType stringType = graph.getTypeSystem().getAtomType(String.class);
		for (HGPersistentHandle h : layout)
			stringType.release(h);
		graph.getStore().removeLink(handle);
	}
}