/*
 * Copyright 2014-15 (C) Tom Parker <thpr@users.sourceforge.net>
 * 
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 * 
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package pcgen.output.actor;

import pcgen.base.util.Indirect;
import pcgen.cdom.base.CDOMObject;
import pcgen.cdom.base.Constants;
import pcgen.cdom.enumeration.CharID;
import pcgen.cdom.enumeration.FactKey;
import pcgen.cdom.facet.FacetLibrary;
import pcgen.cdom.facet.ObjectWrapperFacet;
import pcgen.output.base.OutputActor;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;

/**
 * A FactKeyActor is designed to process an interpolation and convert that into
 * a TemplateModel representing the contents of the specific Fact being
 * requested.
 * 
 * Note that the actual name of the interpolation is stored externally to this
 * Actor (in CDOMObjectWrapperInfo to be precise)
 * 
 * @param <T>
 *            The Type of object stored in the FactKey underlying this
 *            FactKeyActor
 */
public class FactKeyActor<T> implements OutputActor<CDOMObject>
{
	private static final ObjectWrapperFacet WRAPPER_FACET = FacetLibrary
		.getFacet(ObjectWrapperFacet.class);

	/**
	 * The FactKey underlying this FactKeyActor (for which the contents will be
	 * returned)
	 */
	private final FactKey<T> fk;

	/**
	 * Constructs a new FactKeyActor with the given FactKey
	 * 
	 * @param fk
	 *            The FactKey underlying this FactKeyActor
	 */
	public FactKeyActor(FactKey<T> fk)
	{
		if (fk == null)
		{
			throw new IllegalArgumentException("FactKey may not be null");
		}
		this.fk = fk;
	}

	/**
	 * @see pcgen.output.base.OutputActor#process(pcgen.cdom.enumeration.CharID,
	 *      java.lang.Object)
	 */
	@Override
	public TemplateModel process(CharID id, CDOMObject d)
		throws TemplateModelException
	{
		Indirect<?> ind = d.get(fk);
		Object object;
		if (ind == null)
		{
			object = Constants.EMPTY_STRING;
		}
		else
		{
			object = ind.get();
		}
		return WRAPPER_FACET.wrap(id, object);
	}
}