/*
 * Copyright 2015 (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.model;

import pcgen.base.formula.base.ScopeInstance;
import pcgen.base.formula.base.VariableID;
import pcgen.cdom.enumeration.CharID;
import pcgen.cdom.facet.FacetLibrary;
import pcgen.cdom.facet.ObjectWrapperFacet;
import pcgen.cdom.facet.ScopeFacet;
import pcgen.cdom.facet.VariableLibraryFacet;
import pcgen.cdom.facet.VariableStoreFacet;
import freemarker.template.TemplateHashModel;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;

/**
 * GlobalVarModel provides the services to expose global variables for a Player
 * Character to the output system.
 */
public class GlobalVarModel implements TemplateHashModel
{

	/**
	 * The global VariableLibraryFacet used to get VariableIDs
	 */
	private final VariableLibraryFacet variableLibraryFacet = FacetLibrary
		.getFacet(VariableLibraryFacet.class);

	/**
	 * The global VariableStore Facet used to get VariableID values
	 */
	private final VariableStoreFacet variableStoreFacet = FacetLibrary
		.getFacet(VariableStoreFacet.class);

	/**
	 * The global ScopeFacet used to get VariableScopes
	 */
	private final ScopeFacet scopeFacet = FacetLibrary
		.getFacet(ScopeFacet.class);

	/**
	 * The global ObjectWrapperFacet used to wrap the current value of a
	 * variable
	 */
	private final ObjectWrapperFacet wrapperFacet = FacetLibrary
		.getFacet(ObjectWrapperFacet.class);

	/**
	 * The underlying CharID for this InfoModel
	 */
	private final CharID id;

	/**
	 * Constructs a new GlobalVarModel with the given CharID
	 * 
	 * @param id
	 *            The CharID that underlies this GlobalVarModel
	 */
	public GlobalVarModel(CharID id)
	{
		if (id == null)
		{
			throw new IllegalArgumentException("CharID cannot be null");
		}
		this.id = id;
	}

	/**
	 * Gets the global variable (new formula system) represented by the given
	 * key.
	 * 
	 * @see freemarker.template.TemplateHashModel#get(java.lang.String)
	 */
	@Override
	public TemplateModel get(String varName) throws TemplateModelException
	{
		ScopeInstance varScope = scopeFacet.getGlobalScope(id);
		VariableID<?> varID =
				variableLibraryFacet.getVariableID(id.getDatasetID(), varScope,
					varName);
		Object value = variableStoreFacet.getValue(id, varID);
		return wrapperFacet.wrap(id, value);
	}

	/**
	 * @see freemarker.template.TemplateHashModel#isEmpty()
	 */
	@Override
	public boolean isEmpty() throws TemplateModelException
	{
		//Assume there is at least one global variable
		return false;
	}

}