/*
 * Copyright 2016 (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.cdom.formula;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import pcgen.base.formula.base.Function;
import pcgen.system.PluginLoader;
import pcgen.util.Logging;

public final class PluginFunctionLibrary implements PluginLoader
{

	private static PluginFunctionLibrary instance = null;

	private static ArrayList<Function> list = new ArrayList<>();

	private PluginFunctionLibrary()
	{
		// Don't instantiate utility class
	}

	public static PluginFunctionLibrary getInstance()
	{
		if (instance == null)
		{
			instance = new PluginFunctionLibrary();
		}
		return instance;
	}

	@Override
	public void loadPlugin(Class<?> clazz) throws Exception
	{
		Object token = clazz.newInstance();
		if (token instanceof Function)
		{
			Function tok = (Function) token;
			Function existing = existingFunction(tok.getFunctionName());
			if (existing != null)
			{
				Logging.errorPrint("Duplicate Function "
					+ tok.getFunctionName() + " found. Classes were "
					+ existing.getClass().getName() + " and "
					+ tok.getClass().getName());
			}
			else
			{
				list.add(tok);
			}
		}
	}

	private Function existingFunction(String name)
	{
		for (Function f : list)
		{
			if (f.getFunctionName().equalsIgnoreCase(name))
			{
				return f;
			}
		}
		return null;
	}

	@Override
	public Class<?>[] getPluginClasses()
	{
		return new Class[]{Function.class};
	}

	public List<Function> getFunctions()
	{
		return Collections.unmodifiableList(list);
	}

}