/*
 * Copyright 2014 (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.content.fact;

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

import pcgen.base.util.Indirect;
import pcgen.base.util.ObjectContainer;
import pcgen.cdom.base.CDOMObject;
import pcgen.rules.context.AbstractReferenceContext;
import pcgen.rules.context.LoadContext;

/**
 * A FactGroup is an ObjectContainer that contains objects of a specific type
 * (e.g. Skill) that contain a specific value in a given FACT
 * 
 * @param <T>
 *            The Type of object contained in this FactGroup
 * @param <F>
 *            The Type of the Fact being checked in this FactGroup
 */
public class FactGroup<T extends CDOMObject, F> implements ObjectContainer<T>
{

	/**
	 * Contains the underlying FactInfo for this FactGroup (identifying the
	 * "rules of the road")
	 */
	private final FactInfo<T, F> def;

	/**
	 * The Indirect containing the fact to be matched
	 */
	private final Indirect<F> toMatch;

	/**
	 * The ObjectContainer containing all of the objects of the type of object
	 * where this FactGroup (and thus the FactInfo) are usable
	 */
	private final ObjectContainer<T> allObjects;

	/**
	 * The cached answers for this FactGroup.
	 * 
	 * Note that this cache can exist because these items are facts, and thus
	 * semantically can't change. There is also the assumption that the global
	 * list of objects cannot change.
	 */
	private transient List<T> cache;

	/**
	 * Constructs a new FactGroup from the given context, FactInfo and value.
	 * 
	 * @param context
	 *            The LoadContext used to resolve references
	 * @param fi
	 *            The FactInfo indicating the underlying characteristics of the
	 *            Fact that this FactGroup will check
	 * @param value
	 *            The String representation of the value that this FactGroup
	 *            will be looking for
	 */
	public FactGroup(LoadContext context, FactInfo<T, F> fi, String value)
	{
		if (fi.getUsableLocation().equals(CDOMObject.class))
		{
			throw new IllegalArgumentException("FactGroup cannot be global");
		}
		def = fi;
		AbstractReferenceContext refContext = context.getReferenceContext();
		allObjects = refContext.getCDOMAllReference(def.getUsableLocation());
		toMatch = def.getFormatManager().convertIndirect(value);
		if (toMatch == null)
		{
			throw new IllegalArgumentException("Failed to convert " + value
				+ " as a "
				+ def.getFormatManager().getManagedClass().getSimpleName());
		}
	}

	/**
	 * @see pcgen.base.util.ObjectContainer#getContainedObjects()
	 */
	@Override
	public Collection<T> getContainedObjects()
	{
		if (cache == null)
		{
			List<T> setupCache = new ArrayList<>();
			for (T obj : allObjects.getContainedObjects())
			{
				if (contains(obj))
				{
					setupCache.add(obj);
				}
			}
			cache = setupCache;
		}
		return Collections.unmodifiableCollection(cache);
	}

	/**
	 * @see pcgen.base.util.ObjectContainer#getLSTformat(boolean)
	 */
	@Override
	public String getLSTformat(boolean useAny)
	{
		return def.getFactName() + "="
			+ def.getFormatManager().unconvert(toMatch.get());
	}

	/**
	 * @see pcgen.base.util.ObjectContainer#contains(java.lang.Object)
	 */
	@Override
	public boolean contains(T obj)
	{
		Indirect<?> fact = obj.get(def.getFactKey());
		return fact != null && fact.get().equals(toMatch.get());
	}

	/**
	 * @see pcgen.base.util.ObjectContainer#getReferenceClass()
	 */
	@Override
	public Class<T> getReferenceClass()
	{
		return allObjects.getReferenceClass();
	}
}