/*
 * $Id: LuaStateFactory.java,v 1.4 2006/12/22 14:06:40 thiago Exp $
 * Copyright (C) 2003-2007 Kepler Project.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package org.keplerproject.luajava;

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

/**
 * This class is responsible for instantiating new LuaStates. When a new
 * LuaState is instantiated it is put into a List and an index is returned. This
 * index is registred in Lua and it is used to find the right LuaState when lua
 * calls a Java Function.
 *
 * @author Thiago Ponte
 */
public final class LuaStateFactory {
    /**
     * Array with all luaState's instances
     */
    private static final List states = new ArrayList();

    /**
     * Returns a existing instance of LuaState
     *
     * @param index
     * @return LuaState
     */
    public synchronized static LuaState getExistingState(int index) {
        return (LuaState) states.get(index);
    }

    /**
     * Get next available index
     *
     * @return int
     */
    private synchronized static int getNextStateIndex() {
        int i;
        for (i = 0; i < states.size() && states.get(i) != null; i++)
            ;

        return i;
    }

    /**
     * Receives a existing LuaState and checks if it exists in the states list.
     * If it doesn't exist adds it to the list.
     *
     * @param L
     * @return int
     */
    public synchronized static int insertLuaState(LuaState L) {
        int i;
        for (i = 0; i < states.size(); i++) {
            LuaState state = (LuaState) states.get(i);

            if (state != null) {
                if (state.getCPtrPeer() == L.getCPtrPeer())
                    return i;
            }
        }

        i = getNextStateIndex();

        states.set(i, L);

        return i;
    }

    /**
     * Method that creates a new instance of LuaState
     *
     * @return LuaState
     */
    public synchronized static LuaState newLuaState() {
        int i = getNextStateIndex();
        LuaState L = new LuaState(i);

        states.add(i, L);

        return L;
    }

    /**
     * removes the luaState from the states list
     *
     * @param idx
     */
    public synchronized static void removeLuaState(int idx) {
        states.add(idx, null);
    }

    /**
     * Non-public constructor.
     */
    private LuaStateFactory() {
    }
}