/*
 * $Id: LuaInvocationHandler.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.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;

/**
 * Class that implements the InvocationHandler interface. This class is used in
 * the LuaJava's proxy system. When a proxy object is accessed, the method
 * invoked is called from Lua
 *
 * @author Rizzato
 * @author Thiago Ponte
 */
public class LuaInvocationHandler implements InvocationHandler {
    private LuaObject obj;

    public LuaInvocationHandler(LuaObject obj) {
        this.obj = obj;
    }

    /**
     * Function called when a proxy object function is invoked.
     */
    @Override
    public Object invoke(Object proxy, Method method, Object[] args)
            throws LuaException {
        synchronized (obj.L) {
            String methodName = method.getName();
            LuaObject func = obj.getField(methodName);

            if (func.isNil()) {
                return null;
            }

            Class retType = method.getReturnType();
            Object ret;

            // Checks if returned type is void. if it is returns null.
            if (retType.equals(Void.class) || retType.equals(void.class)) {
                func.call(args, 0);
                ret = null;
            } else {
                ret = func.call(args, 1)[0];
                if (ret != null && ret instanceof Double) {
                    ret = LuaState.convertLuaNumber((Double) ret, retType);
                }
            }

            return ret;
        }
    }
}
