/*******************************************************************************
 * Copyright (c) 2000-present Liferay, Inc. All rights reserved.
 *
 * 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.
 *
 *******************************************************************************/
package com.liferay.ide.server.core.proxy;

import com.liferay.ide.server.core.LiferayServerCore;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.Platform;


/**
 * @author Gregory Amerson
 */
public abstract class PortalSupportProxy implements InvocationHandler
{
    protected ClassLoader previousClassLoader;
    protected URLClassLoader proxyClassLoader;
    protected Object serviceObject;

    protected void configureClassloader() throws CoreException {
        if (proxyClassLoader == null) {
            proxyClassLoader = createClassLoader();
        }

        ClassLoader currentClassLoader = Thread.currentThread().getContextClassLoader();

        if (currentClassLoader.equals(proxyClassLoader)) {
            return;
        }
        else {
            previousClassLoader = currentClassLoader;
            Thread.currentThread().setContextClassLoader(proxyClassLoader);
        }

    }

    protected URLClassLoader createClassLoader() throws CoreException
    {
        List<URL> urls = new ArrayList<URL>();

        urls.add( LiferayServerCore.getPortalSupportLibURL() );

        for( URL url : getProxyClasspath() )
        {
            urls.add( url );
        }

        return new URLClassLoader( urls.toArray( new URL[0] ), Platform.class.getClassLoader() );
    }

    protected abstract URL[] getProxyClasspath() throws CoreException;

    protected Object getServiceObject() throws Exception {

        if (serviceObject == null) {
            //serviceObject = ScriptingCore.getGroovyScriptingSupport().newInstanceFromFile( getGroovyFile() );
        }

        return serviceObject;
    }

    public Object invoke( Object proxy, Method method, Object[] args ) throws Throwable
    {
        Object retval = null;
        Throwable error = null;

        configureClassloader();

        try
        {
            Object serviceObject = getServiceObject();

            Method serviceMethod = serviceObject.getClass().getMethod( method.getName(), method.getParameterTypes() );

            retval = serviceMethod.invoke( serviceObject, args );
        }
        catch( Throwable t )
        {
            LiferayServerCore.logError( "Error in proxy method " + method.getName(), t); //$NON-NLS-1$
            error = t;
        }
        finally
        {
            unconfigureClassloader();
        }

        if( error != null )
        {
            throw new RuntimeException( "Error in workflow validation proxy.", error.getCause() ); //$NON-NLS-1$
        }

        return retval;
    }

    protected void unconfigureClassloader()
    {
        if( previousClassLoader != null )
        {
            Thread.currentThread().setContextClassLoader( previousClassLoader );
        }
        else
        {
            Thread.currentThread().setContextClassLoader( this.getClass().getClassLoader() );
        }
    }
}