package org.jboss.weld.servlet.core.tomcat7;

import static org.jboss.weld.environment.servlet.util.Reflections.findDeclaredField;
import static org.jboss.weld.environment.servlet.util.Reflections.findDeclaredMethod;
import static org.jboss.weld.environment.servlet.util.Reflections.getFieldValue;
import static org.jboss.weld.environment.servlet.util.Reflections.invokeMethod;
import static org.jboss.weld.environment.servlet.util.Reflections.setFieldValue;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Map;

import javax.naming.Context;
import javax.naming.NamingException;
import javax.servlet.ServletContextEvent;

import org.apache.catalina.core.ApplicationContext;
import org.apache.catalina.core.ApplicationContextFacade;
import org.apache.catalina.core.DefaultInstanceManager;
import org.apache.catalina.core.StandardContext;
import org.apache.tomcat.InstanceManager;
import org.jboss.weld.environment.servlet.util.Reflections;
import org.jboss.weld.manager.api.WeldManager;

/**
 * @author <a href="mailto:matija.mazi@gmail.com">Matija Mazi</a>
 * 
 *         Forwards all calls in turn to two delegates: first to
 *         originalAnnotationProcessor, then to weldProcessor.
 */
public class WeldForwardingInstanceManager extends ForwardingInstanceManager {
	private final InstanceManager firstProcessor;
	private final InstanceManager secondProcessor;

	public WeldForwardingInstanceManager(
			InstanceManager originalAnnotationProcessor,
			InstanceManager weldProcessor) {
		this.firstProcessor = originalAnnotationProcessor;
		this.secondProcessor = weldProcessor;
	}

	@Override
	protected InstanceManager delegate() {
		return firstProcessor;
	}

	@Override
	public void destroyInstance(Object arg0) throws IllegalAccessException,
			InvocationTargetException {
		// TODO Auto-generated method stub
		super.destroyInstance(arg0);
		secondProcessor.destroyInstance(arg0);
	}

	@Override
	public void newInstance(Object arg0) throws IllegalAccessException,
			InvocationTargetException, NamingException {
		super.newInstance(arg0);
		secondProcessor.newInstance(arg0);
	}

	@Override
	public Object newInstance(String arg0, ClassLoader arg1)
			throws IllegalAccessException, InvocationTargetException,
			NamingException, InstantiationException, ClassNotFoundException {
		Object a = super.newInstance(arg0, arg1);
		secondProcessor.newInstance(a);
		return a;
	}

	@Override
	public Object newInstance(String arg0) throws IllegalAccessException,
			InvocationTargetException, NamingException, InstantiationException,
			ClassNotFoundException {
		Object a = super.newInstance(arg0);
		secondProcessor.newInstance(a);
		return a;
	}

	public static void replaceAnnotationProcessor(ServletContextEvent sce,
			WeldManager manager) {
		StandardContext stdContext = getStandardContext(sce);
		setAnnotationProcessor(stdContext, createInstance(manager, stdContext));
	}
	private static WeldForwardingInstanceManager createInstance(WeldManager manager, StandardContext stdContext)
	   {
	      try
	      {
	       
	         InstanceManager weldProcessor = new WeldInstanceManager(manager);
	         return new WeldForwardingInstanceManager(getAnnotationProcessor(stdContext), weldProcessor);
	      }
	      catch (Exception e)
	      {
	         throw new RuntimeException("Cannot create WeldForwardingAnnotationProcessor", e);
	      }
	   }
	private static StandardContext getStandardContext(ServletContextEvent sce) {
		try {
			// Hack into Tomcat to replace the AnnotationProcessor using
			// reflection to access private fields
			ApplicationContext appContext = (ApplicationContext) getContextFieldValue(
					(ApplicationContextFacade) sce.getServletContext(),
					ApplicationContextFacade.class);
			return (StandardContext) getContextFieldValue(appContext,
					ApplicationContext.class);
		} catch (Exception e) {
			throw new RuntimeException(
					"Cannot get StandardContext from ServletContext", e);
		}
	}

	private static <E> Object getContextFieldValue(E obj, Class<E> clazz)
			throws NoSuchFieldException, IllegalAccessException {
		Field f = clazz.getDeclaredField("context");
		f.setAccessible(true);
		return f.get(obj);
	}

	public static void restoreAnnotationProcessor(ServletContextEvent sce) {
		StandardContext stdContext = getStandardContext(sce);
		InstanceManager ap = getAnnotationProcessor(stdContext);
		if (ap instanceof WeldForwardingInstanceManager) {
			setAnnotationProcessor(stdContext,
					((WeldForwardingInstanceManager) ap).firstProcessor);
		}
	}

	private static InstanceManager getAnnotationProcessor(
			StandardContext stdContext) {
		return stdContext.getInstanceManager();
	}

	private static void setAnnotationProcessor(StandardContext stdContext,
			InstanceManager instanceManager) {
		stdContext.setInstanceManager(instanceManager);
	}

}