package org.jboss.weld.environment.jetty7;


import org.eclipse.jetty.servlet.FilterHolder;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;
import org.eclipse.jetty.util.log.Log;
import org.jboss.weld.environment.jetty.JettyWeldInjector;
import org.jboss.weld.environment.servlet.Listener;
import org.jboss.weld.manager.api.WeldManager;

import javax.servlet.Filter;
import javax.servlet.Servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletException;
import java.util.EventListener;

/**
 * Jetty 7 ServletContextHandler Decorator that performs the injection of weld resources
 */
public class WeldDecorator implements ServletContextHandler.Decorator {

  private ServletContext sco;
  private JettyWeldInjector injector;

  public WeldDecorator(ServletContext sco)
  {
    this.sco = sco;
  }

  @Override
  public <T extends Filter> T decorateFilterInstance(T filter) throws ServletException
  {
    return inject(filter);
  }

  @Override
  public <T extends Servlet> T decorateServletInstance(T servlet) throws ServletException
  {
    return inject(servlet);
  }

  @Override
  public <T extends EventListener> T decorateListenerInstance(T listener) throws ServletException
  {
    // preemptively invoke the Weld Listener
    if (listener instanceof Listener)
    {
       return initializeWeld(listener);
    }
    else
    {
       return inject(listener);
    }
  }

  @Override
  public void decorateFilterHolder(FilterHolder filter) throws ServletException
  {

  }

  @Override
  public void decorateServletHolder(ServletHolder servlet) throws ServletException
  {

  }

  @Override
  public void destroyServletInstance(Servlet s)
  {
    release(s);
  }

  @Override
  public void destroyFilterInstance(Filter f)
  {
    release(f);
  }

  @Override
  public void destroyListenerInstance(EventListener f)
  {
    release(f);
  }

  protected <T> T inject(T injectable)
  {
     if (injector == null)
     {
        initializeInjector();
     }

     if (injector == null)
     {
        Log.warn("Can't find WeldManager in the servlet context; injection is not available for Servlet component: " + injectable);
     }
     else
     {
        injector.inject(injectable);
     }
     return injectable;
  }

  protected void initializeInjector()
  {
     WeldManager manager = (WeldManager) sco.getAttribute(org.jboss.weld.environment.servlet.Listener.BEAN_MANAGER_ATTRIBUTE_NAME);
     if (manager != null)
     {
        injector = new JettyWeldInjector(manager);
     }
  }

  protected <T extends EventListener> T initializeWeld(T weldListener)
  {
     ((Listener) weldListener).contextInitialized(new ServletContextEvent(sco));
     return weldListener;
  }

  protected void release(Object injectable)
  {
     if (injector != null)
     {
        injector.release(injectable);
     }
  }
}