package org.kuali.rice.krms.framework.engine;

 import javax.swing.event.EventListenerList;

 import org.kuali.rice.krms.api.engine.ExecutionEnvironment;

 import org.kuali.rice.krms.api.engine.ExecutionFlag;

 import org.kuali.rice.krms.api.engine.ResultEvent;

 import org.kuali.rice.krms.framework.engine.result.EngineResultListener;

 import org.kuali.rice.krms.framework.engine.result.Log4jResultListener;

 import org.kuali.rice.krms.framework.engine.result.ResultListener;

 public class ResultLogger {

         private EventListenerList listenerList = new EventListenerList();

         private ResultLogger(){}

         /*using inner class provides thread safety.         */

         private static class KRMSLoggerLoader{

                 private static final ResultLogger INSTANCE = new ResultLogger();

         }

         public static ResultLogger getInstance(){

                 return KRMSLoggerLoader.INSTANCE;

         }

         public void addListener(ResultListener l) {

                 listenerList.add(ResultListener.class, l);                

         }

         public void removeListener(ResultListener l){

                 listenerList.remove(ResultListener.class, l);

         }

         /**

          * This method is just for the POC.

          * In the real world, adding listeners will be performed elsewhere.

          */

         public void init(){

                 addListener(new EngineResultListener());

                 addListener(new Log4jResultListener());

         }

         public void logResult(ResultEvent event){

                 if (isEnabled(event.getEnvironment())){

                         // fire event to listeners

                         Object[] listeners = listenerList.getListenerList();

                         for (int i=1; i<listeners.length; i+=2){

                                 ((ResultListener) listeners[i]).handleEvent(event);

                         }

                 }

         }

         public boolean isEnabled(ExecutionEnvironment environment){

             return (

                     environment != null 

                     && environment.getExecutionOptions() != null 

                     && environment.getExecutionOptions().getFlag(ExecutionFlag.LOG_EXECUTION)

             );

         }

 }