/*
   
       dsh-piccolo-identify  Piccolo2D nodes for identifiable beans.
       Copyright (c) 2007-2013 held jointly by the individual authors.
   
       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 3 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; with out even the implied warranty of MERCHANTABILITY or
      FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
      License for more details.
  
      You should have received a copy of the GNU Lesser General Public License
      along with this library;  if not, write to the Free Software Foundation,
      Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA.
  
      > http://www.fsf.org/licensing/licenses/lgpl.html
      > http://www.opensource.org/licenses/lgpl-license.php
  
  */
  package org.dishevelled.piccolo.identify;
  
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  
  import org.apache.commons.scxml.Context;
  import org.apache.commons.scxml.ErrorReporter;
  import org.apache.commons.scxml.Evaluator;
  import org.apache.commons.scxml.EventDispatcher;
  import org.apache.commons.scxml.SCXMLExecutor;
  import org.apache.commons.scxml.SCXMLListener;
  import org.apache.commons.scxml.TriggerEvent;
  
  import org.apache.commons.scxml.env.SimpleDispatcher;
  
  import org.apache.commons.scxml.env.jexl.JexlContext;
  import org.apache.commons.scxml.env.jexl.JexlEvaluator;
  
  import org.apache.commons.scxml.model.ModelException;
  import org.apache.commons.scxml.model.SCXML;
  import org.apache.commons.scxml.model.Transition;
  import org.apache.commons.scxml.model.TransitionTarget;
  
  /**
   * State machine support class, meant to be delegated to.  Provided
   * an instance of a state machine, this class manages a state machine
   * executor, allows delegators to fire state machine events, and responds
   * to transition entry events by invoking methods on the delegating class
   * via reflection.  Most methods on this class fail silently instead of
   * throwing state machine- or reflection-specific exceptions.
   *
   * @author  Michael Heuer
   * @version $Revision$ $Date$
   */
  final class StateMachineSupport
  {
      /** Object to delegate to. */
      private final Object delegator;
  
      /** State machine executor for this support class. */
      private final SCXMLExecutor executor;
  
  
      /**
       * Create a new state machine support class to be delegated to
       * by the specified delegator with the specified state machine.
       *
       * @param delegator object delegating to this state machine support
       *    class, must not be null
       * @param stateMachine state machine for this support class, must
       *    not be null
       */
      StateMachineSupport(final Object delegator, final SCXML stateMachine)
      {
          if (delegator == null)
          {
              throw new IllegalArgumentException("delegator must not be null");
          }
          if (stateMachine == null)
          {
              throw new IllegalArgumentException("stateMachine must not be null");
          }
          this.delegator = delegator;
  
          Evaluator evaluator = new JexlEvaluator();
          EventDispatcher dispatcher = new SimpleDispatcher();
          ErrorReporter errorReporter = new NoopErrorReporter();
          Context rootContext = new JexlContext();
          SCXMLListener listener = new SCXMLListener()
              {
                  @Override
                  public void onEntry(final TransitionTarget entered)
                  {
                      invoke(entered.getId());
                  }
  
                 @Override
                 public void onExit(final TransitionTarget exited)
                 {
                     // empty
                 }
 
                 @Override
                 public void onTransition(final TransitionTarget to,
                                          final TransitionTarget from,
                                          final Transition transition)
                 {
                     // empty
                 }
             };
 
         executor = new SCXMLExecutor(evaluator, dispatcher, errorReporter);
         executor.setStateMachine(stateMachine);
         executor.setSuperStep(false);
         executor.setRootContext(rootContext);
         executor.addListener(stateMachine, listener);
 
         try
         {
             executor.go();
         }
         catch (ModelException e)
         {
             // ignore
         }
     }
 
     /**
      * Reset the state machine for this state machine support class to its
      * "initial" configuration (fails silently).
      */
     void resetStateMachine()
     {
         try
         {
             executor.reset();
         }
         catch (ModelException e)
         {
             // ignore
         }
     }
 
     /**
      * Fire an event with the specified event name on the state machine for
      * this state machine support class (fails silently).
      *
      * @param eventName event name, must not be null
      */
     void fireStateMachineEvent(final String eventName)
     {
         if (eventName == null)
         {
             throw new IllegalArgumentException("eventName must not be null");
         }
         try
         {
             TriggerEvent event = new TriggerEvent(eventName, TriggerEvent.SIGNAL_EVENT, null);
             executor.triggerEvents(new TriggerEvent[] { event });
         }
         catch (ModelException e)
         {
             // ignore
         }
     }
 
     /**
      * Invoke the no-argument method with the following name
      * on the object delegating to this state machine support class
      * (fails silently).
      *
      * @param methodName method name to invoke on the object
      *    delegating to this state machine support class
      */
     private void invoke(final String methodName)
     {
         try
         {
             Class<?> c = delegator.getClass();
             Method method = c.getDeclaredMethod(methodName, new Class[0]);
             method.setAccessible(true);
             method.invoke(delegator, new Object[0]);
         }
         catch (SecurityException se)
         {
             // ignore
         }
         catch (NoSuchMethodException nsme)
         {
             // ignore
         }
         catch (IllegalArgumentException iae)
         {
             // ignore
         }
         catch (IllegalAccessException iae)
         {
             // ignore
         }
         catch (InvocationTargetException ite)
         {
             // ignore
         }
     }
 
     /**
      * No-op error reporter.
      */
     private class NoopErrorReporter
         implements ErrorReporter
     {
 
         @Override
         public void onError(final String errorCode,
                             final String errorDetail,
                             final Object errorContext)
         {
             // empty
         }
     }
 }