/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the

  * "License"); you may not use this file except in compliance

  * with the License.  You may obtain a copy of the License at

  *

  *   http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing,

  * software distributed under the License is distributed on an

  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

  * KIND, either express or implied.  See the License for the

  * specific language governing permissions and limitations

  * under the License.

  */

 package javax.faces.event;

 import javax.el.ELContext;

 import javax.el.ELException;

 import javax.el.ExpressionFactory;

 import javax.el.MethodExpression;

 import javax.el.MethodNotFoundException;

 import javax.faces.component.StateHolder;

 import javax.faces.context.FacesContext;

 /**

  * See Javadoc of <a href="https://javaserverfaces.dev.java.net/nonav/docs/2.0/javadocs/javax/faces/event/

  * MethodExpressionValueChangeListener.html">JSF Specification</a>

  */

 public class MethodExpressionValueChangeListener implements ValueChangeListener, StateHolder

 {

     private static final Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[0];

     private static final Object[] EMPTY_PARAMS = new Object[0];

     private MethodExpression methodExpressionOneArg;

     private MethodExpression methodExpressionZeroArg;

     private boolean isTransient = false;

     /** Creates a new instance of MethodExpressionValueChangeListener */

     public MethodExpressionValueChangeListener()

     {

         // constructor for state-saving 

     }

     public MethodExpressionValueChangeListener(MethodExpression methodExpressionOneArg)

     {

         this.methodExpressionOneArg = methodExpressionOneArg;

         _createZeroArgsMethodExpression(methodExpressionOneArg); 

     }

     public MethodExpressionValueChangeListener(MethodExpression methodExpressionOneArg,

                                                MethodExpression methodExpressionZeroArg)

     {

         this.methodExpressionOneArg = methodExpressionOneArg;

         if (methodExpressionZeroArg != null) 

         {

             this.methodExpressionZeroArg = methodExpressionZeroArg;

         }

         else

         {

             _createZeroArgsMethodExpression(methodExpressionOneArg);

         }

     }

     public void processValueChange(ValueChangeEvent event) throws AbortProcessingException

     {

         try

         {

             try

             {

                 // call to the one argument MethodExpression

                 Object[] params = new Object[] { event };

                 methodExpressionOneArg.invoke(getElContext(), params);

             }

             catch (MethodNotFoundException mnfe)

             {

                 // call to the zero argument MethodExpression

                 methodExpressionZeroArg.invoke(getElContext(), EMPTY_PARAMS);

             }

         }

         catch (ELException e)

         {

             // "... If that fails for any reason, throw an AbortProcessingException,

             // including the cause of the failure ..."

             // -= Leonardo Uribe =- after discussing this topic on MYFACES-3199, the conclusion is the part is an advice

             // for the developer implementing a listener in a method expressions that could be wrapped by this class.

             // The spec wording is poor but, to keep this coherently with ExceptionHandler API,

             // the spec and code on UIViewRoot we need:

             // 2a) "exception is instance of APE or any of the causes of the exception are an APE, 

             // DON'T publish ExceptionQueuedEvent and terminate processing for current event".

             // 2b) for any other exception publish ExceptionQueuedEvent and continue broadcast processing.

             Throwable cause = e.getCause();

             AbortProcessingException ape = null;

             if (cause != null)

             {

                 do

                 {

                     if (cause instanceof AbortProcessingException)

                     {

                         ape = (AbortProcessingException) cause;

                         break;

                     }

                     cause = cause.getCause();

                 }

                 while (cause != null);

             }

             if (ape != null)

             {

                 // 2a) "exception is instance of APE or any of the causes of the exception are an APE, 

                 // DON'T publish ExceptionQueuedEvent and terminate processing for current event".

                 // To do this throw an AbortProcessingException here, later on UIViewRoot.broadcastAll,

                 // this exception will be received and stored to handle later.

                 throw ape;

             }

             //for any other exception publish ExceptionQueuedEvent and continue broadcast processing.

             throw e;

             //Throwable cause = e.getCause();

             //if (cause == null)

             //{

             //    cause = e;

             //}

             //if (cause instanceof AbortProcessingException)

             //{

             //    throw (AbortProcessingException) cause;

             //}

             //else

             //{

             //    throw new AbortProcessingException(cause);

             //}

         }

     }

     public void restoreState(FacesContext context, Object state)

     {

         methodExpressionOneArg = (MethodExpression) ((Object[]) state)[0];

         methodExpressionZeroArg = (MethodExpression) ((Object[]) state)[1];

     }

     public Object saveState(FacesContext context)

     {

         return new Object[] {methodExpressionOneArg, methodExpressionZeroArg};

     }

     public void setTransient(boolean newTransientValue)

     {

         isTransient = newTransientValue;

     }

     public boolean isTransient()

     {

         return isTransient;

     }

     private ELContext getElContext()

     {

         return getFacesContext().getELContext();

     }

     private FacesContext getFacesContext()

     {

         return FacesContext.getCurrentInstance();

     }

     /**

      * Creates a {@link MethodExpression} with no params and with the same Expression as 

      * param <code>methodExpression</code>

      * <b>WARNING!</b> This method creates new {@link MethodExpression} with expressionFactory.createMethodExpression.

      * That means is not decorating MethodExpression passed as parameter -

      * support for EL VariableMapper will not be available!

      * This is a problem when using facelets and <ui:decorate/> with EL params (see MYFACES-2541 for details).

      */

     private void _createZeroArgsMethodExpression(MethodExpression methodExpression)

     {

         ExpressionFactory expressionFactory = getFacesContext().getApplication().getExpressionFactory();

         this.methodExpressionZeroArg = expressionFactory.createMethodExpression(getElContext(), 

                   methodExpression.getExpressionString(), Void.class, EMPTY_CLASS_ARRAY);

     }

 }