/*

  * 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 org.apache.myfaces.taglib.core;

 import javax.el.ELContext;

 import javax.el.ValueExpression;

 import javax.faces.component.StateHolder;

 import javax.faces.component.UIComponent;

 import javax.faces.context.FacesContext;

 import javax.faces.convert.Converter;

 import javax.faces.convert.ConverterException;

 /**

  * This class is used in conjunction with ConverterImplTag. 

  * 

  * When a tag like this is in a jsp page:

  * 

  * <f:converter binding="#{mybean}"/>

  *  

  *  or

  *  

  * <f:converter converterId="#{'anyid'}" binding="#{mybean}"/>

  * 

  * The value of mybean could be already on the context, so this

  * converter avoid creating a new variable and use the previous one.

  * 

  * @author Leonardo Uribe (latest modification by $Author$)

  * @version $Revision$ $Date$ 

  */

 public class DelegateConverter implements Converter, StateHolder

 {

     private ValueExpression _converterId;

     private ValueExpression _binding;

     private String _converterIdString = null;

     public DelegateConverter()

     {

     }

     public DelegateConverter(ValueExpression id, ValueExpression binding, String converterIdString)

     {

         super();

         _converterId = id;

         _binding = binding;

         _converterIdString = converterIdString;

     }

     public boolean isTransient()

     {

         return false;

     }

     public void restoreState(FacesContext facesContext, Object state)

     {

         Object[] values = (Object[]) state;

         _converterId = (ValueExpression) values[0];

         _binding = (ValueExpression) values[1];

         _converterIdString = (String) values[2];

     }

     public Object saveState(FacesContext facesContext)

     {

         Object[] values = new Object[3];

         values[0] = _converterId;

         values[1] = _binding;

         values[2] = _converterIdString;

         return values;

     }

     public void setTransient(boolean arg0)

     {

         // Do nothing        

     }

     public Object getAsObject(FacesContext facesContext, UIComponent component,

             String value)

     {

         return _getDelegate().getAsObject(facesContext, component, value);

     }

     public String getAsString(FacesContext facesContext, UIComponent component,

             Object value)

     {

         return _getDelegate().getAsString(facesContext, component, value);

     }

     private Converter _getDelegate()

     {

         return _createConverter();

     }

     private Converter _createConverter()

     {

         Converter converter = null;

         FacesContext facesContext = FacesContext.getCurrentInstance();

         ELContext elContext = facesContext.getELContext();

         // try to create the converter from the binding expression first, and then from

         // the converterId

         if (_binding != null)

         {

             try

             {

                 converter = (Converter) _binding.getValue(elContext);

                 if (converter != null)

                 {

                     return converter;

                 }

             }

             catch (Exception e)

             {

                 throw new ConverterException("Exception creating converter using binding", e);

             }

         }

         if ((_converterId != null) || (_converterIdString != null))

         {

             try

             {

                 if (null != _converterIdString)

                 {

                     converter = facesContext.getApplication().createConverter(_converterIdString);

                 }

                 else

                 {

                     String converterId = (String) _converterId.getValue(elContext);

                     converter = facesContext.getApplication().createConverter(converterId);

                 }

                 // with binding no converter was created, set its value with the converter

                 // created using the converterId

                 if (converter != null && _binding != null)

                 {

                     _binding.setValue(elContext, converter);

                 }

             }

             catch (Exception e)

             {

                 throw new ConverterException("Exception creating converter with converterId: " + _converterId, e);

             }

         }

         if (converter == null)

         {

             throw new IllegalStateException("Could not create converter. Please specify a valid converterId" +

                     " or a non-null binding.");

         }

         return converter;

     }

 }