/*

  * 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.convert;

 import javax.faces.component.PartialStateHolder;

 import javax.faces.component.UIComponent;

 import javax.faces.context.FacesContext;

 import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFConverter;

 import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFWebConfigParam;

 /**

  * see Javadoc of <a href="http://java.sun.com/j2ee/javaserverfaces/1.2/docs/api/index.html">JSF Specification</a>

  * 

  * @author Stan Silvert

  */

 @JSFConverter

 public class EnumConverter implements Converter, PartialStateHolder

 {

     public static final String CONVERTER_ID = "javax.faces.Enum";

     public static final String ENUM_ID = "javax.faces.converter.EnumConverter.ENUM";

     public static final String ENUM_NO_CLASS_ID = "javax.faces.converter.EnumConverter.ENUM_NO_CLASS";

     /**

      * If value is a String instance and this param is true, pass it directly without try any change.

      */

     @JSFWebConfigParam(name="org.apache.myfaces.ENUM_CONVERTER_ALLOW_STRING_PASSTROUGH", since="2.0.1", expectedValues="true,false",defaultValue="false")

     private static final String ALLOW_STRING_PASSTROUGH = "org.apache.myfaces.ENUM_CONVERTER_ALLOW_STRING_PASSTROUGH";

     // TODO: Find a valid generic usage -= Simon Lessard =-

     private Class targetClass;

     private boolean isTransient = false;

     /** Creates a new instance of EnumConverter */

     public EnumConverter()

     {

     }

     public EnumConverter(Class targetClass)

     {

         if (!targetClass.isEnum())

             throw new IllegalArgumentException("targetClass for EnumConverter must be an Enum");

         this.targetClass = targetClass;

     }

     public String getAsString(FacesContext facesContext, UIComponent uiComponent, Object value)

         throws ConverterException

     {

         if (facesContext == null)

             throw new NullPointerException("facesContext can not be null");

         if (uiComponent == null)

             throw new NullPointerException("uiComponent can not be null");

         checkTargetClass(facesContext, uiComponent, value);

         if (value == null)

             return null;

         if (value instanceof String

                 && _isPassThroughStringValues(facesContext))

         {

             // pass through the String value

             return (String) value;

         }

         // check if the value is an instance of the enum class

         if (targetClass.isInstance(value))

         {

             return ((Enum<?>) value).name();

         }

         Object[] params =

             new Object[] { value, firstConstantOfEnum(), _MessageUtils.getLabel(facesContext, uiComponent) };

         throw new ConverterException(_MessageUtils.getErrorMessage(facesContext, ENUM_ID, params));

     }

     public Object getAsObject(FacesContext facesContext, UIComponent uiComponent, String value)

         throws ConverterException

     {

         if (facesContext == null)

             throw new NullPointerException("facesContext");

         if (uiComponent == null)

             throw new NullPointerException("uiComponent");

         if (value == null)

             return null;

         value = value.trim();

         if (value.length() == 0)

             return null;

         checkTargetClass(facesContext, uiComponent, value);

         // we know targetClass and value can't be null, so we can use Enum.valueOf

         // instead of the hokey looping called for in the javadoc

         try

         {

             return Enum.valueOf(targetClass, value);

         }

         catch (IllegalArgumentException e)

         {

             Object[] params =

                     new Object[] { value, firstConstantOfEnum(), _MessageUtils.getLabel(facesContext, uiComponent) };

             throw new ConverterException(_MessageUtils.getErrorMessage(facesContext, ENUM_ID, params));

         }

     }

     private void checkTargetClass(FacesContext facesContext, UIComponent uiComponent, Object value)

     {

         if (targetClass == null)

         {

             Object[] params = new Object[] { value, _MessageUtils.getLabel(facesContext, uiComponent) };

             throw new ConverterException(_MessageUtils.getErrorMessage(facesContext, ENUM_NO_CLASS_ID, params));

         }

     }

     // find the first constant value of the targetClass and return as a String

     private String firstConstantOfEnum()

     {

         Object[] enumConstants = targetClass.getEnumConstants();

         if (enumConstants.length != 0)

             return enumConstants[0].toString();

         return ""; // if empty Enum

     }

     public void restoreState(FacesContext context, Object state)

     {

         if (state != null)

         {

             targetClass = (Class<?>)state;

         }

     }

     public Object saveState(FacesContext context)

     {

         if (!initialStateMarked())

         {

             return targetClass;

         }

         return null;

     }

     public void setTransient(boolean newTransientValue)

     {

         isTransient = newTransientValue;

     }

     public boolean isTransient()

     {

         return isTransient;

     }

     private boolean _initialStateMarked = false;

     public void clearInitialState()

     {

         _initialStateMarked = false;

     }

     public boolean initialStateMarked()

     {

         return _initialStateMarked;

     }

     public void markInitialState()

     {

         _initialStateMarked = true;

     }

     private boolean _isPassThroughStringValues(FacesContext facesContext)

     {

         String param = facesContext.getExternalContext().getInitParameter(ALLOW_STRING_PASSTROUGH);

         if (param != null)

         {

             return param.trim().equalsIgnoreCase("true");

         }

         // default: false

         return false;

     }

 }