/*

  * 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.StateHolder;

 import javax.faces.component.UIComponent;

 import javax.faces.context.FacesContext;

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

 /**

  * 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, StateHolder {

     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";

     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");

         if (value == null) return "";

         checkTargetClass(facesContext, uiComponent, value);

         for (Object enumConstant : targetClass.getEnumConstants()) {

             if (enumConstant == value) return enumConstant.toString();

         }

         return value.toString();

     }

     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) {

         targetClass = (Class)state;

     }

     public Object saveState(FacesContext context) {

         return targetClass;

     }

     public void setTransient(boolean newTransientValue) {

         isTransient = newTransientValue;

     }

     public boolean isTransient() {

         return isTransient;

     }

 }