/*
    * 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;
     }
     
 }