/*
    * 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.view.facelets.tag.jsf;
  
  import javax.el.MethodExpression;
  import javax.faces.component.EditableValueHolder;
  import javax.faces.component.UIComponent;
  import javax.faces.context.FacesContext;
  import javax.faces.event.MethodExpressionValueChangeListener;
  import javax.faces.event.ValueChangeEvent;
  import javax.faces.validator.MethodExpressionValidator;
  import javax.faces.view.facelets.FaceletContext;
  import javax.faces.view.facelets.MetaRule;
  import javax.faces.view.facelets.Metadata;
  import javax.faces.view.facelets.MetadataTarget;
  import javax.faces.view.facelets.TagAttribute;
  
  import org.apache.myfaces.view.facelets.FaceletCompositionContext;
  
  /**
   * 
   * @author Jacob Hookom
   * @version $Id$
   */
  public final class EditableValueHolderRule extends MetaRule
  {
  
      final static class LiteralValidatorMetadata extends Metadata
      {
  
          private final String validatorId;
  
          public LiteralValidatorMetadata(String validatorId)
          {
              this.validatorId = validatorId;
          }
  
          public void applyMetadata(FaceletContext ctx, Object instance)
          {
              ((EditableValueHolder) instance).addValidator(ctx.getFacesContext().getApplication()
                      .createValidator(this.validatorId));
          }
      }
  
      final static class ValueChangedExpressionMetadata extends Metadata
      {
          private final TagAttribute attr;
  
          public ValueChangedExpressionMetadata(TagAttribute attr)
          {
              this.attr = attr;
          }
  
          public void applyMetadata(FaceletContext ctx, Object instance)
          {
              // From JSF 2.0 it is possible to have valueChangeListener method without ValueChangeEvent parameter. 
              // It seems that MethodExpressionValueChangeListener from API contains support for it but there is one big
              // problem - one-arg constructor will not preserve the current VariableMapper.
              // This is a problem when using facelets and <ui:decorate/> with EL params (see MYFACES-2541 for details).
              // So we must create two MethodExpressions here - both are created from the current 
              // facelets context and thus variable mapping will work.
              final MethodExpression methodExpressionOneArg = attr.getMethodExpression(ctx, null, VALUECHANGE_SIG);
              final MethodExpression methodExpressionZeroArg = attr.getMethodExpression(ctx, null, EMPTY_CLASS_ARRAY);
              if (FaceletCompositionContext.getCurrentInstance(ctx).isUsingPSSOnThisView())
              {
                  ((EditableValueHolder) instance).addValueChangeListener(
                        new PartialMethodExpressionValueChangeListener(methodExpressionOneArg, methodExpressionZeroArg));
              }
              else
              {
                  ((EditableValueHolder) instance).addValueChangeListener(
                          new MethodExpressionValueChangeListener(methodExpressionOneArg, methodExpressionZeroArg));
              }
          }
      }
  
      final static class ValidatorExpressionMetadata extends Metadata
      {
          private final TagAttribute attr;
  
          public ValidatorExpressionMetadata(TagAttribute attr)
          {
              this.attr = attr;
         }
 
         public void applyMetadata(FaceletContext ctx, Object instance)
         {
             if (FaceletCompositionContext.getCurrentInstance(ctx).isUsingPSSOnThisView())
             {
                 ((EditableValueHolder) instance).addValidator(new PartialMethodExpressionValidator(this.attr
                         .getMethodExpression(ctx, null, VALIDATOR_SIG)));
             }
             else
             {
                 ((EditableValueHolder) instance).addValidator(new MethodExpressionValidator(this.attr
                         .getMethodExpression(ctx, null, VALIDATOR_SIG)));
             }
         }
     }
 
     private final static Class<?>[] VALIDATOR_SIG = new Class[] { FacesContext.class, UIComponent.class, Object.class };
 
     private final static Class<?>[] VALUECHANGE_SIG = new Class[] { ValueChangeEvent.class };
     
     private final static Class<?>[] EMPTY_CLASS_ARRAY = new Class[0];
 
     public final static EditableValueHolderRule INSTANCE = new EditableValueHolderRule();
 
     public Metadata applyRule(String name, TagAttribute attribute, MetadataTarget meta)
     {
 
         if (meta.isTargetInstanceOf(EditableValueHolder.class))
         {
 
             if ("validator".equals(name))
             {
                 if (attribute.isLiteral())
                 {
                     return new LiteralValidatorMetadata(attribute.getValue());
                 }
                 else
                 {
                     return new ValidatorExpressionMetadata(attribute);
                 }
             }
 
             if ("valueChangeListener".equals(name))
             {
                 return new ValueChangedExpressionMetadata(attribute);
             }
 
         }
         return null;
     }
 
 }