// Copyright 2007, 2008, 2009 The Apache Software Foundation

 //

 // Licensed 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.tapestry5.internal;

 import org.apache.tapestry5.*;

 import org.apache.tapestry5.dom.Element;

 import org.apache.tapestry5.services.Environment;

 import org.apache.tapestry5.services.FormSupport;

 /**

  * Default implementation that writes an attribute into fields or labels that are in error.

  */

 public final class DefaultValidationDecorator extends BaseValidationDecorator

 {

     private final Environment environment;

     private final Asset spacerAsset;

     private final MarkupWriter markupWriter;

     /**

      * @param environment  used to locate objects and services during the render

      * @param spacerAsset  asset for a one-pixel spacer image used as a placeholder for the error marker icon

      * @param markupWriter

      */

     public DefaultValidationDecorator(Environment environment, Asset spacerAsset, MarkupWriter markupWriter)

     {

         this.environment = environment;

         this.spacerAsset = spacerAsset;

         this.markupWriter = markupWriter;

     }

     @Override

     public void insideField(Field field)

     {

         if (inError(field)) addErrorClassToCurrentElement();

     }

     @Override

     public void insideLabel(Field field, Element element)

     {

         if (field == null) return;

         if (inError(field)) element.addClassName(CSSClassConstants.ERROR);

     }

     /**

      * Writes an icon for field after the field.  The icon has the same id as the field, with ":icon" appended. This is

      * expected by the default client-side JavaScript.  The icon's src is a blank spacer image (this is to allow the

      * image displayed to be overridden via CSS).     The icon's CSS class is "t-error-icon", with "t-invisible" added

      * if the field is not in error when rendered.  If client validation is not enabled for the form containing the

      * field and the field is not in error, then the error icon itself is not rendered.

      *

      * @param field which just completed rendering itself

      */

     @Override

     public void afterField(Field field)

     {

         boolean inError = inError(field);

         boolean clientValidationEnabled = getFormSupport().isClientValidationEnabled();

         if (inError || clientValidationEnabled)

         {

             String iconId = field.getClientId() + "-icon";

             String cssClass = inError ? "t-error-icon" : "t-error-icon t-invisible";

             markupWriter.element("img",

                                  "src", spacerAsset.toClientURL(),

                                  "alt", "",

                                  "class", cssClass,

                                  "id", iconId);

             markupWriter.end();

         }

     }

     private FormSupport getFormSupport()

     {

         return environment.peekRequired(FormSupport.class);

     }

     private boolean inError(Field field)

     {

         ValidationTracker tracker = environment.peekRequired(ValidationTracker.class);

         return tracker.inError(field);

     }

     private void addErrorClassToCurrentElement()

     {

         markupWriter.getElement().addClassName(CSSClassConstants.ERROR);

     }

 }