/*

  * $Id: AddAttributeModel.java 1305937 2012-03-27 18:15:15Z nlebas $

  *

  * 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.tiles.template;

 import java.io.IOException;

 import java.util.Deque;

 import org.apache.tiles.Attribute;

 import org.apache.tiles.Expression;

 import org.apache.tiles.ListAttribute;

 import org.apache.tiles.autotag.core.runtime.ModelBody;

 import org.apache.tiles.request.Request;

 /**

  * <p>

  * <strong>Add an element to the surrounding list. Equivalent to 'putAttribute',

  * but for list element.</strong>

  * </p>

  *

  * <p>

  * Add an element to the surrounding list. This tag can only be used inside

  * 'putListAttribute' or 'addListAttribute' tags. Value can come from a direct

  * assignment (value="aValue")

  * </p>

  *

  * @version $Rev: 1305937 $ $Date: 2012-03-28 05:15:15 +1100 (Wed, 28 Mar 2012) $

  * @since 2.2.0

  */

 public class AddAttributeModel {

     /**

      * Executes the operation.

      * @param value The value of the attribute. Use this parameter, or

      * expression, or body.

      * @param expression The expression to calculate the value from. Use this

      * parameter, or value, or body.

      * @param role A comma-separated list of roles. If present, the attribute

      * will be rendered only if the current user belongs to one of the roles.

      * @param type The type (renderer) of the attribute.

      * @param request The request.

      * @param modelBody The body.

      * @throws IOException If the body cannot be correctly evaluated.

      * @since 2.2.0

      */

     public void execute(Object value, String expression, String role,

             String type, Request request, ModelBody modelBody)

             throws IOException {

         Attribute attribute = new Attribute();

         Deque<Object> composeStack = ComposeStackUtil.getComposeStack(request);

         composeStack.push(attribute);

         String body = modelBody.evaluateAsString();

         attribute = (Attribute) composeStack.pop();

         addAttributeToList(attribute, composeStack, value, expression, body,

                 role, type);

     }

     /**

      * Adds the attribute to the containing list attribute.

      *

      * @param attribute The attribute to add to the list attribute.

      * @param composeStack The composing stack.

      * @param value The value of the attribute. Use this parameter, or

      * expression, or body.

      * @param expression The expression to calculate the value from. Use this

      * parameter, or value, or body.

      * @param body The body of the tag. Use this parameter, or value, or

      * expression.

      * @param role A comma-separated list of roles. If present, the attribute

      * will be rendered only if the current user belongs to one of the roles.

      * @param type The type (renderer) of the attribute.

      * @since 2.2.0

      */

     private void addAttributeToList(Attribute attribute,

             Deque<Object> composeStack, Object value, String expression,

             String body, String role, String type) {

         ListAttribute listAttribute = (ListAttribute) ComposeStackUtil

                 .findAncestorWithClass(composeStack, ListAttribute.class);

         if (listAttribute == null) {

             throw new NullPointerException("There is no ListAttribute in the stack");

         }

         if (value != null) {

             attribute.setValue(value);

         } else if (attribute.getValue() == null && body != null) {

             attribute.setValue(body);

         }

         if (expression != null) {

             attribute.setExpressionObject(Expression

                     .createExpressionFromDescribedExpression(expression));

         }

         if (role != null) {

             attribute.setRole(role);

         }

         if (type != null) {

             attribute.setRenderer(type);

         }

         listAttribute.add(attribute);

     }

 }