/*
 * 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.cocoon.forms.binding;

import org.apache.cocoon.forms.util.DomHelper;

import org.w3c.dom.Element;

/**
 * SetAttributeJXPathBindingBuilder provides a helper class for the Factory
 * implemented in {@link JXPathBindingManager} that helps construct the
 * actual {@link SetAttributeJXPathBinding} out of the configuration in the
 * provided configElement which looks like:
 * <pre><code>
 * <fb:set-attribute name="<i>attribute-name to set to</i>"
 *                      value="<i>attribute-value</i>"/>
 * </code></pre>
 *
 * @version $Id$
 */
public class SetAttributeJXPathBindingBuilder extends JXPathBindingBuilderBase {

    /**
     * Creates an instance of {@link SetAttributeJXPathBinding} according to
     * the attributes of the provided bindingElm.
     */
    public JXPathBindingBase buildBinding(Element bindingElm,
        JXPathBindingManager.Assistant assistant) throws BindingException {

        try {
            CommonAttributes commonAtts =
                JXPathBindingBuilderBase.getCommonAttributes(bindingElm);

            String attName = DomHelper.getAttribute(bindingElm, "name", null);
            String attValue = DomHelper.getAttribute(bindingElm, "value", null);

            // do inheritance
            SetAttributeJXPathBinding otherBinding = (SetAttributeJXPathBinding) assistant.getContext().getSuperBinding();
            if (otherBinding != null) {
                commonAtts = JXPathBindingBuilderBase.mergeCommonAttributes(otherBinding.getCommonAtts(), commonAtts);

                if (attName == null) {
                    attName = otherBinding.getId();
                }
                if (attValue == null) {
                    attValue = otherBinding.getValue();
                }
            }

            return new SetAttributeJXPathBinding(commonAtts, attName, attValue);
        } catch (BindingException e) {
            throw e;
        } catch (Exception e) {
            throw new BindingException("Error building set-attribute binding", e,
                                       DomHelper.getLocationObject(bindingElm));
        }
    }
}