/*
    * Copyright 2004-2009 the original author or authors.
    *
    * 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.springmodules.validation.bean.conf.loader.xml.handler;
  
  import org.springframework.util.StringUtils;
  import org.springmodules.validation.bean.conf.ValidationConfigurationException;
  import org.springmodules.validation.bean.rule.AbstractValidationRule;
  import org.springmodules.validation.bean.rule.ExpressionValidationRule;
  import org.w3c.dom.Element;
  
  /**
   * An {@link AbstractClassValidationElementHandler} that can handle class elements that represent valang validation rules.
   * This handler creates a valang conditoin out of a <valang> element.
   *
   * @author Uri Boness
   */
  public class ExpressionClassValidationElementHandler extends AbstractClassValidationElementHandler {
  
      private static final String ELEMENT_NAME = "expression";
  
      private static final String CONDITION_ATTR = "condition";
  
      /**
       * Constructs a new ExpressionClassValidationElementHandler.
       */
      public ExpressionClassValidationElementHandler(String namespaceUri) {
          super(ExpressionClassValidationElementHandler.ELEMENT_NAME, namespaceUri);
      }
  
      protected AbstractValidationRule createValidationRule(Element element) {
          String expression = element.getAttribute(CONDITION_ATTR);
          if (!StringUtils.hasText(expression)) {
              throw new ValidationConfigurationException("Element '" + ELEMENT_NAME + "' must have a '" + CONDITION_ATTR + "' attribute");
          }
          return new ExpressionValidationRule(getConditionExpressionParser(), expression);
      }
  
  }