/**
    * Copyright 2005-2013 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.rice.core.api.criteria;
  
  import org.apache.commons.lang.StringUtils;
  import org.kuali.rice.core.api.CoreConstants;
  import org.w3c.dom.Element;
  
  import javax.xml.bind.annotation.XmlAccessType;
  import javax.xml.bind.annotation.XmlAccessorType;
  import javax.xml.bind.annotation.XmlAnyElement;
  import javax.xml.bind.annotation.XmlAttribute;
  import javax.xml.bind.annotation.XmlRootElement;
  import javax.xml.bind.annotation.XmlType;
  import java.util.Collection;
  
  /**
   * An immutable predicate which represents an "is null" statement which is
   * evaluated the property defined by the property path on this predicate.
   * 
   * @see PredicateFactory for a convenient way to construct this class.
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org)
   *
   */
  @XmlRootElement(name = NullPredicate.Constants.ROOT_ELEMENT_NAME)
  @XmlAccessorType(XmlAccessType.NONE)
  @XmlType(name = NullPredicate.Constants.TYPE_NAME, propOrder = {
      CoreConstants.CommonElements.FUTURE_ELEMENTS
  })
  public final class NullPredicate extends AbstractPredicate implements PropertyPathPredicate {
  	
  	private static final long serialVersionUID = 2397296074921454859L;
  	
  	@XmlAttribute(name = CriteriaSupportUtils.PropertyConstants.PROPERTY_PATH)
  	private final String propertyPath;
  
      @SuppressWarnings("unused")
      @XmlAnyElement
      private final Collection<Element> _futureElements = null;
  
  	/**
       * Should only be invoked by JAXB.
       */
      @SuppressWarnings("unused")
      private NullPredicate() {
          this.propertyPath = null;
      }
      
      /**
  	 * Constructs a NullPredicate for the given propertyPath.
  	 * 
  	 * @param propertyPath the property path for the predicate, must not be null or blank
  	 * 
  	 * @throws IllegalArgumentException if the propertyPath is null or blank
  	 */
      NullPredicate(String propertyPath) {
      	if (StringUtils.isBlank(propertyPath)) {
  			throw new IllegalArgumentException("Property path cannot be null or blank.");
  		}
  		this.propertyPath = propertyPath;
      }
  
      @Override
      public String getPropertyPath() {
      	return propertyPath;
      }
          
  	/**
       * Defines some internal constants used on this class.
       */
      static class Constants {
          final static String ROOT_ELEMENT_NAME = "null";
          final static String TYPE_NAME = "NullType";
      }
  
      @Override
      public String toString() {
          return new StringBuilder(CriteriaSupportUtils.findDynName(this.getClass().getSimpleName()))
                  .append("(").append(this.getPropertyPath()).append(")").toString();
      }
  }