/*

  * Copyright 2001,2004 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.commons.scaffold.lucene;

 import java.util.ArrayList;

 import java.util.Collection;

 import java.util.Enumeration;

 import java.util.HashMap;

 import org.apache.commons.beanutils.BeanUtils;

 import org.apache.commons.scaffold.lang.PopulateException;

 import org.apache.lucene.document.Document;

 import org.apache.lucene.document.Field;

 import org.apache.lucene.search.Hits;

  /**

   * General purpose utility methods related to Hits

   *

   * @author Craig R. McClanahan

   * @author Ted Husted

   * @version $Revision: 155464 $ $Date: 2005-02-26 13:26:54 +0000 (Sat, 26 Feb 2005) $

   */

  public class SearchUtils {

     /**

      * Populate the properties of the specified JavaBean from the specified

      * Lucene document, based on matching each parameter name against the

      * corresponding JavaBeans "property setter" methods in the bean's class.

      * See <code>BeanUtils.CopyProperites</code> for more about automatic 

      * conversion between types.

      *

      * @param bean The JavaBean whose properties are to be set

      * @param document The Lucene document whose parameters are to be used

      * to populate bean properties

      * @exception PopulateException if an exception is thrown while setting

      * property values

      */

     public static void populate(

             Object bean,

             Document document)

         throws PopulateException {

         // Build a list of relevant fields and values

         HashMap properties = new HashMap();

         // Iterator of field names

         Enumeration fields = document.fields();

         while (fields.hasMoreElements()) {

             Field field = (Field) fields.nextElement();

             properties.put(field.name(),field.stringValue());

         }

         // Set the corresponding properties of our bean

         try {

             BeanUtils.copyProperties(bean, properties);

         } catch (Throwable t) {

             throw new PopulateException(t);

         }

     } // end populate()

     /**

       * Return a ArrayList of hits by looping and calling populate.

       * No assumptions are made about fields in document. Each is

       * processed with a separate call to populate. Whatever fields

       * in each document that match the target bean will be

       * transferred.

       *

       * @param hits The Hits whose documents are to be used

       * to populate bean properties

       * @param target An instance of the bean to populate

       * @exception PopulateException if an exception is thrown while setting

       * property values, populating the bean, or accessing the Hits

       */

      public static Collection getCollection(

             Object target,

             Hits hits)

         throws PopulateException {

         // Use ArrayList to maintain sequence

         ArrayList list = new ArrayList();

         // Acquire target class

         Class factory = target.getClass();

         try {

             // Scroll to each document; populate bean, and add to list

             for (int i=0; i<hits.length(); ++i) {

                 Object bean = factory.newInstance();

                 Document doc = hits.doc(i);

                 populate(bean,doc);

                 list.add(bean);

             }

         } catch (Throwable t) {

             throw new PopulateException(t);

         }

         return ((Collection) list);

     } // end getCollection()

 } // end SearchUtils