EDIT

// $Id$

/**

* Copyright (C) 2012 EDIT

* European Distributed Institute of Taxonomy

* http://www.e-taxonomy.eu

*

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.cdm.hibernate.search;

import org.apache.lucene.document.Document;

import org.apache.lucene.document.Field;

import org.apache.lucene.document.Field.Index;

import org.apache.lucene.document.Field.Store;

import org.apache.lucene.document.Field.TermVector;

import org.apache.lucene.document.SortedDocValuesField;

import org.apache.lucene.document.StringField;

import org.apache.lucene.util.BytesRef;

import org.hibernate.search.bridge.LuceneOptions;

import org.hibernate.search.bridge.TwoWayFieldBridge;

/**

 * This {@link TwoWayFieldBridge} allows to efficiently query for associated

 * entities which are not null. This field bridge works the following way:

 * <p>

 * It adds the id field to the document as if it would be done without the

 * intervention of this class, all field attributes are preserved, additionally

 * this field bridge also adds a field named <code>id.notNull</code> and stores

 * the term "true" for this field. So all associated entities which are not null

 * can now be queried by searching for <code>+id.notNull:true</code> which is

 * much more efficient than using range queries.

 * <p>

 * The <code>id.notNull</code> is stored with the following attributes :

 * {@link Store.NO},{@link Index.NOT_ANALYZED}, {@link TermVector.NO}.

 *

 * @author a.kohlbecker

 * @date Sep 21, 2012

 *

 */

public class NotNullAwareIdBridge implements TwoWayFieldBridge {

    public static final String NOT_NULL_VALUE = "1";

    public static final String NOT_NULL_FIELD_NAME = "notNull";

    public static String NULL_STRING = "";

    /**

     * @param name

     * @return

     */

    public static String notNullField(String name) {

        return name + "." + NOT_NULL_FIELD_NAME;

    }

    /* (non-Javadoc)

     * @see org.hibernate.search.bridge.FieldBridge#set(java.lang.String, java.lang.Object, org.apache.lucene.document.Document, org.hibernate.search.bridge.LuceneOptions)

     */

    @Override

    public void set(String name, Object value, Document document, LuceneOptions luceneOptions) {

        /*

         * DocumentBuilderIndexedEntity<T>.buildDocumentFields(Object, Document, PropertiesMetadata, Map<String,String>, Set<String>)

         * is adding the idField a second time even if it has already been set by an idFieldBrige. this might be fixed in a

         * more recent version of hibernate! TODO after hibernate update: check if we can remove this extra condition.

         * We are avoiding this by checking the document:

         *

         */

        if(name.endsWith("id") && document.getField(name) != null) { // id already set?

            return;

        }

        Field field = new StringField(

                name,

                String.valueOf(value.toString()),

                luceneOptions.getStore());

        document.add(field);

        Field sort_field = new SortedDocValuesField(

                name + "__sort",

                new BytesRef(value.toString()));

        LuceneDocumentUtility.setOrReplaceDocValueField(sort_field, document);

        Field notNullField = new StringField(

                notNullField(name),

                String.valueOf(NOT_NULL_VALUE),

                Store.NO

                );

        document.add(notNullField);

    }

    @Override

    public Object get(String name, Document document) {

        return document.get(name);

    }

    /* (non-Javadoc)

     * @see org.hibernate.search.bridge.TwoWayFieldBridge#objectToString(java.lang.Object)

     */

    @Override

    public String objectToString(Object object) {

        if(object == null){

            return NULL_STRING;

        } else {

            return object.toString();

        }

    }

}