/**

  * Distribution License:

  * JSword is free software; you can redistribute it and/or modify it under

  * the terms of the GNU Lesser General Public License, version 2.1 or later

  * as published by the Free Software Foundation. This program is distributed

  * in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even

  * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

  * See the GNU Lesser General Public License for more details.

  *

  * The License is available on the internet at:

  *      http://www.gnu.org/copyleft/lgpl.html

  * or by writing to:

  *      Free Software Foundation, Inc.

  *      59 Temple Place - Suite 330

  *      Boston, MA 02111-1307, USA

  *

  * © CrossWire Bible Society, 2005 - 2016

  */

 package org.crosswire.jsword.index.lucene;

 import java.util.regex.Matcher;

 import java.util.regex.Pattern;

 import org.crosswire.jsword.index.query.AndNotQuery;

 import org.crosswire.jsword.index.query.AndQuery;

 import org.crosswire.jsword.index.query.BaseQuery;

 import org.crosswire.jsword.index.query.BlurQuery;

 import org.crosswire.jsword.index.query.NullQuery;

 import org.crosswire.jsword.index.query.Query;

 import org.crosswire.jsword.index.query.QueryBuilder;

 import org.crosswire.jsword.index.query.RangeQuery;

 /**

  * A query can have a optional range specifier and an optional blur specifier.

  * The range specifier can be +[range], -[range] or just [range]. This must

  * stand at the beginning of the query and may be surrounded by whitespace. The

  * blur specifier is either ~ or ~n, where ~ means adjacent verses, but ~n means

  * to blur by n verses.

  * 

  * @see gnu.lgpl.License The GNU Lesser General Public License for details.

  * @author DM Smith

  */

 public final class LuceneQueryBuilder implements QueryBuilder {

     /*

      * (non-Javadoc)

      * 

      * @see

      * org.crosswire.jsword.index.query.QueryBuilder#parse(java.lang.String)

      */

     public Query parse(String aSearch) {

         Query query = NULL_QUERY;

         String sought = aSearch;

         if (sought == null || sought.length() == 0) {

             return query;

         }

         int i = 0;

         Query range = null;

         String rangeModifier = "";

         // Look for a range +[...], -[...], or [...]

         Matcher rangeMatcher = RANGE_PATTERN.matcher(sought);

         if (rangeMatcher.find()) {

             rangeModifier = rangeMatcher.group(1);

             range = new RangeQuery(rangeMatcher.group(2));

             sought = sought.replace(rangeMatcher.group(), " ");

         }

         // Look for a blur ~n

         Matcher blurMatcher = BLUR_PATTERN.matcher(sought);

         if (blurMatcher.find()) {

             // Did we have ~ or ~n?

             int blurFactor = 1;

             String blur = blurMatcher.group(1);

             if (blur.length() > 0) {

                 blurFactor = Integer.parseInt(blur);

             }

             Query left = new BaseQuery(sought.substring(i, blurMatcher.start()));

             Query right = new BaseQuery(sought.substring(blurMatcher.end()));

             query = new BlurQuery(left, right, blurFactor);

         } else if (sought.length() > 0) {

             query = new BaseQuery(sought);

         }

         if (range != null && !NULL_QUERY.equals(query)) {

             if (rangeModifier.length() == 0 || rangeModifier.charAt(0) == '+') {

                 query = new AndQuery(range, query);

             } else {

                 // AndNot needs to be after what it is restricting

                 query = new AndNotQuery(query, range);

             }

         }

         return query;

     }

     /**

      * The pattern of a range. This is anything that is contained between a

      * leading [] (but not containing a [ or ]), with a + or - optional prefix,

      * perhaps surrounded by whitespace.

      */

     private static final Pattern RANGE_PATTERN = Pattern.compile("\\s*([-+]?)\\[([^\\[\\]]+)\\]\\s*");

     /**

      * The pattern of a blur. A '~', optionally followed by a number,

      * representing the number of verses.

      */

     private static final Pattern BLUR_PATTERN = Pattern.compile("\\s~(\\d*)?\\s");

     /**

      * A query that returns nothing.

      */

     private static final Query NULL_QUERY = new NullQuery();

 }