/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you 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
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package org.apache.lucene.queryparser.classic;

import org.apache.lucene.index.Term;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.WildcardQuery;
import org.elasticsearch.index.mapper.FieldNamesFieldMapper;
import org.elasticsearch.index.query.ExistsQueryBuilder;
import org.elasticsearch.index.query.QueryShardContext;

public class ExistsFieldQueryExtension implements FieldQueryExtension {

    public static final String NAME = "_exists_";

    @Override
    public Query query(QueryShardContext context, String queryText) {
        final FieldNamesFieldMapper.FieldNamesFieldType fieldNamesFieldType =
            (FieldNamesFieldMapper.FieldNamesFieldType) context.getMapperService().fullName(FieldNamesFieldMapper.NAME);
        if (fieldNamesFieldType.isEnabled() == false) {
            // The field_names_field is disabled so we switch to a wildcard query that matches all terms
            return new WildcardQuery(new Term(queryText, "*"));
        }

        return ExistsQueryBuilder.newFilter(context, queryText);
    }
}
