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 * 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
 * under the License.
 */

package org.elasticsearch.index.analysis;

import org.apache.lucene.analysis.CharArraySet;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.commongrams.CommonGramsFilter;
import org.apache.lucene.analysis.commongrams.CommonGramsQueryFilter;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.env.Environment;
import org.elasticsearch.index.IndexSettings;

public class CommonGramsTokenFilterFactory extends AbstractTokenFilterFactory {

    private final CharArraySet words;

    private final boolean ignoreCase;

    private final boolean queryMode;

    public CommonGramsTokenFilterFactory(IndexSettings indexSettings, Environment env, String name, Settings settings) {
        super(indexSettings, name, settings);
        this.ignoreCase = settings.getAsBooleanLenientForPreEs6Indices(indexSettings.getIndexVersionCreated(), "ignore_case", false, deprecationLogger);
        this.queryMode = settings.getAsBooleanLenientForPreEs6Indices(indexSettings.getIndexVersionCreated(), "query_mode", false, deprecationLogger);
        this.words = Analysis.parseCommonWords(env, settings, null, ignoreCase);

        if (this.words == null) {
            throw new IllegalArgumentException("missing or empty [common_words] or [common_words_path] configuration for common_grams token filter");
        }
    }

    @Override
    public TokenStream create(TokenStream tokenStream) {
        CommonGramsFilter filter = new CommonGramsFilter(tokenStream, words);
        if (queryMode) {
            return new CommonGramsQueryFilter(filter);
        } else {
            return filter;
        }
    }
}