/*
 * Copyright (c) 2017 Data and Web Science Group, University of Mannheim, Germany (http://dws.informatik.uni-mannheim.de/)
 *
 * 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 de.uni_mannheim.informatik.dws.winter.similarity.string;

import com.wcohen.ss.Jaccard;
import com.wcohen.ss.tokens.SimpleTokenizer;
import org.apache.commons.lang3.StringUtils;

import de.uni_mannheim.informatik.dws.winter.similarity.SimilarityMeasure;

/**
 * {@link SimilarityMeasure}, that calculates the Jaccard similarity between two
 * strings.
 * 
 * @author Oliver Lehmberg (oli@dwslab.de)
 * 
 */
public class TokenizingJaccardSimilarity extends SimilarityMeasure<String> {

	private static final long serialVersionUID = 1L;

	/**
	 * Calculates similarity between the first and second string.
	 * @param first
	 * 			the first string (can be null)
	 * @param second
	 * 			the second string (can be null)
	 * @return the similarity score between the first and second string
	 */
	@Override
	public double calculate(String first, String second) {
		if(StringUtils.isEmpty(first) || StringUtils.isEmpty(second)) {
			return 0.0;
		} else {
			Jaccard j = new Jaccard(new SimpleTokenizer(true, true));
			return j.score(first, second);
		}
	}

}
