package org.apache.lucene.analysis.ngram;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.
 */


import java.io.StringReader;

import org.apache.lucene.analysis.BaseTokenStreamTestCase;

/**
 * Tests {@link NGramTokenizer} for correctness.
 */
public class NGramTokenizerTest extends BaseTokenStreamTestCase {
    private StringReader input;
    
    @Override
    protected void setUp() throws Exception {
        super.setUp();
        input = new StringReader("abcde");
    }

    public void testInvalidInput() throws Exception {
        boolean gotException = false;
        try {        
            new NGramTokenizer(input, 2, 1);
        } catch (IllegalArgumentException e) {
            gotException = true;
        }
        assertTrue(gotException);
    }

    public void testInvalidInput2() throws Exception {
        boolean gotException = false;
        try {        
            new NGramTokenizer(input, 0, 1);
        } catch (IllegalArgumentException e) {
            gotException = true;
        }
        assertTrue(gotException);
    }

    public void testUnigrams() throws Exception {
        NGramTokenizer tokenizer = new NGramTokenizer(input, 1, 1);
        assertTokenStreamContents(tokenizer, new String[]{"a","b","c","d","e"}, new int[]{0,1,2,3,4}, new int[]{1,2,3,4,5}, 5 /* abcde */);
    }

    public void testBigrams() throws Exception {
        NGramTokenizer tokenizer = new NGramTokenizer(input, 2, 2);
        assertTokenStreamContents(tokenizer, new String[]{"ab","bc","cd","de"}, new int[]{0,1,2,3}, new int[]{2,3,4,5}, 5 /* abcde */);
    }

    public void testNgrams() throws Exception {
        NGramTokenizer tokenizer = new NGramTokenizer(input, 1, 3);
        assertTokenStreamContents(tokenizer,
          new String[]{"a","b","c","d","e", "ab","bc","cd","de", "abc","bcd","cde"}, 
          new int[]{0,1,2,3,4, 0,1,2,3, 0,1,2},
          new int[]{1,2,3,4,5, 2,3,4,5, 3,4,5},
          5 /* abcde */
        );
    }

    public void testOversizedNgrams() throws Exception {
        NGramTokenizer tokenizer = new NGramTokenizer(input, 6, 7);
        assertTokenStreamContents(tokenizer, new String[0], new int[0], new int[0], 5 /* abcde */);
    }
    
    public void testReset() throws Exception {
      NGramTokenizer tokenizer = new NGramTokenizer(input, 1, 1);
      assertTokenStreamContents(tokenizer, new String[]{"a","b","c","d","e"}, new int[]{0,1,2,3,4}, new int[]{1,2,3,4,5}, 5 /* abcde */);
      tokenizer.reset(new StringReader("abcde"));
      assertTokenStreamContents(tokenizer, new String[]{"a","b","c","d","e"}, new int[]{0,1,2,3,4}, new int[]{1,2,3,4,5}, 5 /* abcde */);
    }
}