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 org.apache.lucene.analysis.Token;

import java.io.StringReader;
import java.util.ArrayList;

import junit.framework.TestCase;

/**
 * Tests {@link NGramTokenizer} for correctness.
 * @author Otis Gospodnetic
 */
public class NGramTokenizerTest extends TestCase {
    private StringReader input;
    private ArrayList tokens = new ArrayList();
    
    public void 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);
        
        Token token = null;
        do { 
            token = tokenizer.next();
            if (token != null) {
                tokens.add(token.toString());
//                System.out.println(token.termText());
//                System.out.println(token);
//                Thread.sleep(1000);
            }
        } while (token != null);

        assertEquals(5, tokens.size());
        ArrayList exp = new ArrayList();
        exp.add("(a,0,1)"); exp.add("(b,1,2)"); exp.add("(c,2,3)"); exp.add("(d,3,4)"); exp.add("(e,4,5)");
        assertEquals(exp, tokens);
    }

    public void testBigrams() throws Exception {
        NGramTokenizer tokenizer = new NGramTokenizer(input, 2, 2);
        
        Token token = null;
        do { 
            token = tokenizer.next();
            if (token != null) {
                tokens.add(token.toString());
//                System.out.println(token.termText());
//                System.out.println(token);
//                Thread.sleep(1000);
            }
        } while (token != null);

        assertEquals(4, tokens.size());
        ArrayList exp = new ArrayList();
        exp.add("(ab,0,2)"); exp.add("(bc,1,3)"); exp.add("(cd,2,4)"); exp.add("(de,3,5)");
        assertEquals(exp, tokens);
    }

    public void testNgrams() throws Exception {
        NGramTokenizer tokenizer = new NGramTokenizer(input, 1, 3);
        
        Token token = null;
        do { 
            token = tokenizer.next();
            if (token != null) {
                tokens.add(token.toString());
//                System.out.println(token.termText());
//                System.out.println(token);
//                Thread.sleep(1000);
            }
        } while (token != null);

        assertEquals(12, tokens.size());
        ArrayList exp = new ArrayList();
        exp.add("(a,0,1)"); exp.add("(b,1,2)"); exp.add("(c,2,3)"); exp.add("(d,3,4)"); exp.add("(e,4,5)");
        exp.add("(ab,0,2)"); exp.add("(bc,1,3)"); exp.add("(cd,2,4)"); exp.add("(de,3,5)");
        exp.add("(abc,0,3)"); exp.add("(bcd,1,4)"); exp.add("(cde,2,5)");
        assertEquals(exp, tokens);
    }

    public void testOversizedNgrams() throws Exception {
        NGramTokenizer tokenizer = new NGramTokenizer(input, 6, 7);
        
        Token token = null;
        do { 
            token = tokenizer.next();
            if (token != null) {
                tokens.add(token.toString());
//                System.out.println(token.termText());
//                System.out.println(token);
//                Thread.sleep(1000);
            }
        } while (token != null);

        assertTrue(tokens.isEmpty());
    }
}