package org.apache.lucene.analysis.hu;

/**
 * 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.
 */

/* 
 * This algorithm is updated based on code located at:
 * http://members.unine.ch/jacques.savoy/clef/
 * 
 * Full copyright for that code follows:
 */

/*
 * Copyright (c) 2005, Jacques Savoy
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this 
 * list of conditions and the following disclaimer. Redistributions in binary 
 * form must reproduce the above copyright notice, this list of conditions and
 * the following disclaimer in the documentation and/or other materials 
 * provided with the distribution. Neither the name of the author nor the names 
 * of its contributors may be used to endorse or promote products derived from 
 * this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

import static org.apache.lucene.analysis.util.StemmerUtil.*;

/**
 * Light Stemmer for Hungarian.
 * <p>
 * This stemmer implements the "UniNE" algorithm in:
 * <i>Light Stemming Approaches for the French, Portuguese, German and Hungarian Languages</i>
 * Jacques Savoy
 */
public class HungarianLightStemmer {
  public int stem(char s[], int len) {
    for (int i = 0; i < len; i++)
      switch(s[i]) {
        case 'á': s[i] = 'a'; break;
        case 'ë':
        case 'é': s[i] = 'e'; break;
        case 'í': s[i] = 'i'; break;
        case 'ó':
        case 'ő':
        case 'õ':
        case 'ö': s[i] = 'o'; break;
        case 'ú':
        case 'ű':
        case 'ũ':
        case 'û':
        case 'ü': s[i] = 'u'; break;
      }
    
    len = removeCase(s, len);
    len = removePossessive(s, len);
    len = removePlural(s, len);
    return normalize(s, len);
  }
  
  private int removeCase(char s[], int len) {
    if (len > 6 && endsWith(s, len, "kent"))
      return len - 4;
    
    if (len > 5) {
      if (endsWith(s, len, "nak") ||
          endsWith(s, len, "nek") ||
          endsWith(s, len, "val") ||
          endsWith(s, len, "vel") ||
          endsWith(s, len, "ert") ||
          endsWith(s, len, "rol") ||
          endsWith(s, len, "ban") ||
          endsWith(s, len, "ben") ||
          endsWith(s, len, "bol") ||
          endsWith(s, len, "nal") ||
          endsWith(s, len, "nel") ||
          endsWith(s, len, "hoz") ||
          endsWith(s, len, "hez") ||
          endsWith(s, len, "tol"))
        return len - 3;
      
      if (endsWith(s, len, "al") || endsWith(s, len, "el")) {
        if (!isVowel(s[len-3]) && s[len-3] == s[len-4])
          return len - 3;
      }
    }
    
    if (len > 4) {
      if (endsWith(s, len, "at") ||
          endsWith(s, len, "et") ||
          endsWith(s, len, "ot") ||
          endsWith(s, len, "va") ||
          endsWith(s, len, "ve") ||
          endsWith(s, len, "ra") ||
          endsWith(s, len, "re") ||
          endsWith(s, len, "ba") ||
          endsWith(s, len, "be") ||
          endsWith(s, len, "ul") ||
          endsWith(s, len, "ig"))
        return len - 2;
      
      if ((endsWith(s, len, "on") || endsWith(s, len, "en")) && !isVowel(s[len-3]))
          return len - 2;
      
      switch(s[len-1]) {
        case 't':
        case 'n': return len - 1;
        case 'a':
        case 'e': if (s[len-2] == s[len-3] && !isVowel(s[len-2])) return len - 2;
      }
    }
    
    return len;
  }

  private int removePossessive(char s[], int len) {
    if (len > 6) {
      if (!isVowel(s[len-5]) && 
         (endsWith(s, len, "atok") || 
          endsWith(s, len, "otok") || 
          endsWith(s, len, "etek")))
        return len - 4;
      
      if (endsWith(s, len, "itek") || endsWith(s, len, "itok"))
        return len - 4;
    }
    
    if (len > 5) {
      if (!isVowel(s[len-4]) &&
        (endsWith(s, len, "unk") ||
         endsWith(s, len, "tok") ||
         endsWith(s, len, "tek")))
        return len - 3;
      
      if (isVowel(s[len-4]) && endsWith(s, len, "juk"))
        return len - 3;
      
      if (endsWith(s, len, "ink"))
        return len - 3;
    }
    
    if (len > 4) {
      if (!isVowel(s[len-3]) &&
         (endsWith(s, len, "am") ||
          endsWith(s, len, "em") ||
          endsWith(s, len, "om") ||
          endsWith(s, len, "ad") ||
          endsWith(s, len, "ed") ||
          endsWith(s, len, "od") ||
          endsWith(s, len, "uk")))
        return len - 2;
      
      if (isVowel(s[len-3]) &&
         (endsWith(s, len, "nk") ||
          endsWith(s, len, "ja") ||
          endsWith(s, len, "je")))
        return len - 2;
      
      if (endsWith(s, len, "im") ||
          endsWith(s, len, "id") ||
          endsWith(s, len, "ik"))
        return len - 2;
    }
    
    if (len > 3)
      switch(s[len-1]) {
        case 'a':
        case 'e': if (!isVowel(s[len-2])) return len - 1; break;
        case 'm':
        case 'd': if (isVowel(s[len-2])) return len - 1; break;
        case 'i': return len - 1;
      }
    
    return len;
  }

  @SuppressWarnings("fallthrough")
  private int removePlural(char s[], int len) {
    if (len > 3 && s[len-1] == 'k')
      switch(s[len-2]) {
        case 'a':
        case 'o':
        case 'e': if (len > 4) return len - 2; /* intentional fallthru */
        default: return len - 1;
      }
    return len;
  }

  private int normalize(char s[], int len) {
    if (len > 3)
      switch(s[len-1]) {
        case 'a':
        case 'e':
        case 'i':
        case 'o': return len - 1;
      }
    return len;
  }

  private boolean isVowel(char ch) {
    switch(ch) {
      case 'a':
      case 'e':
      case 'i':
      case 'o':
      case 'u':
      case 'y': return true;
      default: return false;
    }
  }
}
