using Lucene.Net.Analysis.Util;
using System.IO;

namespace Lucene.Net.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.
	 */

    /// <summary>
    /// Light Stemmer for Hungarian.
    /// <para>
    /// This stemmer implements the "UniNE" algorithm in:
    /// <c>Light Stemming Approaches for the French, Portuguese, German and Hungarian Languages</c>
    /// Jacques Savoy
    /// </para>
    /// </summary>
    public class HungarianLightStemmer
    {
        public virtual 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 && StemmerUtil.EndsWith(s, len, "kent"))
            {
                return len - 4;
            }

            if (len > 5)
            {
                if (StemmerUtil.EndsWith(s, len, "nak") || StemmerUtil.EndsWith(s, len, "nek") || StemmerUtil.EndsWith(s, len, "val") || StemmerUtil.EndsWith(s, len, "vel") || StemmerUtil.EndsWith(s, len, "ert") || StemmerUtil.EndsWith(s, len, "rol") || StemmerUtil.EndsWith(s, len, "ban") || StemmerUtil.EndsWith(s, len, "ben") || StemmerUtil.EndsWith(s, len, "bol") || StemmerUtil.EndsWith(s, len, "nal") || StemmerUtil.EndsWith(s, len, "nel") || StemmerUtil.EndsWith(s, len, "hoz") || StemmerUtil.EndsWith(s, len, "hez") || StemmerUtil.EndsWith(s, len, "tol"))
                {
                    return len - 3;
                }

                if (StemmerUtil.EndsWith(s, len, "al") || StemmerUtil.EndsWith(s, len, "el"))
                {
                    if (!IsVowel(s[len - 3]) && s[len - 3] == s[len - 4])
                    {
                        return len - 3;
                    }
                }
            }

            if (len > 4)
            {
                if (StemmerUtil.EndsWith(s, len, "at") || StemmerUtil.EndsWith(s, len, "et") || StemmerUtil.EndsWith(s, len, "ot") || StemmerUtil.EndsWith(s, len, "va") || StemmerUtil.EndsWith(s, len, "ve") || StemmerUtil.EndsWith(s, len, "ra") || StemmerUtil.EndsWith(s, len, "re") || StemmerUtil.EndsWith(s, len, "ba") || StemmerUtil.EndsWith(s, len, "be") || StemmerUtil.EndsWith(s, len, "ul") || StemmerUtil.EndsWith(s, len, "ig"))
                {
                    return len - 2;
                }

                if ((StemmerUtil.EndsWith(s, len, "on") || StemmerUtil.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;
                        }
                        break;
                }
            }

            return len;
        }

        private int RemovePossessive(char[] s, int len)
        {
            if (len > 6)
            {
                if (!IsVowel(s[len - 5]) && (StemmerUtil.EndsWith(s, len, "atok") || StemmerUtil.EndsWith(s, len, "otok") || StemmerUtil.EndsWith(s, len, "etek")))
                {
                    return len - 4;
                }

                if (StemmerUtil.EndsWith(s, len, "itek") || StemmerUtil.EndsWith(s, len, "itok"))
                {
                    return len - 4;
                }
            }

            if (len > 5)
            {
                if (!IsVowel(s[len - 4]) && (StemmerUtil.EndsWith(s, len, "unk") || StemmerUtil.EndsWith(s, len, "tok") || StemmerUtil.EndsWith(s, len, "tek")))
                {
                    return len - 3;
                }

                if (IsVowel(s[len - 4]) && StemmerUtil.EndsWith(s, len, "juk"))
                {
                    return len - 3;
                }

                if (StemmerUtil.EndsWith(s, len, "ink"))
                {
                    return len - 3;
                }
            }

            if (len > 4)
            {
                if (!IsVowel(s[len - 3]) && (StemmerUtil.EndsWith(s, len, "am") || StemmerUtil.EndsWith(s, len, "em") || StemmerUtil.EndsWith(s, len, "om") || StemmerUtil.EndsWith(s, len, "ad") || StemmerUtil.EndsWith(s, len, "ed") || StemmerUtil.EndsWith(s, len, "od") || StemmerUtil.EndsWith(s, len, "uk")))
                {
                    return len - 2;
                }

                if (IsVowel(s[len - 3]) && (StemmerUtil.EndsWith(s, len, "nk") || StemmerUtil.EndsWith(s, len, "ja") || StemmerUtil.EndsWith(s, len, "je")))
                {
                    return len - 2;
                }

                if (StemmerUtil.EndsWith(s, len, "im") || StemmerUtil.EndsWith(s, len, "id") || StemmerUtil.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;
        }

        private int RemovePlural(char[] s, int len)
        {
            if (len > 3 && s[len - 1] == 'k')
            {
                switch (s[len - 2])
                {
                    case 'a':
                    case 'o':
                    case 'e': // intentional fallthru
                        if (len > 4)
                        {
                            return len - 2;
                        }
                        return len - 1;// LUCENENET NOTE: Cannot fall through, so need to return the same value as default
                    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 bool IsVowel(char ch)
        {
            switch (ch)
            {
                case 'a':
                case 'e':
                case 'i':
                case 'o':
                case 'u':
                case 'y':
                    return true;
                default:
                    return false;
            }
        }
    }
}