/*
 * 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.
 */

/*

   Porter stemmer in Java. The original paper is in

       Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,
       no. 3, pp 130-137,

   See also http://www.tartarus.org/~martin/PorterStemmer/index.html

   Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below.
   Tthe words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1]
   is then out outside the bounds of b.

   Similarly,

   Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below.
   'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and
   b[j] is then outside the bounds of b.

   Release 3.

   [ This version is derived from Release 3, modified by Brian Goetz to
     optimize for fewer object creations.  ]

*/

package opennlp.tools.stemmer;

/**
 * A {@link Stemmer}, implementing the <a href="https://tartarus.org/martin/PorterStemmer/">
 * Porter Stemming Algorithm</a>
 * <p>
 * The Stemmer implementation transforms a word into its root form. The input
 * word can be provided a character at time (by calling {@link #add(char)}),
 * or at once by calling one of the various {@code stem(..)} methods.
 */
// CHECKSTYLE:OFF
public class PorterStemmer implements Stemmer {
  private static final int INC = 50;
  private char[] b;
  private int i,    /* offset into b */
      j, k, k0;
  private boolean dirty = false;

  public PorterStemmer() {
    b = new char[INC];
    i = 0;
  }

  /**
   * reset() resets the stemmer so it can stem another word.  If you invoke
   * the stemmer by calling add(char) and then stem(), you must call reset()
   * before starting another word.
   */
  public void reset() {
    i = 0;
    dirty = false;
  }

  /**
   * Add a character to the word being stemmed.  When you are finished
   * adding characters, you can call stem(void) to process the word.
   */
  public void add(char ch) {
    if (b.length == i) {

      char[] new_b = new char[i + INC];
      System.arraycopy(b, 0, new_b, 0, i);
      {
        b = new_b;
      }
    }
    b[i++] = ch;
  }

  /**
   * After a word has been stemmed, it can be retrieved by toString(),
   * or a reference to the internal buffer can be retrieved by getResultBuffer
   * and getResultLength (which is generally more efficient.)
   */
  @Override
  public String toString() {
    return new String(b, 0, i);
  }

  /**
   * Returns the length of the word resulting from the stemming process.
   */
  public int getResultLength() {
    return i;
  }

  /**
   * Returns a reference to a character buffer containing the results of
   * the stemming process.  You also need to consult getResultLength()
   * to determine the length of the result.
   */
  public char[] getResultBuffer() {
    return b;
  }

  /* cons(i) is true <=> b[i] is a consonant. */

  private boolean cons(int i) {
    return switch (b[i]) {
      case 'a', 'e', 'i', 'o', 'u' -> false;
      case 'y' -> (i == k0) || !cons(i - 1);
      default -> true;
    };
  }

  /* m() measures the number of consonant sequences between k0 and j. if c is
     a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
     presence,

          <c><v>       gives 0
          <c>vc<v>     gives 1
          <c>vcvc<v>   gives 2
          <c>vcvcvc<v> gives 3
          ....
  */

  private int m() {
    int n = 0;
    int i = k0;
    while (true) {
      if (i > j) {
        return n;
      }
      if (!cons(i)) {
        break;
      }
      i++;
    }
    i++;
    while (true) {
      while (true) {
        if (i > j) {
          return n;
        }
        if (cons(i)) {
          break;
        }
        i++;
      }
      i++;
      n++;
      while (true) {
        if (i > j) {
          return n;
        }
        if (!cons(i)) {
          break;
        }
        i++;
      }
      i++;
    }
  }

  /* vowelinstem() is true <=> k0,...j contains a vowel */

  private boolean vowelinstem() {
    int i;
    for (i = k0; i <= j; i++) {
      if (!cons(i)) {
        return true;
      }
    }
    return false;
  }

  /* doublec(j) is true <=> j,(j-1) contain a double consonant. */

  private boolean doublec(int j) {
    return j >= k0 + 1 && b[j] == b[j - 1] && cons(j);
  }

  /* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
     and also if the second c is not w,x or y. this is used when trying to
     restore an e at the end of a short word. e.g.

          cav(e), lov(e), hop(e), crim(e), but
          snow, box, tray.

  */

  private boolean cvc(int i) {
    if (i < k0 + 2 || !cons(i) || cons(i - 1) || !cons(i - 2)) {
      return false;
    } else {
      int ch = b[i];
      if (ch == 'w' || ch == 'x' || ch == 'y') {
        return false;
      }
    }
    return true;
  }

  private boolean ends(String s) {
    int l = s.length();
    int o = k - l + 1;
    if (o < k0) {
      return false;
    }
    for (int i = 0; i < l; i++) {
      if (b[o + i] != s.charAt(i)) {
        return false;
      }
    }
    j = k - l;
    return true;
  }

  /* setto(s) sets (j+1),...k to the characters in the string s, readjusting
     k. */

  void setto(String s) {
    int l = s.length();
    int o = j + 1;
    for (int i = 0; i < l; i++) {
      b[o + i] = s.charAt(i);
    }
    k = j + l;
    dirty = true;
  }

  /* r(s) is used further down. */

  void r(String s) {
    if (m() > 0) {
      setto(s);
    }
  }

  /* step1() gets rid of plurals and -ed or -ing. e.g.

           caresses  ->  caress
           ponies    ->  poni
           ties      ->  ti
           caress    ->  caress
           cats      ->  cat

           feed      ->  feed
           agreed    ->  agree
           disabled  ->  disable

           matting   ->  mat
           mating    ->  mate
           meeting   ->  meet
           milling   ->  mill
           messing   ->  mess

           meetings  ->  meet

  */

  private void step1() {
    if (b[k] == 's') {
      if (ends("sses")) {
        k -= 2;
      } else if (ends("ies")) {
        setto("i");
      } else if (b[k - 1] != 's') {
        k--;
      }
    }
    if (ends("eed")) {
      if (m() > 0) {
        k--;
      }
    } else if ((ends("ed") || ends("ing")) && vowelinstem()) {
      k = j;
      if (ends("at")) {
        setto("ate");
      } else if (ends("bl")) {
        setto("ble");
      } else if (ends("iz")) {
        setto("ize");
      } else if (doublec(k)) {
        int ch = b[k--];
        if (ch == 'l' || ch == 's' || ch == 'z') {
          k++;
        }
      } else if (m() == 1 && cvc(k)) {
        setto("e");
      }
    }
  }

  /* step2() turns terminal y to i when there is another vowel in the stem. */

  private void step2() {
    if (ends("y") && vowelinstem()) {
      b[k] = 'i';
      dirty = true;
    }
  }

  /* step3() maps double suffices to single ones. so -ization ( = -ize plus
     -ation) maps to -ize etc. note that the string before the suffix must give
     m() > 0. */

  private void step3() {
    if (k == k0) {
      return; /* For Bug 1 */
    }
    switch (b[k - 1]) {
      case 'a':
        if (ends("ational")) {
          r("ate");
          break;
        }
        if (ends("tional")) {
          r("tion");
          break;
        }
        break;
      case 'c':
        if (ends("enci")) {
          r("ence");
          break;
        }
        if (ends("anci")) {
          r("ance");
          break;
        }
        break;
      case 'e':
        if (ends("izer")) {
          r("ize");
          break;
        }
        break;
      case 'l':
        if (ends("bli")) {
          r("ble");
          break;
        }
        if (ends("alli")) {
          r("al");
          break;
        }
        if (ends("entli")) {
          r("ent");
          break;
        }
        if (ends("eli")) {
          r("e");
          break;
        }
        if (ends("ousli")) {
          r("ous");
          break;
        }
        break;
      case 'o':
        if (ends("ization")) {
          r("ize");
          break;
        }
        if (ends("ation")) {
          r("ate");
          break;
        }
        if (ends("ator")) {
          r("ate");
          break;
        }
        break;
      case 's':
        if (ends("alism")) {
          r("al");
          break;
        }
        if (ends("iveness")) {
          r("ive");
          break;
        }
        if (ends("fulness")) {
          r("ful");
          break;
        }
        if (ends("ousness")) {
          r("ous");
          break;
        }
        break;
      case 't':
        if (ends("aliti")) {
          r("al");
          break;
        }
        if (ends("iviti")) {
          r("ive");
          break;
        }
        if (ends("biliti")) {
          r("ble");
          break;
        }
        break;
      case 'g':
        if (ends("logi")) {
          r("log");
          break;
        }
    }
  }

  /* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */

  private void step4() {
    switch (b[k]) {
      case 'e':
        if (ends("icate")) {
          r("ic");
          break;
        }
        if (ends("ative")) {
          r("");
          break;
        }
        if (ends("alize")) {
          r("al");
          break;
        }
        break;
      case 'i':
        if (ends("iciti")) {
          r("ic");
          break;
        }
        break;
      case 'l':
        if (ends("ical")) {
          r("ic");
          break;
        }
        if (ends("ful")) {
          r("");
          break;
        }
        break;
      case 's':
        if (ends("ness")) {
          r("");
          break;
        }
        break;
    }
  }

  /* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */

  private void step5() {
    if (k == k0) {
      return; /* for Bug 1 */
    }
    switch (b[k - 1]) {
      case 'a':
        if (ends("al")) {
          break;
        }
        return;
      case 'c':
        if (ends("ance")) {
          break;
        }
        if (ends("ence")) {
          break;
        }
        return;
      case 'e':
        if (ends("er")) {
          break;
        }
        return;
      case 'i':
        if (ends("ic")) {
          break;
        }
        return;
      case 'l':
        if (ends("able")) {
          break;
        }
        if (ends("ible")) {
          break;
        }
        return;
      case 'n':
        if (ends("ant")) {
          break;
        }
        if (ends("ement")) {
          break;
        }
        if (ends("ment")) {
          break;
        }
        /* element etc. not stripped before the m */
        if (ends("ent")) {
          break;
        }
        return;
      case 'o':
        if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't')) {
          break;
        }
        /* j >= 0 fixes Bug 2 */
        if (ends("ou")) {
          break;
        }
        return;
      /* takes care of -ous */
      case 's':
        if (ends("ism")) {
          break;
        }
        return;
      case 't':
        if (ends("ate")) {
          break;
        }
        if (ends("iti")) {
          break;
        }
        return;
      case 'u':
        if (ends("ous")) {
          break;
        }
        return;
      case 'v':
        if (ends("ive")) {
          break;
        }
        return;
      case 'z':
        if (ends("ize")) {
          break;
        }
        return;
      default:
        return;
    }
    if (m() > 1) {
      k = j;
    }
  }

  /* step6() removes a final -e if m() > 1. */

  private void step6() {
    j = k;
    if (b[k] == 'e') {
      int a = m();
      if (a > 1 || a == 1 && !cvc(k - 1)) {
        k--;
      }
    }
    if (b[k] == 'l' && doublec(k) && m() > 1) {
      k--;
    }
  }


  /**
   * Stem a word provided as a String.  Returns the result as a String.
   */
  public String stem(String s) {
    if (stem(s.toCharArray(), s.length())) {
      return toString();
    } else {
      return s;
    }
  }

  /**
   * Stem a word provided as a CharSequence.
   * Returns the result as a CharSequence.
   */
  public CharSequence stem(CharSequence word) {
    return stem(word.toString());
  }

  /**
   * Stem a word contained in a char[].  Returns true if the stemming process
   * resulted in a word different from the input.  You can retrieve the
   * result with getResultLength()/getResultBuffer() or toString().
   */
  public boolean stem(char[] word) {
    return stem(word, word.length);
  }

  /**
   * Stem a word contained in a portion of a char[] array.  Returns
   * true if the stemming process resulted in a word different from
   * the input.  You can retrieve the result with
   * getResultLength()/getResultBuffer() or toString().
   */
  public boolean stem(char[] wordBuffer, int offset, int wordLen) {
    reset();
    if (b.length < wordLen) {
      b = new char[wordLen - offset];
    }
    System.arraycopy(wordBuffer, offset, b, 0, wordLen);
    i = wordLen;
    return stem(0);
  }

  /**
   * Stem a word contained in a leading portion of a char[] array.
   * Returns true if the stemming process resulted in a word different
   * from the input.  You can retrieve the result with
   * getResultLength()/getResultBuffer() or toString().
   */
  public boolean stem(char[] word, int wordLen) {
    return stem(word, 0, wordLen);
  }

  /**
   * Stem the word placed into the Stemmer buffer through calls to add().
   * Returns true if the stemming process resulted in a word different
   * from the input.  You can retrieve the result with
   * getResultLength()/getResultBuffer() or toString().
   */
  public boolean stem() {
    return stem(0);
  }

  public boolean stem(int i0) {
    k = i - 1;
    k0 = i0;
    if (k > k0 + 1) {
      step1();
      step2();
      step3();
      step4();
      step5();
      step6();
    }
    // Also, a word is considered dirty if we lopped off letters
    // Thanks to Ifigenia Vairelles for pointing this out.
    if (i != k + 1) {
      dirty = true;
    }
    i = k + 1;
    return dirty;
  }
}

