package in.sivareddy.util;

/*
 * 
 * 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
 * 
 * History:
 * 
 * Release 1
 * 
 * Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below. The words
 * 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1] is then out outside
 * the bounds of b.
 * 
 * Release 2
 * 
 * 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
 * 
 * Considerably revised 4/9/00 in the light of many helpful suggestions from
 * Brian Goetz of Quiotix Corporation (brian@quiotix.com).
 * 
 * Release 4
 */



/**
 * Stemmer, implementing the Porter Stemming Algorithm
 *
 * The Stemmer class transforms a word into its root form. The input word can be
 * provided a character at time (by calling add()), or at once by calling one of
 * the various stem(something) methods.
 */

public class PorterStemmer {
  private char[] b;
  private int i, /* offset into b */
  i_end, /* offset to end of stemmed word */
  j, k;

  /* unit of size whereby b is increased */
  public PorterStemmer(String word) {
    b = word.toCharArray();
    i = word.length();
    i_end = 0;
  }

  public static String getStem(String word) {
    PorterStemmer ps = new PorterStemmer(word);
    ps.stem();
    String u = ps.toString();
    return u;
  }

  /**
   * 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_end);
  }

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

  /**
   * 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 final boolean cons(int i) {
    switch (b[i]) {
      case 'a':
      case 'e':
      case 'i':
      case 'o':
      case 'u':
        return false;
      case 'y':
        return (i == 0) ? true : !cons(i - 1);
      default:
        return true;
    }
  }

  /*
   * m() measures the number of consonant sequences between 0 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 final int m() {
    int n = 0;
    int i = 0;
    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 <=> 0,...j contains a vowel */

  private final boolean vowelinstem() {
    int i;
    for (i = 0; i <= j; i++)
      if (!cons(i)) {
        return true;
      }
    return false;
  }

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

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

  private final boolean ends(String s) {
    int l = s.length();
    int o = k - l + 1;
    if (o < 0) {
      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.
   */

  private final 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;
  }

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

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

  /*
   * 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 final void step3() {
    if (k == 0) {
      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 final 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 final void step5() {
    if (k == 0) {
      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;
        }
        if (ends("or")) {
          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 final 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 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 void stem() {
    k = i - 1;
    if (k > 1) {
      step1();
      step2();
      step3();
      step4();
      step5();
      step6();
    }
    i_end = k + 1;
    i = 0;
  }

  /**
   * Test program for demonstrating the Stemmer. It reads text from a a list of
   * files, stems each word, and writes the result to standard output. Note that
   * the word stemmed is expected to be in lower case: forcing lower case must
   * be done outside the Stemmer class. Usage: Stemmer file-name file-name ...
   */
  public static void main(String[] args) {
    System.out.println(getStem("investor"));
  }
}
