/*
 * 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.
 */

package opennlp.tools.stemmer;


	import java.io.IOException;
	import java.io.InputStream;
	import java.io.FileInputStream;

	import static org.apache.lucene.util.RamUsageEstimator.NUM_BYTES_CHAR;
	import org.apache.lucene.util.ArrayUtil;

	/**
	 *
	 * 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 PStemmer
	{
	  private char[] b;
	  private int i,    /* offset into b */
	    j, k, k0;
	  private boolean dirty = false;
	  private static final int INITIAL_SIZE = 50;

	  public PStemmer() {
	    b = new char[INITIAL_SIZE];
	    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) {
	      b = ArrayUtil.grow(b, i+1);
	    }
	    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 final boolean cons(int i) {
	    switch (b[i]) {
	    case 'a': case 'e': case 'i': case 'o': case 'u':
	      return false;
	    case 'y':
	      return (i==k0) ? true : !cons(i-1);
	    default:
	      return 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 final 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 final 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 final boolean doublec(int j) {
	    if (j < k0+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 < 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 final 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 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)) {
	        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';
	      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 final 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 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 == 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 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 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 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[ArrayUtil.oversize(wordLen, NUM_BYTES_CHAR)];
	    }
	    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;
	  }

	  /** Test program for demonstrating the Stemmer.  It reads a file and
	   * stems each word, writing the result to standard out.
	   * Usage: Stemmer file-name
	   */
	  public static void main(String[] args) {
	    PStemmer s = new PStemmer();

	    for (int i = 0; i < args.length; i++) {
	      try {
	        InputStream in = new FileInputStream(args[i]);
	        byte[] buffer = new byte[1024];
	        int bufferLen, offset, ch;

	        bufferLen = in.read(buffer);
	        offset = 0;
	        s.reset();

	        while(true) {
	          if (offset < bufferLen)
	            ch = buffer[offset++];
	          else {
	            bufferLen = in.read(buffer);
	            offset = 0;
	            if (bufferLen < 0)
	              ch = -1;
	            else
	              ch = buffer[offset++];
	          }

	          if (Character.isLetter((char) ch)) {
	            s.add(Character.toLowerCase((char) ch));
	          }
	          else {
	             s.stem();
	             System.out.print(s.toString());
	             s.reset();
	             if (ch < 0)
	               break;
	             else {
	               System.out.print((char) ch);
	             }
	           }
	        }

	        in.close();
	      }
	      catch (IOException e) {
	        System.out.println("error reading " + args[i]);
	      }
	    }
	  }
	}