package com.dlj.ir.analysis.be;

import java.util.Map;
import java.util.WeakHashMap;


/**
 * Bengali light stemmer- removes number, gender and case suffixes from nouns and
 * adjectives
 * Done by Ljiljana Dolamic (University of Neuchatel, www.unine.ch/info/clef/)
 * 
 * @author Ljiljana Dolamic. Email: ljiljana.dolamic@unine.ch
 * 
 */
public class BengaliStemmerLight{

	/**
	 * A cache of words and their stems
	 */
	static private Map<String, String> cache = new WeakHashMap<String, String>();

	/**
	 * A buffer of the current word being stemmed
	 */
	private StringBuilder sb = new StringBuilder();

	/**
	 * Default constructor
	 */
	public BengaliStemmerLight() {
	}

	public String stem(String word) {
		String result = cache.get(word);

		if (result != null)
			return result;

		// 
		sb.delete(0, sb.length());

		// 
		sb.append(word);		
		
		/* remove the case endings from nouns and adjectives */
		remove_case(sb);

		remove_article(sb);

		normalize(sb);

		result = sb.toString();
		cache.put(word, result);
		return result;
	}

	private void remove_article(StringBuilder word) {
		int len = word.length() - 1;
		if (len > 5) {
			if (word.substring(len - 3, len + 1).equals("খানা")
					|| word.substring(len - 3, len + 1).equals("খানি")
					|| word.substring(len - 3, len + 1).equals("গুলো")) {
				word.delete(len - 3, len + 1);
				return;
			}
		} /* end if len >5 */
		if (len > 4) {
			if (word.substring(len - 2, len + 1).equals("য়োন")) {
				word.delete(len - 2, len + 1);
				return;
			}

		} /* end if len > 4 */
		if (len > 3) {
			if (word.substring(len - 1, len + 1).equals(" টা")
					|| word.substring(len - 1, len + 1).equals("টি")) {
				word.delete(len - 1, len + 1);
				return;
			}
		}
				return;
	}

	private void remove_case(StringBuilder word) {
		int len = word.length() - 1;

		if (len > 8) {
			if (word.substring(len - 6, len + 1).equals("য়েদেরকে")) {
				word.delete(len - 6, len + 1);
				return;
			}
		} /* end if len >8 */
		if (len > 7 ) {			
			if (word.substring(len - 5, len + 1).equals("েদেরকে")) {
				word.delete(len - 5, len + 1);
				return;
			}
		} /* end if len >7 */
		if (len > 6) {
			if (word.substring(len - 4, len + 1).equals("দেরকে")
					|| word.substring(len - 4, len + 1).equals("য়েদের")) {
				word.delete(len - 4, len + 1);
				return;
			}
		} /* end if len >6 */
		if (len > 5) {
			if (word.substring(len - 3, len + 1).equals("েদের")
					|| word.substring(len - 3, len + 1).equals("য়েরা")) {
				word.delete(len - 3, len + 1);
				return;
			}
		} /* end if len >5 */
		if (len > 4) {
			if (word.substring(len - 2, len + 1).equals("দের")||
					word.substring(len - 2, len + 1).equals("েরা")
					||word.substring(len - 2, len + 1).equals("য়ের")) {
				word.delete(len - 2, len + 1);
				return;
			}
			

		} /* end if len > 4 */
		if (len > 3) {
			if (word.substring(len - 1, len + 1).equals("ের")) {
				word.delete(len - 1, len + 1);
				return;
			}
			if (word.substring(len - 1, len + 1).equals("তে")) {
				word.delete(len - 1, len + 1);
				return;
			}
			if (word.substring(len - 1, len + 1).equals("রা")) {
				word.delete(len, len + 1);
				return;
			}
			if (word.substring(len - 1, len + 1).equals("কে")) {
				word.setCharAt(len - 1, 'ড');
				word.delete(len, len + 1);
				return;
			}			
		} /* end if len > 3 */
		if (len > 2) {
			if (word.charAt(len) == 'ে' 
				|| word.charAt(len) == 'র'
				|| word.charAt(len) == 'য়া') {
				word.delete(len, len + 1);
				return;
			}
		} /* end if len > 2 */
		return;
	}
	private void normalize(StringBuilder word) {
		int len = word.length() - 1;
		if (len > 4) {
			if (word.substring(len - 2, len + 1).equals("িনি")) {
				word.delete(len - 2, len + 1);
				return;
			}
		} /* end if len > 4 */
		if (len > 3) {
			if (word.substring(len - 1, len + 1).equals("নি")) {
				word.delete(len - 1, len + 1);
				len-=2;
			}
		} /* end if len > 3 */
		if (len > 2) {
			if (word.substring(len, len + 1).equals("ো")
				|| word.substring(len, len + 1).equals("ে")) {
				word.delete(len, len + 1);
				return;
			}
		} /* end if len > 2 */
		return;
	}
}