/**
 * This file is part of pinyin4j (http://sourceforge.net/projects/pinyin4j/) 
 * and distributed under GNU GENERAL PUBLIC LICENSE (GPL).
 * 
 * pinyin4j is free software; you can redistribute it and/or modify 
 * it under the terms of the GNU General Public License as published by 
 * the Free Software Foundation; either version 2 of the License, or 
 * (at your option) any later version. 
 * 
 * pinyin4j is distributed in the hope that it will be useful, 
 * but WITHOUT ANY WARRANTY; without even the implied warranty of 
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * GNU General Public License for more details. 
 * 
 * You should have received a copy of the GNU General Public License 
 * along with pinyin4j.
 */

/**
 * 
 */
package net.sourceforge.pinyin4j;

import com.hp.hpl.sparta.Document;
import com.hp.hpl.sparta.Element;
import com.hp.hpl.sparta.ParseException;

/**
 * A class contains logic that translates from Hanyu Pinyin to Gwoyeu Romatzyh
 * 
 * @author Li Min (xmlerlimin@gmail.com)
 * 
 */
class GwoyeuRomatzyhTranslator
{
    /**
     * @param hanyuPinyinStr
     *            Given unformatted Hanyu Pinyin with tone number
     * @return Corresponding Gwoyeu Romatzyh; null if no mapping is found.
     */
    static String convertHanyuPinyinToGwoyeuRomatzyh(String hanyuPinyinStr)
    {
        String pinyinString = TextHelper.extractPinyinString(hanyuPinyinStr);
        String toneNumberStr = TextHelper.extractToneNumber(hanyuPinyinStr);

        // return value
        String gwoyeuStr = null;
        try
        {
            // find the node of source Pinyin system
            String xpathQuery1 = "//"
                    + PinyinRomanizationType.HANYU_PINYIN.getTagName()
                    + "[text()='" + pinyinString + "']";

            Document pinyinToGwoyeuMappingDoc = GwoyeuRomatzyhResource.getInstance().getPinyinToGwoyeuMappingDoc();

            Element hanyuNode = pinyinToGwoyeuMappingDoc.xpathSelectElement(xpathQuery1);

            if (null != hanyuNode)
            {
                // find the node of target Pinyin system
                String xpathQuery2 = "../"
                        + PinyinRomanizationType.GWOYEU_ROMATZYH.getTagName()
                        + tones[Integer.parseInt(toneNumberStr) - 1]
                        + "/text()";
                String targetPinyinStrWithoutToneNumber = hanyuNode.xpathSelectString(xpathQuery2);

                gwoyeuStr = targetPinyinStrWithoutToneNumber;
            }
        } catch (ParseException e)
        {
            e.printStackTrace();
        }

        return gwoyeuStr;
    }

    /**
     * The postfixs to distinguish different tone of Gwoyeu Romatzyh
     * 
     * <i>Should be removed if new xPath parser supporting tag name with number.</i>
     */
    static private String[] tones = new String[] { "_I", "_II", "_III", "_IV",
            "_V" };
}