/*
 * Copyright (C) 2003-2011 eXo Platform SAS.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package org.etk.common.utils;

import org.etk.common.logging.Logger;

/**
 * Created by The eXo Platform SAS
 * Author : eXoPlatform
 *          thanhvucong.78@google.com
 * Aug 4, 2011  
 */
public class UnicodeFormatter {

  public static String byteToHex(byte b) {
    char[] array = {_HEX_DIGITS[(b >> 4) & 0x0f], _HEX_DIGITS[b & 0x0f]};

    return new String(array);
  }

  public static String charToHex(char c) {
    byte hi = (byte)(c >>> 8);
    byte lo = (byte)(c & 0xff);

    char[] array = {
      _HEX_DIGITS[(hi >> 4) & 0x0f], _HEX_DIGITS[hi & 0x0f],
      _HEX_DIGITS[(lo >> 4) & 0x0f], _HEX_DIGITS[lo & 0x0f]
    };

    return new String(array);
  }

  public static String parseString(String hexString) {
    StringBuilder sb = new StringBuilder();

    char[] array = hexString.toCharArray();

    if ((array.length % 6) != 0) {
      _log.error("String is not in hex format");

      return hexString;
    }

    for (int i = 2; i < hexString.length(); i = i + 6) {
      String s = hexString.substring(i, i + 4);

      try {
        char c = (char)Integer.parseInt(s, 16);

        sb.append(c);
      }
      catch (Exception e) {
        _log.error(e.getMessage(), e);

        return hexString;
      }
    }

    return sb.toString();
  }

  public static String toString(char[] array) {
    StringBuilder sb = new StringBuilder(array.length * 6);

    char[] hexes = new char[4];

    for (int i = 0; i < array.length; i++) {
      sb.append(_UNICODE_PREFIX);
      sb.append(_charToHex(array[i], hexes));
    }

    return sb.toString();
  }

  public static String toString(String s) {
    if (s == null) {
      return null;
    }

    StringBuilder sb = new StringBuilder(s.length() * 6);

    char[] hexes = new char[4];

    for (int i = 0; i < s.length(); i++) {
      sb.append(_UNICODE_PREFIX);
      sb.append(_charToHex(s.charAt(i), hexes));
    }

    return sb.toString();
  }

  private static char[] _charToHex(char c, char[] hexes) {
    byte hi = (byte)(c >>> 8);
    byte lo = (byte)(c & 0xff);

    hexes[0] = _HEX_DIGITS[(hi >> 4) & 0x0f];
    hexes[1] = _HEX_DIGITS[hi & 0x0f];
    hexes[2] = _HEX_DIGITS[(lo >> 4) & 0x0f];
    hexes[3] = _HEX_DIGITS[lo & 0x0f];

    return hexes;
  }

  private static final char[] _HEX_DIGITS = {
    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
    'e', 'f'
  };

  private static final String _UNICODE_PREFIX = "\\u";

  private static Logger _log = Logger.getLogger(UnicodeFormatter.class);

}