<?php
/*
    This file is part of Hotseat Corner.

    Hotseat Corner 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 3 of the License, or
    (at your option) any later version.

    Hotseat Corner 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 Hotseat Corner.  If not, see <http://www.gnu.org/licenses/>.
*/
	class HSUtils_ChID {
		private static $mask = array('b'=>'0','c'=>'1','d'=>'2','f'=>'3','g'=>'4','h'=>'5','j'=>'6','k'=>'7','l'=>'8','m'=>'9','n'=>'a','p'=>'b','q'=>'c','r'=>'d','s'=>'e','t'=>'f','v'=>'g','w'=>'h','x'=>'i','y'=>'j');
		private static $padchar = 'z';
		private static $padlength = 4;
		private static $translations = array();
		
		public static function get ($key) 
		{
			$uid = HSUtils_UID::get($key);
			return self::encode($uid);
		}
		
		public static function encode($id) 
		{
			if (!preg_match('/^\d+$/', $id)) {
				throw new exception('not an int');
			}
			$idb20 = base_convert ($id, 10, 20);
			$chars = preg_split('//', $idb20, -1, PREG_SPLIT_NO_EMPTY);
			foreach ($chars as $char) {
				$key .= array_search($char, self::$mask, true);
			}
			$key .= self::$padchar;
			self::$translations[$key] = $id;
			str_pad($key, self::$padlength, self::$padchar, STR_PAD_RIGHT);
			return $key;
		}
		
		public static function decode($key) 
		{
			if (self::$translations[$key]) {
				return self::$translations[$key];
			}
			$chars = preg_split('//', $key, -1, PREG_SPLIT_NO_EMPTY);
			foreach ($chars as $char) {
				$idb20 .= self::$mask[$char];
			}
			$id = base_convert ($idb20, 20, 10);
			self::$translations[$key] = $id;
			return $id;
		}
	}
?>