/* 
 *  Copyright (C) 2000 - 2008 TagServlet Ltd
 *
 *  This file is part of Open BlueDragon (OpenBD) CFML Server Engine.
 *  
 *  OpenBD is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  Free Software Foundation,version 3.
 *  
 *  OpenBD 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 OpenBD.  If not, see http://www.gnu.org/licenses/
 *  
 *  Additional permission under GNU GPL version 3 section 7
 *  
 *  If you modify this Program, or any covered work, by linking or combining 
 *  it with any of the JARS listed in the README.txt (or a modified version of 
 *  (that library), containing parts covered by the terms of that JAR, the 
 *  licensors of this Program grant you additional permission to convey the 
 *  resulting work. 
 *  README.txt @ http://www.openbluedragon.org/license/README.txt
 *  
 *  http://www.openbluedragon.org/
 */

package com.naryx.tagfusion.expression.function;


import com.naryx.tagfusion.cfm.engine.cfArgStructData;
import com.naryx.tagfusion.cfm.engine.cfBooleanData;
import com.naryx.tagfusion.cfm.engine.cfData;
import com.naryx.tagfusion.cfm.engine.cfNumberData;
import com.naryx.tagfusion.cfm.engine.cfSession;
import com.naryx.tagfusion.cfm.engine.cfmRunTimeException;


/**
 * This takes in a string and attempts to convert from Base62
 * 
 * http://en.wikipedia.org/wiki/Base_62
 */
public class fromBase62 extends functionBase {
 
  private static final long serialVersionUID = 1L;
	
  public fromBase62(){ min = 1; max = 1; setNamedParams( new String[]{ "string" } );}
  
	public String[] getParamInfo(){
		return new String[]{
			"string"	
		};
	}
  
	public java.util.Map getInfo(){
		return makeInfo(
				"conversion", 
				"This takes in a string and attempts to convert from Base62", 
				ReturnType.NUMERIC );
	}
  
	public cfData execute(cfSession _session, cfArgStructData argStruct ) throws cfmRunTimeException {
		
		String s 	= getNamedStringParam( argStruct, "string",""); 
  	
  	try{
  		return new cfNumberData( decode(s) );
  	}catch(Exception e){
  		throwException( _session, "invalid Base62 string [" + s + "]" );
  		return cfBooleanData.TRUE;
  	}
  	
	}
  
	private static final String base62Alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
	
	private static long decode(String number) throws Exception {
		if ( number == null || number.length() == 0 ) throw new Exception();

		int x = number.length();
		long n = 0;
		int base = base62Alphabet.length();
		int column = 1;

		while (x > 0) {
			n = n + (base62Alphabet.indexOf(number.substring(x - 1, x)) * column);
			column = column * base;
			--x;
		}
		return n;
	}
}