FlickrBaseEncoder.java

package io.scal.secureshareui.lib;

import timber.log.Timber;

/**
 * Created by josh on 11/15/14.
 */
public class FlickrBaseEncoder {
    protected static String alphabetString = "123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ";
    protected static char[] alphabet = alphabetString.toCharArray();
    protected static int base_count = alphabet.length;

    public static String encode(long num){
        String result = "";
        long div;
        int mod = 0;

        while (num >= base_count) {
            div = num/base_count;
            mod = (int)(num-(base_count*(long)div));
            result = alphabet[mod] + result;
            num = (long)div;
        }
        if (num>0){
            result = alphabet[(int)num] + result;
        }
        return result;
    }

    public static long decode(String link){
        long result= 0;
        long multi = 1;
        while (link.length() > 0) {
            String digit = link.substring(link.length()-1);
            result = result + multi * alphabetString.lastIndexOf(digit);
            multi = multi * base_count;
            link = link.substring(0, link.length()-1);
        }
        return result;
    }
}