001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.web.flickr;
031
032/**
033 * For Flickr's URL shortening
034 * 
035 * @see "http://dl.dropboxusercontent.com/u/1844215/FlickrBaseEncoder.java"
036 * @author David Dupplaw (dpd@ecs.soton.ac.uk)
037 * @created 12 Aug 2013
038 * @version $Author$, $Revision$, $Date$
039 */
040public class FlickrBaseEncoder
041{
042        protected static String alphabetString = "123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ";
043
044        protected static char[] alphabet = alphabetString.toCharArray();
045
046        protected static int base_count = alphabet.length;
047
048        /**
049         * @param num The photo ID number
050         * @return The short URL
051         */
052        public static String encode( long num )
053        {
054                String result = "";
055                long div;
056                int mod = 0;
057
058                while( num >= base_count )
059                {
060                        div = num / base_count;
061                        mod = (int) (num - (base_count * (long) div));
062                        result = alphabet[mod] + result;
063                        num = (long) div;
064                }
065                if( num > 0 )
066                {
067                        result = alphabet[(int) num] + result;
068                }
069                return result;
070        }
071
072        /**
073         *      @param link The short URL
074         *      @return The photo ID
075         */
076        public static long decode( String link )
077        {
078                long result = 0;
079                long multi = 1;
080                while( link.length() > 0 )
081                {
082                        String digit = link.substring( link.length() - 1 );
083                        result = result + multi * alphabetString.lastIndexOf( digit );
084                        multi = multi * base_count;
085                        link = link.substring( 0, link.length() - 1 );
086                }
087                return result;
088        }
089}