<?php
/***********************************************************************************************************
Plugin Name:    Short URL
Description:    Handles the creation and redirection of Short URLs
Version:        0.42
Author:         Konamoxt, Inc.
Author URI:     http://konamoxt.com/
License:    

            THE WORK IS PROVIDED UNDER THE TERMS OF THIS CREATIVE COMMONS PUBLIC LICENSE ("CCPL" OR 
            "LICENSE"). THE WORK IS PROTECTED BY COPYRIGHT AND/OR OTHER APPLICABLE LAW. ANY USE 
            OF THE WORK OTHER THAN AS AUTHORIZED UNDER THIS LICENSE OR COPYRIGHT LAW IS PROHIBITED.

                            Attribution-NonCommercial-ShareAlike 3.0 Unported
                            
            You are free:

                * to Share — to copy, distribute and transmit the work
                * to Remix — to adapt the work

            Under the following conditions:

                * Attribution. You must attribute the work in the manner specified by the author or 
                  licensor (but not in any way that suggests that they endorse you or your use of the work).
                  
                * Noncommercial. You may not use this work for commercial purposes.
                
                * Share Alike. If you alter, transform, or build upon this work, you may distribute 
                  the resulting work only under the same or similar license to this one.

                * For any reuse or distribution, you must make clear to others the license terms of 
                  this work. The best way to do this is with a link to this web page.
                  
                * Any of the above conditions can be waived if you get permission from the copyright holder.
                
                * Nothing in this license impairs or restricts the author's moral rights.

            The complete license can be found here: http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode

            Our reasoning behind this license choice is as follows:

                * We intend for this code and posts related to it to be informative and educational. 
                  They are not intended to be fully functioning implementations. They are intended to 
                  represent reusable ideas. Therefore, you shouldn’t need more than this license to 
                  learn from what we've presented here.
                  
                * If you are planning on using this as is, then we would like you to give us, Konamoxt, Inc.
                  the appropriate level of credit. We retain all copyright and intellectual property ownership
                  rights to this code. 
                  
                * If you are want to use this code as is for commercial purposes, then, well, contact us. 
                  We are a software company. Our business is one based on our intentional licensing of our
                  intellectual property.If you’re making money off our hard work, then we want some control 
                  over that. That being said, we don’t mind teaching you some of what we’ve learned, and 
                  so please feel free to read this code, learn from it, and go about your business as you 
                  see fit. But you can't use this code for commercial purposes without securing a different
                  specific commercial license from us first.

            Also please note the following:
            
                * We make no claims about other intellectual property rights, including but not limited to
                  our or third party patent rights. We make not claims as to the whether or not this code 
                  may or may not implement patents held by Konamoxt, Inc. or other third parties.

                * We make no claims claims or warranties of fitness, merchandisability, or quality of this
                  code. Any use by you of this code is at your own risk.

            If you like this code, and you run into someone from Konamoxt, Inc. in person, then you should say, 
            "Hey, that was cool code, I learned something from it, it helped me out. Thanks!", and offer to buy 
            them a beer or a coffee depending on what you're both in the mood for at the time. 
            
            You may not remove this copyright and license message.
            
            THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING 
            BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
            NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
            DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
            OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.


************************************************************************************************************/ 

/******************************************************************
 * What domain do you want URLS shortened to? This could be the
 * main domain you're running WordpressMU on, or it could be a
 * custom domain you have setup to handle shortend URLS. This is
 * only used to create the short url.
 */
define(KMXT_SHORTURL_MASTER_DOMAIN,'sweat365.com'); 

/******************************************************************
 * Based on feedback from users on Facebook, having the url
 * look too short and cryptic will cause users to not click
 * through. One solution is to sacrafice some URL lenght in
 * order to add readability. setting this stub to ! will give
 * you the shortest URLS, but be more cryptic, setting it to
 * go=, read=, more=, readmore=, read+more=, post= will give 
 * more readability and possibly increase click through
 */
define(KMXT_SHORTURL_STUB           ,'-'); 

/******************************************************************
 * This is used as the delimiter for a post. Currently we don't
 * support archives for date, category, tags, or author, but in the
 * future we may add support for this, and therefore we need some
 * code to indicate that the encoding that follows is for a post.
 */
define(KMXT_SHORTURL_POSTID_STUB    ,'-');

/******************************************************************
 * These constants define the encoding that we will use. The basic
 * idea is that this will be a slightly modified base 46 encoding.
 * Base 46 is an encoding that allows us to compress an integer 
 * into a more compact (yet still 2 way) hash. It is the digits 
 * 0-9, the letters a-z, and the 10 safe url characets. 
 *
 * However, we don't want to use a full base 46 alphabet because
 * we don't want to risk accidentally creating encodings that say
 * bad words. So, we've intentionally removed the 5 vowels: aeiou
 * and can be confident that the most common offensive words won't
 * be created.
 *
 * Also, twitter and facebook have problems with some of the 
 * characters so we limit our encoding to just the 3 characters
 * that they can handle: . - _ 
 *
 * So, when it's all said and done we actually have base35 encoding.
 *
 */
define(KMXT_SHORTURL_BASE_NUM  ,35 );
define(KMXT_SHORTURL_BASE_CHARS,"0123456789bcdfghjklmnpqrstvwxyz.-_");


/******************************************************************
 * Hook:      short-url psuedo-hook
 * Purpose:   This will look for potential short urls and remap 
 *            them accordingly. Note: this will trap all incoming
 *            requests BEFORE the WordpressMU core sees the request
 *            because it is "running inline" as opposed to on some
 *            hook. This means that any urls which match your chosen
 *            shortened pattern will be "masked out" by this plugin.
 *            This is one reason why we set the KMXT_SHORTURL_STUB
 *            to something unusual and unique.
 */
if (0 === stripos($_SERVER['REQUEST_URI'],'/'.KMXT_SHORTURL_STUB) )
{
    $original_url = ( $_SERVER['HTTPS'] ? 'https://' : 'http://').
                    ( $_SERVER['SERVER_NAME'] ).
                    ( $_SERVER['SERVER_PORT']==80 ? '': $_SERVER['SERVER_PORT'] ).
                    ( $_SERVER['REQUEST_URI'] );
    $long_url = kmxt_shorturl_to_url($original_url);
    
    // Note: If the plugin doesn't appear to be working, then comment
    // out the following debug code. You should get a "PHP die()" message
    // whenever an inbound shorten URL hits your server, otherwise
    // you should see your normal page.
    //die ("TRAPPED SHORT URL! short=$original_url, long=$long_url");
    if ($long_url)
    {
        header("Location: $long_url");
        exit();
    }
}

/******************************************************************
 * Function:  kmxt_url_to_shorturl($url)
 * Purpose:   creates a short url for the given long url
 */
function kmxt_url_to_shorturl($url)
{
    $out = '';
    $the_domain = parse_url($url, PHP_URL_HOST);

    // NOTE: VHOST ONLY! We've only implemented support for VHOST 
    // based WordpressMU installs. And really, we haven't tested
    // it beyond vhost with / based roots for all blogs. If you
    // have your WordpressMU install running in subdirectory mode
    // you will need to change this code slightly. Also, if you
    // want to run this on a single instance of WordPress, this would
    // be a good place to make some changes. We'll leave that as
    // an exercise for the class.
    global $wpdb;
    $blog_id = $wpdb->get_var("SELECT blog_id FROM $wpdb->blogs WHERE domain = '$the_domain'");

    if ($blog_id)
    {
		switch_to_blog($blog_id);
		// Call the function from rewrite.php to get the best chance of finding the 
		$post_id = url_to_postid($url);
		restore_current_blog();

		// passing 0 for post_id is ok, because in that case we just
		// make a short url for the blog!
        $out = kmxt_shorturl_from_ids($blog_id,$post_id);
    }
    
    // now, if somehow the short url is longer than the original
    // then, well, we return the original.
    if (strlen($out) > strlen($url)) $out=$url;
    return $out;
}

/******************************************************************
 * Function:  kmxt_shorturl_from_ids($blog_id,$post_id)
 * Purpose:   creates a short url for the blog/post combination
 */
function kmxt_shorturl_from_ids($blog_id,$post_id)
{
    $blog_encode = kmxt_base35encode($blog_id);
    
    // blog part only
    // Note: leading ! is used to differentiate from actual 
    //       urls in the master domain name space.
    $out = ( $_SERVER['HTTPS'] ? 'https://' : 'http://').
           ( KMXT_SHORTURL_MASTER_DOMAIN ).
           ( $_SERVER['SERVER_PORT']==80 ? '': $_SERVER['SERVER_PORT'] ).
           ( '/'.KMXT_SHORTURL_STUB.$blog_encode );

    if ($post_id>0)
    {
        $post_encode = kmxt_base35encode($post_id);
        
        // Note: leading ! is used to indicat that this
        //       is a post. In the future we may use this
        //       leading character to indicate links to
        //       tags, categories, or date ranges. But for 
        //       now we only support posts
        $out .= '/'.KMXT_SHORTURL_POSTID_STUB.$post_encode;
    }
    return $out;
}

/******************************************************************
 * Function:  kmxt_getShortURL_from_ids($blog_id,$post_id)
 * Purpose:   creates a short url for the blog/post combination
 */
function kmxt_shorturl_to_url($shorturl)
{
    $out = '';
    
    $parsed = parse_url($shorturl);
    $host = $parsed['host'];
    $path = $parsed['path'];
    
    // Check that we match our expected format, if not, then return
    // the original url to our caller
    if (0 !== stripos($path,'/'.KMXT_SHORTURL_STUB) )
        return $shorturl;
    
    list($stub,$blog_part,$post_part) = explode('/',$path);
    
    $blog_part_trimmed = substr($blog_part,strlen(KMXT_SHORTURL_STUB));
    $post_part_trimmed = substr($post_part,strlen(KMXT_SHORTURL_POSTID_STUB));

    $blog_id = kmxt_base35decode($blog_part_trimmed);
    $post_id = kmxt_base35decode($post_part_trimmed);
    
    // VHOST ONLY!
    global $wpdb;
    $domain = $wpdb->get_var("SELECT domain FROM $wpdb->blogs WHERE blog_id = '$blog_id'");

    if ($domain)
    {
        $out = "http://$domain/";

        if ($post_id)
        {
            $out .= "?p=$post_id";
        }
    }    
    return $out;
}

/******************************************************************
 * Function:  kmxt_base35encode()
 * Purpose:   converts a number into a 'base35' representation.
 */
function kmxt_base35encode($value)
{
    $out = '';
    $base35chars = KMXT_SHORTURL_BASE_CHARS;
    while($value > 0)
    {
        $floor = floor($value / KMXT_SHORTURL_BASE_NUM);
        $times = $floor*KMXT_SHORTURL_BASE_NUM;
        $remainder = $value - $times;
        $char = substr($base35chars,$remainder,1);
        $out .= $char;
        $value = ($value-$remainder)/KMXT_SHORTURL_BASE_NUM;
    }
    return $out;
}

/******************************************************************
 * Function:  kmxt_base35decode()
 * Purpose:   converts a number into a 'base35' representation.
 */
function kmxt_base35decode($value)
{
    $out = 0;
    $base35chars = KMXT_SHORTURL_BASE_CHARS;
    
    $len = strlen($value);
    for ($i=($len-1); $i >= 0; $i--)
    {
        $char = substr($value,$i,1);
        $charvalue = strpos($base35chars,$char);
        $out = ($out*KMXT_SHORTURL_BASE_NUM) + $charvalue;
    }
    return $out;
}

/******************************************************************
 * Function:  kmxt_test_shorturl()
 * Purpose:   testing function
 */
//add_action('wp_footer','kmxt_test_shorturl');
function kmxt_test_shorturl()
{
    echo "<div style='background:white;color:black'>";
    
    $tests = Array(9999999999,999999999,99999999,9999999,999999,99999,9999,999);
    
    foreach ($tests as $test)
    {
        $encode_result = kmxt_base35encode($test);
        echo "<h2>kmxt_base35encode($test)=$encode_result</h2>";
        $decode_result = kmxt_base35decode($encode_result);
        echo "<h2>kmxt_base35decode($encode_result)=$decode_result</h2>";
    }


    $tests = Array( 'qwrty','bcdfg','brd','102');
    
    foreach ($tests as $test)
    {
        $decode_result = kmxt_base35decode($test);
        echo "<h2>kmxt_base35decode($test)=$decode_result</h2>";
        $encode_result = kmxt_base35encode($decode_result);
        echo "<h2>kmxt_base35encode($decode_result)=$encode_result</h2>";
    }
    
    $url_tests = Array( 'http://'.KMXT_SHORTURL_MASTER_DOMAIN.'/about/' );
    
    foreach ($url_tests as $url)
    {
        $short_url = kmxt_url_to_shorturl($url);
        echo "<h2>kmxt_url_to_shorturl($url)=<a href='$short_url'>$short_url</a></h2>";

        $long_url = kmxt_shorturl_to_url($short_url);
        echo "<h2>kmxt_shorturl_to_url($short_url)=<a href='$long_url'>$long_url</a></h2>";
    }
    
    echo "</div>";
}
?>