<?php
 
class SHORTEN
{
 
 
    // vars
    private $id = null;
    private $url_long = null;
    private $url_short = null;
    private $base = null;
    private $limit_ip = null; // set to world
    private $tracking = true;
    public $check_url = null;
    private $caching = false;
    private $cache_dir = null;
    
    private $allowed_chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    
     
    // contructor 
    public function __construct( $mode = 'create', $url = null, $check_url = false ) {
        global $DIR_ROOT, $CONF;        
        /**
          * uncomment this and reload site
          * to clear db.
          **/
        //$this->clearDb();    
 
        $this->base = 'http://'. $CONF['IndexURL'] .'/'; // . $_SERVER['HTTP_HOST'] . '/';
        $this->limit_ip = $_SERVER['REMOTE_ADDR'];
        $this->cache_dir = $DIR_ROOT . 'cache/';
        $this->check_url = $check_url;
        
        if($mode == 'redirect')
            return $this->load($url);
        
                
        // short circuit to create    
        return $this->store($url);    
    }
    
    
    public function getShortUrl() {
        global $CONF;
        
        if( !empty( $this->url_short ) )
            return 'http://'. $CONF['ShortURL'] . '/' . $this->url_short;
        
        return false;
    }
    
    
    public function redirect() {
        global $CONF;
            
        if( empty($this->url_long) ) {
            header('Location: ' . $CONF['IndexURL']);
            exit;
        }    
        
        // $CONF['IndexURL'] .  $this->url_long;
        //die();
    
        header('Location: '  .  $this->url_long);
        exit;
    
    }
    
    
    private function load($url) {
        
        if(!preg_match('|^[0-9a-zA-Z]{1,6}$|', $url))
            return false;
        
        $this->id = $this->getIdFromSurl($url);
        if($this->caching)
            $this->cache();
        
        
        $this->url_long = quickQuery( 'SELECT surl_long as result FROM ' . sql_table('shorturls') . ' WHERE sid = "' . $this->id . '"');
        
        if($this->tracking)
            $this->track();
        
        return true;
    }
    
    
    private function store($url_long) {
        global $CONF;
    
        // if class var limit_ip is limiting short linking
        if($_SERVER['REMOTE_ADDR'] != $this->limit_ip)
            return false;
                
        // if url is empty
        if( empty( $url_long ) )
            //return false; 
            $url_long = $CONF['IndexURL'];
            
        //if( !preg_match( '|^https?://|', $url_long ) ) return false;
        
        /** 
          * if the url contains the shortener's 
          * url don't allow recursive linking
          */
        if( strstr( $url_long, $CONF['ShortURL'] ) )
            return false;
        
        // don't allow just http:// to be a link
        if($url_long == 'http://')
            return false;
            
         $this->url_long = $url_long;
     
         // check if record exists and if so offer it
         if(true == ( $r = $this->recordExists() ) )
             return $this->url_short = $this->getSurlFromId($r);
    
        
         // if we are checking url for validity 
         if(true != ( $r = $this->checkUrl() ) )
             return false;
         
         //echo 'this is long url ' . $this->url_long;
        
                                   
         // if not create it
         $this->url_short =  $this->createRecord();
    
        return true;
        
    }
    
    
    private function getSurlFromId( $integer, $base = null ) {
        
        if( empty($base) )
            $base = $this->allowed_chars;
        
        $length = strlen($base);
        
        $out = null;
        while($integer > $length - 1) {
            $out = $base[fmod($integer, $length)] . $out;
            $integer = floor( $integer / $length );
        }
        
        return $base[$integer] . $out;
    }
    
    
    function getIdFromSurl($string, $base = null ) {
    
        if( empty($base) )
            $base = $this->allowed_chars;
 
        $length = strlen($base);
        $size = strlen($string) - 1;
        $string = str_split($string);
        $out = strpos($base, array_pop($string));
 
        foreach($string as $i => $char) {
            $out += strpos($base, $char) * pow($length, $size - $i);
        }
        
        return $out;
    }
    
    
    private function track() {
        $r = sql_query('UPDATE ' . sql_table('shorturls') . ' SET sreferrals=sreferrals+1 WHERE sid="' . addslashes($this->id) . '"');
        return $r;
    }
    
    
    // everything else if private
    private function checkUrl() {
        
        if(!$this->check_url)
            return true;
        
        $ch = curl_init();
        curl_setopt( $ch, CURLOPT_URL, $this->url_long );
        curl_setopt( $ch,  CURLOPT_RETURNTRANSFER, true );
        
        $r = curl_exec($ch);
        
        
        $flag = true;
        if( !curl_getinfo( $ch, CURLINFO_HTTP_CODE ) == '404' )
            $flag = false;
                
        curl_close($ch);
        
        return $flag;
        
    }
    
    
    
    private function recordExists() {
    
        /*if( !table_exists('shorturls') ) {    
            sql_query( "CREATE TABLE `nuke_shorturls` (
                 `sid` int(10) unsigned NOT NULL auto_increment,
                `surl_long` varchar(255) NOT NULL,
                 `screated` int(10) unsigned NOT NULL,
                  `screator` char(15) NOT NULL,
                  `sreferrals` int(10) unsigned NOT NULL default '0',
                  PRIMARY KEY  (`sid`),
                  UNIQUE KEY `long` (`surl_long`),
                  KEY `referrals` (`sreferrals`)
                ) ENGINE=MyISAM DEFAULT CHARSET=utf8;" 
            );  
        }*/
        
        $r = quickQuery( 'SELECT sid as result FROM ' . sql_table('shorturls') . ' WHERE surl_long ="' . $this->url_long.'"');        
        
        if( $r )
            return $r;
        
        return false;        
    }
    
    
    private function createRecord() {
    
        // URL not in database, insert
        sql_query('LOCK TABLES ' . sql_table('shorturls')  . ' WRITE;');
        sql_query('INSERT INTO ' . sql_table('shorturls') . ' (surl_long, screated, screator) VALUES ("' . addslashes($this->url_long) . '", "' . time() . '", "' . addslashes($_SERVER['REMOTE_ADDR']) . '")');
        $this->url_short = $this->getSurlFromID(mysql_insert_id());
        sql_query('UNLOCK TABLES');
 
        return $this->url_short;
    }
    
        
    private function cache() {
        
        if(is_file($this->cache_dir . $this->id))
            $url_long = file_get_contents($this->cache_dir . $this->id);
                
        if( empty( $url_long ) || !preg_match( '|^https?://|', $url_long ) ) {
            $r = quickQuery( 'SELECT surl_long as result FROM ' . sql_table('shorturls') . ' WHERE sid = "' . $this->id . '"');
            //@mkdir(CACHE_DIR, 0777);
            $handle = fopen($this->cache_dir . $this->id, 'w+');
            fwrite($handle, $r);
            fclose($handle);
        }
        
        return true;
        
    }
    
    
    private function clearDb() {
        global $CONF;
        
        $query = 'TRUNCATE TABLE '. sql_table('shorturls');
        
        if(!sql_query($query))
            echo 'Error emptying database<br />';
    
        $this->url_long = $CONF['IndexURL'];
         
         // check if record exists and if so offer it
         if(true == ( $r = $this->recordExists() ) )
             return $this->url_short = $this->getSurlFromId($r);
         
         // if not create it
         $this->url_short =  $this->createRecord();
 
        return true;
        
    }
    
 
}
 
?>