<?php

$manager = new url_manager();
$manager->process();


/**
---
-- Tabellenstruktur für Tabelle `urls`
--

CREATE TABLE IF NOT EXISTS `urls` (
  `code` varchar(15) COLLATE utf8_bin NOT NULL,
  `url` text COLLATE utf8_bin NOT NULL,
  `time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `counter` int(11) NOT NULL,
  PRIMARY KEY (`code`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_bin COMMENT='Code zu URL Zuordnung';


//////////////////////
Code für die .htaccess Datei

RewriteEngine On

# SHORTENER: IHRE_DOMAIN.TLD/-CODE wird durch das Script short.php bearbeitet.
RewriteRule ^-(.*)$   /short.php?code=$1 [R=301,L]


//////////////////////
Weitere Information finden Sie unter 

http://webblog.servicehome.net/2010/06/02/url-shortener-aber-warum-unter-fremder-domane/

und

http://webblog.servicehome.net/2010/06/03/url-shortener-bookmark-im-firefox/

*/

class url_manager {

    private $db_connection;

    private $BASE_URL = "http://IHRE_DOMAIN.TLD"; // z.B. "http://servicehome.net/";
    
    private $code_length = 6; // Länge des generierten Codes. 

    /**
     * Create db-connection. if used in shop-environment use given db-connection!
     */
    function __construct() {
        $this->db_connection = mysql_connect("localhost", "DB_BENUTZERNAME", "PASSWORT");
        if ($this->db_connection) {
            mysql_select_db("DATENBANK_NAME", $this->db_connection);
        }
    }

    function __desctruct() {
        // NOTHING YET
    }

    function process() {
        // redirect?
        $code = isset($_GET['code']) ? $_GET['code'] : null;
        if (!is_null($code)) {
            $url = $this->getUrlByCode($code);
            if ($url != "") {
		$this->count($code);
		 $this->redirect($url);
	     }
            die("");
        }

        // generate code?
        $url = isset($_GET['url']) ? $_GET['url'] : null;
        if (!is_null($url)) {
            $code = $this->storeUrlAndReturnCode($url);
            $this->displayShortenedUrl($code);
        }

	if (isset($_GET['stats'])) {
	  $this->showStatistics();
	}
    }

    private function showStatistics() {
      $query = 'SELECT code, url, counter, time FROM urls ORDER BY counter DESC;';
      $rec = mysql_query($query);
      if ($rec) {
        while ($row = mysql_fetch_array($rec)) {
          $time = $row['time'];
          $code = $row['code'];
          $url  = $row['url'];
	  $counter = sprintf("%'.4d", $row['counter']);

          echo "{$counter} - {$time} / {$code}: {$url}\n<br>";
        }
      }
    }

    private function count($code) {
        $query = "UPDATE urls SET counter=(counter+1) WHERE code='".$code."'";
        mysql_query($query, $this->db_connection);
    }

    private function displayShortenedUrl($code) {
        echo $this->BASE_URL . "-" . $code;
    }

    private function storeUrlAndReturnCode($url) {
        $code = "";
        if ($url != "") {
            $code = $this->getCodeByUrl($url);

            if ($code == "") {
                for ($i=0; $i < $this->code_length; $i++) {
                    $c1 = rand(48,57);
                    $c2 = rand(65,90);
                    $c3 = rand(97,122);

                    $selector = rand(1,3);
                    switch ($selector) {
                        case 1:
                            $code .= chr($c1);
                            break;
                        case 2:
                            $code .= chr($c2);
                            break;
                        case 3:
                            $code .= chr($c3);
                            break;
                    }
                }

                // store new entry
                $this->createEntry($url, $code);
            }
        }

        return $code;
    }

    private function getCodeByUrl($url) {
        $code = $this->queryCodeByUrl($url);
        return $code;
    }

    private function createEntry($url, $code) {
	$url = urldecode($url);
        $query = "INSERT INTO urls (url,code) VALUES ('".$url."', '".$code."')";
        mysql_query($query, $this->db_connection);
        
        $error_number = mysql_errno($this->db_connection);
        if ($error_number != 0) echo "Fehler beim speichern! (ERR:".$error_number.") url:".$url." code:".$code;
    }

    private function queryCodeByUrl($url) {
        $code = "";
        $query = "SELECT code FROM urls WHERE url='".$url."'";
        $rec = mysql_query($query, $this->db_connection);
        if ($rec) {
            $data = mysql_fetch_assoc($rec);
            $code = $data['code'];
        }

        return $code;
    }

    private function queryUrlByCode($code) {
        $url = "";
        $query = "SELECT url FROM urls WHERE code = '".$code."'";
        $rec = mysql_query($query, $this->db_connection);
        if ($rec) {
            $data = mysql_fetch_assoc($rec);
            $url = $data['url'];
        }

        return $url;
    }

    function getUrlByCode($code) {
        $url = $this->queryUrlByCode($code);
        return $url;
    }

    private function redirect($url) {
        header('Location: '.$url);
    }
}