<?
/* ==========================================================
 * URLLog PHP-script for redirecting ShortURLs
 * (C) Copyright 2006-2011 Tecnic Software productions (TNSP)
 * ==========================================================
 * How to set up short URL redirection:
 *
 * 1) Set up URLLog database (see urllog.tcl for more information)
 *
 * 2) In this example we assume that your short URL prefix is:
 *    http://example.com/u/
 *    This setting is called urllog_shorturl_prefix in urllog.tcl
 * 
 * 3) Place this PHP script under your www-server root. In this
 *    example we will use "/var/www/urlredirect.php" that is
 *    visible as http://example.com/urlredirect.php
 *
 *    Edit script dbFilename setting below to point to correct
 *    URLLog SQLite database file location.
 *
 * 4) Create or edit /var/www/.htaccess and add following:
 *    RewriteEngine on
 *    RewriteRule ^u/([^\?\&]+)$ /urlredirect.php?u=$1
 *
 * 5) You may need to restart/reload your www-server. 
 *
 * 6) Profit.
 */
// SQLite3 database file path and name
$dbFilename = "/path/to/urllog.sqlite";

// ==========================================================
// Helper functions
$idStr = "ABCDEFGHIJKLNMOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

function myerr($str = "") {
  header("Status: 404 Not Found");
  echo "404 Not Found - ".$str;
  exit;
}

// Check arguments
if (isset($_GET["u"]))
  $urlStr = $_GET["u"];
else
  myerr("No ID given.");

// Calculate urlID
$urlLen = strlen($urlStr);
if ($urlLen < 1) myerr("Invalid ID length.");

for ($urlID = 0, $i = 0; $i < $urlLen; $i++) {
  $urlID *= strlen($idStr);
  $n = strpos($idStr, $urlStr[$i]);
  if ($n !== FALSE) {
    $urlID += $n;
  } else
    myerr("Invalid ID.");
}

// Find the URL
try {
  $db = new PDO("sqlite:".$dbFilename);
}
catch (PDOException $e) {
  myerr("Could not connect to URL database: ".$e->getMessage().".");
}

foreach ($db->query("SELECT url FROM urls WHERE id=".$urlID) as $row) {
  header("Location: ".$row["url"]);
  exit;
}

$db = null;
// Output result
myerr("No such ID in database.");
?>