<?php
/**
  Redirect to a Piwik webbug (1 pixel image), or the Google-Analytics one.
  OLnet.org / OER tracking project.
  @copyright 2010 The Open University.
 
  Usage - Piwik - title=X, r=referrer are optional,
    <img alt="" src="http://localhost/track/PI-1/example.org/path/to/123?title=My+Title" />
 
  Usage - Google-Analytics,
    <img alt="" src="http://localhost/track/UA-1234-5/example.org/path/to/123?title=My+Title&r=http%3A//referer.example.com/" />
 
 
  An Apache .htaccess/httpd.conf edit is required:
 
  <IfModule mod_rewrite.c>
    RewriteEngine on
    # If the file/dir is NOT real go to index
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)$ index.php/$1 [QSA,L]
  </IfModule>
  <IfModule !mod_rewrite.c>
    # If mod_rewrite is NOT installed go to index.php
    ErrorDocument 404 index.php
  </IfModule>
 
*/
// Substitute your local Piwik here.
#define('PIWIK_TRACKER',  "http://localhost/my_piwik/piwik.php");
define('PIWIK_TRACKER',  "http://piwik.org/demo/piwik.php");
define('GOOGLE_TRACKER', "http://www.google-analytics.com/__utm.gif");
 
  date_default_timezone_set('Europe/London');#Prevent warnings.
 
  $local_url = $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
  $path = parse_url($local_url, PHP_URL_PATH);
 
  // Optional Referrer/title - use parse_url for crude parsing.
  $referer = isset($_GET['r']) && 'array'==gettype(@parse_url($_GET['r'])) ? $_GET['r'] : NULL;
  $referer = !$referer && isset($_SERVER['HTTP_REFERER']) ? isset($_SERVER['HTTP_REFERER']) : $referer;
  $title   = isset($_GET['title']) ? $_GET['title'] : NULL;
 
  $request_string = NULL;
  if (preg_match('#/PI-(\d+?)/(.+)$#', $path, $matches)) {
    // Piwik
    $request_string = piwik_analytics_bug_url($matches, $title, $referer);
  }
  elseif (preg_match('#/(UA-\d+?(-\d+)?)/(.+)$#', $path, $matches)) {
    // Google/Urchin?
    $request_string = google_analytics_bug_url($matches, $title, $referer);
  }
  //ELSE: Yahoo?
 
  // Error.
  if (!$request_string) {
    @header("HTTP/1.1 400", TRUE, 400);
    die("Error, bad request.");
  }
 
  // OK, do the redirect to the web bug (temporary).
  @header("HTTP/1.1 302 Moved", TRUE, 302);
  header("Location: $request_string");  exit;
 
echo " DEBUG, redirect: $request_string ";
 
 
/* Based on,
 http://dev.piwik.org/svn/trunk/core/Tracker/Visit.php
 http://www.burtonkent.com/wp-content/uploads/piwik-tag.php
*/
function piwik_analytics_bug_url($matches, $title=NULL, $referer=NULL) {
    // non-Javascript solution can't get screen-resolution, Flash, Java, other plugin capabilities.
    $request = array();
 
    # idsite - Piwik site ID.
    $request['idsite'] = $matches[1];
 
    # url - Requested URL.
    $scheme = 80==$_SERVER['SERVER_PORT'] ? 'http://' : 'https://';
    $request['url'] = $scheme . $matches[2];
 
    # urlref - Referrer.
    $request['urlref'] = $referer;
 
    # title, action_name?
    $request['title']      = $title;
    $request['action_name']= $title;
 
    # cookie - Are cookies enabled?
    /*if (isset($_SERVER['HTTP_COOKIE']) && $_SERVER['HTTP_COOKIE'] != '') {
      $request['cookie'] = 1;
    }
    else {
      $request['cookie'] = 0;  # or possibly not set? Hmm, not convinced!
    }*/
 
    # (d,) h, m, s - hours, minutes, seconds (, days?)
    list($request['d'], $request['h'], $request['m'], $request['s'])
        = explode('|', date('d|H|i|s', $_SERVER['REQUEST_TIME']));
 
    # rand - random number - quick 17 precision random number.
    $request['rand'] = '0.' . mt_rand(0, mt_getrandmax());
 
    # rec - record?  1 by default
    $request['rec'] = 1;
 
    return PIWIK_TRACKER .'?'. http_build_query($request);
}
 
 
/* Based on http://nojsstats.blogspot.com/ */
function google_analytics_bug_url($matches, $title=NULL, $referer=NULL) {
    $request = array('utmwv'=>1, 'utmsr'=>'-', 'utmsc'=>'-', 'utmul'=>'-', 
        'utmje'=>'0', 'utmfl'=>'-', 'utmjv'=>'-'); //'hid' Another number?
 
    $request['utmac'] = $matches[1];
 
    $p = parse_url('http://'.$matches[3]);
    $request['utmhn'] = $p['host'];
    $request['utmp' ] = $p['path']. (isset($p['query']) ? '?'.$p['query'] : '');
 
    $request['utmdt'] = $title;
    $request['utmr' ] = $referer;
 
    # utmn - Random number?
    $request['utmn' ] = mt_rand(0, mt_getrandmax());
 
    return GOOGLE_TRACKER .'?'. http_build_query($request);
}