<?php

//*************************************************************
//
// ClickBank Tracking Script
// Version 1.0
// Copyright 2010 by Eric Giguere
// ericgiguere@ericgiguere.com
//
// You may use this script for free on as many sites as you want.
// You cannot sell this script or otherwise claim ownership.
// This script is provided as-is, no warranties are implied.
//
// For installation instructions, see 
// http://www.memwg.com/clickbank-tracking-script/
//
//*************************************************************
// Modify these values to set your affiliate ID, the vendor ID,
// and any additional data (i.e. '&page=1928') to append to the
// final hoplink after the tracking ID.
//*************************************************************

$affiliateid = $_GET['affiliateid'];
$vendorid    = $_GET['vendorid'];
$extra       = $_GET['extra'];

if( empty( $affiliateid ) ) $affiliateid = 'egiguere';
if( empty( $vendorid ) )    $vendorid    = 'burnthefat';

//*************************************************************
// You shouldn't need to change anything below this point.
//*************************************************************

// Gather information about the visitor.

$ip       = $_SERVER['REMOTE_ADDR'];
$referrer = $_SERVER['HTTP_REFERER'];
$browser  = $_SERVER['HTTP_USER_AGENT'];
$request  = $_SERVER['REQUEST_URI'];
$reqtime  = date( 'Y/m/d H:i:s T' );
$logfile  = 'clicks.' . date( 'Y-m-d' ) . '.csv';
$prefix   = date( 'mdHi' );
$source   = '';
$tid      = '';

// Check query parameters to determine if we are being called
// from AdWords. If we are, gather the requisite info. If not,
// try to figure out where we're being called from using the
// referrer header.

if( !empty( $_GET['kw'] ) || !empty( $_GET['ag'] ) || !empty( $_GET['nw'] ) ){
    $nw      = strtolower( $_GET['nw'] );
    
    if( strlen( $nw ) != 1 ){
        $nw = 'u';
    }
    
    $source  = 'aw' . $nw;
    $keyword = $_GET['kw'];
    $adgroup = $_GET['ag'];
    
    $tid = substr( $prefix . $source . $adgroup . makealphanum( $keyword ), 0, 24 );
} 

// If we weren't called from AdWords, check the referrer header and
// see if we can suss out an identifier of some kind and combine it
// with the domain name to create a tracking ID.

if( empty( $tid ) && !empty( $referrer ) ){
    $referrerparts = parse_url( trim( $referrer ) );
    
    $host = ( $referrerparts['host'] ? $referrerparts['host'] : 
               array_shift( explode( '/', $referrerparts['path'], 2 ) ) );
    
    $params = parse_query( $referrerparts['query'] );
    
    $hostparts = preg_split( '/\./', $host );
    $tld = count( $hostparts ) - 1;
    
    if( $tld > 0 ){
        $domain = $hostparts[$tld-1];
    $ids = array( 'id', 'C', 'kw' );
    
    foreach( $ids as $param ){
        if( !empty( $params[$param] ) ){
            $source = makealphanum( $params[$param] );
        }
        
        if( $source ) break;
    }
    
    if( !empty( $source ) ){
        $tid = $prefix . substr( $domain . $source, -16 );
    }
    }
}

// Last resort: we weren't able to create a tracking ID, so
// generate a unique string to server as our ID.

if( empty( $tid ) ){
    $tid = substr( getfaketid( $prefix ), 0, 24 );
}

$afflink = 'http://' . $affiliateid . '.' . $vendorid . 
           '.hop.clickbank.net/?tid=' . $tid . $extra;
     
header( "Location: $afflink" );

// Write out the data to our CSV file

$fp = fopen( $logfile, 'a' );
    
if( $fp ){
  fputs( $fp, logmsg() );
  fclose( $fp );
}

//*************************************************************
// Functions used by the code above...
//*************************************************************

// Convert the string to a lower case alphanumeric-only string

function makealphanum( $str ){
    return ereg_replace( '[^a-z0-9]', '', strtolower( urldecode( $str ) ) );
}

// Parse a query string into its constituent parts

function parse_query( $var ){
    $var = html_entity_decode( $var );
    $var = explode( '&', $var );
    $arr = array();
    
    foreach( $var as $val ){
        $x          = explode( '=', $val );
        $arr[$x[0]] = $x[1];
    }
    
    unset( $val, $x, $var );
    return $arr;
}

// Encode URLs for saving in the CSV file by converting
// quotes and commas to URL escapes.
 
function csvencode( $str ){
    $str = str_replace( '"', '%22', $str );
    $str = str_replace( ',', '%2C', $str );
    return $str;
}

// Create the line of CSV data to append to the log file

function logmsg(){
    global $request;
    global $ip;
    global $referrer;
    global $browser;
    global $tid;
    global $reqtime;
    global $afflink;
    
    $msg = "$reqtime,$tid,$afflink,$ip," . csvencode( $request ) . "," 
         . csvencode( $referrer ) . "," . csvencode( $browser );
    
    return $msg . "\n";
}

// Generate a fake TID with the given prefix.

function getfaketid( $prefix ){
    return uniqid( $prefix );
}

?>