A class to track campaign and visitors source via session.

demo.php

<?php

/*
* Developer: Mohammad Sharaf Ali
* Version: 1.0
* Description: Demo Page displaying actual MTracker class usage
* Dated: 03-02-2016
*/

/*
** Use the code on the actual registration or whatever page you want to track than get the details using STEP5 and save it to db / file as per your requirements.
** Things to remember: 
	- STEP 4 will start the session once and save all the relevant info in session. Calling it on every page will not affect the data saved on the
	first instance.
	- STEP 5 will return the saved data in the session. The "true" parameter plays an important role in a sense, if suppose on page 1 you passed in it as "true" it
	will save the url in the session as "page1.php" and on the page 2 again you passed in it as "true" so it will override and save in the session as "page 2". Leaving
	it blank or passing in as "false" will pertain "page1.php".
	- The flow of the script is simple:
		- First it will look for UTM parameters in the url. If found okay else
		- It will look HTTP_REFERER in the http headers. If found okay else
		- It will set the default values as set in MTracker.php class
** With this script you can track more of the things you want with a little customization and build beautiful dashboards to analyze your data.
*/

#STEP 0: Ensure you are using UTM url's as that is the way the script will track your campaign and visitors source

#STEP1: include the lib
require_once 'MTracker.php';

#STEP2: create namespace alias to access the class
use MSharaf\MTracker as MTracker;

#STEP3: create singleton class object
$coolTracker = MTracker::getInstance();

#STEP4: start the tracker
# session name (optional) {The session name can't consist of digits only, at least one letter must be present.}
$coolTracker->startTracker('any2016'); 

#STEP5: get the tracker tracked data
# track page url (optional) {true, false}
print_r($coolTracker->getTracker(true));

MTracker.php

<?php

/*
* Developer: Mohammad Sharaf Ali
* Version: 1.0
* Description: Class to track visitor registration source
* Dated: 23-04-2016
*/

namespace MSharaf;

class MTracker 
{
	private static $instance;
	private static $defaultSource = 'Any';
    private static $defaultMedium = 'Direct Link';
    
    private function __construct() 
    {
    }

    public static function getInstance()
    {
        if (!self::$instance) {
	    	self::$instance = new MTracker();
        }
            
        return self::$instance;
    }
    
	private function initSession($name = '')
	{
	    $phpVersion = phpversion();

	    if ($phpVersion  < '5.4.0') {
	        if (session_id() == '') {
	            if (!empty($name)) {
	                session_name($name);
	            }

	            session_start();
	        }
	    } else if ($phpVersion  >= '5.4.0') {
	        if (session_status() == PHP_SESSION_NONE) {
	            if (!empty($name)) {
	                session_name($name);
	            }

	            session_start();
	        }
	    }
	}

	private function unsetSessionVars($vars)
	{
    	foreach ($vars as $var) {
        	unset($_SESSION["{$var}"]);
    	}
	}

	private function destroySession()
	{
    	session_unset();
    	session_destroy();
	}

	private function getName($url)
	{
	 	$pieces = parse_url($url);
	  	$domain = isset($pieces['host']) ? $pieces['host'] : '';
	  
	  	if (preg_match('/(?P<domain>[a-z0-9][a-z0-9\-]{1,63}\.[a-z\.]{2,6})$/i', $domain, $regs)) {
	    	return explode('.', $regs['domain'])[0];
	  	}

	  	return false;
	}

	public function getSiteUrl($customUri = '')
	{
	    $scheme = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on') ? 'https://' : 'http://';

	    if (empty($customUri)) {
	        return ($scheme . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI']);
	    } else {
	        return ($scheme . $_SERVER['HTTP_HOST'] . $customUri);
	    }
	}

	private function getHostAndKeyword($url = '')
	{
	    $output = array(self::$defaultSource, self::$defaultMedium);
	    $matches = array();

	    $referrer = (!empty($_SERVER['HTTP_REFERER'])) ? $_SERVER['HTTP_REFERER'] : '';
	    $referrer = (!empty($url)) ? $url : $referrer;
	    
	    if (empty($referrer)) {
	        return $output;
	    }

	    $parsedUrl = parse_url($referrer);
	    
	    if (empty($parsedUrl['host'])) {
	        return $output;
	    }

	    $host = $parsedUrl['host'];
	    $queryStr = (!empty($parsedUrl['query'])) ? $parsedUrl['query'] : '';
	    $queryStr = (empty($queryStr) && !empty($queryStr['fragment'])) ? $queryStr['fragment'] : $queryStr;
	    
	    if (empty($queryStr)) {
	        $output = array(
	            $this->getName($referrer) !== false ? $this->getName($referrer) : self::$defaultSource, '');

	        return $output;
	    }

	    parse_str($queryStr, $query);

	    $searchEngines = array(
	        'q'         => 'alltheweb|aol|ask|lycos|hotbot|infospace|looksmart|dogpile|gigablast|webcrawler|contenko|alhea|zapmeta|teoma|duckduckgo|bestsearch|entireweb|msn|bing|google',
	        'p'         => 'yahoo',
	        'wd'        => 'baidu',
	        'text'      => 'yandex',
	        'qs'        => 'virgilio',
	        'searchfor' => 'mywebsearch',
	        'qkw'       => 'info',
	        'query'     => 'carrot2|yippy|iseek|startpage'
	    );

	    foreach ($searchEngines as $queryVar => $se) {
	        $se = trim($se);
	        preg_match('/(' . $se . ')\./', $host, $matches);
	        
	        if (!empty($matches[1]) && !empty($query[$queryVar])) {
	            $output = array(
	                $this->getName($referrer) !== false ? $this->getName($referrer) : self::$defaultSource,
	                $query[$queryVar]);
	            
	            return $output;
	        }
	    }
	    
	    if (empty($matches)) {
	        $output = array(
	            $this->getName($referrer) !== false ? $this->getName($referrer) : self::$defaultSource, '');
	        
	        return $output;
	    }
	}

	private function setTracker()
	{
	    $parsedUrl = parse_url($this->getSiteUrl());

	    if (isset($parsedUrl['query'])) {
	        parse_str($parsedUrl['query'], $parsedQueryStrArr);
	    }

	    if (isset($parsedQueryStrArr) && !empty($parsedQueryStrArr) &&
	    	isset($parsedQueryStrArr['utm_source']) && !empty($parsedQueryStrArr['utm_source']) &&
	        isset($parsedQueryStrArr['utm_medium']) && !empty($parsedQueryStrArr['utm_medium'])) {
	        
	        $_SESSION['SessData']['Tracker'] = array(
	            'Source' => isset($parsedQueryStrArr['utm_source']) ? urldecode($parsedQueryStrArr['utm_source']) : self::$defaultSource, 
	            'Medium' => isset($parsedQueryStrArr['utm_medium']) ? urldecode($parsedQueryStrArr['utm_medium']) : self::$defaultMedium,
	            'QueryString' => isset($parsedQueryStrArr['utm_source']) ? '?'. $parsedUrl['query'] : '?v='. self::$defaultSource);

	    } else if(isset($_SERVER['HTTP_REFERER']) && $this->getName($_SERVER['HTTP_REFERER']) != $this->getName($this->getSiteUrl())) {
	        list($host, $keyword) = $this->getHostAndKeyword();

	        $_SESSION['SessData']['Tracker'] = array(
	            'Source' => isset($host) && !empty($host) ? $host : self::$defaultSource, 
	            'Medium' => isset($keyword) && !empty($keyword) ? urldecode($keyword) : '',
	            'QueryString' => '?v='. self::$defaultSource);

	    } else {
	        $_SESSION['SessData']['Tracker'] = array(
	            'Source' => self::$defaultSource, 
	            'Medium' => self::$defaultMedium,
	            'QueryString' => '?v='. self::$defaultSource);
	    }
	}
	
	public function startTracker($sessName = '')
	{
	    $this->initSession($sessName);

	    if (!isset($_SESSION['SessData'])) {
	        $this->setTracker();

	    }  else if(isset($_SESSION['SessData']) && empty($_SESSION['SessData']['Tracker']['Source'])) { // could also check for other parameters
	    	$this->destroySession();
	    	$this->initSession($sessName);
	    	$this->setTracker();
	    }
	} 

	public function getTracker($withTrackUrl = false)
	{
		if ($withTrackUrl === true) {
			$finalUrl = $this->getSiteUrl();
			$urlWithoutUri = strtok($finalUrl, '?');
			
			if ($urlWithoutUri !== false) {
				$finalUrl = $urlWithoutUri. $_SESSION['SessData']['Tracker']['QueryString'];
			}

			$_SESSION['SessData']['Tracker']['Url'] = $finalUrl;
		}

	    return $_SESSION['SessData']['Tracker'];
	}
}

With a little customization from your end you can use easily convert the session based logic to cookie based logic.