Class for server-side submission of data to Google Analytics

Analytics.inc.php

<?php
/*
* Analytics.inc.php
*
* Class for server-side submission of data to Google Analytics.
* TODO: Would be better to save the request to a queue to process submissions in the background. Currently, requests are blocked until the POST to GA completes or timeout is reached. 
*
* @author   Quinn Comendant <quinn@strangecode.com>
* @version  1.0
* @since    24 Aug 2014 15:35:43
*
* Example of use:
---------------------------------------------------------------------
require_once 'lib/Analytics.inc.php';
$ga = new Analytics(array(
    'tid' => $google_analytics_property_id,
));
$ga->submit($page_title);
---------------------------------------------------------------------
*/

class Analytics {

    // Configuration parameters for this object.
    protected $_params = array(
        // 'url' => 'http://www.google-analytics.com/collect', // The Google Analytics Measurement Protocol URL.
        'url' = 'https://ssl.google-analytics.com/collect', // The Google Analytics Measurement Protocol URL.
        'tid' => '', // The ID that distinguishes to which Google Analytics property to send data.
        'timeout' => 5,
    );

    /**
     * Analytics constructor.
     *
     * @access public
     * @param string  Namespace for this object, used to avoid collisions in global contexts.
     * @param string     Configuration parameters for this object.
     */
    public function __construct($params=null)
    {
        // Set custom parameters.
        $this->setParam($params);
    }

    /**
     * Set the params of this object.
     *
     * @access public
     * @param  array $params   Array of param keys and values to set.
     */
    public function setParam($params=null)
    {
        if (isset($params) && is_array($params)) {
            // Merge new parameters with old overriding only those passed.
            $this->_params = array_merge($this->_params, $params);
        }
    }

    /**
     * Return the value of a parameter, if it exists.
     *
     * @access public
     * @param string $param        Which parameter to return.
     * @return mixed               Configured parameter value.
     */
    public function getParam($param)
    {
        if (isset($this->_params[$param])) {
            return $this->_params[$param];
        } else {
            return null;
        }
    }

    /*
    * Send a tracking request to the Measurement Protocol API. This is not an asynchronous request, and will delay page loading times.
    * TODO: modify this to use a non-blocking POST to the API.
    *
    * @access   public
    * @param    string  $dt Document title.
    * @param    string  $dl The full URL (document location) of the page on which content resides.
    * @param    string  $t  The type of hit. Must be one of 'pageview', 'screenview', 'event', 'transaction', 'item', 'social', 'exception', 'timing'.
    * @return   bool        True or false indicating success or error.
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @version  1.0
    * @since    24 Aug 2014 15:33:52
    */
    public function submit($dt='', $dl=null, $t='pageview')
    {
        // Use the cid provided by GA if it exists.
        if (isset($_COOKIE['_ga']) && substr_count($_COOKIE['_ga'], '.')) {
            $cid = join('.', array_slice(explode('.', $_COOKIE['_ga']), 2));
        } else {
            // Otherwise use the fp (fingerprint) cookie, which may be set by fingerprint.js or here by uniqid().
            if (isset($_COOKIE['fp'])) {
                $cid = $_COOKIE['fp'];
            } else {
                $cid = uniqid('', true);
                setcookie('fp', $cid, strtotime('+10 years'), '/');
            }
        }

        $dl = is_null($dl) ? sprintf('%s://%s%s', $_SERVER['REQUEST_SCHEME'], $_SERVER['HTTP_HOST'], $_SERVER['REQUEST_URI']) : $dl;

        $params = array(
            'v' => '1', // The protocol version. The value should be 1.
            'tid' => $this->getParam('tid'), // The ID that distinguishes to which Google Analytics property to send data.
            'cid' => $cid, // An ID unique to a particular user.
            't' => $t, // The type of hit. Must be one of 'pageview', 'screenview', 'event', 'transaction', 'item', 'social', 'exception', 'timing'.
            'dl' => $dl, // The full URL (document location) of the page on which content resides.
            'dt' => $dt, // Title.
            'dr' => isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : '',
            'z' => mt_rand(),
        );

        $context = stream_context_create(array('http' =>
            array(
                'method'  => 'POST',
                'header' => array('Content-Type: text/html'),
                'content' => http_build_query($params),
                'timeout' => $this->getParam('timeout'),
            )
        ));

        return file_get_contents($this->getParam('url'), false, $context);
    }
}