ga_event.php

<?php
function getRandomString($lng = 12) {
	$charset = '0123456789';
	$randString = "";
	while(strlen($randString) < $lng) {
		$randChar = substr(str_shuffle($charset), mt_rand(0, strlen($charset)), 1);
		$randString .= $randChar;
	}
	return $randString;
}

function sendGoogleEvent($ga_id, $items, $order_id, $amount)
{
	if ($order_id != $_SESSION['ga_event']) {
		eventGoogle($ga_id, $items, $order_id, $amount);
	}
}

function setFieldsGoogle($ga_id, $items, $order_id, $amount) {
	$data = json_decode($items, true);
	$source = json_decode($_SESSION['ga_utm'], true);
	$fields = array(
		'v' => 1,
		'tid'=> $ga_id,
		'cid' => (!empty($_COOKIE['_ga'])) ? str_replace("GA1.2.", "", $_COOKIE['_ga']) : getRandomString(8),
		't' => 'event',
		'dl' => 'https://ecomm-space.violetanailsspa.com',
		'ec' => 'Ecommerce',
		'ea' => 'Purchase',
		'ni' => 0,
		'cd2' => $source['utm_source'],
		'cd3' => $source['utm_medium'],
		'cm1' => 0,
		'pa' => 'purchase',
		'ti' => $order_id,
		'ta' => 'https://ecomm-space.violetanailsspa.com',
		'tr' => $amount,
		'tt' => 0,
		'ts' => 0,
		'tcc' => 0,
		'cu' => 'USD'
	);

	foreach($data as $key => $val) {
		$fields['pr'.($key+1)."nm"] = $val['name'];
		$fields['pr'.($key+1)."id"] = $val['id'];
		$fields['pr'.($key+1)."pr"] = $val['price'];
		$fields['pr'.($key+1)."qt"] = $val['quantity'];
	}
	return $fields;
}

function eventGoogle($ga_id, $pr, $order_id, $amount) {
	$strCookie='';
	foreach ($_COOKIE as $key => $value) {
		$strCookie .= $key.'='.$value.'; ';
	}

	$fields = setFieldsGoogle($ga_id, $pr, $order_id, $amount);
	
	$fields_string = '';
	foreach($fields as $key=>$value) {
		$fields_string .= $key.'='.$value.'&'; 
	}
	rtrim($fields_string, '&');

	$ch = curl_init();
	curl_setopt($ch, CURLOPT_POST, count($fields));
	curl_setopt($ch, CURLOPT_POSTFIELDS, utf8_encode($fields_string));
	curl_setopt($ch, CURLOPT_URL, "https://google-analytics.com/collect");
	curl_setopt($ch, CURLOPT_HTTPHEADER,array('Content-type: application/x-www-form-urlencoded'));
	curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
	curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($ch, CURLOPT_COOKIE, $strCookie );
	$result = curl_exec($ch);
	curl_close($ch);

	$_SESSION['ga_event'] = $order_id;
}

/*
Usage usage: 
$amount = number_format($_SESSION['amount'], 2, ".", "");
$order_id = $_SESSION['order_id'];
$items = $_SESSION['dataItems'];
sendGoogleEvent('UA-199153759-1', $items, $order_id, $amount);
*/