Creating a new Gava checkout with PHP

gava.php

<?php

$orderId = 12; //Doesn't have to be numeric
$amount = 1.00;
$returnUrl = "http://example.com/thankyou";
$cancelUrl = "http://example.com/cart";

$payload = [
	'reference' => $orderId,
	'amount' => $amount,
	'return_url' => $returnUrl,
	'cancel_url' => $cancelUrl,
];

$payload['signature'] = $sign($payload, "examp1216");

$res = Requests::post('http://example.com/checkout', [], $payload);

$checkoutUrl = $res->body;

//Then you can redirect the user to $checkoutUrl, or show it a a link

/**
 * Given an iterable $payload, it signs it with the provided secret key
 *
 * @param 	mixed $payload Object or array
 * @param 	string $secret Secret key
 * @return 	mixed
 */
function sign($payload, $secret)
{
	$string = '';

	foreach ($payload as $key => $value) {
		if ($key === 'signature') continue;

		$string .= $value;
	}

	return hash('sha512', $string . $secret);
}