Api.php

<?php
namespace SlimDash\Payeezy;

use Payum\Core\Bridge\Guzzle\HttpClientFactory;
use Payum\Core\Bridge\Spl\ArrayObject;
use Payum\Core\Exception;
use Payum\Core\Exception\Http\HttpException;
use Payum\Core\HttpClientInterface;

class Api
{
    /**
     * @var HttpClientInterface
     */
    protected $client;

    /**
     * @var array
     */
    protected $options = array(
        'apiKey'        => null,
        'apiSecret'     => null,
        'merchantToken' => null,
        'sandbox'       => null,
    );

    /**
     * @param  array                                          $options
     * @param  HttpClientInterface                            $client
     * @throws \Payum\Core\Exception\InvalidArgumentException if an option is invalid
     */
    public function __construct(array $options, HttpClientInterface $client)
    {
        $options = ArrayObject::ensureArrayObject($options);
        $options->defaults($this->options);
        $options->validateNotEmpty(array(
            'apiKey',
            'apiSecret',
            'merchantToken',
        ));
        if (false == is_bool($options['sandbox'])) {
            throw new LogicException('The boolean sandbox option must be set.');
        }

        $this->options = $options;
        $this->client  = $client ?: HttpClientFactory::create();
    }

    /**
     * @return string
     */
    protected function getApiEndpoint()
    {
        return
        $this->options['sandbox']
        ? 'https://api-cert.payeezy.com/v1/transactions'
        : 'https://api.payeezy.com/v1/transactions'
        ;
    }

    /**
     * @param  string  $payload
     * @return array
     */
    public function getHeaders($payload)
    {
        $nonce         = strval(hexdec(bin2hex(openssl_random_pseudo_bytes(4, $cstrong))));
        $timestamp     = strval(time() * 1000); //time stamp in milli seconds
        $data          = $this->options['apiKey'] . $nonce . $timestamp . $this->options['merchantToken'] . $payload;
        $hashAlgorithm = "sha256";
        $hmac          = hash_hmac($hashAlgorithm, $data, $this->options['apiSecret'], false); // HMAC Hash in hex
        $authorization = base64_encode($hmac);

        return array(
            'Authorization' => $authorization,
            'nonce'         => $nonce,
            'timestamp'     => $timestamp,
            'apikey'        => $this->options['apiKey'],
            'token'         => $this->options['merchantToken'],
            'Content-Type'  => 'application/json',
        );
    }

    /**
     * @param  array   $fields
     * @param  string  $transaction_id
     * @return array
     */
    public function doRequest($fields = array(), $transaction_id = null)
    {
        $url = $this->getApiEndpoint();
        if (isset($transaction_id)) {
            $url = $url . '/' . $transaction_id;
        }

        $payload  = json_encode($fields, JSON_FORCE_OBJECT);
        $headers  = $this->getHeaders($payload);
        $request  = new \GuzzleHttp\Psr7\Request('POST', $url, $headers, $payload);
        $response = $this->client->send($request);

        if (false == ($response->getStatusCode() >= 200 && $response->getStatusCode() < 300)) {
            throw HttpException::factory($request, $response);
        }

        $result = json_decode($response->getBody()->getContents());
        if (null === $result) {
            throw new LogicException("Response content is not valid json: \n\n{$response->getBody()->getContents()}");
        }

        return $result;
    }
}