README

• Installation
• Usage
  • Adapters
    • Custom Adapters
• Plugins
• Framework Integration/Bridges
  • Laravel
• Example Application

Installation

Install Gbowo via one of the following methods :

• Composer (Recommended) :

    composer require "adelowo/gbowo" : "~1.0"

Usage

require_once 'vendor/autoload.php';

$adapter = new \Gbowo\Adapter\Paystack\PaystackAdapter();

$response = $adapter->charge();

For the paystack and amplifypay adapters, the response received would be a string, which denotes an authorization__url. You are to make a redirect to the url to complete the transaction.

Other adapters implementation may do something much different like redirect internally ( from the adapter) but this isn't done for good reasons. This is because different systems may have different ways of performing redirects via Request or Response objects, or whatever have they. So as long as you can get the returned url, you can use the Adapter in your framework or whatever have you.

A basic example would be something like

header("Location : {$response}");
exit();

Adapters

Quick usage

$adapter = (new \Gbowo\GbowoFactory())->createAdapter("paystack"); //or "amplifypay"

return $adapter->charge();

Usage in depth

Gbowo ships with two adapters : one for paystack and the other for Amplifypay.

While both payment gateway offer similar features, there are a few subtle differences (obviously).

Gbowo requires some value to be present in the environment i.e $_ENV. For paystack, this is $_ENV['PAYSTACK_SECRET_KEY'] while the amplifypay adapter requires two values : your merchant id and an api key. This should be present in the following format : $_ENV['AMPLIFYPAY_MERCHANT_ID'] and $_ENV['AMPLIFYPAY_API_KEY'].

You are strongly advised to keep your keys and/or tokens out of your code and instead load them into $_ENV by some other means. We don't enforce this but it is a best practice, 12 Factor App Guideline. A library that would help with this is vlucas/phpdotenv. All it needs is a .env file and you are golden. Remember not to commit the .env else it still isn't out of your "code". A sample .env.example has been provided in the resources directory. You can copy and rename that to .env in your root dir.

$paystack = new \Gbowo\Adapter\Paystack\PaystackAdapter();

$amplifyPay = new \Gbowo\Adapter\Amplifypay\AmplifypayAdapter()

A GuzzleHttp Client instance would be created automatically and values gotten from the $_ENV would be used to set the appropriate authorization headers where applicable.

You can prevent this "auto-wiring" by providing an instance of Guzzlehttp Client in the constructor.

$client = new \GuzzleHttp\Client(['key' => "value"]);

$amplifyPay = new \Gbowo\Adapter\Amplifypay\AmplifypayAdapter($client)

The payment flow for both adapters is pretty much the same. User initiates first time / one time transaction and is redirected to a secure page where payment details are to be inputted. After this (a successful payment request), the gateway would issue a redirect to a url you have supplied them as a callback. In this url, you should fetch the details of a user (who is now a customer) such as an authorization_code , transaction_reference among others. This is for recurrent transactions and should be persisted to a storage mechanism.

Initiating the transaction should be performed by calling the charge method on the adapter. And making a redirect where applicable to the response as described earlier.

To fetch the data from the url callback you have registered on your chosen gateway, you have to call the getPaymentData method on the adapter. It's response would contain some data about the customer.

//paystack adapter
var_dump($adapter->getPaymentData($_GET['trxref'])) ; //you should clean this up.

//amplifypay adapter
var_dump($adapter->getPaymentData($_GET['tran_response'])); // clean up

The getPaymentData method can also be called on some transaction reference you have stored in your db or some other form of storage mechanism.

When you call the getPaymentData on the paystack adapter. The reference is verified by paystack before a response is sent

Adapters Methods.

Paystack :

• charge(array $data = [])
• getCustomer(int $id)
• getAllCustomers()
• chargeWithToken(array $userToken) // a token plus email address (or custom stuff)
• getPaymentData(string $transRef)
• fetchPlan($planIdentifier)
• fetchAllPlans()

Checkout gbowo-paystack . It contains an additional set of plugins for the paystack adapter.

Amplifypay :

• charge(array $data = [])
• unsubcribeCustomerFromPlan(array $data)
• chargeWithToken(array $userToken) //a token in amplifypay is a key pair of values.
• getPaymentData(string $transRef)
• fetchPlan($planIdentifier)
• fetchAllPlans()

The charge method parameter (array $data = []) should contain stuffs like amount, email, x, y, z). Those would be handed over to the payment gateway

Custom Adapters

Using laravel, please check out how to add your custom adapter

//let's assume it is an enterprisey app

$interswitch = new class implements \Gbowo\Contract\Adapter\AdapterInterface
{
    protected $interswitch;

    public function __construct()
    {
        $this->interswitch = new \stdClass(new \ArrayObject(new \stdClass())); // It wasn't me
    }

    public function charge(array $data = [])
    {
        return "charged by interswitch";
    }
};

$adapter = new \Gbowo\GbowoFactory(["interswitch" => $interswitch]); //add the interswith adapter as a custom one.

$interswitchAdapter = $adapter->createAdapter("interswitch");

$interswitchAdapter->charge(['a' => 'b', 'c' => 'd']);

Extending Adapters via Plugins

Different gateways implement various features and there's no way we can support all of them without losing our sanity.

Supporting all features would lead to a bloat (an interface, class bloat). Take for instance : create InterfaceX to support feature X for AdapterE while AdapterE still makes use of features (and therefore interfaces) for AdapterA,AdapterQ and so on. Now imagine this scenario plays out for 4 -5 adapters.

Apart from the bloat, we cannot create a (visual) diagram of which interfaces are being used and it'd lead to a situation where we cannot remove a certain class or interface because we do not know who (what adapter) depends on them.

To prevent this, Gbowo implements a plugin architecture that eases extension or "adding new methods/behaviours" to an existing adapter without inheritance or touching core code. To achieve this, there is a Pluggable trait that contains the logic and MUST be imported by an adapter implementation.

A look at the paystack adapter and amplifypay would reveal that they do not have the methods described above in their public api. In fact they expose only 3 methods :

• __construct(Client $client = null) // if it counts as one
• getHttpClient()
• charge(array $data = []) //This is gotten from the AdapterInterface implemented.

But a look at their registerPlugins method - which is gotten from the Pluggable trait - tells how the methods described in the Adapters method section above come about.

A plugin is a plain PHP class that MUST implement the PluginInterface. This interface exposes two methods :

• getPluginAccessor() : string
• setAdapter(Adapter $adapter)
• handle(string $reference) //Typehint as much as you want. 2,3 args ? Your call.

I have written a detailed post about this here

namespace Vendor\AdapterName\Plugin;

use Gbowo/Contract/Plugin/PluginInterface;
use Gbowo\Exception\TransactionVerficationFailedException;

class ApiPinger implements PluginInterface
{

    public function getPluginAccessor():string
    {
        return "pingApi"; //Oops.. Let's confirm if the api isn't dead before making any request. And it must be a string without parenthesis
    }

    /**
     * You can also leave this method out but you must extend the `AbstractPlugin` class. Doing so, means you'd have to get rid of the plugin interface here as the abstract plugin already does that.
     */
    public function setAdapter(AdapterInterface $adapter)
    {
        //useful for helpers like getting stuffs from "accessors" on the adapter instance like the already configured HttpClient object
        $this->adapter = $adapter ;
        return $this;
    }

    /**
     * Ping the gateway Api
     * @param  bool $shouldThrow. Should an exception be thrown if the api is down ?.
     * @return bool true - if the api is up and running.
                   false - if the api is down and $throw is set to false.
     * @throws \Exception if the api is down and $throw is set to false.
     */
    public function handle(bool $shouldThrow = false)
    {
        $response = $this->adapter->getHttpClient()->get("https://api.homepage.com");

        if ($response->getStatusCode() === 200 ) {
            return true;
        }

        if ($shouldThrow) {
            throw TransactionVerficationFailedException::createFromResponse($response);
        }

        return false;
    }
}

createFromResponse is a wrapper that allows client code inspect the response for why there was a failure (say an invalid HTTP status code).. You should call getResponse on the exception in other to inspect it. This is also true for official plugins provided by Gbowo.

The getPluginAccessor is of tremendous interest here since it determines what plugin the method call should be deferred to. This is done by the magic method __call in the Pluggable trait.

$adapter->addPlugin(new Vendor\AdapterName\Plugin\ApiPinger(PaystackAdapter::API_LINK));
//Usage like this

$adapter->pingApi(true);
$adapter->pingApi();

Not all plugins would make it to the core eventually and not even all plugins in the core would be "added" on instantiation. For instance, the GetAllCustomers plugin isn't added to the PaystackAdapter internally. To use the plugin, you'd have to add it yourself.

$adapter->addPlugin(new GetAllCustomers(PaystackAdapter::API_LINK))

Framework Integration

Laravel

Prior to v1.5.0, a Laravel bridge was provided alongside this package but in light of best interests, it has been moved to it's own repository.

If upgrading from a previous version to v1.5.0, please note that you would have to run composer require adelowo/laravel-gbowo

Please note that the decision to give the Laravel bridge a life of it's own doesn't mean BC break. The namespaces were preserved and would continue to work as is.

Sample App

Gbowo-app - Built with SlimPHP.

Contributing

Awesome, I'd love that. Fork, send PR. But hey, unit testing is one honking great idea. Let's have more of that.

Bug Reports, Issue tracking and Security Vulnerabilities

Please make use of the issue tracker for bug reports, feature request and others except Security issues. If you do discover a vulnerability, please send a mail to me@lanreadelowo.com.

License

MIT