// In your providers array.
'providers' => [
    ...
    Shetabit\Payment\Provider\PaymentServiceProvider::class,
],

// In your aliases array.
'aliases' => [
    ...
    'Payment' => Shetabit\Payment\Facade\Payment::class,
],

// Eg. if you want to use zarinpal.
'default' => 'zarinpal',

'drivers' => [
    'zarinpal' => [
        // Fill in the credentials here.
        'apiPurchaseUrl' => 'https://www.zarinpal.com/pg/rest/WebGate/PaymentRequest.json',
        'apiPaymentUrl' => 'https://www.zarinpal.com/pg/StartPay/',
        'apiVerificationUrl' => 'https://www.zarinpal.com/pg/rest/WebGate/PaymentVerification.json',
        'merchantId' => '',
        'callbackUrl' => 'http://yoursite.com/path/to',
        'description' => 'payment in '.config('app.name'),
    ],
    ...
]

// At the top of the file.
use Shetabit\Multipay\Invoice;
...

// Create new invoice.
$invoice = new Invoice;

// Set invoice amount.
$invoice->amount(1000);

// Add invoice details: There are 4 syntax available for this.
// 1
$invoice->detail(['detailName' => 'your detail goes here']);
// 2 
$invoice->detail('detailName','your detail goes here');
// 3
$invoice->detail(['name1' => 'detail1','name2' => 'detail2']);
// 4
$invoice->detail('detailName1','your detail1 goes here')
        ->detail('detailName2','your detail2 goes here');

// At the top of the file.
use Shetabit\Multipay\Invoice;
use Shetabit\Payment\Facade\Payment;
...

// Create new invoice.
$invoice = (new Invoice)->amount(1000);

// Purchase the given invoice.
Payment::purchase($invoice,function($driver, $transactionId) {
	// We can store $transactionId in database.
});

// Purchase method accepts a callback function.
Payment::purchase($invoice, function($driver, $transactionId) {
    // We can store $transactionId in database.
});

// You can specify callbackUrl
Payment::callbackUrl('http://yoursite.com/verify')->purchase(
    $invoice, 
    function($driver, $transactionId) {
    	// We can store $transactionId in database.
	}
);

// At the top of the file.
use Shetabit\Multipay\Invoice;
use Shetabit\Payment\Facade\Payment;
...

// Create new invoice.
$invoice = (new Invoice)->amount(1000);
// Purchase and pay the given invoice.
// You should use return statement to redirect user to the bank page.
return Payment::purchase($invoice, function($driver, $transactionId) {
    // Store transactionId in database as we need it to verify payment in the future.
})->pay()->render();

// Do all things together in a single line.
return Payment::purchase(
    (new Invoice)->amount(1000), 
    function($driver, $transactionId) {
    	// Store transactionId in database.
        // We need the transactionId to verify payment in the future.
	}
)->pay()->render();

// Retrieve json format of Redirection (in this case you can handle redirection to bank gateway)
return Payment::purchase(
    (new Invoice)->amount(1000), 
    function($driver, $transactionId) {
    	// Store transactionId in database.
        // We need the transactionId to verify payment in the future.
	}
)->pay()->toJson();

// At the top of the file.
use Shetabit\Payment\Facade\Payment;
use Shetabit\Multipay\Exceptions\InvalidPaymentException;
...

// You need to verify the payment to ensure the invoice has been paid successfully.
// We use transaction id to verify payments
// It is a good practice to add invoice amount as well.
try {
	$receipt = Payment::amount(1000)->transactionId($transaction_id)->verify();

    // You can show payment referenceId to the user.
    echo $receipt->getReferenceId();

    ...
} catch (InvalidPaymentException $exception) {
    /**
    	when payment is not verified, it will throw an exception.
    	We can catch the exception to handle invalid payments.
    	getMessage method, returns a suitable message that can be used in user interface.
    **/
    echo $exception->getMessage();
}

'drivers' => [
    'zarinpal' => [...],
    'my_driver' => [
        ... // Your Config Params here.
    ]
]

namespace App\Packages\PaymentDriver;

use Shetabit\Multipay\Abstracts\Driver;
use Shetabit\Multipay\Exceptions\InvalidPaymentException;
use Shetabit\Multipay\{Contracts\ReceiptInterface, Invoice, Receipt};

class MyDriver extends Driver
{
    protected $invoice; // Invoice.

    protected $settings; // Driver settings.

    public function __construct(Invoice $invoice, $settings)
    {
        $this->invoice($invoice); // Set the invoice.
        $this->settings = (object) $settings; // Set settings.
    }

    // Purchase the invoice, save its transactionId and finaly return it.
    public function purchase() {
        // Request for a payment transaction id.
        ...
            
        $this->invoice->transactionId($transId);
        
        return $transId;
    }
    
    // Redirect into bank using transactionId, to complete the payment.
    public function pay() {
        // It is better to set bankApiUrl in config/payment.php and retrieve it here:
        $bankUrl = $this->settings->bankApiUrl; // bankApiUrl is the config name.

        // Prepare payment url.
        $payUrl = $bankUrl.$this->invoice->getTransactionId();

        // Redirect to the bank.
        return redirect()->to($payUrl);
    }
    
    // Verify the payment (we must verify to ensure that user has paid the invoice).
    public function verify(): ReceiptInterface {
        $verifyPayment = $this->settings->verifyApiUrl;
        
        $verifyUrl = $verifyPayment.$this->invoice->getTransactionId();
        
        ...
        
        /**
			Then we send a request to $verifyUrl and if payment is not valid we throw an InvalidPaymentException with a suitable message.
        **/
        throw new InvalidPaymentException('a suitable message');
        
        /**
        	We create a receipt for this payment if everything goes normally.
        **/
        return new Receipt('driverName', 'payment_receipt_number');
    }
}

'map' => [
    ...
    'my_driver' => App\Packages\PaymentDriver\MyDriver::class,
]