Mage2\Paypal\Payment\Paypal::process PHP Method

    public function process($orderData, $cartProducts = [])
    {
        $this->setApiContext();
        $this->_apiContext->setConfig(['mode' => Configuration::getConfiguration('paypal_payment_mode'), 'service.EndPoint' => Configuration::getConfiguration('paypal_payment_url'), 'http.ConnectionTimeOut' => 30, 'log.LogEnabled' => Configuration::getConfiguration('paypal_payment_log'), 'log.FileName' => storage_path('logs/paypal.log'), 'log.LogLevel' => 'FINE']);
        $payer = new Payer();
        $payer->setPaymentMethod('paypal');
        $itemList = new ItemList();
        $subTotal = 0;
        $taxTotal = 0;
        foreach ($cartProducts as $product) {
            $item = new Item();
            $model = $product['model'];
            $item->setName($model->title)->setCurrency('USD')->setQuantity($product['qty'])->setSku($model->sku)->setPrice($product['price']);
            $itemList->addItem($item);
            $subTotal += $product['price'] * $product['qty'];
            $taxTotal += $product['tax_amount'] * $product['qty'];
        }
        $total = $subTotal + $taxTotal;
        $shippingOption = $orderData['shipping_method'];
        $shipping = Shipping::get($shippingOption);
        $details = new Details();
        $details->setShipping($shipping->getAmount())->setTax($taxTotal)->setSubtotal($subTotal);
        $amount = new Amount();
        $amount->setCurrency('USD')->setTotal($total)->setDetails($details);
        $transaction = new Transaction();
        $transaction->setAmount($amount)->setItemList($itemList)->setDescription('Payment description')->setInvoiceNumber(uniqid());
        $redirectUrls = new RedirectUrls();
        $redirectUrls->setReturnUrl(route('paypal.store'));
        $redirectUrls->setCancelUrl(route('paypal.cancel'));
        $payment = new Payment();
        $payment->setIntent('sale');
        $payment->setPayer($payer);
        $payment->setRedirectUrls($redirectUrls);
        $payment->setTransactions([$transaction]);
        $response = $payment->create($this->_apiContext);
        $redirectUrl = $response->links[1]->href;
        return $redirectUrl;
    }