Stripe custom Checkout form and corresponding controller action and Payment model method

_payments.html.erb

        <!-- STRIPE CUSTOM CHECKOUT FORM -->
        <div>
          <script src="https://checkout.stripe.com/checkout.js"></script>

          <a class="cta-red-copy" id="customButton">Pay with Card</a>

          <script>
            var amountValue;
            var handler = StripeCheckout.configure({
              key: '<%= Rails.configuration.stripe[:publishable_key] %>',
              image: '/assets/fp_square_logo.png',
              token: function(token, args) {
                // Use the token to create the charge with a server-side script.
                $.ajax({
                  type: 'POST',
                  data: { 'token' : token, 'amount' : amountValue },
                  url: '/application/<%= @submission.id %>/payments/credit_card_charge',
                  success: function(data) {
                    location.reload();
                    $('body').scrollTop(0);
                    $('#stripeSuccess').show();
                  },
                  error: function(data) {
                    $('#stripeError').show();
                  }
                });
              }
            });

            document.getElementById('customButton').addEventListener('click', function(e) {
              amountValue = $('#payment_amount').val();
              var pmtInputBox = document.getElementById('payment_amount');
              var errorText = document.getElementById('stripeErrorText');
              
              if (isNaN(amountValue)) {
                pmtInputBox.style.border='1px solid red';
                errorText.style.display='';
              } else if (amountValue < 500) {
                pmtInputBox.style.border='1px solid red';
                errorText.style.display='';
              }
              else {
                var dim = document.getElementById('stripeProcessing');
                amountValue = amountValue * 100;
                // Open Checkout with further options
                handler.open({
                  name: 'Fullbridge, Inc.',
                  description: 'The Fullbridge Program Tuition',
                  amount: amountValue,
                  closed: dim.style.display='none'
                });
              }

              e.preventDefault();
            });
          </script>
        </div>

payment.rb

  def self.new_stripe_charge(submission, charge)
    payment = submission.payments.new(
      name: 'Stripe Credit Card Charge',
      amount: charge.amount.to_f / 100, # in dollars
      is_successful: true,
      _type: 'Credit Card',
      stripe_charge_id: charge.id,
      stripe_is_paid: charge.paid,
      stripe_is_live: charge.livemode,
      stripe_is_refunded: charge.refunded,
      stripe_card_id: charge.card.id,
      stripe_card_last4: charge.card.last4,
      stripe_card_type: charge.card.type,
      stripe_card_exp_month: charge.card.exp_month,
      stripe_card_exp_year: charge.card.exp_year,
      stripe_customer_id: charge.customer
    )
    payment.save!
    payment
  end

payments_controller.rb

class PaymentsController < ApplicationController
  helper_method :submission
  
  # POST /application/:submission_id/payments/credit_card_charge
  def credit_card_charge
    amount = params[:amount].to_i
    profile = submission.profile
    
    if profile.stripe_customer_id
      customer = Stripe::Customer.retrieve(profile.stripe_customer_id)
    else
      customer = Stripe::Customer.create(email: profile.email, card: params[:token])
      profile.stripe_customer_id = customer.id
      profile.save
    end
    
    charge = Stripe::Charge.create(customer: customer.id, amount: amount, description: 'The Fullbridge Program Tuition', currency: 'usd')
    
    if charge.paid
      payment = Payment.new_stripe_charge(submission, charge)
    end
    redirect_to submission_tuition_url(submission), notice: "Thank you! Your payment for $#{payment.amount} was processed successfully."
  rescue Stripe::CardError => e
    redirect_to request.referer, notice: e.message
  end
  
  # HELPER METHOD
  def submission
    @submission ||= Submission.find(params[:submission_id])
  end
end

I was thinking of moving the if-else for the profile.stripe_customer_id piece into a separate method and wrapping that as well as the Payment.new_stripe_charge method in a delayed_job (background job).