app/controllers/spree/payment_method/bit_payments_controller.rb
module Spree
class PaymentMethod::BitPaymentsController < ApplicationController
include Spree::Backend::Callbacks
def authenticate
payment_method = Spree::PaymentMethod::BitPayment.find(params[:payment_method_id])
pairing_code = payment_method.authenticate_with_bitpay params[:bitcoin_network]
url = "#{params[:bitcoin_network]}/api-access-request?pairingCode=#{pairing_code}&redirect=#{params[:redirect_url]}"
redirect_to url
end
end
end