capture-payment.ex

defmodule Capture do
 def run(checkout, payment) do
   with {:ok, prepared_checkout} <- prepare_request(checkout, payment),
        {:ok, response} <- perform_request(prepared_checkout.request),
        {:ok, final_checkout} <- handle_response(prepared_checkout, response) do
     :ok
   end
 end

 def prepare_request(checkout, payment) do
   request = %{
     amount: checkout.amount,
     card_pan: payment.card_pan,
     request_id: UUID.uuid4()
   }
   persist_checkout(%{checkout | capture_request: request})
 end

 def perform_request(request) do
   send_request(request)
 end

 def handle_response(checkout, response) do
   if response.success do
     persist_checkout(%{checkout | captured_amount: response.amount})
   else
     {:error, response.error}
   end
 end
end