merchant.rb

# We want to be sure that we keep a log into our Bank.Log table of all responses got from the Bank. 
# Can you state if that will happen with this code? Please answer yes/no and *why*.
#
# Please consider all input values correct.

class User < ApplicationRecord
  validates :customer_confidence, numericality: { greater_than_or_equal_to: 0 }
end

class Merchant
  def self.pay_purchase(user, purchase_id, amount)
    ActiveRecord::Base.transaction do    
      response = Bank::API::Http.pay_with(credit_card: user.credit_card, amount: amount)

      Bank::Log.create(user: user,
                       purchase_id: purchase_id,
                       credit_card_id: user.credit_card.id, 
                       amount: amount, 
                       data: response.to_json)

      user.customer_confidence += (response.status == "201") ? 1 : -1
      
      user.save!
      
      response.status == "201"
    rescue StandardError => e
      Rollbar.error("Unexpected error: #{e.message}")
      raise ActiveRecord::Rollback.new(e)
    end
  end
end