gistfile1.rb

user_addons = profile.charges.where(:parent_id => nil)
total_charge = 0
user_addons.each do |user_addon|
  addon_history = user_addon.children.where(["timestamp > ", Time.beginning_of_the_month]).order(:version).asc
  unless addon_history.blank?
    duration_in_use = 0
    last_active_timestamp = Time.beginning_of_the_month
    addon_history.each do |record|
      if(record.active?)
        duration_in_use += record.updated_at - last_active_timestamp
        last_active_timestamp = record.updated_at
      else
        last_active_timestamp = record.updated_at
      end
    end
  elsif(user_addon.active?)
    timediff = (Time.now - Time.beginning_of_the_month).days
    total_charge += (user_addon.addon.charge*timediff)/user_addon.addon.duration
  end
  
end