gistfile1.txt

#InvoiceItem Class

def self.filter_by_item(item_id)
  InvoiceItem.all_successful.select { |ii| ii.item_id == item_id }
end

def self.revenue_per_item(item_id)
  filter_by_item(item_id).collect { |ii| ii.unit_price * ii.quantity }.inject(:+)
end

#Item Class

def most_revenue(total_num)
  hash = Hash.new
  InvoiceItem.all_successful.each do |ii|
    hash[ii.item_id] = InvoiceItem.revenue_per_item(ii.item_id)
  end
  sorted_revenue = hash.each { |k,v| v.sort }.reverse
  sorted_revenue[0..total_num]
end