#---
# Excerpted from "Everyday Scripting in Ruby"
# We make no guarantees that this code is fit for any purpose. 
# Visit http://www.pragmaticprogrammer.com/titles/bmsft for more book information.
#---
unless ARGV.length == 2 
  puts "Usage: differences.rb old-inventory new-inventory"
  exit
end


def boring?(line)
  line.split('/').include?('temp') or
    line.split('/').include?('recycler')
end 

def inventory_from(filename)
  inventory = File.open(filename) #(1)
  downcased = inventory.collect do | line | #(2)
    line.downcase
  end
  downcased.reject do | line |  #(3)
    boring?(line)
  end
end


old_inventory = inventory_from(ARGV[0])
new_inventory = inventory_from(ARGV[1])

puts "The following files have been added:"
puts new_inventory - old_inventory

puts ""
puts "The following files have been deleted:"
puts old_inventory - new_inventory