#!/usr/bin/env ruby

raise ArgumentError, "Usage: #{$0} <file>" unless ARGV.length >= 1
email = []
File.new(ARGV[0]).read.scan(/([\w_.+-]+)@([\w.+_-]+\.)+(\w{2,3}|\d{1,3})/) do | user , server, tld |
  email.push({:user=>user,:server=>server,:tld=>tld})
end

puts "Please set the sort order 1 = user, 2 = server, 3 = top level domain:\n"
order = case STDIN.gets.strip
  when '2' then [:server,:tld,:user] 
  when '3' then [:tld,:server,:user]
  else [:user,:server,:tld]
end

email.sort! do | a, b | 
  d = 0
  order.each do | o |
    d = a[o].downcase <=> b[o].downcase 
    break unless d == 0
  end 
  d
end

email.each do | e | puts "#{e[:user]}@#{e[:server]}#{e[:tld]}" end