check the availability of twitter screen names

twitter-screenname-check.rb

#! /usr/bin/env ruby
require 'rubygems'
require 'json'
require 'open-uri'
require 'optparse'

OPT = Struct.
  new(:auto, :wait).
  new(false, 0.3)

OptionParser.new do |opts|
  opts.on('--[no-]auto') do |v|
    OPT.auto = v
  end
  opts.on('--wait ', Float) do |v|
    OPT.wait = v
  end
end.parse!

def check(name)
  url = "http://twitter.com/users/username_available?username=#{name}"
  open(url) do |io|
    s = io.read
    res = JSON.parse(s)
    res.each_pair do |k,_|
      k.sub!(/"(.*)"/, '<\1>')
    end
    # res.to_a.map{|x| x.join(': ')}.join(', ')
    STDERR.puts "#{res['valid']?'available':'unavailable'}: #{name}"
  end
end

class Array
  def lexicographical_each(&block)
    if self.length == 0 then
      return
    end
    self.each do |x|
      block.call(x)
    end
    self.lexicographical_each do |y|
      self.each do |x|
        block.call(y+x)
      end
    end
  end
end

wait = OPT.wait
if OPT.auto then
  Enumerable::Enumerator.new(('a'..'z').to_a+('0'..'9').to_a+['_'], :lexicographical_each)
else
  ARGF
end.each do |name|
  name.strip!
  begin
    check(name)
  rescue Errno::ECONNRESET, OpenURI::HTTPError
    sleep(wait)
    wait *= 2
    redo
  end
  wait = OPT.wait
  sleep(OPT.wait)
end