fetch.rb

require "rubygems"
require "open-uri"
require "json"
require "set"
require "date"

if ARGV.length != 1
  STDERR.puts "usage: fetch.rb username"
end

followers =  JSON.parse(open("http://twitter.com/followers/ids.json?screen_name=#{ARGV[0]}").read).sort
old_followers = if File.exists? "followers" then IO.read("followers").split("\n").map{|x| x.to_i} end

def name_of_id(id)
  JSON.parse(open("http://twitter.com/users/show.json?id=#{id}").read)["screen_name"] || (raise "couldn't find user with ID #{id}")
end

followed = nil
unfollowed = nil

if old_followers
  fs = Set[*followers]
  ofs = Set[*old_followers] 

  followed = (fs - ofs).map{|x| name_of_id(x) rescue nil}.compact
  unfollowed = (ofs - fs).map{|x| name_of_id(x) rescue nil}.compact

  if followed.empty? && unfollowed.empty?
    exit(0)
  end

  now = DateTime.now
  date = now.strftime "%d %B %Y"
  time = now.strftime "%H:%M"


  File.open("follow.log", "a"){ |o|
    followed.each{|p|
      o.puts "#{p} started following you at #{time} on #{date}"
    } 
    unfollowed.each{|p|
      o.puts "#{p} stopped following you at #{time} on #{date}"
    } 
  }
end

File.open("followers", "w"){ |o|
  o.puts followers
}

system "git add followers"
system "git add follow.log"
system "git commit followers follow.log -m 'updated follow list'"