mtgox.rb

require 'json'
require 'open-uri'

def most_recent_timestamp
  data = JSON.parse(open('http://bitcoincharts.com/t/markets_timestamps.json').read)
  data['mtgoxUSD'].to_i
end

def new_transactions(n)
  data = JSON.parse(open("http://mtgox.com/code/data/getTrades.php").read)
  data.select{|d|d['date'] > n }
end

prev = most_recent_timestamp
loop do
  sleep 20
  curr = most_recent_timestamp 
  if curr > prev 
    txns = new_transactions(prev)
    txns.each do |e|
      system "echo 'trade: #{e['amount']} at #{e['price']}' | growlnotify -a Bitcoin mtgoxUSD"
    end 
    prev = curr 
  end
end