build poller

#!/usr/bin/env ruby
require 'rubygems'
require 'curb'
require 'xmlsimple'

# NB: currently throws errors to cron if build server is down
# NB: keeps track of build number on disk, so if build server is reset this script gets screwy

DATA_FILE = File.join(File.dirname(__FILE__), 'build_poller.data')

class Poller
  CURRENT_BUILD_URL = "http://username:password@builddomain.com/job/jobname/api/xml?depth=1&xpath=//build[result=%27SUCCESS%27%20or%20result=%27FAILURE%27][1]"

  def self.execute
    if File.exist?(DATA_FILE)
      last_build = Build.new(*File.read(DATA_FILE).split(':'))
    else
      last_build = Build.empty
    end

    easy = Curl::Easy.perform(CURRENT_BUILD_URL)
    current_build_info = XmlSimple.xml_in(easy.body_str)
    current_build = Build.new(current_build_info['number'][0], current_build_info['result'][0])

    if current_build.number > last_build.number
      if current_build.failed? || current_build.state != last_build.state
        current_build.announce
      end
      current_build.save
    end
  end
end

class Build
  attr_reader :number, :state
  
  def self.empty
    Build.new(-1, 'NONE')
  end
  
  def initialize(number, state)
    @number = number.to_i
    @state = state
  end
  
  def announce
    case @state
    when 'SUCCESS'
      `afplay /Users/build/hudson/sounds/build_fixed.wav`
      `/Users/build/bin/flag.rb 1`
    when 'FAILURE'
      `afplay /Users/build/hudson/sounds/build_failed.wav`
      `/Users/build/bin/flag.rb 0`
    else
      raise 'Unrecognized state'
    end
  end
  
  def failed?
    state == 'FAILURE'
  end
  
  def save
    File.open(DATA_FILE, 'w') {|f| f << self.to_s }
  end
  
  def to_s
    "#{number}:#{state}"
  end
end

Poller.execute