send browser events on new orders

app/assets/javascripts/home/donations.js.coffee

@@ -72,5 +72,13 @@ $.fn.donations = ()->
   new Donations(this, $('.pagination', this))
 
 $(document).ready ->
-  $('#donations').donations() if $('#donations').length > 0
+  if $('#donations').length > 0
+    $('#donations').donations()
 
+    if EventSource?
+      src = new EventSource('/orders.es')
+      src.onmessage = (e) ->
+        payload = JSON.parse e.data
+        order   = payload.order
+        user    = order.user
+        Notifier.notify "We've got another one!", "#{user.name} just donated $#{order.total}!", user.gravatar_url, 2000

app/models/order_observer.rb

@@ -0,0 +1,5 @@
+class OrderObserver < ActiveRecord::Observer
+  def after_create(order)
+    OrderStream.send_json(order: order.as_json) 
+  end
+end

config.ru

@@ -1,4 +1,7 @@
 # This file is used by Rack-based servers to start the application.
 
 require ::File.expand_path('../config/environment',  __FILE__)
-run Travis::Application
+require 'order_stream'
+
+map('/') { run Travis::Application }
+map('/orders.es') { run OrderStream }

config/application.rb

@@ -50,6 +50,7 @@ class Application < Rails::Application
 
     config.action_mailer.default_url_options = { :host => 'support.travis-ci.org' }
 
+    config.active_record.observers = :order_observer
     config.threadsafe!
   end
 end

lib/order_stream.rb

@@ -0,0 +1,43 @@
+require 'eventmachine'
+
+class OrderStream
+  @streams ||= []
+
+  def self.call(env)
+    stream = new
+    @streams << stream
+    env['async.close'].callback { @streams.delete(stream) }
+    EM.next_tick { env['async.callback'].call [200, {'Content-Type' => 'text/event-stream'}, stream] }
+    throw :async
+  end
+
+  def self.send_json(data)
+    send_message(data.as_json.to_json)
+    @streams.each { |s| s << data.as_json.to_json }
+  end
+
+  def self.send_message(data)
+    data.split(/\n/).each { |l| send_raw("data: #{l}\n") }
+    send_raw("\n")
+  end
+
+  def self.send_raw(data)
+    @streams.each { |s| s << data.to_s }
+  end
+
+  include EventMachine::Deferrable
+
+  def <<(data)
+    @body_callback.call(data)
+  end
+
+  def initialize
+    @body_callback = proc { |_| }
+  end
+
+  def each(&block)
+    @body_callback = block
+  end
+
+  #EventMachine.schedule { EventMachine::PeriodicTimer.new(10) { send_raw "\0" } }
+end

test/unit/order_observer_test.rb

@@ -0,0 +1,7 @@
+require 'test_helper'
+
+class OrderObserverTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end