sacca.rb

require 'rubygems'
require 'simplegeo' # gem install sg-ruby
require 'nokogiri' # gem install nokogiri
require 'typhoeus' # gem install typhoeus
require 'sinatra' # gem install sinatra

##
# About:
# This little script, sacca.rb allows you to save a gowalla user's checkins to a layer on SimpleGeo. 
# it's using PubSubHubbub (Gowalla's hub is at http://hub.gowalla.com/) to subscribe to the Atom feed 
# of this user. Whenever the user checks in, a notification is sent, and the data is saved to SimpleGeo.

##
# To start : ruby sacca.rb
# Then, in yoru browser, go to http://$host:$port/start
# Then, checkin!

# Don't forget to change these params :)

$sg_token      = 'token'
$sg_secret     = 'secret'
$gowalla_user  = 'juliuseren'
$sg_layer      = "com.gowalla.#{$gowalla_user}"
$port          = 4568
$host          = 'host.tld'

set :port, $port

configure do
  SimpleGeo::Client.set_credentials($sg_token, $sg_secret)
end

##
# Accepts subscriptions vcerification and unsubscription verification
# See PubSubHubub spec http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.3.html#verifysub
get '/' do 
  if params['hub.topic'] == "http://gowalla.com/users/#{$gowalla_user}/checkins.atom"
    params['hub.challenge'] # confirmed subscription
  else
    "" # We don't want to confirm subscription
  end
end

##
# Called upon checkin. See http://pubsubhubbub.googlecode.com/svn/trunk/pubsubhubbub-core-0.3.html#contentdistribution
post '/' do
  # Parse the ATOM
  xml = Nokogiri::XML(request.body.read)
  
  xml.xpath("/atom:feed/atom:entry", {"atom" => "http://www.w3.org/2005/Atom"}).each do |entry|
    point = entry.at_xpath("./geo:point", {"geo" => "http://www.georss.org/georss"})
    if !point.nil?
      title = entry.at_xpath("./atom:title", {"atom" => "http://www.w3.org/2005/Atom"}).text
      link = entry.at_xpath("./atom:link[@rel='alternate']", {"atom" => "http://www.w3.org/2005/Atom"})["href"]
      id = entry.at_xpath("./atom:id", {"atom" => "http://www.w3.org/2005/Atom"}).text
      lat, lon = point.text.split(" ")
      
      record = SimpleGeo::Record.new({
          :id => id,
          :created => Time.now,
          :lat => lat,
          :lon => lon,
          :layer => $sg_layer,
          :properties => {
            :title => title,
            :link => link
          }
      })
      puts "Saving #{id} : #{lat}, #{lon} (#{title} => #{link})"
      SimpleGeo::Client.add_record(record)      
    end
  end
end


get '/start' do
  # Perform Susbcription to the feed.
  res = Typhoeus::Request.post("http://hub.gowalla.com/", :params => {
    :"hub.topic" => "http://gowalla.com/users/#{gowalla_user}/checkins.atom", 
    :"hub.callback" => "http://#{host}:#{port}/",
    :"hub.mode" => "subscribe",
    :"hub.verify" => "sync"})
  if res.code == 204
    puts "App is now subscribed to http://gowalla.com/users/#{gowalla_user}/checkins.atom, please checkin on gowalla!"
  else
    puts "App couldn't be checked in. Please make sure your app is accessible from outside (not behind a firewall)"
  end
end