an example of auth for facebook

gistfile1.rb

require 'thread'
require 'facebook_oauth'
require 'launchy'
require 'sinatra/base'

callback_uri = URI.parse('http://localhost:6789/')

fb_client = FacebookOAuth::Client.new(
    :application_id     => 'XXXXXXXXXXXX',
    :application_secret => 'XXXXXXXXXXXXXXXXXXXXXXXX',
    :callback           => callback_uri.to_s
)

class CallbackHanlder < Sinatra::Base
  get '/' do
    res = if params[:code]
      settings.fb_client.authorize(:code => params[:code])
    else
      'error'
    end

    Thread.start do
      sleep 1
      $_callback_hanlder_server.stop
    end

    res
  end
end

authorize_url = fb_client.authorize_url
puts "open #{authorize_url}"
Launchy.open(authorize_url)

CallbackHanlder.run!(:port => callback_uri.port, :fb_client => fb_client) do |server|
  $_callback_hanlder_server = server
end

p fb_client.me.info
puts "access_token: #{fb_client.send(:access_token).token}"