Extending Ruby on Rails Contacts Gem to invite Facebook friends

Contacts Gem 是一個能夠從Web Mail服務中匯入聯絡人列表的Rails插件，我們可以擴充它來支援匯入Facebook朋友列表，並發送邀請訊息給他們。

首先必須安裝Contacts plugin：
$script/plugin install git://github.com/cardmagic/contacts.git

另外我們還需要安裝Json Gem：
$sudo gem i jason

另外我們還需要安裝Mechanize Gem來使用其相依的Nokogiri：
$sudo gem i mechanize

現在我們可以打開Rails Console來檢查一下：

	david@workstation:~/workspace/railscode$ script/console
	Loading development environment (Rails 2.2.2)
	>> Contacts
	=> Contacts

view raw console hosted with ❤ by GitHub

現在到#{RAILS_ROOT}/vendor/plugins/contacts/lib/contacts目錄下建立一個page_scraper.rb：

	require 'mechanize'
	class Contacts
	class PageScraper < Base
	attr_accessor :agent
	# creates the Mechanize agent used to do the scraping
	def create_agent
	self.agent = Mechanize.new
	agent.keep_alive = false
	agent
	end
	# Logging in
	def prepare; end # stub
	def strip_html( html )
	html.gsub(/<\/?[^>]*>/, '')
	end
	end
	end

view raw page_scraper.rb hosted with ❤ by GitHub

然後在同樣這個目錄下新增facebook.rb：

	require 'page_scraper'
	class Contacts
	class Facebook < PageScraper
	URL = "http://www.facebook.com/"
	LOGIN_URL = "http://m.facebook.com/"
	PROTOCOL_ERROR = "Facebook has changed its protocols, please upgrade this library."
	def real_connect
	create_agent
	prepare
	end
	def prepare
	page = agent.get(LOGIN_URL)
	login_form = page.forms.first
	login_form.email = @login
	login_form.pass = @password
	page = agent.submit(login_form, login_form.buttons.first)
	raise AuthenticationError, "電郵地址或密碼有錯誤。" if page.body =~ /電郵地址或密碼有誤。/
	#Friends Page
	friends_links = page.links_with(:href => /\/friends.php/)
	friends_link = ''
	friends_links.each{ |flink| friends_link = flink.href if flink && flink.href && flink.text == 'Friends'}
	raise ConnectionError, PROTOCOL_ERROR unless friends_link
	friends_url = 'http://m.facebook.com' + friends_link
	page = agent.get(friends_url)
	#My Friends Page
	friends_link = page.links_with(:href => /\/friends.php/)
	@my_friends_link = ''
	friends_link.each{|f| @my_friends_link = f.href if f.text == '朋友'}
	@logout_url = page.link_with(:href => /logout/)
	return true
	end
	def contacts
	contacts = []
	next_page = true
	current_page = 2
	my_friends_url = 'http://m.facebook.com' + @my_friends_link
	page = agent.get(my_friends_url)
	raise AuthenticationError, "請先登入。" if page.body =~ /輸入帳號和密碼。/
	while(next_page)
	next_page = false
	data = page.search('//tr[@valign="top"]')
	if data
	data.each do |node|
	td_nodes = node.children
	if td_nodes
	childs = td_nodes[0]
	fr_name = childs.child.text
	fr_href = ''
	childs.children.each do |nd|
	if nd.name == 'small'
	nd.children.each do |n|
	fr_href = n.attributes['href'] if n.name == 'a' && n.text == '訊息'
	end
	end
	end
	contacts << [fr_name, fr_href.to_s] unless fr_href.blank?
	end
	end
	end # End Outer if
	data = page.search('//div[@class="pad"]')
	data.each do |node|
	childs = node.children
	next if childs.empty?
	childs.each do |c|
	if c.name == 'a' && c.text.to_i == current_page
	next_page = 'http://m.facebook.com' + c.attributes['href'].to_s
	break
	end
	end
	end
	current_page += 1
	page = agent.get(next_page) unless next_page == false
	end #End While
	return contacts
	end
	def send_message(contact, message, subj=nil)
	success = false
	if contact
	url_inbox = "http://m.facebook.com" + contact.last
	page = agent.get(url_inbox)
	raise AuthenticationError, "請先登入。" if page.body =~ /輸入帳號和密碼。/
	page.forms.each do |f|
	if f.has_field?('body')
	f.subject = subj if subj && !subj.empty?
	f.body = message
	page = agent.submit(f, f.buttons.first)
	return true if page.code == '200'
	end
	end
	end
	return success
	end
	def logout
	agent.click @logout_url if @logout_url
	return true
	end
	end
	TYPES[:facebook] = Facebook
	end

view raw facebook.rb hosted with ❤ by GitHub

最後編輯#{RAILS_ROOT}/vendor/plugins/contacts/lib/contact.rb添加下面內容：

require 'facebook'

view raw contacts.rb hosted with ❤ by GitHub

OK！完成了，現在可以打開Rails Console來測試一下：

	david@workstation:~/workspace/railscode$ script/console
	Loading development environment (Rails 2.2.2)
	>> fb=Contacts::Facebook.new('你的facebook帳號','你的密碼')
	...
	...
	>> contacts = fb.contacts
	=> [["User1", "/inbox/?compose&ids=xxxxxxxxx&r22287202&refid=5"], ["User2", "/inbox/?compose&ids=xxxxxxxxx&rd297796c&refid=5"], ["User3", "/inbox/?compose&ids=xxxxxxxxx&raf7be31a&refid=5"]]
	>> contacts.each{|c|fb.send_message(c, '你要發送的邀請內容', '訊息主旨')}

view raw console hosted with ❤ by GitHub

ps.目前聯絡人列表中，分頁的問題尚待解決！