I've added helpers for supporing Disqus Single Sign-on

disqus.gemspec

@@ -1,3 +1,5 @@
+require 'lib/disqus/version'
+
 spec = Gem::Specification.new do |s|
 
   s.name              = "disqus"
@@ -8,7 +10,6 @@ spec = Gem::Specification.new do |s|
   s.summary           = "Integrates Disqus commenting system into your Ruby-powered site."
   s.description       = 'Integrates Disqus into your Ruby-powered site. Works with any Ruby website, and has view helpers for Rails and Merb.'
   s.homepage          = 'http://github.com/norman/disqus'
-  s.has_rdoc          = true
   s.platform          = Gem::Platform::RUBY
 
   s.files             = Dir["lib/**/*.rb", "lib/**/*.rake", "*.rdoc", "LICENSE", "Rakefile", "test/**/*.*"]

lib/disqus.rb

@@ -1,4 +1,4 @@
-%w[api author forum post thread version view_helpers widget].each do |file|
+%w[api author forum post thread view_helpers widget].each do |file|
   require File.join(File.dirname(__FILE__), "disqus", file)
 end
 
@@ -49,4 +49,4 @@ def self.defaults
     @defaults
   end
 
-end
+end

lib/disqus/view_helpers.rb

@@ -1,9 +1,9 @@
 # Shortcuts to access the widgets as simple functions as opposed to using
 # their full qualified names.
-%w[combo comment_counts popular_threads recent_comments thread top_commenters].each do |method|
+%w[combo comment_counts popular_threads recent_comments thread top_commenters sso_login sso_logout].each do |method|
   eval(<<-EOM)
     def disqus_#{method}(options = {})
       Disqus::Widget.#{method}(options)
     end
   EOM
-end
+end

lib/disqus/widget.rb

@@ -1,3 +1,6 @@
+require 'base64'
+require 'openssl'
+
 module Disqus
 
   # Disqus Widget generator.
@@ -21,6 +24,9 @@ class Widget
     RECENT = ROOT_PATH + 'recent_comments_widget.js?num_items=%d&avatar_size=%d'
     POPULAR = ROOT_PATH + 'popular_threads_widget.js?num_items=%d'
     TOP = ROOT_PATH + 'top_commenters_widget.js?num_items=%d&avatar_size=%d&orientation=%s'
+
+    DIGEST  = OpenSSL::Digest::Digest.new('sha1')
+
     class << self
 
       # Show the main Disqus thread widget.
@@ -34,6 +40,7 @@ def thread(opts = {})
         if opts[:developer]
           s << '<script type="text/javascript">var disqus_developer = 1;</script>'
         end
+
         s << '<div id="disqus_thread"></div>'
         s << '<script type="text/javascript" src="' + THREAD + '"></script>'
         s << '<noscript><a href="http://%s.disqus.com/?url=ref">'
@@ -166,9 +173,53 @@ def combo(opts = {})
         s << '"></script>' 
         s % [opts[:account], opts[:num_items], opts[:color], opts[:default_tab]]
       end
+
+
+      # Single Sign-On | Login
+      # Options:
+      # * <tt>:public_key:</tt>
+      # * <tt>:secret_key:</tt>
+      # * <tt>:user_id:</tt> any unique user ID number associated with that account within your user database. This will be used to generate a unique username to reference in the Disqus system.
+      # * <tt>:username:</tt> The displayed name for that account
+      # * <tt>:email:</tt> The registered email address for that account
+      # * <tt>:avatar:</tt> A link to that user's avatar (optional)
+      # * <tt>:url:</tt> A link to the user's website (optional)
+      def sso_login(opts = {})
+        opts = Disqus::defaults.merge(opts)
+        sso :login, opts
+      end
+
+      # Single Sign-On | Logout
+      # Options:
+      # * <tt>:public_key:</tt>
+      # * <tt>:secret_key:</tt>
+      def sso_logout(opts = {})
+        opts = Disqus::defaults.merge(opts)
+        sso :logout, opts
+      end
 
       private
 
+      def sso action, opts
+        message = (action == :login ? {'id' => opts[:user_id], 'username' => opts[:username], 'email' => opts[:email]} : {})
+        message = Base64.encode64(message.to_json).gsub("\n", "")
+        timestamp = Time.now.to_i
+
+        signature = OpenSSL::HMAC.hexdigest(DIGEST, opts[:secret_key], "#{message} #{timestamp}")
+
+        s = '<script type="text/javascript">'
+        s << 'var disqus_config = function() {'
+
+        if opts[:logout_link]
+          s << 'this.sso = {'
+          s << 'logout:  "%s"};' % opts[:logout_link]
+        end
+
+        s << 'this.page.remote_auth_s3 = "%s %s %s";' % [message, signature, timestamp]
+        s << 'this.page.api_key = "%s";}' % opts[:public_key]        
+        s << '</script>'
+      end
+
       def validate_opts!(opts)
         raise ArgumentError.new("You must specify an :account") if !opts[:account]
         raise ArgumentError.new("Invalid color") if opts[:color] && !VALID_COLORS.include?(opts[:color])

test/widget_test.rb

@@ -28,6 +28,14 @@ def test_top_commenters
     assert disqus_top_commenters
   end
 
+  def test_sso_login
+    assert disqus_sso_login(:public_key => 'app_public', :secret_key => 'app_secret', :user_id => 1, :username => 'Vasya Pupkin', :email => 'vasya@pupkin.ru')
+  end
+
+  def test_sso_logout
+    assert disqus_sso_logout(:public_key => 'app_public', :secret_key => 'app_secret')
+  end
+
   def test_invalid_default_tab
     assert_raises ArgumentError do
       disqus_combo(:default_tab => "test")
@@ -52,4 +60,4 @@ def test_invalid_avatar_size
     end
   end
 
-end
+end