Adding ability to link provider to already authenticated user

lib/sorcery/controller/submodules/external.rb

@@ -40,15 +40,23 @@ def login_at(provider, args = {})
             end
           end
 
-          # tries to login the user from provider's callback
+          # links provider to account if user is logged in
+          # otherwise it tries to login the user from provider's callback
           def login_from(provider)
             @provider = Config.send(provider)
             @provider.process_callback(params,session)
             @user_hash = @provider.get_user_hash
-            if user = user_class.load_from_provider(provider,@user_hash[:uid].to_s)
-              reset_session
-              auto_login(user)
-              user
+            if logged_in?
+              if current_user.link_from_provider(provider, @user_hash[:uid])
+                session[:"#{provider}_access_token"] = @user_hash[:access_token]
+                current_user
+              end
+            else
+              if user = user_class.load_from_provider(provider,@user_hash[:uid].to_s)
+                reset_session
+                auto_login(user)
+                user
+              end
             end
           end
 

lib/sorcery/model/submodules/external.rb

@@ -47,7 +47,21 @@ def load_from_provider(provider,uid)
         end
 
         module InstanceMethods
-
+          def link_from_provider(provider,uid)
+            config = sorcery_config
+            authentication = config.authentications_class.find_by_provider_and_uid(provider, uid)
+            unless authentication
+              config.authentications_class.create!({config.authentications_user_id_attribute_name => id, config.provider_attribute_name => provider, config.provider_uid_attribute_name => uid})
+            else
+              #raise exception if we're trying to link a provider when it's linked to another account
+              if id == authentication.send(config.authentications_user_id_attribute_name)
+                self
+              else
+                #TODO make a more specific error
+                raise StandardError.new
+              end
+            end
+          end
         end
 
       end