gistfile1.txt

# in routes.rb
match '/oauth/create' => 'oauth#create', :as => 'oauth_callback'
resource :oauth, :only => :new, :controller => 'oauth'

# controller
class OauthController < ApplicationController
  def new
    session[:token] = nil
    flash[:next] = params[:next]
    top_redirect_to authenticator.authorize_url(:scope => params[:scope], :display => :page)
  end

  def create
    # oauth callback is invoked if denied as well, so make sure we have a code
    if params[:code]
      client = Mogli::Client.create_from_code_and_authenticator(params[:code], authenticator)
      session[:token] = client.access_token
    end
    top_redirect_to flash[:next]
  end

  private

    def authenticator
      @authenticator ||= Mogli::Authenticator.new(current_account.app_id,
                                                  current_account.api_secret,
                                                  oauth_callback_url(:host => current_account_canvas))
    end
end