* Code: https://github.com/applegrain/oauth-example 
* OAuth Protocol: http://tools.ietf.org/html/rfc6749#section-1.2
* Omniauth: https://github.com/intridea/omniauth
	
# Implement OAuth in your Rails application: 

1. Create an app on github (make sure the callback url is http://localhost:3000/auth/github/callback)

2. Add an initializer, config/initializers/omniauth.rb

  ```
    Rails.application.config.middleware.use OmniAuth::Builder do
      provider :github, ENV['GITHUB_KEY'], ENV['GITHUB_SECRET']
    end
  ```	
		
3. Add key and secret. Make sure that you can access the keys in the rails console like this: 
	* `ENV["GITHUB_SECRET"]`
	* `ENV["GITHUB_KEY"]`

4. Change login link in home.html.erb to “/auth/github”
	
5. Create callback route: routes.rb, `get '/auth/:provider/callback', to: 'sessions#create'`
	
6. Create a sessions controller
    * add a #create action in the sessions controller 
    ```rb
    def create
      @user = User.find_or_create_from_auth(request.env['omniauth.auth'])
      if @user
        session[:user_id] = @user.id
        redirect_to dashboard_path
      else
        redirect_to root_path
      end
    end
    ```

7. Create user model: nickname, email, provider, token, uid, image_url, token

8. In the user model, build the class method #find_or_create_from_auth that we referenced in sessions#create
  ```    
    def self.find_or_create_by_auth(auth)
      user = User.find_or_create_by(provider: auth['provider'], uid: auth['uid'])

      user.nickname = auth['info']['nickname']
      user.name = auth['info']['name']
      user.email = auth['info']['email']
      user.image_url = auth['info']['image']
      user.token = auth['credentials']['token']

      user.save
      user
    end
  ```

9. Create current user method in application controller 
  ```
  	  helper_method :current_user
  	
  	  def current_user
  	    @current_user ||= User.find(session[:user_id]) if session[:user_id]
  	  end
  	
  	  def authorize!
  	    redirect_to root_path unless current_user
  	  end
  ```

10. Add destroy action in sessions controller 

11. routes.rb: “delete '/logout', to: 'sessions#destroy'”