Add instagram background implementation and generalize application for other identity providers

app/controllers/users/omniauth_callbacks_controller.rb

@@ -7,22 +7,24 @@ class Users::OmniauthCallbacksController < Devise::OmniauthCallbacksController
   end
 
   def facebook
-    @user = User.find_for_facebook_oauth(request.env["omniauth.auth"], current_user)
+    @user = User.find_for_oauth(request.env["omniauth.auth"], current_user)
 
     if @user.persisted?
-      flash[:notice] = I18n.t "devise.omniauth_callbacks.success", :kind => "Facebook"
+      flash[:notice] = I18n.t "devise.omniauth_callbacks.success", :kind => @user.provider.to_s.capitalize
       sign_in @user
       #redirect_to user_root_path, :event => :authentication, :current_user => @user # infinite loop
       redirect_to user_obtain_token_path, :event => :authentication, :current_user => @user
     else
       session["devise.facebook_data"] = request.env["omniauth.auth"]
       Rails.logger.error("Failed to persist user: #{@user.errors.full_messages.join(', ')}")
-      #TAG: facebook
-      # redirect_to new_user_registration_url
       redirect_to '/'
     end
   end
 
+  def instagram
+    facebook # same same
+  end
+
   def failure(env = {})
     #binding.pry
     show_404