Use Omniauthable user model with admin role

app/models/admin.rb

@@ -1,6 +0,0 @@
-class Admin < ApplicationRecord
-  # Include default devise modules. Others available are:
-  # :confirmable, :lockable, :timeoutable and :omniauthable
-  devise :database_authenticatable,
-         :recoverable, :rememberable, :trackable, :validatable
-end

app/models/user.rb

@@ -0,0 +1,11 @@
+class User < ApplicationRecord
+  devise :omniauthable, :rememberable
+
+  enum role: [:user, :admin]
+
+  def self.from_omniauth(auth)
+    where(provider: auth.provider, uid: auth.uid).first_or_create do |user|
+      user.name = auth.info.name
+    end
+  end
+end