class OmniauthCallbacksController < Devise::OmniauthCallbacksController
  def linkedin
    return redirect_to new_user_session_path unless user.persisted?

    sign_in user

    redirect_to root_url
  end


  private

  def response
    request.env['omniauth.auth']
  end

  def user
    @user ||= Devise::OmniauthCallbacks::Linkedin.(response)
  end
end

Devise.setup do |config|
    ...

  config.omniauth :linkedin, Rails.application.secrets.linkedin_app, Rails.application.secrets.linkedin_secret

    ...
end

Rails.application.routes.draw do
  mount RailsAdmin::Engine => '/admin', as: 'rails_admin'
  root 'home#index'

  devise_for :users, controllers: {
    registrations:      'registrations',
    omniauth_callbacks: 'omniauth_callbacks'
  }

  devise_scope :user do
    patch '/password', to: 'registrations#change_password', as: :change_password
  end

  resources :users
  resources :profiles
end

class User < ApplicationRecord
  include User::DeviseSettings::Callbacks

  devise :database_authenticatable, :registerable, :recoverable, :rememberable,
         :trackable, :validatable, :confirmable, :omniauthable

  ...
end

class User
  module DeviseSettings
    module Callbacks
      extend ActiveSupport::Concern

      included do
        def after_confirmation
          self.update(role: User::ADMIN_ROLE) if User.confirmed.exists?
        end
      end
    end
  end
end

module Devise
  module OmniauthCallbacks
    class Linkedin < ::ApplicationService::Base
      def call
        find_user!

        return user if user.present?

        create_user!
      end

      private

      attr_reader :user

      delegate :info, :extra, :uid, to: :params
      delegate :raw_info,           to: :extra

      delegate :email, :first_name, :last_name, :nickname, :image, to: :info

      def find_user!
        @user = User.find_by_uid(params.extra.raw_info.sub)
      end

      def create_user!
        @user = UserForm::CreateSocial.new(built_user)

        user.skip_confirmation!
        user.save

        user.model
      end

      def built_user
        @built_user ||= User.new(user_attributes)
      end

      def user_attributes
        @user_attributes ||= {
          email:    email,
          password: Devise.friendly_token[0, 20],
          provider: :linkedin,
          uid:      uid,
          profile_attributes: {
            first_name: first_name,
            last_name:  last_name,
            nickname:   nickname,
            avatar:     image_file
          }
        }
      end

      def image_file
        open(image) if image.present?
      end
    end
  end
end