OmniAuth Devise

omniauth_callbacks_controller.rb

class Users::OmniauthCallbacksController < Devise::OmniauthCallbacksController

  def facebook 
    create_auth
  end

  def twitter
    create_auth
  end

  def google
    create_auth
  end

  private

  def omniauth
    @omniauth ||= (env["omniauth.auth"] || {}).except("extra")
  end

  def create_auth
    data = omniauth['user_info']

    @uid      ||= omniauth['uid']
    @provider ||= omniauth['provider'] || params[:action]
    @email    ||= data['email']
    
    @auth = Api::V2::Service.where(provider: @provider, uid: @uid).first

    user_signed_in? ? handle_signed_in_user : handle_not_signed_in_user
  end

  def handle_signed_in_user
    # the user is currently signed in

    try_to_update_avatar current_user

    # check if this service is already linked to his/her account,
    # if not, add it
    if @auth
      flash[:notice] = I18n.t 'devise.omniauth_callbacks.success',
                              kind: @provider.capitalize
      redirect_to services_path
    else
      current_user.services.create(provider: @provider,
                                        uid: @uid,
                                       auth: omniauth)
      flash[:notice] = I18n.t 'devise.omniauth_callbacks.success', kind: @provider.capitalize
      redirect_to services_path
    end

  end

  def handle_not_signed_in_user
    # check if user has already signed in using this service provider and
    # continue with sign in process if yes
    if @auth
      flash[:notice] = I18n.t 'devise.omniauth_callbacks.success', kind: @provider.capitalize
      sign_in_and_redirect(:user, @auth.user)
    else
      # search for a user with this email address
      if existing_user = Api::V2::User.where(email:(@email || '').downcase).first
        try_to_update_avatar existing_user
        # map this new login method via a service provider to an existing account if the email address is the same
        existing_user.services.create(provider: @provider,
                                           uid: @uid,
                                          auth: omniauth)
        flash[:notice] = I18n.t 'devise.omniauth_callbacks.success',
                                kind: @provider.capitalize
        sign_in_and_redirect(:user, existing_user)
      else
        session["devise.omniauth"] = omniauth
        user = Api::V2::User.new_with_session(params, session)
        # do not send confirmation email, we directly save and confirm 
        # the new document
        if user.valid?
          user.skip_confirmation!
          user.save!
          user.confirm!          

          flash[:notice] = I18n.t 'devise.omniauth_callbacks.success',
                                  kind: @provider.capitalize
          sign_in_and_redirect(:user, user)
        else
          flash[:notice] = I18n.t 'devise.omniauth_callbacks.more_fields_to_fill'
          redirect_to new_user_registration_path
        end
      end
    end
  end

  private

  def try_to_update_avatar user
    # We don't support avatars yet
    # if user.avatar.blank?
    #   user.remote_avatar_url = omniauth['user_info']['image']
    #   user.save
    # end
  end
end