Slack oauth2 omniauth devise implementation

_slack_button.html.erb

<%=
  button_to(omniauth_authorize_path(resource_name, provider),
            method: :post,
            style: "margin:1rem;align-items:center;color:#fff;background-color:#4A154B;border:0;border-radius:48px;display:inline-flex;font-family:Lato, sans-serif;font-size:16px;font-weight:600;height:48px;justify-content:center;text-decoration:none;width:256px",
            "data-turbo": false) do
%>
  <svg
    xmlns="http://www.w3.org/2000/svg"
    style="height:20px;width:20px;margin-right:12px"
    viewBox="0 0 122.8 122.8"
  >
    <path
      d="M25.8 77.6c0 7.1-5.8 12.9-12.9 12.9S0 84.7 0 77.6s5.8-12.9 12.9-12.9h12.9v12.9zm6.5 0c0-7.1 5.8-12.9 12.9-12.9s12.9 5.8 12.9 12.9v32.3c0 7.1-5.8 12.9-12.9 12.9s-12.9-5.8-12.9-12.9V77.6z"
      fill="#e01e5a"
    ></path>
    <path
      d="M45.2 25.8c-7.1 0-12.9-5.8-12.9-12.9S38.1 0 45.2 0s12.9 5.8 12.9 12.9v12.9H45.2zm0 6.5c7.1 0 12.9 5.8 12.9 12.9s-5.8 12.9-12.9 12.9H12.9C5.8 58.1 0 52.3 0 45.2s5.8-12.9 12.9-12.9h32.3z"
      fill="#36c5f0"
    ></path>
    <path
      d="M97 45.2c0-7.1 5.8-12.9 12.9-12.9s12.9 5.8 12.9 12.9-5.8 12.9-12.9 12.9H97V45.2zm-6.5 0c0 7.1-5.8 12.9-12.9 12.9s-12.9-5.8-12.9-12.9V12.9C64.7 5.8 70.5 0 77.6 0s12.9 5.8 12.9 12.9v32.3z"
      fill="#2eb67d"
    ></path>
    <path
      d="M77.6 97c7.1 0 12.9 5.8 12.9 12.9s-5.8 12.9-12.9 12.9-12.9-5.8-12.9-12.9V97h12.9zm0-6.5c-7.1 0-12.9-5.8-12.9-12.9s5.8-12.9 12.9-12.9h32.3c7.1 0 12.9 5.8 12.9 12.9s-5.8 12.9-12.9 12.9H77.6z"
      fill="#ecb22e"
    ></path>
  </svg>
  Sign in with Slack
<% end %>

devise.rb

require "omniauth/slack_oauth2"

  config.omniauth(
    :slack_oauth2,
    ENV.fetch("SLACK_CLIENT_ID"),
    ENV.fetch("SLACK_CLIENT_SECRET"),
    {
      scope: "openid,email,profile",
      redirect_uri: Rails.env.development? ? "https://localhost:3000/user/auth/slack_oauth2/callback" : nil,
      provider_ignores_state: Rails.env.development?
    }
  )

omniauth_callbacks_controller.rb

class User::OmniauthCallbacksController < Devise::OmniauthCallbacksController
  skip_before_action :verify_authenticity_token

  # NOTE: slack redirect_url is https://host:port/user/auth/slack_oauth2/callback
  def slack_oauth2
    if !auth[:extra][:data].email_verified ||
         auth[:extra][:data].team_domain != ENV.fetch("SLACK_TEAM_DOMAIN")
      redirect_to root_path, alert: "You are not authorized to use this app."
      return
    end

    user_session =
      UserSession.find_by(provider: auth["provider"], uid: auth["uid"])
    @user = user_session&.user || User.find_or_create_with_omniauth(auth)

    user_session ||=
      @user.user_sessions.find_or_create_by(provider: auth["provider"])
    user_session.assign_attributes(
      name: auth["info"]["name"],
      avatar_url: auth["info"]["image"]
    )
    user_session.data = {
      "access_token" => auth.credentials.token,
      "user_id" => auth[:extra][:data].user_id,
      "team_id" => auth[:extra][:data].team_id,
      "name" => auth[:extra][:data].name,
      "team_name" => auth[:extra][:data].team_name,
      "team_domain" => auth[:extra][:data].team_domain,
      "picture" => auth[:extra][:data].picture
    }
    user_session.save!

    flash[:notice] = I18n.t("devise.omniauth_callbacks.success", kind: "Slack")
    sign_in @user
    redirect_to root_path
  end

  def auth
    request.env["omniauth.auth"]
  end
end

routes.rb

      devise_for(
        :user,
        controllers: {
          sessions: "user/sessions",
          omniauth_callbacks: "user/omniauth_callbacks"
        }
      )

sessions_new.html.erb

        <%- if devise_mapping.omniauthable? %>
          <%- resource_class.omniauth_providers.each do |provider| %>
            <% case provider %>
            <% when :google_oauth2 %>
              <%= render partial: "google_button", locals: { provider: provider, resource_name: resource_name } %>
            <% when :slack_oauth2 %>
              <%= render partial: "slack_button", locals: { provider: provider, resource_name: resource_name } %>
            <% end %>
          <% end %>
        <% end %>

slack_oauth2.rb

require "omniauth/strategies/oauth2"

module OmniAuth
  module Strategies
    class SlackOauth2 < OmniAuth::Strategies::OAuth2
      AUTH_OPTIONS = %i[scope user_scope team team_domain]

      INFO_DATA =
        Data.define(
          :user_id,
          :team_id,
          :email,
          :email_verified,
          :name,
          :picture,
          :given_name,
          :family_name,
          :locale,
          :team_name,
          :team_domain
        )

      option :name, "slack_oauth2"
      option :client_options,
             {
               site: "https://slack.com",
               authorize_url: "/openid/connect/authorize",
               token_url: "/api/openid.connect.token"
             }

      option :redirect_uri

      uid {
        "#{raw_info.dig("https://slack.com/team_id")}-#{raw_info.dig("https://slack.com/user_id")}"
      }

      info { {
        name: raw_info.dig("name"),
        email: raw_info.dig("email"),
        image: raw_info.dig("picture")
      } }

      extra do
        {
          data:
            INFO_DATA.new(
              user_id: raw_info.dig("https://slack.com/user_id"),
              team_id: raw_info.dig("https://slack.com/team_id"),
              email: raw_info.dig("email"),
              email_verified: raw_info.dig("email_verified"),
              name: raw_info.dig("name"),
              picture: raw_info.dig("picture"),
              given_name: raw_info.dig("given_name"),
              family_name: raw_info.dig("family_name"),
              locale: raw_info.dig("locale"),
              team_name: raw_info.dig("https://slack.com/team_name"),
              team_domain: raw_info.dig("https://slack.com/team_domain")
            ),
          raw_info: raw_info
        }
      end

      def callback_url
        options.redirect_uri || full_host + script_name + callback_path
      end

      def raw_info
        @raw_info ||= access_token.get("/api/openid.connect.userInfo").parsed
      end
    end
  end
end

user.rb

  devise(
    :database_authenticatable,
    :trackable,
    :omniauthable,
    omniauth_providers: %i[google_oauth2 slack_oauth2]
  )