feat: Google OAuth for login & signup (#6346)

This PR adds Google OAuth for all existing users, allowing users to log in or sign up via their Google account.

---------

Co-authored-by: Pranav Raj S <pranav@chatwoot.com>
Co-authored-by: Fayaz Ahmed <15716057+fayazara@users.noreply.github.com>
Co-authored-by: Sojan <sojan@pepalo.com>

app/controllers/devise_overrides/omniauth_callbacks_controller.rb

@@ -0,0 +1,75 @@
+class DeviseOverrides::OmniauthCallbacksController < DeviseTokenAuth::OmniauthCallbacksController
+  include EmailHelper
+
+  def omniauth_success
+    get_resource_from_auth_hash
+
+    @resource.present? ? sign_in_user : sign_up_user
+  end
+
+  private
+
+  def sign_in_user
+    @resource.skip_confirmation! if confirmable_enabled?
+
+    # once the resource is found and verified
+    # we can just send them to the login page again with the SSO params
+    # that will log them in
+    encoded_email = ERB::Util.url_encode(@resource.email)
+    redirect_to login_page_url(email: encoded_email, sso_auth_token: @resource.generate_sso_auth_token)
+  end
+
+  def sign_up_user
+    return redirect_to login_page_url(error: 'no-account-found') unless account_signup_allowed?
+    return redirect_to login_page_url(error: 'business-account-only') unless validate_business_account?
+
+    create_account_for_user
+    token = @resource.send(:set_reset_password_token)
+    frontend_url = ENV.fetch('FRONTEND_URL', nil)
+    redirect_to "#{frontend_url}/app/auth/password/edit?config=default&reset_password_token=#{token}"
+  end
+
+  def login_page_url(error: nil, email: nil, sso_auth_token: nil)
+    frontend_url = ENV.fetch('FRONTEND_URL', nil)
+    params = { email: email, sso_auth_token: sso_auth_token }.compact
+    params[:error] = error if error.present?
+
+    "#{frontend_url}/app/login?#{params.to_query}"
+  end
+
+  def account_signup_allowed?
+    # set it to true by default, this is the behaviour across the app
+    GlobalConfigService.load('ENABLE_ACCOUNT_SIGNUP', 'false') != 'false'
+  end
+
+  def resource_class(_mapping = nil)
+    User
+  end
+
+  def get_resource_from_auth_hash # rubocop:disable Naming/AccessorMethodName
+    # find the user with their email instead of UID and token
+    @resource = resource_class.where(
+      email: auth_hash['info']['email']
+    ).first
+  end
+
+  def validate_business_account?
+    # return true if the user is a business account, false if it is a gmail account
+    auth_hash['info']['email'].exclude?('@gmail.com')
+  end
+
+  def create_account_for_user
+    @resource, @account = AccountBuilder.new(
+      account_name: extract_domain_without_tld(auth_hash['info']['email']),
+      user_full_name: auth_hash['info']['name'],
+      email: auth_hash['info']['email'],
+      locale: I18n.locale,
+      confirmed: auth_hash['info']['email_verified']
+    ).perform
+    Avatar::AvatarFromUrlJob.perform_later(@resource, auth_hash['info']['image'])
+  end
+
+  def default_devise_mapping
+    'user'
+  end
+end