mastodon/app/controllers/auth/sessions_controller.rb

# frozen_string_literal: true

class Auth::SessionsController < Devise::SessionsController
  include Devise::Controllers::Rememberable

  layout 'auth'

  skip_before_action :require_no_authentication, only: [:create]
  skip_before_action :require_functional!

  before_action :set_instance_presenter, only: [:new]
  before_action :set_body_classes

  def new
    Devise.omniauth_configs.each do |provider, config|
      return redirect_to(omniauth_authorize_path(resource_name, provider)) if config.strategy.redirect_at_sign_in
    end

    super
  end

  def create
    self.resource = begin
      if user_params[:email].blank? && session[:otp_user_id].present?
        User.find(session[:otp_user_id])
      else
        warden.authenticate!(auth_options)
      end
    end

    if resource.otp_required_for_login?
      if user_params[:otp_attempt].present? && session[:otp_user_id].present?
        authenticate_with_two_factor_via_otp(resource)
      else
        prompt_for_two_factor(resource)
      end
    else
      authenticate_and_respond(resource)
    end
  end

  def destroy
    tmp_stored_location = stored_location_for(:user)
    super
    flash.delete(:notice)
    store_location_for(:user, tmp_stored_location) if continue_after?
  end

  protected

  def user_params
    params.require(:user).permit(:email, :password, :otp_attempt)
  end

  def after_sign_in_path_for(resource)
    last_url = stored_location_for(:user)

    if home_paths(resource).include?(last_url)
      root_path
    else
      last_url || root_path
    end
  end

  def after_sign_out_path_for(_resource_or_scope)
    Devise.omniauth_configs.each_value do |config|
      return root_path if config.strategy.redirect_at_sign_in
    end

    super
  end

  def valid_otp_attempt?(user)
    user.validate_and_consume_otp!(user_params[:otp_attempt]) ||
      user.invalidate_otp_backup_code!(user_params[:otp_attempt])
  rescue OpenSSL::Cipher::CipherError
    false
  end

  def authenticate_with_two_factor_via_otp(user)
    if valid_otp_attempt?(user)
      session.delete(:otp_user_id)
      authenticate_and_respond(user)
    else
      flash.now[:alert] = I18n.t('users.invalid_otp_token')
      prompt_for_two_factor(user)
    end
  end

  def prompt_for_two_factor(user)
    session[:otp_user_id] = user.id
    render :two_factor
  end

  def authenticate_and_respond(user)
    sign_in(user)
    remember_me(user)

    respond_with user, location: after_sign_in_path_for(user)
  end

  private

  def set_instance_presenter
    @instance_presenter = InstancePresenter.new
  end

  def set_body_classes
    @body_classes = 'lighter'
  end

  def home_paths(resource)
    paths = [about_path]

    if single_user_mode? && resource.is_a?(User)
      paths << short_account_path(username: resource.account)
    end

    paths
  end

  def continue_after?
    truthy_param?(:continue)
  end
end