mastodon/app/controllers/home_controller.rb

# frozen_string_literal: true

class HomeController < ApplicationController
  before_action :authenticate_user!
  before_action :set_initial_state_json

  def index
    @body_classes = 'app-body'
    @frontend     = (params[:frontend] and Rails.configuration.x.available_frontends.include? params[:frontend] + '.js') ? params[:frontend] : 'mastodon'
  end

  private

  def authenticate_user!
    redirect_to(single_user_mode? ? account_path(Account.first) : about_path) unless user_signed_in?
  end

  def set_initial_state_json
    serializable_resource = ActiveModelSerializers::SerializableResource.new(InitialStatePresenter.new(initial_state_params), serializer: InitialStateSerializer)
    @initial_state_json   = serializable_resource.to_json
  end

  def initial_state_params
    {
      settings: Web::Setting.find_by(user: current_user)&.data || {},
      push_subscription: current_account.user.web_push_subscription(current_session),
      current_account: current_account,
      token: current_session.token,
      admin: Account.find_local(Setting.site_contact_username),
    }
  end
end