application.rb

class UI::Application
  attr_reader :navigation

  @@instance = nil
  def initialize(navigation, context)
    UI.context = context
    @navigation = navigation
    UI.context.contentView = proxy
    UI.context.supportActionBar.elevation = UI.density # one bottom border line
    @@instance = self
  end

  def self.instance
    @@instance
  end

  def start
    fragment = @navigation.root_screen.proxy
    transaction = UI.context.fragmentManager.beginTransaction
    transaction.add(proxy.id, fragment, nil)
    transaction.addToBackStack(nil)
    transaction.commit
  end

  def proxy
    @proxy ||= begin
      frame_layout = Android::Widget::FrameLayout.new(UI.context)
      frame_layout.id = Android::View::View.generateViewId
      frame_layout
    end
  end

  def version_number
    UI.context.applicationContext.packageManager.getPackageInfo(UI.context.applicationContext.packageName, 0).versionName
  end

  def build_number
    UI.context.applicationContext.packageManager.getPackageInfo(UI.context.applicationContext.packageName, 0).versionCode
  end
end