module ProMotion
  module ScreenTabs
    def tab_bar_controller(*screens)
      tab_bar_controller = UITabBarController.alloc.init

      view_controllers = []
      tag_index = 0

      screens.map! { |s| s.respond_to?(:new) ? s.new : s } # Initialize any classes

      screens.each do |s|
        s = s.new if s.respond_to?(:new)

        s.tabBarItem.tag = tag_index

        s.parent_screen = self if self.is_a?(UIViewController) && s.respond_to?("parent_screen=")
        s.tab_bar = tab_bar_controller if s.respond_to?("tab_bar=")

        vc = s.respond_to?(:main_controller) ? s.main_controller : s
        view_controllers << vc

        tag_index += 1

        s.on_load if s.respond_to?(:on_load)
      end

      tab_bar_controller.viewControllers = view_controllers
      tab_bar_controller
    end

    # Open a UITabBarController with the specified screens as the
    # root view controller of the current app.
    # @param [Array] A comma-delimited list of screen classes or instances.
    # @return [UITabBarController]
    def open_tab_bar(*screens)
      tab_bar = tab_bar_controller(*screens)

      a = self.respond_to?(:load_root_screen) ? self : UIApplication.sharedApplication.delegate

      a.load_root_screen(tab_bar)
      tab_bar
    end

    def open_tab(tab)
      if tab.is_a? String
        return self.select(self.tab_bar, title: tab)
      elsif tab.is_a? Numeric
        tab_bar_controller.selectedIndex = tab
        return tab_bar_controller.viewControllers[tab]
      else
        $stderr.puts "Unable to open tab #{tab.to_s} because it isn't a string."
      end
    end

    def create_tab_bar_icon(icon, tag)
      return UITabBarItem.alloc.initWithTabBarSystemItem(icon, tag: tag)
    end

    def create_tab_bar_icon_custom(title, image_name, tag)
      icon_image = UIImage.imageNamed(image_name)
      return UITabBarItem.alloc.initWithTitle(title, image:icon_image, tag:tag)
    end

    def create_tab_bar_item(tab={})
      title = "Untitled"
      title = tab[:title] if tab[:title]
      tab[:tag] ||= @current_tag ||= 0
      @current_tag = tab[:tag] + 1

      tab_bar_item = create_tab_bar_icon(tab[:system_icon], tab[:tag]) if tab[:system_icon]
      tab_bar_item = create_tab_bar_icon_custom(title, tab[:icon], tab[:tag]) if tab[:icon]

      tab_bar_item.badgeValue = tab[:badge_number].to_s unless tab[:badge_number].nil? || tab[:badge_number] <= 0

      return tab_bar_item
    end

    def select(tab_bar_controller, title: title)
      root_controller = nil
      tab_bar_controller.viewControllers.each do |vc|
        if vc.tabBarItem.title == title
          tab_bar_controller.selectedViewController = vc
          root_controller = vc
          break
        end
      end
      root_controller
    end

    def replace_current_item(tab_bar_controller, view_controller: vc)
      controllers = NSMutableArray.arrayWithArray(tab_bar_controller.viewControllers)
      controllers.replaceObjectAtIndex(tab_bar_controller.selectedIndex, withObject: vc)
      tab_bar_controller.viewControllers = controllers
    end
  end
end