module ProMotion
  module ScreenNavigation

    def open_screen(screen, args = {})
      args = { in_detail: false, in_master: false, close_all: false, modal: false, in_tab: false, animated: true }.merge args

      # Apply properties to instance
      screen = set_up_screen_for_open(screen, args)
      ensure_wrapper_controller_in_place(screen, args)

      if args[:in_detail] && self.split_screen
        self.split_screen.detail_screen = screen

      elsif args[:in_master] && self.split_screen
        self.split_screen.master_screen = screen

      elsif args[:close_all]
        open_root_screen screen

      elsif args[:modal]
        present_modal_view_controller screen, args[:animated], args[:completion]

      elsif args[:in_tab] && self.tab_bar
        present_view_controller_in_tab_bar_controller screen, args[:in_tab]

      elsif self.navigationController
        push_view_controller screen, self.navigationController, args[:animated].nil? ? true : args[:animated]

      else
        open_root_screen (screen.navigationController || screen)

      end

      screen
    end
    alias :open :open_screen

    def open_root_screen(screen)
      app_delegate.open_root_screen(screen)
    end

    def open_modal(screen, args = {})
      open screen, args.merge({ modal: true })
    end

    def app_delegate
      UIApplication.sharedApplication.delegate
    end

    def close_screen(args = {})
      args ||= {}
      args = { sender: args } unless args.is_a?(Hash)
      args[:animated] = true unless args.has_key?(:animated)

      if self.modal?
        close_modal_screen args

      elsif self.navigationController
        close_nav_screen args
        send_on_return(args) # TODO: this would be better implemented in a callback or view_did_disappear.

      else
        PM.logger.warn "Tried to close #{self.to_s}; however, this screen isn't modal or in a nav bar."

      end
    end
    alias :close :close_screen

    def send_on_return(args = {})
      if self.parent_screen && self.parent_screen.respond_to?(:on_return)
        if args && self.parent_screen.method(:on_return).arity != 0
          self.parent_screen.send(:on_return, args)
        else
          self.parent_screen.send(:on_return)
        end
      end
    end

    def push_view_controller(vc, nav_controller=nil, animated=true)
      unless self.navigationController
        PM.logger.error "You need a nav_bar if you are going to push #{vc.to_s} onto it."
      end
      nav_controller ||= self.navigationController
      vc.first_screen = false if vc.respond_to?(:first_screen=)
      nav_controller.pushViewController(vc, animated: animated)
    end

    protected

    def set_up_screen_for_open(screen, args={})

      # Instantiate screen if given a class
      screen = screen.new if screen.respond_to?(:new)

      # Set parent
      screen.parent_screen = self if screen.respond_to?(:parent_screen=)

      # Set title & modal properties
      screen.title = args[:title] if args[:title] && screen.respond_to?(:title=)
      screen.modal = args[:modal] if args[:modal] && screen.respond_to?(:modal=)

      # Hide bottom bar?
      screen.hidesBottomBarWhenPushed = args[:hide_tab_bar] == true

      # Wrap in a PM::NavigationController?
      screen.add_nav_bar(args) if args[:nav_bar] && screen.respond_to?(:add_nav_bar)

      # Return modified screen instance
      screen

    end

    def ensure_wrapper_controller_in_place(screen, args={})
      unless args[:close_all] || args[:modal] || args[:in_detail] || args[:in_master]
        screen.navigationController ||= self.navigationController if screen.respond_to?("navigationController=")
        screen.tab_bar ||= self.tab_bar if screen.respond_to?("tab_bar=")
      end
    end

    def present_modal_view_controller(screen, animated, completion)
      self.presentViewController((screen.navigationController || screen), animated:animated, completion:completion)
    end

    def present_view_controller_in_tab_bar_controller(screen, tab_name)
      vc = open_tab tab_name
      if vc

        if vc.is_a?(UINavigationController)
          push_view_controller(screen, vc)
        else
          # TODO: This should probably open the vc, shouldn't it?
          # This isn't well tested and needs to work better.
          self.tab_bar.selectedIndex = vc.tabBarItem.tag
        end

      else
        PM.logger.error "No tab bar item '#{tab_name}'"
      end
    end

    def close_modal_screen(args={})
      args[:animated] = true unless args.has_key?(:animated)
      self.parent_screen.dismissViewControllerAnimated(args[:animated], completion: lambda {
        send_on_return(args)
      })
    end

    def close_nav_screen(args={})
      args[:animated] = true unless args.has_key?(:animated)
      if args[:to_screen] == :root
        self.navigationController.popToRootViewControllerAnimated args[:animated]
      elsif args[:to_screen] && args[:to_screen].is_a?(UIViewController)
        self.parent_screen = args[:to_screen]
        self.navigationController.popToViewController(args[:to_screen], animated: args[:animated])
      else
        self.navigationController.popViewControllerAnimated(args[:animated])
      end
    end

  end
end