#Taken from Radiant Nav Tab API
require 'singleton'

module Radmin
  class AdminUI

    class DuplicateTabNameError < StandardError; end

    class NavTab < Array
      attr_reader :name

      def initialize(name)
        @name = name
        @items = []
      end

      def [](id)
        unless id.kind_of? Fixnum
          self.find {|subnav_item| subnav_item.name.to_s.titleize == id.to_s.titleize }
        else
          super
        end
      end

      def <<(*args)
        options = args.extract_options!
        item = args.first
        raise DuplicateTabNameError.new("duplicate tab name '#{item.name}'") if self[item.name]
        item.tab = self if item.respond_to?(:tab=)
        if options.empty?
          super(item)
        else
          options.symbolize_keys!
          before = options.delete(:before)
          after = options.delete(:after)
          tab_name = before || after
          if self[tab_name]
            _index = index(self[tab_name])
            _index += 1 unless before
            insert(_index, item)
          else
            super(item)
          end
        end
      end

      alias :add :<<
      
      def add_item(*args)
        options = args.extract_options!
        options.symbolize_keys!
        before = options.delete(:before)
        after = options.delete(:after)
        tab_name = before || after
        if self[tab_name]
          _index = index(self[tab_name])
          _index += 1 unless before
          insert(_index, NavSubItem.new(args.first, args.second))
        else
          add NavSubItem.new(args.first, args.second)
        end
      end

      def visible?(user)
        any? { |sub_item| sub_item.visible?(user) }
      end
    end

    class NavSubItem
      attr_reader :name, :url
      attr_accessor :tab

      def initialize(name, url = "#")
        @name, @url = name, url
      end

      def visible?(user)
        visible_by_controller?(user)
      end

      def relative_url
        File.join('/', url)
      end

      private
        def visible_by_controller?(user)
          params = Rails.application.routes.recognize_path(url, :method => :get)
          if params && params[:controller]
            ctx = params[:controller].sub('/','_').to_sym
            Authorization::Engine.instance.permit?(params[:action], :context => ctx, :user => user)
          else
            false
          end
        end
    end

    class << self
      def tab(name,&block)
        the_tab = instance.nav[name]
        unless the_tab
          the_tab = NavTab.new(name)
          instance.nav << the_tab
        end
        if block_given?
          yield(the_tab)
        end
        the_tab
      end
    end

    include Singleton
    attr_accessor :nav

    def initialize
      @nav = NavTab.new("Tab Container")
      load_default_nav
    end

    def nav_tab(*args)
      NavTab.new(*args)
    end
    
    def nav_item(*args)
      NavSubItem.new(*args)
    end

    protected
      def load_default_nav
        settings = nav_tab("Settings")
        settings << nav_item("Account", "/admin/account/edit")
        settings << nav_item("Users", "/admin/users")
        settings << nav_item("Application", "/admin/settings")
        nav << settings
      end
  end
end