module SimpleNavigation

  # View helpers to render the navigation.
  #
  # Use render_navigation as following to render your navigation:
  # * call <tt>render_navigation</tt> without :level option to render your complete navigation as nested tree.
  # * call <tt>render_navigation(:level => x)</tt> to render a specific navigation level (e.g. :level => 1 to render your primary navigation, :level => 2 to render the sub navigation and so forth)
  # * call <tt>render_navigation(:level => 2..3)</tt> to render navigation levels 2 and 3).
  #   For example, you could use render_navigation(:level => 1) to render your primary navigation as tabs and render_navigation(:level => 2..3) to render the rest of the navigation as a tree in a sidebar.
  #
  # ==== Examples (using Haml)
  #   #primary_navigation= render_navigation(:level => 1)
  #
  #   #sub_navigation= render_navigation(:level => 2)
  #
  #   #nested_navigation= render_navigation
  #
  #   #top_navigation= render_navigation(:level => 1..2)
  #   #sidebar_navigation= render_navigation(:level => 3)
  module Helpers

    # Renders the navigation according to the specified options-hash.
    #
    # The following options are supported:
    # * <tt>:level</tt> - defaults to :all which renders the the sub_navigation for an active primary_navigation inside that active primary_navigation item.
    #   Specify a specific level to only render that level of navigation (e.g. :level => 1 for primary_navigation etc...).
    #   Specifiy a Range of levels to render only those specific levels (e.g. :level => 1..2 to render both your first and second levels, maybe you want to render your third level somewhere else on the page)
    # * <tt>:expand_all</tt> - defaults to false. If set to true the all specified levels will be rendered as a fully expanded tree (always open). This is useful for javascript menus like Superfish.
    # * <tt>:context</tt> - specifies the context for which you would render the navigation. Defaults to :default which loads the default navigation.rb (i.e. config/navigation.rb).
    #   If you specify a context then the plugin tries to load the configuration file for that context, e.g. if you call <tt>render_navigation(:context => :admin)</tt> the file config/admin_navigation.rb
    #   will be loaded and used for rendering the navigation.
    # * <tt>:items</tt> - you can specify the items directly (e.g. if items are dynamically generated from database). See SimpleNavigation::ItemsProvider for documentation on what to provide as items.
    # * <tt>:renderer</tt> - specify the renderer to be used for rendering the navigation. Either provide the Class or a symbol matching a registered renderer. Defaults to :list (html list renderer).
    #
    # Instead of using the <tt>:items</tt> option, a block can be passed to specify the items dynamically
    #
    #   render_navigation do |menu|
    #     menu.item :posts, "Posts", posts_path
    #   end
    #
    def render_navigation(options={},&block)
      container = active_navigation_item_container(options,&block)
      container && container.render(options)
    end

    # Returns the name of the currently active navigation item belonging to the specified level.
    #
    # See Helpers#active_navigation_item for supported options.
    #
    # Returns an empty string if no active item can be found for the specified options
    def active_navigation_item_name(options={})
      active_navigation_item(options,'') { |item| item.name(:apply_generator => false) }
    end

    # Returns the key of the currently active navigation item belonging to the specified level.
    #
    # See Helpers#active_navigation_item for supported options.
    #
    # Returns <tt>nil</tt> if no active item can be found for the specified options
    def active_navigation_item_key(options={})
      active_navigation_item(options) { |item| item.key }
    end

    # Returns the currently active navigation item belonging to the specified level.
    #
    # The following options are supported:
    # * <tt>:level</tt> - defaults to :all which returns the most specific/deepest selected item (the leaf).
    #   Specify a specific level to only look for the selected item in the specified level of navigation (e.g. :level => 1 for primary_navigation etc...).
    # * <tt>:context</tt> - specifies the context for which you would like to find the active navigation item. Defaults to :default which loads the default navigation.rb (i.e. config/navigation.rb).
    #   If you specify a context then the plugin tries to load the configuration file for that context, e.g. if you call <tt>active_navigation_item_name(:context => :admin)</tt> the file config/admin_navigation.rb
    #   will be loaded and used for searching the active item.
    # * <tt>:items</tt> - you can specify the items directly (e.g. if items are dynamically generated from database). See SimpleNavigation::ItemsProvider for documentation on what to provide as items.
    #
    # Returns the supplied <tt>value_for_nil</tt> object (<tt>nil</tt>
    # by default) if no active item can be found for the specified
    # options
    def active_navigation_item(options={},value_for_nil = nil)
      options[:level] = :leaves if options[:level].nil? || options[:level] == :all
      container = active_navigation_item_container(options)
      if container && (item = container.selected_item)
        block_given? ? yield(item) : item
      else
        value_for_nil
      end
    end

    # Returns the currently active item container belonging to the specified level.
    #
    # The following options are supported:
    # * <tt>:level</tt> - defaults to :all which returns the least specific/shallowest selected item.
    #   Specify a specific level to only look for the selected item in the specified level of navigation (e.g. :level => 1 for primary_navigation etc...).
    # * <tt>:context</tt> - specifies the context for which you would like to find the active navigation item. Defaults to :default which loads the default navigation.rb (i.e. config/navigation.rb).
    #   If you specify a context then the plugin tries to load the configuration file for that context, e.g. if you call <tt>active_navigation_item_name(:context => :admin)</tt> the file config/admin_navigation.rb
    #   will be loaded and used for searching the active item.
    # * <tt>:items</tt> - you can specify the items directly (e.g. if items are dynamically generated from database). See SimpleNavigation::ItemsProvider for documentation on what to provide as items.
    #
    # Returns <tt>nil</tt> if no active item container can be found
    def active_navigation_item_container(options={},&block)
      options = SimpleNavigation::Helpers::apply_defaults(options)
      SimpleNavigation::Helpers::load_config(options,self,&block)
      container = SimpleNavigation.active_item_container_for(options[:level])
    end

    class << self
      def load_config(options,includer,&block)
        ctx = options.delete(:context)
        SimpleNavigation.init_adapter_from includer
        SimpleNavigation.load_config(ctx)
        SimpleNavigation::Configuration.eval_config(ctx)
        if block_given? || options[:items]
          SimpleNavigation.config.items(options[:items],&block)
        end
        SimpleNavigation.handle_explicit_navigation if SimpleNavigation.respond_to?(:handle_explicit_navigation)
        raise "no primary navigation defined, either use a navigation config file or pass items directly to render_navigation" unless SimpleNavigation.primary_navigation
      end

      def apply_defaults(options)
        options[:level] = options.delete(:levels) if options[:levels]
        {:context => :default, :level => :all}.merge(options)
      end
    end
  end
end