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module CollectiveIdea #:nodoc:

  module Acts #:nodoc:

    module NestedSet #:nodoc:

      # This module provides some helpers for the model classes using acts_as_nested_set.

      # It is included by default in all views.

      #

      module Helper

        # Returns options for select.

        # You can exclude some items from the tree.

        # You can pass a block receiving an item and returning the string displayed in the select.

        #

        # == Params

        #  * +class_or_item+ - Class name or top level times

        #  * +mover+ - The item that is being move, used to exlude impossible moves

        #  * +&block+ - a block that will be used to display: { |item| ... item.name }

        #

        # == Usage

        #

        #   <%= f.select :parent_id, nested_set_options(Category, @category) {|i|

        #       "#{'–' * i.level} #{i.name}"

        #     }) %>

        #

        def nested_set_options(class_or_item, mover = nil)

          class_or_item = class_or_item.roots if class_or_item.is_a?(Class)

          items = Array(class_or_item)

          result = []

          items.each do |root|

            result += root.self_and_descendants.map do |i|

              if mover.nil? || mover.new_record? || mover.move_possible?(i)

                [yield(i), i.id]

              end

            end.compact

          end

          result

        end  

      end

    end  

  end

end