Bootstrap 2 tabs helper method for Ruby on Rails

tabbable.rb

# helpers/bootstrap_helper/tabbable.rb

# Bootstrap 2 tabs helper method for Ruby on Rails 
# http://getbootstrap.com/2.3.2/components.html
# 
# == Usage (slim):
# 
#     = tabbable do |t|
#       = t.section :tab_1 do
#         / Content for Tab #1
#         = render "partial"
#       = t.section :tab_2, "Title for tab 2" do
#         / Content for Tab #2
#         / ...

module BootstrapHelper
  module Tabbable
    TABBABLE_CLASS_KEY = [:below, :right, :left]
    
    def tabbable(*args, &block)
      return unless block_given?
      options = args.extract_options!.reverse_merge class: %w(tabbable)
      options[:class] << "tabs-#{args.shift.to_s}" if TABBABLE_CLASS_KEY.include?(args.first)
      
      tabbable_block = Wrapper.new(self)
      block.call tabbable_block
      content_tag(:div, options) { tabbable_block.call }
    end
    
    # Wrapper delegator
    class Wrapper < SimpleDelegator
      attr_accessor :tabs
      
      def tabs
        @tabs ||= []
      end
      
      def section(*args, &block)
        self.tabs << SectionDecorator.new(Section.new(tabs.count, *args, &block), __getobj__)
        return
      end
      
      def call
        safe_join [
          content_tag(:ul, show_each_tab(&:as_nav_item), class: %w(nav nav-tabs)).html_safe, 
          content_tag(:div, show_each_tab(&:as_tab_pane), class: %w(tab-content)).html_safe
        ]
      end
      
      private
      def show_each_tab(&block)
        safe_join tabs.map(&block)
      end
    end
    
    # Section model
    class Section
      attr_reader :key, :title, :block
      
      def initialize(*args, &block)
        @position, @key, @title = args
        @title ||= I18n.t @key, default: @key.to_s.humanize, scope: "helpers.tabs"
        @block = block
      end
      
      def first?
        @position == 0
      end
      
      def to_href
        "##{key}"
      end
    end
    
    # Section decorator
    class SectionDecorator < SimpleDelegator
      attr_accessor :template
      delegate :content_tag, :link_to, to: :template
      
      def initialize(object, template)
        super(object)
        @template = template
      end
      
      def as_nav_item
        content_tag(:li, as_link.html_safe, html_attrs).html_safe
      end
      
      def as_tab_pane
        content_tag(:div, html_attrs(class: %w(tab-pane), id: key), &block).html_safe
      end
      
      def as_link
        link_to title, to_href, data: { toggle: 'tab' }
      end
      
      private
      def html_attrs(attrs={})
        (attrs[:class] ||= []) << "active" if first?
        attrs
      end
    end
  end
end