tumblr-author.rb

require 'mechanize'

module TumblrGateway
  class Blog
    def initialize(base_url)
      @base_url = base_url
    end

    def author_for(post_id)
      PostPage.new(post_url_for(post_id)).author_name
    end

    private

    def post_url_for(post_id)
      URI.join(@base_url, 'post', post_id)
    end

    class PostPage
      def initialize(url)
        @url = url
      end

      def author_name
        mechanize = Mechanize.new
        page = mechanize.get(@url)
        page.search(".authorname").text
      end
    end
  end
end

blog = TumblrGateway::Blog.new('http://blog.gaslight.co')
blog.author_for('52640678160')