Refactoring example for Extract Class

before.rb

require 'uri'

class MediaParser

  def initialize(text)
    @text = text
    @links = URI.extract @text
  end

  def parse_links
    @links.each do |link|
      embedable_media = convert_to_media(link)
      replace_url_with_html_embed link, embedable_media
    end
    @parsed_text
  end

  def convert_to_media(link)
    url_components = URI.split(link)
    path = url_components[5]
    query = url_components[7]

    if url_is_an_image? link
      "<img src=\"#{link}\" />"
    elsif url_is_a_youtube_regular? link
      video_id = query[2..-1]
      "<iframe width=\"560\" height=\"315\" src=\"http://www.youtube.com/embed/#{video_id}\" frameborder=\"0\" allowfullscreen></iframe>"
    elsif url_is_a_youtube_short? link
      video_id = path.gsub('/', '')
      "<iframe width=\"560\" height=\"315\" src=\"http://www.youtube.com/embed/#{video_id}\" frameborder=\"0\" allowfullscreen></iframe>"
    else
      "<a href=\"#{link}\">#{link}</a>"
    end
  end

  private

  def url_is_an_image?(url)
    path = URI.split(url)[5]
    path.end_with? 'png', 'gif', 'jpeg'
  end

  def url_is_a_youtube_regular?(url)
    host = URI.split(url)[2]
    query = URI.split(url)[7]
    host.include?("youtube") && query && query.include?('v=')
  end

  def url_is_a_youtube_short?(url)
    host = URI.split(url)[2]
    host.include? "youtu.be"
  end

  def replace_url_with_html_embed(link, html_snippet)
    source = @parsed_text || @text
    @parsed_text = source.gsub(link, html_snippet)
  end
end

extract_class.rb

require 'uri'

class MediaParser

  def initialize(text)
    @text = text
    @links = URI.extract @text
  end

  def parse_links
    @links.each do |link|
      embedable_media = convert_to_media(link)
      replace_url_with_html_embed link, embedable_media
    end
    @parsed_text
  end

  def convert_to_media(link)
    image_embedder = ImageEmbedder.new link
    youtube_embedder = YouTubeEmbedder.new link
    hyperlink_embedder = HyperlinkEmbedder.new link

    if image_embedder.can_process_url?
      image_embedder.convert_to_media_markup
    elsif youtube_embedder.can_process_url?
      youtube_embedder.convert_to_media_markup
    else
     hyperlink_embedder.convert_to_media_markup
    end
  end

  private

  def replace_url_with_html_embed(link, html_snippet)
    source = @parsed_text || @text
    @parsed_text = source.gsub(link, html_snippet)
  end
end


class ImageEmbedder

  def initialize(url)
    @url = url
  end

  def can_process_url?
    path = URI.split(@url)[5]
    path.end_with? 'png', 'gif', 'jpeg'
  end

  def convert_to_media_markup
    "<img src=\"#{@url}\" />"
  end
end


class YouTubeEmbedder

  def initialize(url)
    @url = url
    url_components = URI.split(url)
    @host = url_components[2]
    @path = url_components[5]
    @query = url_components[7]
  end

  def can_process_url?
    url_is_a_youtube_short? || url_is_a_youtube_regular?
  end

  def convert_to_media_markup
    "<iframe width=\"560\" height=\"315\" src=\"http://www.youtube.com/embed/#{video_id}\" frameborder=\"0\" allowfullscreen></iframe>"
  end

  private

  def video_id
    url_is_a_youtube_regular? ? @query[2..-1] : @path.gsub('/', '')
  end

  def url_is_a_youtube_regular?
    @host.include?("youtube") && @query && @query.include?('v=')
  end

  def url_is_a_youtube_short?
    @host.include? "youtu.be"
  end
end


class HyperlinkEmbedder

  def initialize(url)
    @url = url
  end

  def can_process_url?
    true
  end

  def convert_to_media_markup
    "<a href=\"#{@url}\">#{@url}</a>"
  end
end