discourse/lib/cooked_post_processor.rb

# Post processing that we can do after a post has already been cooked. For
# example, inserting the onebox content, or image sizes.

require_dependency 'oneboxer'

class CookedPostProcessor

  def initialize(post, opts={})
    @dirty = false
    @opts = opts
    @post = post
    @doc = Nokogiri::HTML::fragment(post.cooked)
    @size_cache = {}
    @has_been_uploaded_cache = {}
  end

  def post_process
    return unless @doc.present?
    post_process_images
    post_process_oneboxes
  end

  def post_process_images
    images = @doc.search("img")
    return unless images.present?

    images.each do |img|
      # keep track of the original src
      src = img['src']
      # make sure the src is absolute (when working with locally uploaded files)
      img['src'] = Discourse.base_url_no_prefix + img['src'] if img['src'] =~ /^\/[^\/]/

      if src.present?
        # make sure the img has both width and height attributes
        update_dimensions!(img)
        # retrieve the associated upload, if any
        upload = get_upload_from_url(img['src'])
        if upload.present?
          # create a thumbnail
          upload.create_thumbnail!
          # optimize image
          img['src'] = optimize_image(img)
          # lightbox treatment
          convert_to_link!(img, upload.thumbnail_url)
        else
          convert_to_link!(img)
        end
        # mark the post as dirty whenever the src has changed
        @dirty |= src != img['src']
      end
    end

    # Extract the first image from the first post and use it as the 'topic image'
    if @post.post_number == 1
      img = images.first
      @post.topic.update_column :image_url, img['src'] if img['src'].present?
    end

  end

  def post_process_oneboxes
    args = { post_id: @post.id }
    args[:invalidate_oneboxes] = true if @opts[:invalidate_oneboxes]
    # bake onebox content into the post
    result = Oneboxer.apply(@doc) do |url, element|
      Oneboxer.onebox(url, args)
    end
    # mark the post as dirty whenever a onebox as been baked
    @dirty |= result.changed?
  end

  def update_dimensions!(img)
    return if img['width'].present? && img['height'].present?

    w, h = get_size_from_image_sizes(img['src'], @opts[:image_sizes]) || image_dimensions(img['src'])

    if w && h
      img['width'] = w.to_s
      img['height'] = h.to_s
      @dirty = true
    end
  end

  def get_upload_from_url(url)
    if Upload.has_been_uploaded?(url) && m = Upload.uploaded_regex.match(url)
      Upload.where("id = ?", m[:upload_id]).first
    end
  end

  def optimize_image(img)
    return img["src"]
    # 1) optimize using image_optim
    # 2) .png vs. .jpg
  end

  def convert_to_link!(img, thumbnail=nil)
    src = img["src"]
    width, height = img["width"].to_i, img["height"].to_i

    return unless src.present? && width > SiteSetting.auto_link_images_wider_than

    original_width, original_height = get_size(src)

    return unless original_width.to_i > width && original_height.to_i > height

    parent = img.parent
    while parent
      return if parent.name == "a"
      break unless parent.respond_to? :parent
      parent = parent.parent
    end

    # not a hyperlink so we can apply
    img['src'] = thumbnail if thumbnail
    a = Nokogiri::XML::Node.new "a", @doc
    img.add_next_sibling(a)
    a["href"] = src
    a["class"] = "lightbox"
    a.add_child(img)
    @dirty = true

  end

  def get_size_from_image_sizes(src, image_sizes)
    if image_sizes.present?
      if dim = image_sizes[src]
        ImageSizer.resize(dim['width'], dim['height'])
      end
    end
  end

  # Retrieve the image dimensions for a url
  def image_dimensions(url)
    uri = get_image_uri(url)
    return unless uri
    w, h = get_size(url)
    ImageSizer.resize(w, h) if w && h
  end

  def get_size(url)
    # we can always crawl our own images
    return unless SiteSetting.crawl_images? || Upload.has_been_uploaded?(url)
    @size_cache[url] ||= FastImage.size(url)
  rescue Zlib::BufError # FastImage.size raises BufError for some gifs
  end

  def get_image_uri(url)
    uri = URI.parse(url)
    uri if %w(http https).include?(uri.scheme)
  end

  def dirty?
    @dirty
  end

  def html
    @doc.try(:to_html)
  end

end