Class: TopicEmbed

Inherits:
ActiveRecord::Base
  • Object
show all
Includes:
Trashable
Defined in:
app/models/topic_embed.rb

Defined Under Namespace

Classes: FetchResponse

Class Method Summary collapse

Methods included from Trashable

#recover!, #trash!, #trashed?

Class Method Details

.absolutize_urls(url, contents) ⇒ Object

Convert any relative URLs to absolute. RSS is annoying for this.



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# File 'app/models/topic_embed.rb', line 233

def self.absolutize_urls(url, contents)
  url = normalize_url(url)
  begin
    uri = URI(UrlHelper.normalized_encode(url))
  rescue URI::Error
    return contents
  end
  prefix = "#{uri.scheme}://#{uri.host}"
  prefix += ":#{uri.port}" if uri.port != 80 && uri.port != 443

  fragment = Nokogiri::HTML5.fragment("<div>#{contents}</div>")
  fragment
    .css("a")
    .each do |a|
      if a["href"].present?
        begin
          a["href"] = URI.join(prefix, a["href"]).to_s
        rescue URI::InvalidURIError
          # NOOP, URL is malformed
        end
      end
    end

  fragment
    .css("img")
    .each do |a|
      if a["src"].present?
        begin
          a["src"] = URI.join(prefix, a["src"]).to_s
        rescue URI::InvalidURIError
          # NOOP, URL is malformed
        end
      end
    end

  fragment.at("div").inner_html
end

.expanded_for(post) ⇒ Object 



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# File 'app/models/topic_embed.rb', line 299

def self.expanded_for(post)
  Discourse
    .cache
    .fetch("embed-topic:#{post.topic_id}", expires_in: 10.minutes) do
      url = TopicEmbed.where(topic_id: post.topic_id).pick(:embed_url)
      response = TopicEmbed.find_remote(url)

      body = response.body
      body << TopicEmbed.imported_from_html(url)
      body
    end
end

.find_remote(url) ⇒ Object 



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# File 'app/models/topic_embed.rb', line 120

def self.find_remote(url)
  url = UrlHelper.normalized_encode(url)
  URI.parse(url) # ensure url parses, will raise if not
  fd = FinalDestination.new(url, validate_uri: true, max_redirects: 5, follow_canonical: true)

  uri = fd.resolve
  return if uri.blank?

  begin
    html = uri.read
  rescue OpenURI::HTTPError, Net::OpenTimeout
    return
  end

  parse_html(html, uri.to_s)
end

.first_paragraph_from(html) ⇒ Object 



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# File 'app/models/topic_embed.rb', line 281

def self.first_paragraph_from(html)
  doc = Nokogiri.HTML5(html)

  result = +""
  doc
    .css("p")
    .each do |p|
      if p.text.present?
        result << p.to_s
        return result if result.size >= 100
      end
    end
  return result unless result.blank?

  # If there is no first paragraph, return the first div (onebox)
  doc.css("div").first.to_s
end

.import(user, url, title, contents, category_id: nil, cook_method: nil, tags: nil) ⇒ Object

Import an article from a source (RSS/Atom/Other)



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# File 'app/models/topic_embed.rb', line 43

def self.import(user, url, title, contents, category_id: nil, cook_method: nil, tags: nil)
  return unless url =~ %r{\Ahttps?\://}

  contents = first_paragraph_from(contents) if SiteSetting.embed_truncate && cook_method.nil?
  contents ||= ""
  contents = contents.dup << imported_from_html(url)

  url = normalize_url(url)

  embed = topic_embed_by_url(url)
  content_sha1 = Digest::SHA1.hexdigest(contents)
  post = nil

  # If there is no embed, create a topic, post and the embed.
  if embed.blank?
    Topic.transaction do
      eh = EmbeddableHost.record_for_url(url)

      cook_method ||=
        if SiteSetting.embed_support_markdown
          Post.cook_methods[:regular]
        else
          Post.cook_methods[:raw_html]
        end

      create_args = {
        title: title,
        raw: absolutize_urls(url, contents),
        skip_validations: true,
        cook_method: cook_method,
        category: category_id || eh.try(:category_id),
        tags: SiteSetting.tagging_enabled ? tags : nil,
      }
      create_args[:visible] = false if SiteSetting.embed_unlisted?

      creator = PostCreator.new(user, create_args)
      post = creator.create
      if post.present?
        TopicEmbed.create!(
          topic_id: post.topic_id,
          embed_url: url,
          content_sha1: content_sha1,
          post_id: post.id,
        )
      end
    end
  else
    absolutize_urls(url, contents)
    post = embed.post

    # Update the topic if it changed
    if post&.topic
      if post.user != user
        PostOwnerChanger.new(
          post_ids: [post.id],
          topic_id: post.topic_id,
          new_owner: user,
          acting_user: Discourse.system_user,
        ).change_owner!

        # make sure the post returned has the right author
        post.reload
      end

      if (content_sha1 != embed.content_sha1) || (title && title != post&.topic&.title)
        changes = { raw: absolutize_urls(url, contents) }
        changes[:title] = title if title.present?

        post.revise(user, changes, skip_validations: true, bypass_rate_limiter: true)
        embed.update!(content_sha1: content_sha1)
      end
    end
  end

  post
end

.import_remote(url, opts = nil) ⇒ Object 



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# File 'app/models/topic_embed.rb', line 219

def self.import_remote(url, opts = nil)
  opts = opts || {}
  response = find_remote(url)
  return if response.nil?

  response.title = opts[:title] if opts[:title].present?
  import_user = opts[:user] if opts[:user].present?
  import_user = response.author if response.author.present?
  url = normalize_url(response.url) if response.url.present?

  TopicEmbed.import(import_user, url, response.title, response.body)
end

.imported_from_html(url) ⇒ Object 



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# File 'app/models/topic_embed.rb', line 35

def self.imported_from_html(url)
  url = UrlHelper.normalized_encode(url)
  I18n.with_locale(SiteSetting.default_locale) do
    "\n<hr>\n<small>#{I18n.t("embed.imported_from", link: "<a href='#{url}'>#{url}</a>")}</small>\n"
  end
end

.normalize_url(url) ⇒ Object 



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# File 'app/models/topic_embed.rb', line 27

def self.normalize_url(url)
  # downcase
  # remove trailing forward slash/
  # remove consecutive hyphens
  # remove leading and trailing whitespace
  url.downcase.sub(%r{/\z}, "").sub(/\-+/, "-").strip
end

.parse_html(html, url) ⇒ Object 



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# File 'app/models/topic_embed.rb', line 137

def self.parse_html(html, url)
  require "ruby-readability"

  opts = {
    tags: %w[div p code pre h1 h2 h3 b em i strong a img ul li ol blockquote figure figcaption],
    attributes: %w[href src class],
    remove_empty_nodes: false,
  }

  opts[
    :whitelist
  ] = SiteSetting.allowed_embed_selectors if SiteSetting.allowed_embed_selectors.present?
  opts[
    :blacklist
  ] = SiteSetting.blocked_embed_selectors if SiteSetting.blocked_embed_selectors.present?
  allowed_embed_classnames =
    SiteSetting.allowed_embed_classnames if SiteSetting.allowed_embed_classnames.present?

  response = FetchResponse.new

  raw_doc = Nokogiri.HTML5(html)

  response.url = url

  auth_element =
    raw_doc.at('meta[@name="discourse-username"]') || raw_doc.at('meta[@name="author"]')
  if auth_element.present?
    response.author = User.where(username_lower: auth_element[:content].strip).first
  end

  read_doc = Readability::Document.new(html, opts)

  title = +(raw_doc.title || "")
  title.strip!

  if SiteSetting.embed_title_scrubber.present?
    title.sub!(Regexp.new(SiteSetting.embed_title_scrubber), "")
    title.strip!
  end
  response.title = title
  doc = Nokogiri.HTML5(read_doc.content)

  tags = { "img" => "src", "script" => "src", "a" => "href" }
  doc
    .search(tags.keys.join(","))
    .each do |node|
      url_param = tags[node.name]
      src = node[url_param]
      unless (src.nil? || src.empty?)
        begin
          # convert URL to absolute form
          node[url_param] = URI.join(url, UrlHelper.normalized_encode(src)).to_s
        rescue URI::Error, Addressable::URI::InvalidURIError
          # If there is a mistyped URL, just do nothing
        end
      end
      # only allow classes in the allowlist
      allowed_classes =
        if allowed_embed_classnames.blank?
          []
        else
          allowed_embed_classnames.split(/[ ,]+/i)
        end
      doc
        .search('[class]:not([class=""])')
        .each do |classnode|
          classes =
            classnode[:class]
              .split(" ")
              .select { |classname| allowed_classes.include?(classname) }
          if classes.length === 0
            classnode.delete("class")
          else
            classnode[:class] = classes.join(" ")
          end
        end
    end

  response.body = doc.at("body").children.to_html
  response
end

.topic_embed_by_url(embed_url) ⇒ Object 



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# File 'app/models/topic_embed.rb', line 271

def self.topic_embed_by_url(embed_url)
  embed_url = normalize_url(embed_url).sub(%r{\Ahttps?\://}, "")
  TopicEmbed.where("embed_url ~* ?", "^https?://#{Regexp.escape(embed_url)}$").first
end

.topic_id_for_embed(embed_url) ⇒ Object 



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# File 'app/models/topic_embed.rb', line 276

def self.topic_id_for_embed(embed_url)
  topic_embed = topic_embed_by_url(embed_url)
  topic_embed&.topic_id
end