discourse/lib/onebox/engine/standard_embed.rb

# frozen_string_literal: true

require "cgi"
require "onebox/open_graph"
require 'onebox/oembed'

module Onebox
  module Engine
    module StandardEmbed
      def self.oembed_providers
        @@oembed_providers ||= {}
      end

      def self.add_oembed_provider(regexp, endpoint)
        oembed_providers[regexp] = endpoint
      end

      def self.opengraph_providers
        @@opengraph_providers ||= []
      end

      def self.add_opengraph_provider(regexp)
        opengraph_providers << regexp
      end

      # Some oembed providers (like meetup.com) don't provide links to themselves
      add_oembed_provider(/www\.meetup\.com\//, 'http://api.meetup.com/oembed')
      add_oembed_provider(/www\.mixcloud\.com\//, 'https://www.mixcloud.com/oembed/')
      # In order to support Private Videos
      add_oembed_provider(/vimeo\.com\//, 'https://vimeo.com/api/oembed.json')
      # NYT requires login so use oembed only
      add_oembed_provider(/nytimes\.com\//, 'https://www.nytimes.com/svc/oembed/json/')

      def always_https?
        AllowlistedGenericOnebox.host_matches(uri, AllowlistedGenericOnebox.https_hosts) || super
      end

      def raw
        return @raw if defined?(@raw)

        og = get_opengraph
        twitter = get_twitter
        oembed = get_oembed

        @raw = {}

        og.data.each do |k, v|
          next if k == "title_attr"
          v = og.send(k)
          @raw[k] ||= v unless v.nil?
        end

        twitter.each { |k, v| @raw[k] ||= v unless Onebox::Helpers::blank?(v) }

        oembed.data.each do |k, v|
          v = oembed.send(k)
          @raw[k] ||= v unless v.nil?
        end

        favicon = get_favicon
        @raw[:favicon] = favicon unless Onebox::Helpers::blank?(favicon)

        unless @raw[:description]
          description = get_description
          @raw[:description] = description unless Onebox::Helpers::blank?(description)
        end

        @raw
      end

      protected

      def html_doc
        return @html_doc if defined?(@html_doc)

        headers = nil
        headers = { 'Cookie' => options[:cookie] } if options[:cookie]

        @html_doc = Onebox::Helpers.fetch_html_doc(url, headers)
      end

      def get_oembed
        @oembed ||= Onebox::Oembed.new(get_json_response)
      end

      def get_opengraph
        @opengraph ||= ::Onebox::OpenGraph.new(html_doc)
      end

      def get_twitter
        return {} unless html_doc

        twitter = {}

        html_doc.css('meta').each do |m|
          if (m["property"] && m["property"][/^twitter:(.+)$/i]) || (m["name"] && m["name"][/^twitter:(.+)$/i])
            value = (m["content"] || m["value"]).to_s
            twitter[$1.tr('-:' , '_').to_sym] ||= value unless (Onebox::Helpers::blank?(value) || value == "0 minutes")
          end
        end

        twitter
      end

      def get_favicon
        return nil unless html_doc

        favicon = html_doc.css('link[rel="shortcut icon"], link[rel="icon shortcut"], link[rel="shortcut"], link[rel="icon"]').first
        favicon = favicon.nil? ? nil : (favicon['href'].nil? ? nil : favicon['href'].strip)

        Onebox::Helpers::get_absolute_image_url(favicon, url)
      end

      def get_description
        return nil unless html_doc

        description = html_doc.at("meta[name='description']").to_h['content']
        description ||= html_doc.at("meta[name='Description']").to_h['content']

        description
      end

      def get_json_response
        oembed_url = get_oembed_url

        return "{}" if Onebox::Helpers.blank?(oembed_url)

        Onebox::Helpers.fetch_response(oembed_url) rescue "{}"
      rescue Errno::ECONNREFUSED, Net::HTTPError, Net::HTTPFatalError, MultiJson::LoadError
        "{}"
      end

      def get_oembed_url
        oembed_url = nil

        StandardEmbed.oembed_providers.each do |regexp, endpoint|
          if url =~ regexp
            oembed_url = "#{endpoint}?url=#{url}"
            break
          end
        end

        if html_doc
          if Onebox::Helpers.blank?(oembed_url)
            application_json = html_doc.at("//link[@type='application/json+oembed']/@href")
            oembed_url = application_json.value if application_json
          end

          if Onebox::Helpers.blank?(oembed_url)
            text_json = html_doc.at("//link[@type='text/json+oembed']/@href")
            oembed_url ||= text_json.value if text_json
          end
        end

        oembed_url
      end
    end
  end
end