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- # frozen_string_literal: true
-
- class FetchLinkCardService < BaseService
- URL_PATTERN = %r{
- ( # $1 URL
- (https?:\/\/)? # $2 Protocol (optional)
- (#{Twitter::Regex[:valid_domain]}) # $3 Domain(s)
- (?::(#{Twitter::Regex[:valid_port_number]}))? # $4 Port number (optional)
- (/#{Twitter::Regex[:valid_url_path]}*)? # $5 URL Path and anchor
- (\?#{Twitter::Regex[:valid_url_query_chars]}*#{Twitter::Regex[:valid_url_query_ending_chars]})? # $6 Query String
- )
- }iox
-
- def call(status)
- @status = status
- @url = parse_urls
-
- return if @url.nil? || @status.preview_cards.any?
-
- @url = @url.to_s
-
- RedisLock.acquire(lock_options) do |lock|
- if lock.acquired?
- @card = PreviewCard.find_by(url: @url)
- process_url if @card.nil? || @card.updated_at <= 2.weeks.ago
- end
- end
-
- attach_card if @card&.persisted?
- rescue HTTP::Error, Addressable::URI::InvalidURIError => e
- Rails.logger.debug "Error fetching link #{@url}: #{e}"
- nil
- end
-
- private
-
- def process_url
- @card ||= PreviewCard.new(url: @url)
- res = Request.new(:head, @url).perform
-
- return if res.code != 200 || res.mime_type != 'text/html'
-
- attempt_oembed || attempt_opengraph
- end
-
- def attach_card
- @status.preview_cards << @card
- end
-
- def parse_urls
- if @status.local?
- urls = @status.text.scan(URL_PATTERN).map { |array| Addressable::URI.parse(array[0]).normalize }
- else
- html = Nokogiri::HTML(@status.text)
- links = html.css('a')
- urls = links.map { |a| Addressable::URI.parse(a['href']).normalize unless skip_link?(a) }.compact
- end
-
- urls.reject { |uri| bad_url?(uri) }.first
- end
-
- def bad_url?(uri)
- # Avoid local instance URLs and invalid URLs
- uri.host.blank? || TagManager.instance.local_url?(uri.to_s) || !%w(http https).include?(uri.scheme)
- end
-
- def skip_link?(a)
- # Avoid links for hashtags and mentions (microformats)
- a['rel']&.include?('tag') || a['class']&.include?('u-url')
- end
-
- def attempt_oembed
- response = OEmbed::Providers.get(@url)
-
- @card.type = response.type
- @card.title = response.respond_to?(:title) ? response.title : ''
- @card.author_name = response.respond_to?(:author_name) ? response.author_name : ''
- @card.author_url = response.respond_to?(:author_url) ? response.author_url : ''
- @card.provider_name = response.respond_to?(:provider_name) ? response.provider_name : ''
- @card.provider_url = response.respond_to?(:provider_url) ? response.provider_url : ''
- @card.width = 0
- @card.height = 0
-
- case @card.type
- when 'link'
- @card.image = URI.parse(response.thumbnail_url) if response.respond_to?(:thumbnail_url)
- when 'photo'
- @card.url = response.url
- @card.width = response.width.presence || 0
- @card.height = response.height.presence || 0
- when 'video'
- @card.width = response.width.presence || 0
- @card.height = response.height.presence || 0
- @card.html = Formatter.instance.sanitize(response.html, Sanitize::Config::MASTODON_OEMBED)
- when 'rich'
- # Most providers rely on <script> tags, which is a no-no
- return false
- end
-
- @card.save_with_optional_image!
- rescue OEmbed::NotFound
- false
- end
-
- def attempt_opengraph
- response = Request.new(:get, @url).perform
-
- return if response.code != 200 || response.mime_type != 'text/html'
-
- html = response.to_s
-
- detector = CharlockHolmes::EncodingDetector.new
- detector.strip_tags = true
-
- guess = detector.detect(html, response.charset)
- page = Nokogiri::HTML(html, nil, guess&.fetch(:encoding))
-
- if meta_property(page, 'twitter:player')
- @card.type = :video
- @card.width = meta_property(page, 'twitter:player:width') || 0
- @card.height = meta_property(page, 'twitter:player:height') || 0
- @card.html = content_tag(:iframe, nil, src: meta_property(page, 'twitter:player'),
- width: @card.width,
- height: @card.height,
- allowtransparency: 'true',
- scrolling: 'no',
- frameborder: '0')
- else
- @card.type = :link
- @card.image_remote_url = meta_property(page, 'og:image') if meta_property(page, 'og:image')
- end
-
- @card.title = meta_property(page, 'og:title').presence || page.at_xpath('//title')&.content || ''
- @card.description = meta_property(page, 'og:description').presence || meta_property(page, 'description') || ''
-
- return if @card.title.blank? && @card.html.blank?
-
- @card.save_with_optional_image!
- end
-
- def meta_property(html, property)
- html.at_xpath("//meta[@property=\"#{property}\"]")&.attribute('content')&.value || html.at_xpath("//meta[@name=\"#{property}\"]")&.attribute('content')&.value
- end
-
- def lock_options
- { redis: Redis.current, key: "fetch:#{@url}" }
- end
- end
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