forked from treehouse/mastodon
142 lines
4.6 KiB
Ruby
142 lines
4.6 KiB
Ruby
# frozen_string_literal: true
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class FetchLinkCardService < BaseService
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include ActionView::Helpers::TagHelper
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URL_PATTERN = %r{https?://\S+}
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def call(status)
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@status = status
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@url = parse_urls
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return if @url.nil? || @status.preview_cards.any?
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@url = @url.to_s
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RedisLock.acquire(lock_options) do |lock|
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if lock.acquired?
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@card = PreviewCard.find_by(url: @url)
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process_url if @card.nil? || @card.updated_at <= 2.weeks.ago
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end
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end
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attach_card if @card&.persisted?
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rescue HTTP::ConnectionError, OpenSSL::SSL::SSLError
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nil
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end
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private
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def process_url
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@card ||= PreviewCard.new(url: @url)
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res = Request.new(:head, @url).perform
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return if res.code != 200 || res.mime_type != 'text/html'
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attempt_oembed || attempt_opengraph
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end
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def attach_card
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@status.preview_cards << @card
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end
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def parse_urls
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if @status.local?
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urls = @status.text.match(URL_PATTERN).to_a.map { |uri| Addressable::URI.parse(uri).normalize }
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else
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html = Nokogiri::HTML(@status.text)
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links = html.css('a')
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urls = links.map { |a| Addressable::URI.parse(a['href']).normalize unless skip_link?(a) }.compact
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end
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urls.reject { |uri| bad_url?(uri) }.first
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end
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def bad_url?(uri)
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# Avoid local instance URLs and invalid URLs
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uri.host.blank? || TagManager.instance.local_url?(uri.to_s) || !%w(http https).include?(uri.scheme)
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end
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def skip_link?(a)
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# Avoid links for hashtags and mentions (microformats)
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a['rel']&.include?('tag') || a['class']&.include?('u-url')
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end
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def attempt_oembed
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response = OEmbed::Providers.get(@url)
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@card.type = response.type
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@card.title = response.respond_to?(:title) ? response.title : ''
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@card.author_name = response.respond_to?(:author_name) ? response.author_name : ''
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@card.author_url = response.respond_to?(:author_url) ? response.author_url : ''
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@card.provider_name = response.respond_to?(:provider_name) ? response.provider_name : ''
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@card.provider_url = response.respond_to?(:provider_url) ? response.provider_url : ''
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@card.width = 0
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@card.height = 0
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case @card.type
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when 'link'
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@card.image = URI.parse(response.thumbnail_url) if response.respond_to?(:thumbnail_url)
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when 'photo'
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@card.url = response.url
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@card.width = response.width.presence || 0
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@card.height = response.height.presence || 0
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when 'video'
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@card.width = response.width.presence || 0
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@card.height = response.height.presence || 0
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@card.html = Formatter.instance.sanitize(response.html, Sanitize::Config::MASTODON_OEMBED)
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when 'rich'
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# Most providers rely on <script> tags, which is a no-no
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return false
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end
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@card.save_with_optional_image!
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rescue OEmbed::NotFound
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false
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end
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def attempt_opengraph
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response = Request.new(:get, @url).perform
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return if response.code != 200 || response.mime_type != 'text/html'
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html = response.to_s
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detector = CharlockHolmes::EncodingDetector.new
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detector.strip_tags = true
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guess = detector.detect(html, response.charset)
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page = Nokogiri::HTML(html, nil, guess&.fetch(:encoding))
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if meta_property(page, 'twitter:player')
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@card.type = :video
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@card.width = meta_property(page, 'twitter:player:width') || 0
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@card.height = meta_property(page, 'twitter:player:height') || 0
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@card.html = content_tag(:iframe, nil, src: meta_property(page, 'twitter:player'),
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width: @card.width,
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height: @card.height,
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allowtransparency: 'true',
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scrolling: 'no',
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frameborder: '0')
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else
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@card.type = :link
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@card.image_remote_url = meta_property(page, 'og:image') if meta_property(page, 'og:image')
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end
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@card.title = meta_property(page, 'og:title').presence || page.at_xpath('//title')&.content || ''
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@card.description = meta_property(page, 'og:description').presence || meta_property(page, 'description') || ''
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return if @card.title.blank? && @card.html.blank?
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@card.save_with_optional_image!
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end
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def meta_property(html, property)
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html.at_xpath("//meta[@property=\"#{property}\"]")&.attribute('content')&.value || html.at_xpath("//meta[@name=\"#{property}\"]")&.attribute('content')&.value
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end
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def lock_options
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{ redis: Redis.current, key: "fetch:#{@url}" }
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end
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end
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