Fix #463 - Fetch and display previews of URLs using OpenGraph tags

app/services/fetch_link_card_service.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+class FetchLinkCardService < BaseService
+  def call(status)
+    # Get first URL
+    url = URI.extract(status.text).reject { |uri| (uri =~ /\Ahttps?:\/\//).nil? }.first
+
+    return if url.nil?
+
+    response = http_client.get(url)
+
+    return if response.code != 200
+
+    page = Nokogiri::HTML(response.to_s)
+    card = PreviewCard.where(status: status).first_or_initialize(status: status, url: url)
+
+    card.title       = meta_property(page, 'og:title') || page.at_xpath('//title')&.content
+    card.description = meta_property(page, 'og:description') || meta_property(page, 'description')
+    card.image       = URI.parse(meta_property(page, 'og:image')) if meta_property(page, 'og:image')
+
+    card.save_with_optional_image!
+  end
+
+  private
+
+  def http_client
+    HTTP.timeout(:per_operation, write: 10, connect: 10, read: 10).follow
+  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
+end