Add cache for OEmbed endpoints to avoid extra HTTP requests (#12403)

* add youtube oembed endpoint

* add check for oembed endpoint

* change unless for a more readable if

* clear blank lines

* endpoint via https

* Fix string literal in condition

* use cache for endpoints

* use cache for endpoints

* clean up and adding check

* clean up and remove redundant return

* add html check

* add false to return

* use double quotes

* use double quotes

* Clean up

1 files changed, 16 insertions, 7 deletions

diff --git a/app/services/fetch_link_card_service.rb b/app/services/fetch_link_card_service.rb
index 640c60fd4..29880e8d8 100644
--- a/app/services/fetch_link_card_service.rb
+++ b/app/services/fetch_link_card_service.rb
@@ -39,6 +39,12 @@ class FetchLinkCardService < BaseService
   def process_url
     @card ||= PreviewCard.new(url: @url)
 
+    attempt_oembed || attempt_opengraph
+  end
+
+  def html
+    return @html if defined?(@html)
+
     Request.new(:get, @url).perform do |res|
       if res.code == 200 && res.mime_type == 'text/html'
         @html = res.body_with_limit
@@ -48,10 +54,6 @@ class FetchLinkCardService < BaseService
         @html_charset = nil
       end
     end
-
-    return if @html.nil?
-
-    attempt_oembed || attempt_opengraph
   end
 
   def attach_card
@@ -88,12 +90,17 @@ class FetchLinkCardService < BaseService
   end
 
   def attempt_oembed
-    service = FetchOEmbedService.new
-    embed   = service.call(@url, html: @html)
-    url     = Addressable::URI.parse(service.endpoint_url)
+    service         = FetchOEmbedService.new
+    url_domain      = Addressable::URI.parse(@url).normalized_host
+    cached_endpoint = Rails.cache.read("oembed_endpoint:#{url_domain}")
+
+    embed   = service.call(@url, cached_endpoint: cached_endpoint) unless cached_endpoint.nil?
+    embed ||= service.call(@url, html: html) unless html.nil?
 
     return false if embed.nil?
 
+    url = Addressable::URI.parse(service.endpoint_url)
+
     @card.type          = embed[:type]
     @card.title         = embed[:title]         || ''
     @card.author_name   = embed[:author_name]   || ''
@@ -127,6 +134,8 @@ class FetchLinkCardService < BaseService
   end
 
   def attempt_opengraph
+    return if html.nil?
+
     detector = CharlockHolmes::EncodingDetector.new
     detector.strip_tags = true