Retry oEmbed cache after redirect

app/services/fetch_link_card_service.rb

@@ -106,12 +106,11 @@ class FetchLinkCardService < BaseService
   end
 
   def attempt_oembed
-    service         = FetchOEmbedService.new
+    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, use_cached_endpoint: true)
     embed ||= service.call(@url, html: html) unless html.nil?
+    embed ||= service.call(@url, use_cached_endpoint: true) if @url != @original_url.to_s
 
     return false if embed.nil?
 

app/services/fetch_oembed_service.rb

@@ -10,7 +10,7 @@ class FetchOEmbedService
     @url     = url
     @options = options
 
-    if @options[:cached_endpoint]
+    if @options[:use_cached_endpoint]
       parse_cached_endpoint!
     else
       discover_endpoint!
@@ -57,9 +57,9 @@ class FetchOEmbedService
   end
 
   def parse_cached_endpoint!
-    cached = @options[:cached_endpoint]
+    cached = Rails.cache.read(cache_key)
 
-    return if cached[:endpoint].nil? || cached[:format].nil?
+    return if cached.nil? || cached[:endpoint].nil? || cached[:format].nil?
 
     @endpoint_url = Addressable::Template.new(cached[:endpoint]).expand(url: @url).to_s
     @format       = cached[:format]
@@ -68,14 +68,16 @@ class FetchOEmbedService
   def cache_endpoint!
     return unless URL_REGEX.match?(@endpoint_url)
 
-    url_domain = Addressable::URI.parse(@url).normalized_host
-
     endpoint_hash = {
       endpoint: @endpoint_url.gsub(URL_REGEX, '={url}'),
       format: @format,
     }
 
-    Rails.cache.write("oembed_endpoint:#{url_domain}", endpoint_hash, expires_in: ENDPOINT_CACHE_EXPIRES_IN)
+    Rails.cache.write(cache_key, endpoint_hash, expires_in: ENDPOINT_CACHE_EXPIRES_IN)
+  end
+
+  def cache_key
+    "oembed_endpoint:#{Addressable::URI.parse(@url).normalized_host}"
   end
 
   def fetch!

spec/services/fetch_link_card_service_spec.rb

@@ -13,6 +13,7 @@ RSpec.describe FetchLinkCardService do
     stub_request(:get, 'http://example.com/not-found').to_return(status: 404, headers: { 'Content-Type' => 'text/html' }, body: html)
     stub_request(:get, 'http://example.com/text').to_return(status: 404, headers: { 'Content-Type' => 'text/plain' }, body: 'Hello')
     stub_request(:get, 'http://example.com/redirect').to_return(status: 302, headers: { 'Location' => 'http://example.com/html' })
+    stub_request(:get, 'http://example.net/redirect-to-other-domain').to_return(status: 302, headers: { 'Location' => 'http://example.com/html' })
     stub_request(:get, 'http://example.com/redirect-to-404').to_return(status: 302, headers: { 'Location' => 'http://example.com/not-found' })
     stub_request(:get, 'http://example.com/oembed?url=http://example.com/html').to_return(headers: { 'Content-Type' => 'application/json' }, body: '{ "version": "1.0", "type": "link", "title": "oEmbed title" }')
     stub_request(:get, 'http://example.com/oembed?format=json&url=http://example.com/html').to_return(headers: { 'Content-Type' => 'application/json' }, body: '{ "version": "1.0", "type": "link", "title": "oEmbed title" }')
@@ -264,6 +265,39 @@ RSpec.describe FetchLinkCardService do
         end
       end
 
+      context 'when oEmbed endpoint cache populated with redirect target' do
+        let(:status) { Fabricate(:status, text: 'http://example.net/redirect-to-other-domain') }
+        let(:oembed_cache) { { endpoint: 'http://example.com/oembed?format=json&url={url}', format: :json } }
+
+        it 'uses the cached oEmbed response' do
+          expect(a_request(:get, 'http://example.net/redirect-to-other-domain')).to have_been_made
+          expect(a_request(:get, 'http://example.com/oembed?url=http://example.com/html')).to have_been_made
+        end
+
+        it 'creates preview card' do
+          expect(status.preview_card).to_not be_nil
+          expect(status.preview_card.url).to eq 'http://example.com/html'
+          expect(status.preview_card.title).to eq 'oEmbed title'
+        end
+      end
+
+      context 'when oEmbed endpoint cache populated with redirect target but page contains no oEmbed tags' do
+        let(:status) { Fabricate(:status, text: 'http://example.net/redirect-to-other-domain') }
+        let(:html) { 'Please fill out CAPTCHA' }
+        let(:oembed_cache) { { endpoint: 'http://example.com/oembed?format=json&url={url}', format: :json } }
+
+        it 'uses the cached oEmbed response' do
+          expect(a_request(:get, 'http://example.net/redirect-to-other-domain')).to have_been_made
+          expect(a_request(:get, 'http://example.com/oembed?format=json&url=http://example.com/html')).to have_been_made
+        end
+
+        it 'creates preview card' do
+          expect(status.preview_card).to_not be_nil
+          expect(status.preview_card.url).to eq 'http://example.com/html'
+          expect(status.preview_card.title).to eq 'oEmbed title'
+        end
+      end
+
       # If the original HTML URL for whatever reason (e.g. DOS protection) redirects to
       # an error page, we can still use the cached oEmbed but should not use the
       # redirect URL on the card.

spec/services/fetch_oembed_service_spec.rb

@@ -160,10 +160,12 @@ RSpec.describe FetchOEmbedService do
           headers: { 'Content-Type': 'text/html' },
           body: request_fixture('oembed_json_empty.html')
         )
+
+        Rails.cache.write('oembed_endpoint:www.youtube.com', { endpoint: 'http://www.youtube.com/oembed?format=json&url={url}', format: :json })
       end
 
       it 'returns new provider without fetching original URL first' do
-        subject.call('https://www.youtube.com/watch?v=dqwpQarrDwk', cached_endpoint: { endpoint: 'http://www.youtube.com/oembed?format=json&url={url}', format: :json })
+        subject.call('https://www.youtube.com/watch?v=dqwpQarrDwk', use_cached_endpoint: true)
         expect(a_request(:get, 'https://www.youtube.com/watch?v=dqwpQarrDwk')).to_not have_been_made
         expect(subject.endpoint_url).to eq 'http://www.youtube.com/oembed?format=json&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DdqwpQarrDwk'
         expect(subject.format).to eq :json