Add alternate links to ActivityPub resources from HTML/HEAD variants (#4586)

app/controllers/concerns/account_controller_concern.rb

@@ -23,6 +23,7 @@ module AccountControllerConcern
       [
         webfinger_account_link,
         atom_account_url_link,
+        actor_url_link,
       ]
     )
   end
@@ -41,6 +42,13 @@ module AccountControllerConcern
     ]
   end
 
+  def actor_url_link
+    [
+      ActivityPub::TagManager.instance.uri_for(@account),
+      [%w(rel alternate), %w(type application/activity+json)],
+    ]
+  end
+
   def webfinger_account_url
     webfinger_url(resource: @account.to_webfinger_s)
   end

app/controllers/statuses_controller.rb

@@ -36,7 +36,12 @@ class StatusesController < ApplicationController
   end
 
   def set_link_headers
-    response.headers['Link'] = LinkHeader.new([[account_stream_entry_url(@account, @status.stream_entry, format: 'atom'), [%w(rel alternate), %w(type application/atom+xml)]]])
+    response.headers['Link'] = LinkHeader.new(
+      [
+        [account_stream_entry_url(@account, @status.stream_entry, format: 'atom'), [%w(rel alternate), %w(type application/atom+xml)]],
+        [ActivityPub::TagManager.instance.uri_for(@status), [%w(rel alternate), %w(type application/activity+json)]],
+      ]
+    )
   end
 
   def set_status

app/controllers/stream_entries_controller.rb

@@ -38,7 +38,12 @@ class StreamEntriesController < ApplicationController
   end
 
   def set_link_headers
-    response.headers['Link'] = LinkHeader.new([[account_stream_entry_url(@account, @stream_entry, format: 'atom'), [%w(rel alternate), %w(type application/atom+xml)]]])
+    response.headers['Link'] = LinkHeader.new(
+      [
+        [account_stream_entry_url(@account, @stream_entry, format: 'atom'), [%w(rel alternate), %w(type application/atom+xml)]],
+        [ActivityPub::TagManager.instance.uri_for(@stream_entry.activity), [%w(rel alternate), %w(type application/activity+json)]],
+      ]
+    )
   end
 
   def set_stream_entry

app/views/accounts/show.html.haml

@@ -7,6 +7,7 @@
 
   %link{ rel: 'salmon', href: api_salmon_url(@account.id) }/
   %link{ rel: 'alternate', type: 'application/atom+xml', href: account_url(@account, format: 'atom') }/
+  %link{ rel: 'alternate', type: 'application/activity+json', href: ActivityPub::TagManager.instance.uri_for(@account) }/
 
   %meta{ property: 'og:type', content: 'profile' }/
   = render 'og', account: @account, url: short_account_url(@account, only_path: false)

app/views/stream_entries/show.html.haml

@@ -4,6 +4,7 @@
 
   %link{ rel: 'alternate', type: 'application/atom+xml', href: account_stream_entry_url(@account, @stream_entry, format: 'atom') }/
   %link{ rel: 'alternate', type: 'application/json+oembed', href: api_oembed_url(url: account_stream_entry_url(@account, @stream_entry), format: 'json') }/
+  %link{ rel: 'alternate', type: 'application/activity+json', href: ActivityPub::TagManager.instance.uri_for(@stream_entry.activity) }/
 
   %meta{ property: 'og:site_name', content: site_title }/
   %meta{ property: 'og:type', content: 'article' }/

spec/controllers/concerns/account_controller_concern_spec.rb

@@ -33,7 +33,7 @@ describe ApplicationController, type: :controller do
     it 'sets link headers' do
       account = Fabricate(:account, username: 'username')
       get 'success', params: { account_username: 'username' }
-      expect(response.headers['Link'].to_s).to eq '<http://test.host/.well-known/webfinger?resource=acct%3Ausername%40cb6e6126.ngrok.io>; rel="lrdd"; type="application/xrd+xml", <http://test.host/users/username.atom>; rel="alternate"; type="application/atom+xml"'
+      expect(response.headers['Link'].to_s).to eq '<http://test.host/.well-known/webfinger?resource=acct%3Ausername%40cb6e6126.ngrok.io>; rel="lrdd"; type="application/xrd+xml", <http://test.host/users/username.atom>; rel="alternate"; type="application/atom+xml", <https://cb6e6126.ngrok.io/users/username>; rel="alternate"; type="application/activity+json"'
     end
 
     it 'returns http success' do

spec/controllers/stream_entries_controller_spec.rb

@@ -21,7 +21,7 @@ RSpec.describe StreamEntriesController, type: :controller do
 
         get route, params: { account_username: alice.username, id: status.stream_entry.id }
 
-        expect(response.headers['Link'].to_s).to eq "<http://test.host/users/alice/updates/#{status.stream_entry.id}.atom>; rel=\"alternate\"; type=\"application/atom+xml\""
+        expect(response.headers['Link'].to_s).to eq "<http://test.host/users/alice/updates/#{status.stream_entry.id}.atom>; rel=\"alternate\"; type=\"application/atom+xml\", <https://cb6e6126.ngrok.io/users/alice/statuses/#{status.id}>; rel=\"alternate\"; type=\"application/activity+json\""
       end
     end