Fix Mastodon not understanding as:Public and Public (#15948)

Fixes #5551

app/lib/activitypub/activity/announce.rb

@@ -43,9 +43,9 @@ class ActivityPub::Activity::Announce < ActivityPub::Activity
   end
 
   def visibility_from_audience
-    if audience_to.include?(ActivityPub::TagManager::COLLECTIONS[:public])
+    if audience_to.any? { |to| ActivityPub::TagManager.instance.public_collection?(to) }
       :public
-    elsif audience_cc.include?(ActivityPub::TagManager::COLLECTIONS[:public])
+    elsif audience_cc.any? { |cc| ActivityPub::TagManager.instance.public_collection?(cc) }
       :unlisted
     elsif audience_to.include?(@account.followers_url)
       :private

app/lib/activitypub/activity/create.rb

@@ -123,7 +123,7 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
 
   def process_audience
     (audience_to + audience_cc).uniq.each do |audience|
-      next if audience == ActivityPub::TagManager::COLLECTIONS[:public]
+      next if ActivityPub::TagManager.instance.public_collection?(audience)
 
       # Unlike with tags, there is no point in resolving accounts we don't already
       # know here, because silent mentions would only be used for local access
@@ -356,9 +356,9 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
   end
 
   def visibility_from_audience
-    if audience_to.include?(ActivityPub::TagManager::COLLECTIONS[:public])
+    if audience_to.any? { |to| ActivityPub::TagManager.instance.public_collection?(to) }
       :public
-    elsif audience_cc.include?(ActivityPub::TagManager::COLLECTIONS[:public])
+    elsif audience_cc.any? { |cc| ActivityPub::TagManager.instance.public_collection?(cc) }
       :unlisted
     elsif audience_to.include?(@account.followers_url)
       :private

app/lib/activitypub/tag_manager.rb

@@ -12,6 +12,10 @@ class ActivityPub::TagManager
     public: 'https://www.w3.org/ns/activitystreams#Public',
   }.freeze
 
+  def public_collection?(uri)
+    uri == COLLECTIONS[:public] || uri == 'as:Public' || uri == 'Public'
+  end
+
   def url_for(target)
     return target.url if target.respond_to?(:local?) && !target.local?
 

spec/lib/activitypub/activity/create_spec.rb

@@ -67,7 +67,7 @@ RSpec.describe ActivityPub::Activity::Create do
         end
       end
 
-      context 'public' do
+      context 'public with explicit public address' do
         let(:object_json) do
           {
             id: [ActivityPub::TagManager.instance.uri_for(sender), '#bar'].join,
@@ -85,7 +85,43 @@ RSpec.describe ActivityPub::Activity::Create do
         end
       end
 
-      context 'unlisted' do
+      context 'public with as:Public' do
+        let(:object_json) do
+          {
+            id: [ActivityPub::TagManager.instance.uri_for(sender), '#bar'].join,
+            type: 'Note',
+            content: 'Lorem ipsum',
+            to: 'as:Public',
+          }
+        end
+
+        it 'creates status' do
+          status = sender.statuses.first
+
+          expect(status).to_not be_nil
+          expect(status.visibility).to eq 'public'
+        end
+      end
+
+      context 'public with Public' do
+        let(:object_json) do
+          {
+            id: [ActivityPub::TagManager.instance.uri_for(sender), '#bar'].join,
+            type: 'Note',
+            content: 'Lorem ipsum',
+            to: 'Public',
+          }
+        end
+
+        it 'creates status' do
+          status = sender.statuses.first
+
+          expect(status).to_not be_nil
+          expect(status.visibility).to eq 'public'
+        end
+      end
+
+      context 'unlisted with explicit public address' do
         let(:object_json) do
           {
             id: [ActivityPub::TagManager.instance.uri_for(sender), '#bar'].join,
@@ -103,6 +139,42 @@ RSpec.describe ActivityPub::Activity::Create do
         end
       end
 
+      context 'unlisted with as:Public' do
+        let(:object_json) do
+          {
+            id: [ActivityPub::TagManager.instance.uri_for(sender), '#bar'].join,
+            type: 'Note',
+            content: 'Lorem ipsum',
+            cc: 'as:Public',
+          }
+        end
+
+        it 'creates status' do
+          status = sender.statuses.first
+
+          expect(status).to_not be_nil
+          expect(status.visibility).to eq 'unlisted'
+        end
+      end
+
+      context 'unlisted with Public' do
+        let(:object_json) do
+          {
+            id: [ActivityPub::TagManager.instance.uri_for(sender), '#bar'].join,
+            type: 'Note',
+            content: 'Lorem ipsum',
+            cc: 'Public',
+          }
+        end
+
+        it 'creates status' do
+          status = sender.statuses.first
+
+          expect(status).to_not be_nil
+          expect(status.visibility).to eq 'unlisted'
+        end
+      end
+
       context 'private' do
         let(:object_json) do
           {