When web UI URL used while logged out, redirect to static page (#4954)

app/controllers/home_controller.rb

@@ -11,7 +11,30 @@ class HomeController < ApplicationController
   private
 
   def authenticate_user!
-    redirect_to(single_user_mode? ? account_path(Account.first) : about_path) unless user_signed_in?
+    return if user_signed_in?
+
+    matches = request.path.match(/\A\/web\/(statuses|accounts)\/([\d]+)\z/)
+
+    if matches
+      case matches[1]
+      when 'statuses'
+        status = Status.find_by(id: matches[2])
+
+        if status && (status.public_visibility? || status.unlisted_visibility?)
+          redirect_to(ActivityPub::TagManager.instance.url_for(status))
+          return
+        end
+      when 'accounts'
+        account = Account.find_by(id: matches[2])
+
+        if account
+          redirect_to(ActivityPub::TagManager.instance.url_for(account))
+          return
+        end
+      end
+    end
+
+    redirect_to(default_redirect_path)
   end
 
   def set_initial_state_json
@@ -28,4 +51,14 @@ class HomeController < ApplicationController
       admin: Account.find_local(Setting.site_contact_username),
     }
   end
+
+  def default_redirect_path
+    if request.path.start_with?('/web')
+      new_user_session_path
+    elsif single_user_mode?
+      short_account_path(Account.first)
+    else
+      about_path
+    end
+  end
 end

spec/controllers/home_controller_spec.rb

@@ -6,6 +6,7 @@ RSpec.describe HomeController, type: :controller do
   describe 'GET #index' do
     context 'when not signed in' do
       it 'redirects to about page' do
+        @request.path = '/'
         get :index
         expect(response).to redirect_to(about_path)
       end
@@ -13,6 +14,7 @@ RSpec.describe HomeController, type: :controller do
 
     context 'when signed in' do
       let(:user) { Fabricate(:user) }
+
       subject do
         sign_in(user)
         get :index