Add support for reversible suspensions through ActivityPub (#14989)

app/services/resolve_account_service.rb

@@ -5,8 +5,6 @@ class ResolveAccountService < BaseService
   include DomainControlHelper
   include WebfingerHelper
 
-  class WebfingerRedirectError < StandardError; end
-
   # Find or create an account record for a remote user. When creating,
   # look up the user's webfinger and fetch ActivityPub data
   # @param [String, Account] uri URI in the username@domain format or account record
@@ -40,13 +38,18 @@ class ResolveAccountService < BaseService
 
     @account ||= Account.find_remote(@username, @domain)
 
-    return @account if @account&.local? || !webfinger_update_due?
+    if gone_from_origin? && not_yet_deleted?
+      queue_deletion!
+      return
+    end
+
+    return @account if @account&.local? || gone_from_origin? || !webfinger_update_due?
 
     # Now it is certain, it is definitely a remote account, and it
     # either needs to be created, or updated from fresh data
 
     process_account!
-  rescue Webfinger::Error, WebfingerRedirectError, Oj::ParseError => e
+  rescue Webfinger::Error, Oj::ParseError => e
     Rails.logger.debug "Webfinger query for #{@uri} failed: #{e}"
     nil
   end
@@ -86,10 +89,12 @@ class ResolveAccountService < BaseService
     elsif !redirected
       return process_webfinger!("#{confirmed_username}@#{confirmed_domain}", true)
     else
-      raise WebfingerRedirectError, "The URI #{uri} tries to hijack #{@username}@#{@domain}"
+      raise Webfinger::RedirectError, "The URI #{uri} tries to hijack #{@username}@#{@domain}"
     end
 
     @domain = nil if TagManager.instance.local_domain?(@domain)
+  rescue Webfinger::GoneError
+    @gone = true
   end
 
   def process_account!
@@ -131,6 +136,18 @@ class ResolveAccountService < BaseService
     @actor_json = supported_context?(json) && equals_or_includes_any?(json['type'], ActivityPub::FetchRemoteAccountService::SUPPORTED_TYPES) ? json : nil
   end
 
+  def gone_from_origin?
+    @gone
+  end
+
+  def not_yet_deleted?
+    @account.present? && !@account.local?
+  end
+
+  def queue_deletion!
+    AccountDeletionWorker.perform_async(@account.id, reserve_username: false)
+  end
+
   def lock_options
     { redis: Redis.current, key: "resolve:#{@username}@#{@domain}" }
   end