Set and store report URIs (#10303)

Fixes #10271

app/models/report.rb

@@ -13,6 +13,7 @@
 #  action_taken_by_account_id :bigint(8)
 #  target_account_id          :bigint(8)        not null
 #  assigned_account_id        :bigint(8)
+#  uri                        :string
 #
 
 class Report < ApplicationRecord
@@ -28,6 +29,12 @@ class Report < ApplicationRecord
 
   validates :comment, length: { maximum: 1000 }
 
+  def local?
+    false # Force uri_for to use uri attribute
+  end
+
+  before_validation :set_uri, only: :create
+
   def object_type
     :flag
   end
@@ -89,4 +96,8 @@ class Report < ApplicationRecord
 
     Admin::ActionLog.from("(#{sql}) AS admin_action_logs")
   end
+
+  def set_uri
+    self.uri = ActivityPub::TagManager.instance.generate_uri_for(self) if uri.nil? && account.local?
+  end
 end