Add Status::Visibility concern to hold visibility logic (#33578)

app/models/concerns/status/visibility.rb

@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+module Status::Visibility
+  extend ActiveSupport::Concern
+
+  included do
+    enum :visibility,
+         { public: 0, unlisted: 1, private: 2, direct: 3, limited: 4 },
+         suffix: :visibility,
+         validate: true
+
+    scope :distributable_visibility, -> { where(visibility: %i(public unlisted)) }
+    scope :list_eligible_visibility, -> { where(visibility: %i(public unlisted private)) }
+    scope :not_direct_visibility, -> { where.not(visibility: :direct) }
+
+    validates :visibility, exclusion: { in: %w(direct limited) }, if: :reblog?
+
+    before_validation :set_visibility, unless: :visibility?
+  end
+
+  class_methods do
+    def selectable_visibilities
+      visibilities.keys - %w(direct limited)
+    end
+  end
+
+  def hidden?
+    !distributable?
+  end
+
+  def distributable?
+    public_visibility? || unlisted_visibility?
+  end
+
+  alias sign? distributable?
+
+  private
+
+  def set_visibility
+    self.visibility ||= reblog.visibility if reblog?
+    self.visibility ||= visibility_from_account
+  end
+
+  def visibility_from_account
+    account.locked? ? :private : :public
+  end
+end