discourse/lib/pinned_check.rb

# Helps us determine whether a topic should be displayed as pinned or not,
# taking into account anonymous users and users who have dismissed it
class PinnedCheck

  def self.unpinned?(topic, topic_user = nil)
    topic.pinned_at &&
    topic_user &&
    topic_user.cleared_pinned_at &&
    topic_user.cleared_pinned_at > topic.pinned_at
  end

  def self.pinned?(topic, topic_user = nil)
    !!topic.pinned_at &&
    !unpinned?(topic, topic_user)
  end

end