class ActionView::CacheExpiry::ViewReloader

def all_view_paths
  ActionView::PathRegistry.all_file_system_resolvers.map(&:path)
end

def dirs_to_watch
  all_view_paths.uniq.sort
end

def execute
  watcher = nil
  @mutex.synchronize do
    @previous_change = false
    watcher = @watcher
  end
  watcher.execute
end

def initialize(watcher:, &block)
  @mutex = Mutex.new
  @watcher_class = watcher
  @watched_dirs = nil
  @watcher = nil
  @previous_change = false
  rebuild_watcher
  ActionView::PathRegistry.file_system_resolver_hooks << method(:rebuild_watcher)
end

def rebuild_watcher
  @mutex.synchronize do
    old_watcher = @watcher
    if @watched_dirs != dirs_to_watch
      @watched_dirs = dirs_to_watch
      new_watcher = @watcher_class.new([], @watched_dirs) do
        reload!
      end
      @watcher = new_watcher
      # We must check the old watcher after initializing the new one to
      # ensure we don't miss any events
      @previous_change ||= old_watcher&.updated?
    end
  end
end

def reload!
  ActionView::LookupContext::DetailsKey.clear
end

def updated?
  @previous_change || @watcher.updated?
end