class Jekyll::Tags::IncludeRelativeTag

def page_path(context)
  page, site = context.registers.values_at(:page, :site)
  return site.source unless page
  site.in_source_dir File.dirname(resource_path(page, site))
end

def resource_path(page, site)
  path = page["path"]
  path = File.join(site.config["collections_dir"], path) if page["collection"]
  path.delete_suffix("/#excerpt")
end

def tag_includes_dirs(context)
  Array(page_path(context)).freeze
end