module Middleman::Sitemap::Extensions::Proxies::ResourceInstanceMethods

def get_source_file
  if proxy?
    proxy_resource = store.find_resource_by_path(proxied_to)

    unless proxy_resource
      raise "Path #{path} proxies to unknown file #{proxied_to}"
    end

    proxy_resource.source_file
  end
end

def proxied_to
  @proxied_to
end

def proxy?
  !!@proxied_to
end

def proxy_to(target)
  @proxied_to = target
end

def template?
  if proxy?
    store.find_resource_by_path(proxied_to).template?
  else
    super
  end
end