class Bundler::RubygemsIntegration

def download_gem(spec, uri, cache_dir)
  require "rubygems/remote_fetcher"
  uri = Bundler.settings.mirror_for(uri)
  fetcher = gem_remote_fetcher
  fetcher.headers = { "X-Gemfile-Source" => spec.remote.original_uri.to_s } if spec.remote.original_uri
  Bundler::Retry.new("download gem from #{uri}").attempts do
    gem_file_name = spec.file_name
    local_gem_path = File.join cache_dir, gem_file_name
    return if File.exist? local_gem_path
    begin
      remote_gem_path = uri + "gems/#{gem_file_name}"
      remote_gem_path = remote_gem_path.to_s if provides?("< 3.2.0.rc.1")
      SharedHelpers.filesystem_access(local_gem_path) do
        fetcher.cache_update_path remote_gem_path, local_gem_path
      end
    rescue Gem::RemoteFetcher::FetchError
      raise if spec.original_platform == spec.platform
      original_gem_file_name = "#{spec.original_name}.gem"
      raise if gem_file_name == original_gem_file_name
      gem_file_name = original_gem_file_name
      retry
    end
  end
rescue Gem::RemoteFetcher::FetchError => e
  raise Bundler::HTTPError, "Could not download gem from #{uri} due to underlying error <#{e.message}>"
end