class Bundler::Fetcher::Downloader

def fetch(uri, headers = {}, counter = 0)
  raise HTTPError, "Too many redirects" if counter >= redirect_limit
  response = request(uri, headers)
  Bundler.ui.debug("HTTP #{response.code} #{response.message} #{uri}")
  case response
  when Net::HTTPSuccess, Net::HTTPNotModified
    response
  when Net::HTTPRedirection
    new_uri = URI.parse(response["location"])
    if new_uri.host == uri.host
      new_uri.user = uri.user
      new_uri.password = uri.password
    end
    fetch(new_uri, headers, counter + 1)
  when Net::HTTPRequestedRangeNotSatisfiable
    new_headers = headers.dup
    new_headers.delete("Range")
    new_headers["Accept-Encoding"] = "gzip"
    fetch(uri, new_headers)
  when Net::HTTPRequestEntityTooLarge
    raise FallbackError, response.body
  when Net::HTTPUnauthorized
    raise AuthenticationRequiredError, uri.host
  when Net::HTTPNotFound
    raise FallbackError, "Net::HTTPNotFound"
  else
    raise HTTPError, "#{response.class}#{": #{response.body}" unless response.body.empty?}"
  end
end

def initialize(connection, redirect_limit)
  @connection = connection
  @redirect_limit = redirect_limit
end

def request(uri, headers)
  validate_uri_scheme!(uri)
  Bundler.ui.debug "HTTP GET #{uri}"
  req = Net::HTTP::Get.new uri.request_uri, headers
  if uri.user
    user = CGI.unescape(uri.user)
    password = uri.password ? CGI.unescape(uri.password) : nil
    req.basic_auth(user, password)
  end
  connection.request(uri, req)
rescue NoMethodError => e
  raise unless ["undefined method", "use_ssl="].all? {|snippet| e.message.include? snippet }
  raise LoadError.new("cannot load such file -- openssl")
rescue OpenSSL::SSL::SSLError
  raise CertificateFailureError.new(uri)
rescue *HTTP_ERRORS => e
  Bundler.ui.trace e
  case e.message
  when /host down:/, /getaddrinfo: nodename nor servname provided/
    raise NetworkDownError, "Could not reach host #{uri.host}. Check your network " \
      "connection and try again."
  else
    raise HTTPError, "Network error while fetching #{URICredentialsFilter.credential_filtered_uri(uri)}" \
      " (#{e})"
  end
end

def validate_uri_scheme!(uri)
  return if uri.scheme =~ /\Ahttps?\z/
  raise InvalidOption,
    "The request uri `#{uri}` has an invalid scheme (`#{uri.scheme}`). " \
    "Did you mean `http` or `https`?"
end