class Google::Cloud::Storage::File::SignerV4

def canonical_and_signed_headers headers, virtual_hosted_style, bucket_bound_hostname
  if virtual_hosted_style && bucket_bound_hostname
    raise "virtual_hosted_style: #{virtual_hosted_style} and bucket_bound_hostname: " \
          "#{bucket_bound_hostname} params cannot both be passed together"
  end
  canonical_headers = headers || {}
  headers_arr = canonical_headers.map do |k, v|
    [k.downcase, v.strip.gsub(/[^\S\t]+/, " ").gsub(/\t+/, " ")]
  end
  canonical_headers = headers_arr.to_h
  canonical_headers["host"] = host_name virtual_hosted_style, bucket_bound_hostname
  canonical_headers = canonical_headers.sort_by(&:first).to_h
  canonical_headers_str = canonical_headers.map { |k, v| "#{k}:#{v}\n" }.join
  signed_headers_str = canonical_headers.keys.join ";"
  [canonical_headers_str, signed_headers_str]
end