class Aws::Plugins::Sign::SignatureV4

def initialize(auth_scheme, config, sigv4_overrides = {})
  scheme_name = auth_scheme['name']
  unless %w[sigv4 sigv4a sigv4-s3express].include?(scheme_name)
    raise ArgumentError,
          "Expected sigv4, sigv4a, or sigv4-s3express auth scheme, got #{scheme_name}"
  end
  region = if scheme_name == 'sigv4a'
             auth_scheme['signingRegionSet'].join(',')
           else
             auth_scheme['signingRegion']
           end
  begin
    @signer = config.sigv4_signer || Aws::Sigv4::Signer.new(
      service: config.sigv4_name || auth_scheme['signingName'],
      region: sigv4_overrides[:region] || config.sigv4_region || region,
      credentials_provider: sigv4_overrides[:credentials] || config.credentials,
      signing_algorithm: scheme_name.to_sym,
      uri_escape_path: !!!auth_scheme['disableDoubleEncoding'],
      normalize_path: !!!auth_scheme['disableNormalizePath'],
      unsigned_headers: %w[content-length user-agent x-amzn-trace-id expect transfer-encoding connection]
    )
  rescue Aws::Sigv4::Errors::MissingCredentialsError
    raise Aws::Errors::MissingCredentialsError
  end
end