class Aws::ErrorHandler

def call(context)
  @handler.call(context).on(300..599) do |response|
    if empty_body?(context.http_response)
      error_code = error_code_for_empty_response(context.http_response)
      error_message = ''
    else
      error_code, error_message = @parser.extract_error(response)
    end
    response.error = error(context, error_code, error_message)
    response.data = nil
  end
end

def empty_body?(http_resp)
  http_resp.body_contents.empty?
end

def error(context, code, message)
  svc = context.client.class.name.split('::')[1]
  errors_module = Aws.const_get(svc).const_get(:Errors)
  errors_module.error_class(code).new(context, message)
end

def error_code_for_empty_response(http_resp)
  status_code = http_resp.status_code
  {
    302 => 'MovedTemporarily',
    304 => 'NotModified',
    400 => 'BadRequest',
    403 => 'Forbidden',
    404 => 'NotFound',
  }[status_code] || "#{status_code}Error"
end

def initialize(parser)
  @parser = parser
end