class Aws::Xml::ErrorHandler

def apply_error_headers(rule, context, data)
  headers = Aws::Rest::Response::Headers.new(rule)
  headers.apply(context.http_response, data)
end

def call(context)
  @handler.call(context).on(300..599) do |response|
    response.error = error(context) unless response.error
    response.data = nil
  end
end

def error_code(body, context)
  if (matches = body.match(/<Code>(.+?)<\/Code>/))
    remove_prefix(unescape(matches[1]), context)
  else
    http_status_error_code(context)
  end
end

def error_data(context, body, code)
  data = EmptyStructure.new
  if (error_rules = context.operation.errors)
    error_rules.each do |rule|
      # query protocol may have custom error code
      # reference: https://smithy.io/2.0/aws/protocols/aws-query-protocol.html#error-code-resolution
      error_shape_code = rule.shape['error']['code'] if rule.shape['error']
      match = (code == error_shape_code || code == rule.shape.name)
      next unless match && rule.shape.members.any?
      data = parse_error_data(rule, body)
      # supporting HTTP bindings
      apply_error_headers(rule, context, data)
    end
  end
  data
rescue Xml::Parser::ParsingError
  EmptyStructure.new
end

def error_message(body)
  if (matches = body.match(/<Message>(.+?)<\/Message>/m))
    unescape(matches[1])
  else
    ''
  end
end

def extract_error(body, context)
  context[:request_id] = request_id(body)
  code = error_code(body, context)
  [
    code,
    error_message(body),
    error_data(context, body, code)
  ]
end

def parse_error_data(rule, body)
  # errors may nested under <Errors><Error>structure_data</Error></Errors>
  # Or may be flat and under <Error>structure_data</Error>
  body = body.tr("\n", '')
  if (matches = body.match(/<Error>(.+?)<\/Error>/))
    Parser.new(rule).parse("<#{rule.shape.name}>#{matches[1]}</#{rule.shape.name}>")
  else
    EmptyStructure.new
  end
end

def remove_prefix(error_code, context)
  if (prefix = context.config.api.metadata['errorPrefix'])
    error_code.sub(/^#{prefix}/, '')
  else
    error_code
  end
end

def request_id(body)
  if (matches = body.match(/<RequestId>(.+?)<\/RequestId>/m))
    matches[1]
  end
end

def unescape(str)
  CGI.unescapeHTML(str)
end