class Aws::Plugins::EndpointPattern::Handler

def _apply_endpoint_trait(context, trait)
  # currently only support host pattern
  ori_host = context.http_request.endpoint.host
  if pattern = trait['hostPrefix']
    host_prefix = pattern.gsub(/\{.+?\}/) do |label|
      label = label.delete("{}")
      _replace_label_value(
        ori_host, label, context.operation.input, context.params)
    end
    context.http_request.endpoint.host = host_prefix + context.http_request.endpoint.host
  end
end

def _replace_label_value(ori, label, input_ref, params)
  name = nil
  input_ref.shape.members.each do |m_name, ref|
    if ref['hostLabel'] && ref['hostLabelName'] == label
      name = m_name
    end
  end
  if name.nil? || params[name].nil?
    raise Errors::MissingEndpointHostLabelValue.new(name)
  end
  params[name]
end

def call(context)
  if !context.config.disable_host_prefix_injection
    endpoint_trait = context.operation.endpoint_pattern
    if endpoint_trait && !endpoint_trait.empty?
      _apply_endpoint_trait(context, endpoint_trait)
    end
  end
  @handler.call(context)
end