class Aws::Plugins::EndpointPattern::Handler

def apply_endpoint_trait(context, trait)
  pattern = trait['hostPrefix']
  return unless pattern
  host_prefix = pattern.gsub(/\{.+?}/) do |label|
    label = label.delete('{}')
    replace_label_value(label, context.operation.input, context.params)
  end
  context.http_request.endpoint.host = host_prefix + context.http_request.endpoint.host
end

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

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