module Aws
  module Plugins

    # Disable host prefix per operation when available
    #
    # @seahorse.client.option [Boolean] :disable_host_prefix_injection
    #   Set to true to disable SDK automatically adding host prefix
    #   to default service endpoint when available.
    #
    class EndpointPattern < Seahorse::Client::Plugin

      option(:disable_host_prefix_injection, false)

      def add_handlers(handlers, config)
        if config.regional_endpoint && !config.disable_host_prefix_injection
          handlers.add(Handler, priority: 90)
        end
      end

      class Handler < Seahorse::Client::Handler

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

        private

        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

      end

    end
  end
end
