module Aws
  module Binary

    # @api private
    class DecodeHandler < Seahorse::Client::Handler

      def call(context)
        if eventstream_member = eventstream?(context)
          attach_eventstream_listeners(context, eventstream_member)
        end
        @handler.call(context)
      end

      private

      def eventstream?(ctx)
        ctx.operation.output.shape.members.each do |_, ref|
          return ref if ref.eventstream
        end
      end

      def attach_eventstream_listeners(context, rules)

        context.http_response.on_headers(200) do
          protocol = context.config.api.metadata['protocol']
          output_handler = context[:output_event_stream_handler] || context[:event_stream_handler]
          context.http_response.body = EventStreamDecoder.new(
            protocol,
            rules,
            context.operation.output,
            context.operation.errors,
            context.http_response.body,
            output_handler)
          if input_emitter = context[:input_event_emitter]
            # events need to be send in order
            # every event signature requries prior signature
            thread = Thread.new do
              # polling for buffered emit events until stream not active
              while input_emitter.stream.state == :open
                while callback = input_emitter.buffer.shift
                  callback.call if input_emitter.stream.state == :open
                end
              end
            end
            thread.abort_on_exception = true
            # attach thread to current stream context
            # make sure when stream closes (#wait or #join! is called)
            # input signal thread is also killed
            context[:input_signal_thread] = thread
          end
        end

        context.http_response.on_success(200) do
          context.http_response.body = context.http_response.body.events
        end

        context.http_response.on_error do
          # Potential enhancement to made
          # since we don't want to track raw bytes in memory
          context.http_response.body = StringIO.new
        end

      end

    end

  end
end