server.rb

require_relative 'helper'

class MyApp

  def half_close(request)
    [200, { 'content-type' => 'text/plan' }, 'Hello HTTP 2.0! GET request']
  end

  def promise(request)
    [200, { 'content-type' => 'text/plan' }, 'A promise']
  end
end

class Message

  def initialize(response)
    @status, @headers, @data = response
  end

  def response
    [headers, @data]
  end

  private

  def headers
    @headers.merge(
      'status' => @status.to_s,
      'content-length' => @data.bytesize.to_s,
    )
  end

end


class Server
  attr_reader :app, :server
  protected :app, :server

  def initialize(app, server)
    @app, @server = app, server
  end

  def sock
    @sock ||= server.accept
  end

  def conn
    @conn ||= HTTP2::Server.new
  end

  def listen
    loop do
      conn.on(:frame) do |bytes|
        sock.write bytes
      end

      conn.on(:stream) do |stream|
        req =  {}

        stream.on(:headers) do |h|
          req = Hash[*h.flatten]
        end

        stream.on(:half_close) do
          headers, data = Message.new(app.half_close(req)).response

          stream.headers(headers, end_stream: false)

          # split response into multiple DATA frames
          stream.data(data.slice!(0, 5), end_stream: false)
          stream.data(data)
        end
      end

      while !sock.closed? && !(sock.eof? rescue true) # rubocop:disable Style/RescueModifier
        data = sock.readpartial(1024)
        # puts "Received bytes: #{data.unpack("H*").first}"

        begin
          conn << data
        rescue => e
          puts "#{e.class} exception: #{e.message} - closing socket."
          e.backtrace.each { |l| puts "\t" + l }
          sock.close
        end
      end
    end
  end
end

Server.new(MyApp.new, TCPServer.new(8080)).listen