# frozen_string_literal: true

require_relative "helper"
require "http_parser"

options = { port: 8080 }
OptionParser.new do |opts|
  opts.banner = "Usage: server.rb [options]"

  opts.on("-s", "--secure", "HTTPS mode") do |v|
    options[:secure] = v
  end

  opts.on("-p", "--port [Integer]", "listen port") do |v|
    options[:port] = v
  end
end.parse!

puts "Starting server on port #{options[:port]}"
server = TCPServer.new(options[:port])

if options[:secure]
  ctx = OpenSSL::SSL::SSLContext.new
  ctx.cert = OpenSSL::X509::Certificate.new(File.open("keys/server.crt"))
  ctx.key = OpenSSL::PKey::RSA.new(File.open("keys/server.key"))
  ctx.npn_protocols = [DRAFT]

  server = OpenSSL::SSL::SSLServer.new(server, ctx)
end

def request_header_hash
  Hash.new do |hash, key|
    k = key.to_s.downcase
    k.tr! "_", "-"
    _, value = hash.find { |header_key, _| header_key.downcase == k }
    hash[key] = value if value
  end
end

class UpgradeHandler
  VALID_UPGRADE_METHODS = %w[GET OPTIONS].freeze
  UPGRADE_RESPONSE = <<RESP
HTTP/1.1 101 Switching Protocols
Connection: Upgrade
Upgrade: h2c

RESP

  attr_reader :complete, :headers, :body, :parsing

  def initialize(conn, sock)
    @conn = conn
    @sock = sock
    @complete = false
    @parsing = false
    @headers = request_header_hash
    @body = ""
    @parser = ::HTTP::Parser.new(self)
  end

  def <<(data)
    @parsing ||= true
    @parser << data
    return unless complete

    @sock.write UPGRADE_RESPONSE

    settings = headers["http2-settings"]
    request = {
      ":scheme" => "http",
      ":method" => @parser.http_method,
      ":authority" => headers["Host"],
      ":path" => @parser.request_url
    }.merge(headers)

    @conn.upgrade(settings, request, @body)
  end

  def complete!
    @complete = true
  end

  def on_headers_complete(headers)
    @headers.merge! headers
  end

  def on_body(chunk)
    @body << chunk
  end

  def on_message_complete
    raise unless VALID_UPGRADE_METHODS.include?(@parser.http_method)

    @parsing = false
    complete!
  end
end

loop do
  sock = server.accept
  puts "New TCP connection!"

  conn = HTTP2::Server.new
  conn.on(:frame) do |bytes|
    # puts "Writing bytes: #{bytes.unpack("H*").first}"
    sock.write bytes
  end
  conn.on(:frame_sent) do |frame|
    puts "Sent frame: #{frame.inspect}"
  end
  conn.on(:frame_received) do |frame|
    puts "Received frame: #{frame.inspect}"
  end

  conn.on(:stream) do |stream|
    log = Logger.new(stream.id)
    req = request_header_hash
    buffer = ""

    stream.on(:active) { log.info "client opened new stream" }
    stream.on(:close) do
      log.info "stream closed"
    end

    stream.on(:headers) do |h|
      req.merge! Hash[*h.flatten]
      log.info "request headers: #{h}"
    end

    stream.on(:data) do |d|
      log.info "payload chunk: <<#{d}>>"
      buffer << d
    end

    stream.on(:half_close) do
      log.info "client closed its end of the stream"

      if req["Upgrade"]
        log.info "Processing h2c Upgrade request: #{req}"
        if req[":method"] != "OPTIONS" # Don't respond to OPTIONS...
          response = "Hello h2c world!"
          stream.headers({
                           ":status" => "200",
                           "content-length" => response.bytesize.to_s,
                           "content-type" => "text/plain"
                         }, end_stream: false)
          stream.data(response)
        end
      else

        response = nil
        if req[":method"] == "POST"
          log.info "Received POST request, payload: #{buffer}"
          response = "Hello HTTP 2.0! POST payload: #{buffer}"
        else
          log.info "Received GET request"
          response = "Hello HTTP 2.0! GET request"
        end

        stream.headers({
                         ":status" => "200",
                         "content-length" => response.bytesize.to_s,
                         "content-type" => "text/plain"
                       }, end_stream: false)

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

  uh = UpgradeHandler.new(conn, sock)

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

    begin
      if !uh.parsing && !uh.complete

        if data.start_with?(*UpgradeHandler::VALID_UPGRADE_METHODS)
          uh << data
        else
          uh.complete!
          conn << data
        end

      elsif uh.parsing && !uh.complete
        uh << data

      elsif uh.complete
        conn << data
      end
    rescue StandardError => e
      puts "Exception: #{e}, #{e.message} - closing socket."
      puts e.backtrace.last(10).join("\n")
      sock.close
    end
  end
end

# echo foo=bar | nghttp -d - -t 0 -vu http://127.0.0.1:8080/
# nghttp -vu http://127.0.0.1:8080/