class DEBUGGER__::UI_CDP::WebSocketServer

def extract_data
  first_group = @sock.getbyte
  fin = first_group & 0b10000000 != 128
  raise 'Unsupported' if fin
  opcode = first_group & 0b00001111
  raise Detach if opcode == 8
  raise "Unsupported: #{opcode}" unless opcode == 1
  second_group = @sock.getbyte
  mask = second_group & 0b10000000 == 128
  raise 'The client must mask all frames' unless mask
  payload_len = second_group & 0b01111111
  # TODO: Support other payload_lengths
  if payload_len == 126
    payload_len = @sock.gets(2).unpack('n*')[0]
  end
  masking_key = []
  4.times { masking_key << @sock.getbyte }
  unmasked = []
  payload_len.times do |n|
    masked = @sock.getbyte
    unmasked << (masked ^ masking_key[n % 4])
  end
  msg = unmasked.pack 'c*'
  show_protocol :>, msg
  JSON.parse msg
end

def handshake
  req = @sock.readpartial 4096
  show_protocol '>', req
  if req.match /^Sec-WebSocket-Key: (.*)\r\n/
    accept = Base64.strict_encode64 Digest::SHA1.digest "#{$1}258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
    res = "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: #{accept}\r\n\r\n"
    @sock.print res
    show_protocol :<, res
  else
    "Unknown request: #{req}"
  end
end

def initialize s
  @sock = s
end

def send **msg
  msg = JSON.generate(msg)
  show_protocol :<, msg
  frame = Frame.new
  fin = 0b10000000
  opcode = 0b00000001
  frame.char fin + opcode
  mask = 0b00000000 # A server must not mask any frames in a WebSocket Protocol.
  bytesize = msg.bytesize
  if bytesize < 126
    payload_len = bytesize
    frame.char mask + payload_len
  elsif bytesize < 2 ** 16
    payload_len = 0b01111110
    frame.char mask + payload_len
    frame.uint16 bytesize
  elsif bytesize < 2 ** 64
    payload_len = 0b01111111
    frame.char mask + payload_len
    frame.ulonglong bytesize
  else
    raise 'Bytesize is too big.'
  end
  frame << msg
  @sock.print frame.b
end