class MQTT::Packet::Publish

def duplicate
  @flags[3]
end

def duplicate=(arg)
  @flags[3] = arg.is_a?(Integer) ? (arg == 0x1) : arg
end

def encode_body
  body = ''
  if @topic.nil? || @topic.to_s.empty?
    raise 'Invalid topic name when serialising packet'
  end
  body += encode_string(@topic)
  body += encode_short(@id) unless qos.zero?
  body += payload.to_s.dup.force_encoding('ASCII-8BIT')
  body
end

def initialize(args = {})
  super(ATTR_DEFAULTS.merge(args))
end

def inspect
  "\#<#{self.class}: " \
    "d#{duplicate ? '1' : '0'}, " \
    "q#{qos}, " \
    "r#{retain ? '1' : '0'}, " \
    "m#{id}, " \
    "'#{topic}', " \
    "#{inspect_payload}>"
end

def inspect_payload
  str = payload.to_s
  if str.bytesize < 16 && str =~ /^[ -~]*$/
    "'#{str}'"
  else
    "... (#{str.bytesize} bytes)"
  end
end

def parse_body(buffer)
  super(buffer)
  @topic = shift_string(buffer)
  @id = shift_short(buffer) unless qos.zero?
  @payload = buffer
end

def qos
  (@flags[1] ? 0x01 : 0x00) | (@flags[2] ? 0x02 : 0x00)
end

def qos=(arg)
  @qos = arg.to_i
  raise "Invalid QoS value: #{@qos}" if @qos < 0 || @qos > 2
  @flags[1] = (arg & 0x01 == 0x01)
  @flags[2] = (arg & 0x02 == 0x02)
end

def retain
  @flags[0]
end

def retain=(arg)
  @flags[0] = arg.is_a?(Integer) ? (arg == 0x1) : arg
end

def validate_flags
  raise ProtocolException, 'Invalid packet: QoS value of 3 is not allowed' if qos == 3
  raise ProtocolException, 'Invalid packet: DUP cannot be set for QoS 0' if qos.zero? && duplicate
end