import serial

BROADCAST = 0xfe


class MDC(serial.Serial):
    """Samsung 400MX MDC remote control client

    Docs: https://www.samsung.com/us/pdf/MDC_400DXn460DXn570DXn700DXn820DXn460TXn_v1.pdf
    """
    def command(self, command, data=[], target_id=BROADCAST):
        if target_id == 0:
            target_id = 0xff

        payload = bytearray([0xaa, command, target_id, len(data)] + data)

        # Checksum
        payload.append(sum(payload[1:]) & 0xff)

        self.write(payload)

    def read_frame(self):
        payload = bytearray([])

        payload.extend(self.read(4))
        if payload[0] != 0xaa:
            raise Exception('Invalid preamble %r' % payload[0])

        if payload[1] != 0xff:
            raise Exception('Unexpected command field? %r' % command)

        payload.extend(self.read(payload[3]))

        checksum = ord(self.read(1))
        expected_checksum = sum(payload[1:]) & 0xff

        if checksum != expected_checksum:
            raise Exception('Invalid checksum %r != %r' % (checksum, expected_checksum))

        return payload[2], payload[4:]

    def request(self, *args, **kwargs):
        self.command(*args, **kwargs)
        return self.read_frame()

if __name__ == '__main__':
    mdc = MDC('/dev/serial/by-id/usb-Prolific_Technology_Inc._USB-Serial_Controller-if00-port0', 9600)
    mdc.command(0x10, [])
    while True:
        print(mdc.read_frame())