import gnuradio
import numpy
import serial


class SerialSourceBlock(gnuradio.gr.sync_block):
    def __init__(
        self,
        port="/dev/ttyUSB0",
        baud_rate=115200,
        buffer_max_length=10,
        timeout=2,
        invert=False,
    ):
        # pylint: disable=too-many-arguments
        gnuradio.gr.sync_block.__init__(
            self, name="Serial Source Block", in_sig=None, out_sig=[numpy.uint8]
        )
        self._serial_port = serial.Serial(
            port=port, baudrate=baud_rate, bytesize=serial.EIGHTBITS, timeout=timeout
        )
        # remove first bytes that may have unexpected values > 1, unclear why
        # seen [0b110000000, 0] and [0, 0b11111110] so far
        self._serial_port.read(2)
        self._buffer_max_length = buffer_max_length
        self._invert = invert

    def work(self, input_items, output_items):
        # pylint: disable=unused-argument
        buffer = self._serial_port.read(
            min(len(output_items[0]), self._buffer_max_length)
        )
        output_items[0][: len(buffer)] = numpy.frombuffer(buffer, dtype="u1")
        if output_items[0][: len(buffer)].max() > 1:
            raise ValueError(output_items[0][: len(buffer)])
        if self._invert:
            output_items[0] ^= 1
        return len(buffer)