import bitstring

# Reference for H10301 card format:
# https://www.hidglobal.com/sites/default/files/hid-understanding_card_data_formats-wp-en.pdf


class Credential:
    def __init__(self, code=None, hex=None):
        if code is None and hex is None:
            raise TypeError("Must set either code or hex for a Credential")
        elif code is not None and hex is not None:
            raise TypeError("Cannot set both code and hex for a Credential")
        elif code is not None:
            self.bits = bitstring.pack(
                "0b000000, 0b0, uint:8=facility, uint:16=number, 0b0",
                facility=code[0],
                number=code[1],
            )
            self.bits[6] = self.bits[7:19].count(1) % 2  # even parity
            self.bits[31] = not (self.bits[19:31].count(1) % 2)  # odd parity
        elif hex is not None:
            self.bits = bitstring.Bits(hex=hex)

    def __repr__(self):
        return f"Credential({self.code})"

    def __eq__(self, other):
        return self.bits == other.bits

    def __hash__(self):
        return self.bits.int

    @property
    def code(self):
        facility = self.bits[7:15].uint
        code = self.bits[15:31].uint
        return (facility, code)

    @property
    def hex(self):
        return self.bits.hex.upper()