import struct


class BrComMessage:
    SOH = 0x0A
    OP_READ = 0
    OP_WRITE = 1
    RES_READ = 100
    RES_WRITE = 101

    def __init__(self, operation, addr: int, val: float = 0.0):
        self.operation = operation
        self.addr = addr
        self.val = val

    def gen_message(self):
        # 消息内容的组成：
        # [SOH, operation_code, addr, val, checksum]
        msg_pre = [self.SOH, self.operation] + \
            list(struct.pack('H', self.addr)) + \
            list(struct.pack('f', self.val)) + \
            [self.compute_checksum()]
        return msg_pre

    def compute_checksum(self):
        _sum = self.SOH
        _sum += self.operation

        for a_byte in struct.pack('<i', self.addr):
            print(a_byte)
            _sum += int(a_byte)

        for a_byte in struct.pack('<f', self.val):
            print('f', a_byte)
            _sum += int(a_byte)
        return _sum & 0xFF

    # 静态方法：将一个消息内容列表解析为消息对象
    @classmethod
    def resolve_message(cls, message: list):
        if message[0] != cls.SOH:
            return (False,)
        else:
            # 获取操作码
            op_code = message[1]
            # 获取操作地址
            addr = struct.unpack('H', bytes(message[2:4]))
            # 获取操作值
            val = struct.unpack('<f', bytes(message[4:8]))
            print(val)
            return True, BrComMessage(op_code, addr[0], val[0])


if __name__ == "__main__":
    my_message = BrComMessage(BrComMessage.OP_READ, 100, val=1)
    print(my_message.gen_message())
    test_message = [0x0A, 0, 1, 0, 0, 0, 128, 63, 100]
    res, msg = BrComMessage.resolve_message(test_message)
    print(msg.val)