1import logging
2
3
4class Message(object):
5    """represents a message of Remote serial protocol"""
6    def __init__(self, data):
7        super().__init__()
8        self.data = data
9
10    def __str__(self):
11        return "Message: %s" % (self.data)
12
13    def getData(self):
14        #TODO need to parse data and unescape
15        return self.data
16
17    def getRSPByteData(self):
18        retval = ''.join(['$',self.data,'#'])
19        checksum = 0
20        for i in self.data:
21            checksum += ord(i)
22        checksum = checksum % 0x100
23        checksum_str = "{:02x}".format(checksum)
24        retval += checksum_str
25        return retval
26
27    @classmethod
28    def fromRSPByteData(cls, bytedata):
29        data_begin = 0
30        data_end = 0
31        try:
32            data_begin = bytedata.index('$')
33            data_end = bytedata.index('#')
34        except ValueError as e:
35            logging.error('Invalid bytedata considered as message %s' % bytedata)
36            return None
37
38        #validate the data
39        if data_begin + 1 >= data_end:
40            logging.debug("empty message %s"%bytedata)
41            data_begin -= 1
42
43        data_begin += 1
44        logging.debug("Creating message from data %s" % bytedata[data_begin:data_end])
45        ret_obj = cls(bytedata[data_begin:data_end])
46        return ret_obj
47
48class ProtocolAcknowledgement(Message):
49    """Ack Messages"""
50    def __init__(self, ack_str):
51        super().__init__(ack_str)
52        self.data = ack_str
53
54    def getRSPByteData(self):
55        return self.data
56
57
58OKMessage = Message('OK')
59
60AckMessage = ProtocolAcknowledgement('+')
61NAckMessage = ProtocolAcknowledgement('-')
62UnSupportedMessage = Message('')
63