# Source code for can.message

    # coding: utf-8

    """
    This module contains the implementation of :class:`can.Message`.

    .. note::
        Could use `@dataclass <https://docs.python.org/3.7/library/dataclasses.html>`__
        starting with Python 3.7.
    """

    from __future__ import absolute_import, division

    import warnings
    from copy import deepcopy
    from math import isinf, isnan

    class Message(object):
        """
        The :class:`~can.Message` object is used to represent CAN messages for
        sending, receiving and other purposes like converting between different
        logging formats.

        Messages can use extended identifiers, be remote or error frames, contain
        data and may be associated to a channel.

        Messages are always compared by identity and never by value, because that
        may introduce unexpected behaviour. See also :meth:`~can.Message.equals`.

        :func:`~copy.copy`/:func:`~copy.deepcopy` is supported as well.

        Messages do not support "dynamic" attributes, meaning any others than the
        documented ones, since it uses :attr:`~object.__slots__`.
        """

        __slots__ = (
            "timestamp",
            "arbitration_id",
            "is_extended_id",
            "is_remote_frame",
            "is_error_frame",
            "channel",
            "dlc",
            "data",
            "is_fd",
            "bitrate_switch",
            "error_state_indicator",
            "__weakref__",              # support weak references to messages
            "_dict"                     # see __getattr__
        )

        def __getattr__(self, key):
            # TODO keep this for a version, in order to not break old code
            # this entire method (as well as the _dict attribute in __slots__ and the __setattr__ method)
            # can be removed in 4.0
            # this method is only called if the attribute was not found elsewhere, like in __slots__
            try:
                warnings.warn("Custom attributes of messages are deprecated and will be removed in 4.0", DeprecationWarning)
                return self._dict[key]
            except KeyError:
                raise AttributeError("'message' object has no attribute '{}'".format(key))

        def __setattr__(self, key, value):
            # see __getattr__
            try:
                super(Message, self).__setattr__(key, value)
            except AttributeError:
                warnings.warn("Custom attributes of messages are deprecated and will be removed in 4.0", DeprecationWarning)
                self._dict[key] = value

        @property
        def id_type(self):
            # TODO remove in 4.0
            warnings.warn("Message.id_type is deprecated and will be removed in 4.0, use is_extended_id instead", DeprecationWarning)
            return self.is_extended_id

        @id_type.setter
        def id_type(self, value):
            # TODO remove in 4.0
            warnings.warn("Message.id_type is deprecated and will be removed in 4.0, use is_extended_id instead", DeprecationWarning)
            self.is_extended_id = value

        def __init__(self, timestamp=0.0, arbitration_id=0, is_extended_id=None,
                     is_remote_frame=False, is_error_frame=False, channel=None,
                     dlc=None, data=None,
                     is_fd=False, bitrate_switch=False, error_state_indicator=False,
                     extended_id=None, # deprecated in 3.x, TODO remove in 4.x
                     check=False):
            """
            To create a message object, simply provide any of the below attributes
            together with additional parameters as keyword arguments to the constructor.

            :param bool check: By default, the constructor of this class does not strictly check the input.
                               Thus, the caller must prevent the creation of invalid messages or
                               set this parameter to `True`, to raise an Error on invalid inputs.
                               Possible problems include the `dlc` field not matching the length of `data`
                               or creating a message with both `is_remote_frame` and `is_error_frame` set to `True`.

            :raises ValueError: iff `check` is set to `True` and one or more arguments were invalid
            """
            self._dict = dict() # see __getattr__

            self.timestamp = timestamp
            self.arbitration_id = arbitration_id

            if extended_id is not None:
                # TODO remove in 4.0
                warnings.warn("The extended_id parameter is deprecated and will be removed in 4.0, use is_extended_id instead", DeprecationWarning)

            if is_extended_id is not None:
                self.is_extended_id = is_extended_id
            else:
                self.is_extended_id = True if extended_id is None else extended_id

            self.is_remote_frame = is_remote_frame
            self.is_error_frame = is_error_frame
            self.channel = channel

            self.is_fd = is_fd
            self.bitrate_switch = bitrate_switch
            self.error_state_indicator = error_state_indicator

            if data is None or is_remote_frame:
                self.data = bytearray()
            elif isinstance(data, bytearray):
                self.data = data
            else:
                try:
                    self.data = bytearray(data)
                except TypeError:
                    err = "Couldn't create message from {} ({})".format(data, type(data))
                    raise TypeError(err)

            if dlc is None:
                self.dlc = len(self.data)
            else:
                self.dlc = dlc

            if check:
                self._check()

        def __str__(self):
            field_strings = ["Timestamp: {0:>15.6f}".format(self.timestamp)]
            if self.is_extended_id:
                arbitration_id_string = "ID: {0:08x}".format(self.arbitration_id)
            else:
                arbitration_id_string = "ID: {0:04x}".format(self.arbitration_id)
            field_strings.append(arbitration_id_string.rjust(12, " "))

            flag_string = " ".join([
                "X" if self.is_extended_id else "S",
                "E" if self.is_error_frame else " ",
                "R" if self.is_remote_frame else " ",
                "F" if self.is_fd else " ",
                "BS" if self.bitrate_switch else "  ",
                "EI" if self.error_state_indicator else "  "
            ])

            field_strings.append(flag_string)

            field_strings.append("DLC: {0:2d}".format(self.dlc))
            data_strings = []
            if self.data is not None:
                for index in range(0, min(self.dlc, len(self.data))):
                    data_strings.append("{0:02x}".format(self.data[index]))
            if data_strings:  # if not empty
                field_strings.append(" ".join(data_strings).ljust(24, " "))
            else:
                field_strings.append(" " * 24)

            if (self.data is not None) and (self.data.isalnum()):
                field_strings.append("'{}'".format(self.data.decode('utf-8', 'replace')))

            if self.channel is not None:
                try:
                    field_strings.append("Channel: {}".format(self.channel))
                except UnicodeEncodeError:
                    pass

            return "    ".join(field_strings).strip()

        def __len__(self):
            # return the dlc such that it also works on remote frames
            return self.dlc

        def __bool__(self):
            # For Python 3
            return True

        def __nonzero__(self):
            # For Python 2
            return self.__bool__()

        def __repr__(self):
            args = ["timestamp={}".format(self.timestamp),
                    "arbitration_id={:#x}".format(self.arbitration_id),
                    "extended_id={}".format(self.is_extended_id)]

            if self.is_remote_frame:
                args.append("is_remote_frame={}".format(self.is_remote_frame))

            if self.is_error_frame:
                args.append("is_error_frame={}".format(self.is_error_frame))

            if self.channel is not None:
                args.append("channel={!r}".format(self.channel))

            data = ["{:#02x}".format(byte) for byte in self.data]
            args += ["dlc={}".format(self.dlc),
                     "data=[{}]".format(", ".join(data))]

            if self.is_fd:
                args.append("is_fd=True")
                args.append("bitrate_switch={}".format(self.bitrate_switch))
                args.append("error_state_indicator={}".format(self.error_state_indicator))

            return "can.Message({})".format(", ".join(args))

        def __format__(self, format_spec):
            if not format_spec:
                return self.__str__()
            else:
                raise ValueError("non empty format_specs are not supported")

        def __bytes__(self):
            return bytes(self.data)

        def __copy__(self):
            new = Message(
                timestamp=self.timestamp,
                arbitration_id=self.arbitration_id,
                is_extended_id=self.is_extended_id,
                is_remote_frame=self.is_remote_frame,
                is_error_frame=self.is_error_frame,
                channel=self.channel,
                dlc=self.dlc,
                data=self.data,
                is_fd=self.is_fd,
                bitrate_switch=self.bitrate_switch,
                error_state_indicator=self.error_state_indicator
            )
            new._dict.update(self._dict)
            return new

        def __deepcopy__(self, memo):
            new = Message(
                timestamp=self.timestamp,
                arbitration_id=self.arbitration_id,
                is_extended_id=self.is_extended_id,
                is_remote_frame=self.is_remote_frame,
                is_error_frame=self.is_error_frame,
                channel=deepcopy(self.channel, memo),
                dlc=self.dlc,
                data=deepcopy(self.data, memo),
                is_fd=self.is_fd,
                bitrate_switch=self.bitrate_switch,
                error_state_indicator=self.error_state_indicator
            )
            new._dict.update(self._dict)
            return new

        def _check(self):
            """Checks if the message parameters are valid.
            Assumes that the types are already correct.

            :raises ValueError: iff one or more attributes are invalid
            """

            if self.timestamp < 0.0:
                raise ValueError("the timestamp may not be negative")
            if isinf(self.timestamp):
                raise ValueError("the timestamp may not be infinite")
            if isnan(self.timestamp):
                raise ValueError("the timestamp may not be NaN")

            if self.is_remote_frame and self.is_error_frame:
                raise ValueError("a message cannot be a remote and an error frame at the sane time")

            if self.arbitration_id < 0:
                raise ValueError("arbitration IDs may not be negative")

            if self.is_extended_id:
                if 0x20000000 <= self.arbitration_id:
                    raise ValueError("Extended arbitration IDs must be less than 2^29")
            elif 0x800 <= self.arbitration_id:
                raise ValueError("Normal arbitration IDs must be less than 2^11")

            if self.dlc < 0:
                raise ValueError("DLC may not be negative")
            if self.is_fd:
                if 64 < self.dlc:
                    raise ValueError("DLC was {} but it should be <= 64 for CAN FD frames".format(self.dlc))
            elif 8 < self.dlc:
                raise ValueError("DLC was {} but it should be <= 8 for normal CAN frames".format(self.dlc))

            if self.is_remote_frame:
                if self.data is not None and len(self.data) != 0:
                    raise ValueError("remote frames may not carry any data")
            elif self.dlc != len(self.data):
                raise ValueError("the DLC and the length of the data must match up for non remote frames")

            if not self.is_fd:
                if self.bitrate_switch:
                    raise ValueError("bitrate switch is only allowed for CAN FD frames")
                if self.error_state_indicator:
                    raise ValueError("error state indicator is only allowed for CAN FD frames")

        def equals(self, other, timestamp_delta=1.0e-6):
            """
            Compares a given message with this one.

            :param can.Message other: the message to compare with

            :type timestamp_delta: float or int or None
            :param timestamp_delta: the maximum difference at which two timestamps are
                                    still considered equal or None to not compare timestamps

            :rtype: bool
            :return: True iff the given message equals this one
            """
            # see https://github.com/hardbyte/python-can/pull/413 for a discussion
            # on why a delta of 1.0e-6 was chosen
            return (
                # check for identity first and finish fast
                self is other or
                # then check for equality by value
                (
                    (
                        timestamp_delta is None or
                        abs(self.timestamp - other.timestamp) <= timestamp_delta
                    ) and
                    self.arbitration_id == other.arbitration_id and
                    self.is_extended_id == other.is_extended_id and
                    self.dlc == other.dlc and
                    self.data == other.data and
                    self.is_remote_frame == other.is_remote_frame and
                    self.is_error_frame == other.is_error_frame and
                    self.channel == other.channel and
                    self.is_fd == other.is_fd and
                    self.bitrate_switch == other.bitrate_switch and
                    self.error_state_indicator == other.error_state_indicator
                )
            )