# Source code for canlib.device

    from collections import namedtuple
    from importlib import import_module
    import itertools
    import sys

    class _Libs(object):
        """Class to facilitate importing canlib modules on-demand

        The main problem this class solves is that kvrlib is not available on
        linux, so unconditionally importing kvrlib is not an option. However, it is
        also preferable that simply importing this module loads most of pycanlib,
        if a user wants to use `Device` to interact with canlib, they should not
        need to load e.g. kvmlib.

        This class is instanced, once, in device.py as `_libs`. Any time a library,
        for example `canlib`, is used in device.py it will be accessed with
        ``_libs.canlib``. The first time this happens, there will be no ``canlib``
        attribute on ` libs``, and `_Libs.__getattr__` will be called. This looks
        up the library name provided in `_Libs._imports`, which should give a
        no-argument function that imports that library and returns
        it. `_Libs.__getattr__` then saves the returned module as an attribute,
        making sure that `_Libs.__getattr__` is only called the first time any
        particular library is requested.

        """
        def import_kvrlib(self=None):
            try:
                module = import_module('canlib.kvrlib')
            except AttributeError:
                if not sys.platform.startswith('win'):
                    raise ImportError("kvrlib is only available on Windows")
                else:
                    raise
            else:
                return module

        _imports = {
            'canlib': lambda: import_module('canlib.canlib'),
            'kvmlib': lambda: import_module('canlib.kvmlib'),
            'linlib': lambda: import_module('canlib.linlib'),
            'kvrlib': import_kvrlib,
        }

        def __getattr__(self, name):
            setattr(self, name, self._imports[name]())
            return getattr(self, name)

    _libs = _Libs()

    _ChannelInfo = namedtuple(
        '_channel_info',
        "channel_number ean serial channel_name",
    )
    _ChannelInfo.__new__.__defaults__ = tuple(None for _ in _ChannelInfo._fields)

    def connected_devices():
        """Get all currently connected devices as `Device`\s

        Returns an iterator of `Device` object, one object for every physical
        device currently connected.

        .. versionadded:: 1.6

        """
        last_device = None
        for curr_channel in itertools.count():
            try:
                data = _libs.canlib.ChannelData(curr_channel)
                ean = data.card_upc_no
                serial = data.card_serial_no
            except _libs.canlib.CanNotFound:
                return
            else:
                dev = Device(ean=ean, serial=serial)
                if dev != last_device:
                    yield dev
                    last_device = dev

    def _find_channel(info, last=None):
        assert info is not None

        if last is not None:
            new_info = _match_channel(last, info)
            if new_info is not None:
                return new_info

        for curr_channel in itertools.count():
            new_info = _match_channel(curr_channel, info)
            if new_info is not None:
                return new_info

    def _match_channel(channel_number, info):
        target_ch = info.channel_number
        target_ean = info.ean
        target_serial = info.serial
        target_name = info.channel_name
        if (target_ch is not None) and (channel_number != target_ch):
            return None
        data = _libs.canlib.ChannelData(channel_number)
        ean = data.card_upc_no
        if (target_ean is not None) and (ean != target_ean):
            return None
        serial = data.card_serial_no
        if (target_serial is not None) and (serial != target_serial):
            return None
        name = data.custom_name
        if (target_name is not None) and (name != target_name):
            return None

        return _ChannelInfo(channel_number, ean, serial, name)

    class Device(object):
        """Class for keeping track of a physical device

        This class represents a physical device regardless of whether it is
        currently connected or not, and on which channel it is connected.

        If the device is currently connected, `Device.find` can be used to get a
        `Device` object::

            dev = Device.find(ean=EAN.from_string('67890-1'))

        `Device.find` supports searching for devices based on a variety of
        information, and will return a `Device` object corresponding to the first
        physical device that matched its arguments. In this case, it would be the
        first device found with an EAN of 73-30130-67890-1.

        If the device wanted is not currently connected, `Device` objects can be
        created with their EAN and serial number (as this is the minimal
        information needed to uniquely identify a specific device)::

            dev = Device(ean=EAN.from_string('67890-1'), serial=42)

        Two `Device` objects can be checked for equality (whether they refer to the same
        device) and be converted to a `str`. `Device.probe_info` can also be used
        for a more verbose string representation that queries the device (if
        connected) for various pieces of information.

        This class also provides functions for creating the other objects of `canlib`:

        * `canlib.canlib.Channel` -- `Device.channel`
        * `canlib.canlib.ChannelData` -- `Device.channel_data`
        * `canlib.canlib.IOControl` -- `Device.iocontrol`
        * `canlib.kvmlib.Memorator`-- `Device.memorator`
        * `canlib.linlib.Channel` -- `Device.lin_master` and `Device.lin_slave`

        Attributes:
            ean (`canlib.ean.EAN`): The EAN of this device.
            serial (`int`): The serial number of this device.

            last_channel_number (`int`): The channel number this device was last
                found on (used as an optimization; while the device stays on the
                same CANlib channel there is no need for a linear search of all
                channels).

        .. versionadded:: 1.6

        """
        @classmethod
        def find(cls, channel_number=None, ean=None, serial=None, channel_name=None):
            """Searches for a specific device

            Goes through all CANlib channels (from zero and up), until one of them
            matches the given arguments. If an argument is omitted or `None`, any
            device will match it. If no devices matches a
            `canlib.canlib.CanNotFound` exception will be raised.

            Args:
                channel_number (`int`): Find a device on this CANlib channel (number).
                ean (`canlib.ean.EAN`): Find a device with this EAN.
                serial (`int`): Find a device with this serial number.
                channel_name (`str`): Find a device with this CANlib channel name.

            """
            target_info = _ChannelInfo(channel_number, ean, serial, channel_name)
            info = _find_channel(target_info)
            dev = cls(ean=info.ean, serial=info.serial)
            dev.last_channel_number = info.channel_number  # last known CANlib channel
            return dev

        def __init__(self, ean, serial):
            self.ean = ean
            self.serial = serial
            # The last channel number this device was found on
            self.last_channel_number = None

        def __ne__(self, other):
            # required in python 2
            eq = self == other
            if eq is NotImplemented:
                return eq
            else:
                return not eq

        def __eq__(self, other):
            if not isinstance(other, Device):
                return NotImplemented

            return self.ean == other.ean and self.serial == other.serial

        def __str__(self):
            return "{cls}(ean={ean}, serial={serial})".format(
                cls=self.__class__.__name__, ean=self.ean, serial=self.serial)

        def channel(self, *args, **kwargs):
            """A `canlib.canlib.Channel` for this device's first channel

            Arguments to `canlib.canlib.openChannel` other than the channel number
            can be passed to this function.

            """
            return _libs.canlib.openChannel(self.channel_number(), *args, **kwargs)

        def channel_data(self):
            """A `canlib.canlib.ChannelData` for this device's first channel"""
            return _libs.canlib.ChannelData(self.channel_number())

        def channel_number(self):
            """An `int` with this device's CANlib channel number"""
            info = _find_channel(
                _ChannelInfo(ean=self.ean, serial=self.serial),
                last=self.last_channel_number,
            )
            self.last_channel_number = info.channel_number
            return info.channel_number

        def iocontrol(self):
            """A `canlib.canlib.IOControl` for this device's first channel"""
            return _libs.canlib.IOControl(self.channel())

        def isconnected(self):
            """A `bool` whether this device can currently be found"""
            try:
                self.channel_number()
            except _libs.canlib.CanNotFound:
                return False
            else:
                return True

        def lin_master(self, *args, **kwargs):
            """A `canlib.linlib.Channel` master for this device's first channel

            Arguments to `canlib.linlib.openMaster` other than the channel number
            can be passed to this function.

            """
            return _libs.linlib.openMaster(self.channel_number(), *args, **kwargs)

        def lin_slave(self, *args, **kwargs):
            """A `canlib.linlib.Channel` slave for this device's first channel

            Arguments to `canlib.linlib.openSlave` other than the channel number
            can be passed to this function.

            """
            return _libs.linlib.openSlave(self.channel_number(), *args, **kwargs)

        def memorator(self, *args, **kwargs):
            """A `canlib.kvmlib.Memorator` for this device's first channel

            Arguments to `canlib.canlib.openChannel` other than the channel number
            can be passed to this function.

            """
            return _libs.kvmlib.openDevice(self.channel_number(), *args, **kwargs)

        def probe_info(self):
            """A `str` with information about this device

            This function is useful when the `Device`'s `str()` does not give
            enough information while debugging. When the device is connected
            various pieces of information such as the device name, firmware, and
            driver name is given. When the device is not connected only basic
            information can be given.

            Note:

                Never inspect the return value of this function, only use it for
                displaying information. Exactly what is shown depends on whether
                the device is connected or not, and is not guaranteed to stay
                consistent between versions.

            """
            try:
                data = self.channel_data()
                infos = {
                    'CANlib Channel': self.channel_number(),
                    'Card Number': data.card_number,
                    'Device': data.device_name,
                    'Driver Name': data.driver_name,
                    'EAN': self.ean,
                    'Firmware': data.card_firmware_rev,
                    'Serial Number': self.serial,
                }
            except _libs.canlib.CanNotFound:
                infos = {
                    'EAN': self.ean,
                    'Last CANlib Channel': self.last_channel_number,
                    'Serial Number': self.serial,
                }
            width = max(len(label) for label in infos.keys())
            # We sort the keys before printing as pre python 3.6 the order of
            # dictionary keys is arbitrary, and can change between calls.
            text = '\n'.join(
                key.ljust(width) + ': ' + str(val) for key, val in sorted(infos.items()))
            return text

        def remote(self, *args, **kwargs):
            """A `canlib.kvrlib.RemoteDevice` for this device

            Arguments to `canlib.kvrlib.openDevice` other than the channel number
            can be passed to this function.

            """
            return _libs.kvrlib.openDevice(self.channel_number(), *args, **kwargs)