"""
Interface for isCAN from *Thorsis Technologies GmbH*, former *ifak system GmbH*.
"""

import ctypes
import logging
import time
from typing import Optional, Tuple, Union

from can import (
    BusABC,
    CanError,
    CanInitializationError,
    CanInterfaceNotImplementedError,
    CanOperationError,
    CanProtocol,
    Message,
)

logger = logging.getLogger(__name__)

CanData = ctypes.c_ubyte * 8


class MessageExStruct(ctypes.Structure):
    _fields_ = [
        ("message_id", ctypes.c_ulong),
        ("is_extended", ctypes.c_ubyte),
        ("remote_req", ctypes.c_ubyte),
        ("data_len", ctypes.c_ubyte),
        ("data", CanData),
    ]


def check_status_initialization(result: int, function, arguments) -> int:
    if result > 0:
        raise IscanInitializationError(function, result, arguments)
    return result


def check_status(result: int, function, arguments) -> int:
    if result > 0:
        raise IscanOperationError(function, result, arguments)
    return result


try:
    iscan = ctypes.cdll.LoadLibrary("iscandrv")
except OSError as e:
    iscan = None
    logger.warning("Failed to load IS-CAN driver: %s", e)
else:
    iscan.isCAN_DeviceInitEx.argtypes = [ctypes.c_ubyte, ctypes.c_ubyte]
    iscan.isCAN_DeviceInitEx.errcheck = check_status_initialization
    iscan.isCAN_DeviceInitEx.restype = ctypes.c_ubyte

    iscan.isCAN_ReceiveMessageEx.errcheck = check_status
    iscan.isCAN_ReceiveMessageEx.restype = ctypes.c_ubyte

    iscan.isCAN_TransmitMessageEx.errcheck = check_status
    iscan.isCAN_TransmitMessageEx.restype = ctypes.c_ubyte

    iscan.isCAN_CloseDevice.errcheck = check_status
    iscan.isCAN_CloseDevice.restype = ctypes.c_ubyte


class IscanBus(BusABC):
    """isCAN interface"""

    BAUDRATES = {
        5000: 0,
        10000: 1,
        20000: 2,
        50000: 3,
        100000: 4,
        125000: 5,
        250000: 6,
        500000: 7,
        800000: 8,
        1000000: 9,
    }

    def __init__(
        self,
        channel: Union[str, int],
        bitrate: int = 500000,
        poll_interval: float = 0.01,
        **kwargs,
    ) -> None:
        """
        :param channel:
            Device number
        :param bitrate:
            Bitrate in bits/s
        :param poll_interval:
            Poll interval in seconds when reading messages
        """
        if iscan is None:
            raise CanInterfaceNotImplementedError("Could not load isCAN driver")

        self.channel = ctypes.c_ubyte(int(channel))
        self.channel_info = f"IS-CAN: {self.channel}"
        self._can_protocol = CanProtocol.CAN_20

        if bitrate not in self.BAUDRATES:
            raise ValueError(f"Invalid bitrate, choose one of {set(self.BAUDRATES)}")

        self.poll_interval = poll_interval
        iscan.isCAN_DeviceInitEx(self.channel, self.BAUDRATES[bitrate])

        super().__init__(
            channel=channel,
            bitrate=bitrate,
            poll_interval=poll_interval,
            **kwargs,
        )

    def _recv_internal(
        self, timeout: Optional[float]
    ) -> Tuple[Optional[Message], bool]:
        raw_msg = MessageExStruct()
        end_time = time.time() + timeout if timeout is not None else None
        while True:
            try:
                iscan.isCAN_ReceiveMessageEx(self.channel, ctypes.byref(raw_msg))
            except IscanError as e:
                if e.error_code != 8:  # "No message received"
                    # An error occurred
                    raise
                if end_time is not None and time.time() > end_time:
                    # No message within timeout
                    return None, False
                # Sleep a short time to avoid hammering
                time.sleep(self.poll_interval)
            else:
                # A message was received
                break

        msg = Message(
            arbitration_id=raw_msg.message_id,
            is_extended_id=bool(raw_msg.is_extended),
            timestamp=time.time(),  # Better than nothing...
            is_remote_frame=bool(raw_msg.remote_req),
            dlc=raw_msg.data_len,
            data=raw_msg.data[: raw_msg.data_len],
            channel=self.channel.value,
        )
        return msg, False

    def send(self, msg: Message, timeout: Optional[float] = None) -> None:
        raw_msg = MessageExStruct(
            msg.arbitration_id,
            bool(msg.is_extended_id),
            bool(msg.is_remote_frame),
            msg.dlc,
            CanData(*msg.data),
        )
        iscan.isCAN_TransmitMessageEx(self.channel, ctypes.byref(raw_msg))

    def shutdown(self) -> None:
        super().shutdown()
        iscan.isCAN_CloseDevice(self.channel)


class IscanError(CanError):
    ERROR_CODES = {
        0: "Success",
        1: "No access to device",
        2: "Device with ID not found",
        3: "Driver operation failed",
        4: "Invalid parameter",
        5: "Operation allowed only in online state",
        6: "Device timeout",
        7: "Device is transmitting a message",
        8: "No message received",
        9: "Thread not started",
        10: "Thread already started",
        11: "Buffer overrun",
        12: "Device not initialized",
        15: "Found the device, but it is being used by another process",
        16: "Bus error",
        17: "Bus off",
        18: "Error passive",
        19: "Data overrun",
        20: "Error warning",
        30: "Send error",
        31: "Transmission not acknowledged on bus",
        32: "Error critical bus",
        35: "Callbackthread is blocked, stopping thread failed",
        40: "Need a licence number under NT4",
    }

    def __init__(self, function, error_code: int, arguments) -> None:
        try:
            description = ": " + self.ERROR_CODES[error_code]
        except KeyError:
            description = ""

        super().__init__(
            f"Function {function.__name__} failed{description}",
            error_code=error_code,
        )

        #: Status code
        self.error_code = error_code
        #: Function that failed
        self.function = function
        #: Arguments passed to function
        self.arguments = arguments


class IscanOperationError(IscanError, CanOperationError):
    pass


class IscanInitializationError(IscanError, CanInitializationError):
    pass