# ========================================================================== #
#                                                                            #
#    KVMD - The main PiKVM daemon.                                           #
#                                                                            #
#    Copyright (C) 2018-2022  Maxim Devaev <mdevaev@gmail.com>               #
#                                                                            #
#    This program is free software: you can redistribute it and/or modify    #
#    it under the terms of the GNU General Public License as published by    #
#    the Free Software Foundation, either version 3 of the License, or       #
#    (at your option) any later version.                                     #
#                                                                            #
#    This program is distributed in the hope that it will be useful,         #
#    but WITHOUT ANY WARRANTY; without even the implied warranty of          #
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           #
#    GNU General Public License for more details.                            #
#                                                                            #
#    You should have received a copy of the GNU General Public License       #
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.  #
#                                                                            #
# ========================================================================== #


import asyncio
import contextlib
import functools

from typing import Dict
from typing import Set
from typing import Callable
from typing import Optional
from typing import Any

import hid

from ...logging import get_logger

from ... import tools
from ... import aiotools

from ...yamlconf import Option

from ...validators.basic import valid_number
from ...validators.basic import valid_float_f01
from ...validators.os import valid_abs_path

from . import GpioDriverOfflineError
from . import UserGpioModes
from . import BaseUserGpioDriver


# =====
class Plugin(BaseUserGpioDriver):
    # http://vusb.wikidot.com/project:driver-less-usb-relays-hid-interface
    # https://github.com/trezor/cython-hidapi/blob/6057d41b5a2552a70ff7117a9d19fc21bf863867/chid.pxd

    def __init__(  # pylint: disable=super-init-not-called
        self,
        instance_name: str,
        notifier: aiotools.AioNotifier,

        device_path: str,
        state_poll: float,
    ) -> None:

        super().__init__(instance_name, notifier)

        self.__device_path = device_path
        self.__state_poll = state_poll

        self.__device: Optional[hid.device] = None
        self.__stop = False

        self.__initials: Dict[int, Optional[bool]] = {}

    @classmethod
    def get_plugin_options(cls) -> Dict:
        return {
            "device":     Option("",  type=valid_abs_path, unpack_as="device_path"),
            "state_poll": Option(5.0, type=valid_float_f01),
        }

    @classmethod
    def get_modes(cls) -> Set[str]:
        return set([UserGpioModes.OUTPUT])

    @classmethod
    def get_pin_validator(cls) -> Callable[[Any], Any]:
        return functools.partial(valid_number, min=0, max=7, name="HID relay channel")

    def register_output(self, pin: str, initial: Optional[bool]) -> None:
        self.__initials[int(pin)] = initial

    def prepare(self) -> None:
        logger = get_logger(0)
        logger.info("Probing driver %s on %s ...", self, self.__device_path)
        try:
            with self.__ensure_device("probing"):
                pass
        except Exception as err:
            logger.error("Can't probe %s on %s: %s",
                         self, self.__device_path, tools.efmt(err))
        self.__reset_pins()

    async def run(self) -> None:
        prev_raw = -1
        while True:
            try:
                raw = self.__inner_read_raw()
            except Exception:
                raw = -1
            if raw != prev_raw:
                await self._notifier.notify()
                prev_raw = raw
            await asyncio.sleep(self.__state_poll)

    async def cleanup(self) -> None:
        self.__reset_pins()
        self.__close_device()
        self.__stop = True

    async def read(self, pin: str) -> bool:
        try:
            return self.__inner_read(int(pin))
        except Exception:
            raise GpioDriverOfflineError(self)

    async def write(self, pin: str, state: bool) -> None:
        try:
            return self.__inner_write(int(pin), state)
        except Exception:
            raise GpioDriverOfflineError(self)

    # =====

    def __reset_pins(self) -> None:
        logger = get_logger(0)
        for (pin, state) in self.__initials.items():
            if state is not None:
                logger.info("Resetting pin=%d to state=%d of %s on %s: ...",
                            pin, state, self, self.__device_path)
                try:
                    self.__inner_write(pin, state)
                except Exception as err:
                    logger.error("Can't reset pin=%d of %s on %s: %s",
                                 pin, self, self.__device_path, tools.efmt(err))

    def __inner_read(self, pin: int) -> bool:
        assert 0 <= pin <= 7
        return bool(self.__inner_read_raw() & (1 << pin))

    def __inner_read_raw(self) -> int:
        with self.__ensure_device("reading") as device:
            return device.get_feature_report(1, 8)[7]

    def __inner_write(self, pin: int, state: bool) -> None:
        assert 0 <= pin <= 7
        with self.__ensure_device("writing") as device:
            report = [(0xFF if state else 0xFD), pin + 1]  # Pin numeration starts from 0
            result = device.send_feature_report(report)
            if result < 0:
                raise RuntimeError(f"Retval of send_feature_report() < 0: {result}")

    @contextlib.contextmanager
    def __ensure_device(self, context: str) -> hid.device:
        assert not self.__stop
        if self.__device is None:
            device = hid.device()
            device.open_path(self.__device_path.encode("utf-8"))
            device.set_nonblocking(True)
            self.__device = device
            get_logger(0).info("Opened %s on %s while %s", self, self.__device_path, context)
        try:
            yield self.__device
        except Exception as err:
            get_logger(0).error("Error occured on %s on %s while %s: %s",
                                self, self.__device_path, context, tools.efmt(err))
            self.__close_device()
            raise

    def __close_device(self) -> None:
        if self.__device:
            try:
                self.__device.close()
            except Exception:
                pass
            self.__device = None
            get_logger(0).info("Closed %s on %s", self, self.__device_path)

    def __str__(self) -> str:
        return f"HidRelay({self._instance_name})"

    __repr__ = __str__
