#!/usr/bin/python3
# -*- coding: utf-8 -*-
# input-remapper - GUI for device specific keyboard mappings
# Copyright (C) 2022 sezanzeb <proxima@sezanzeb.de>
#
# This file is part of input-remapper.
#
# input-remapper 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.
#
# input-remapper 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 input-remapper.  If not, see <https://www.gnu.org/licenses/>.


"""Keeps injecting keycodes in the background based on the preset."""

import os
import sys
import asyncio
import time
import multiprocessing

import evdev

from typing import Dict, List, Optional

from inputremapper.configs.preset import Preset

from inputremapper.logger import logger
from inputremapper.groups import classify, GAMEPAD, _Group
from inputremapper.injection.context import Context
from inputremapper.injection.numlock import set_numlock, is_numlock_on, ensure_numlock
from inputremapper.injection.event_reader import EventReader
from inputremapper.event_combination import EventCombination


CapabilitiesDict = Dict[int, List[int]]
GroupSources = List[evdev.InputDevice]

DEV_NAME = "input-remapper"

# messages
CLOSE = 0
UPGRADE_EVDEV = 7

# states
UNKNOWN = -1
STARTING = 2
FAILED = 3
RUNNING = 4
STOPPED = 5

# for both states and messages
NO_GRAB = 6


def is_in_capabilities(
    combination: EventCombination, capabilities: CapabilitiesDict
) -> bool:
    """Are this combination or one of its sub keys in the capabilities?"""
    for event in combination:
        if event.code in capabilities.get(event.type, []):
            return True

    return False


def get_udev_name(name: str, suffix: str) -> str:
    """Make sure the generated name is not longer than 80 chars."""
    max_len = 80  # based on error messages
    remaining_len = max_len - len(DEV_NAME) - len(suffix) - 2
    middle = name[:remaining_len]
    name = f"{DEV_NAME} {middle} {suffix}"
    return name


class Injector(multiprocessing.Process):
    """Initializes, starts and stops injections.

    Is a process to make it non-blocking for the rest of the code and to
    make running multiple injector easier. There is one process per
    hardware-device that is being mapped.
    """

    group: _Group
    preset: Preset
    context: Optional[Context]
    _state: int
    _msg_pipe: multiprocessing.Pipe
    _consumer_controls: List[EventReader]
    _stop_event: asyncio.Event

    regrab_timeout = 0.2

    def __init__(self, group: _Group, preset: Preset) -> None:
        """

        Parameters
        ----------
        group : _Group
            the device group
        preset : Preset
        """
        self.group = group
        self._state = UNKNOWN

        # used to interact with the parts of this class that are running within
        # the new process
        self._msg_pipe = multiprocessing.Pipe()

        self.preset = preset
        self.context = None  # only needed inside the injection process

        self._consumer_controls = []
        self._stop_event = None

        super().__init__(name=group)

    """Functions to interact with the running process"""

    def get_state(self) -> int:
        """Get the state of the injection.

        Can be safely called from the main process.
        """
        # figure out what is going on step by step
        alive = self.is_alive()

        if self._state == UNKNOWN and not alive:
            # `self.start()` has not been called yet
            return self._state

        if self._state == UNKNOWN and alive:
            # if it is alive, it is definitely at least starting up.
            self._state = STARTING

        if self._state == STARTING and self._msg_pipe[1].poll():
            # if there is a message available, it might have finished starting up
            # and the injector has the real status for us
            msg = self._msg_pipe[1].recv()
            self._state = msg

        if self._state in [STARTING, RUNNING] and not alive:
            # we thought it is running (maybe it was when get_state was previously),
            # but the process is not alive. It probably crashed
            self._state = FAILED
            logger.error("Injector was unexpectedly found stopped")

        return self._state

    @ensure_numlock
    def stop_injecting(self) -> None:
        """Stop injecting keycodes.

        Can be safely called from the main procss.
        """
        logger.info('Stopping injecting keycodes for group "%s"', self.group.key)
        self._msg_pipe[1].send(CLOSE)
        self._state = STOPPED

    """Process internal stuff"""

    def _grab_devices(self) -> GroupSources:
        """Grab all devices that are needed for the injection."""
        sources = []
        for path in self.group.paths:
            source = self._grab_device(path)
            if source is None:
                # this path doesn't need to be grabbed for injection, because
                # it doesn't provide the events needed to execute the preset
                continue
            sources.append(source)

        return sources

    def _grab_device(self, path: os.PathLike) -> Optional[evdev.InputDevice]:
        """Try to grab the device, return None if not needed/possible.

        Without grab, original events from it would reach the display server
        even though they are mapped.
        """
        try:
            device = evdev.InputDevice(path)
        except (FileNotFoundError, OSError):
            logger.error('Could not find "%s"', path)
            return None

        capabilities = device.capabilities(absinfo=False)

        needed = False
        for mapping in self.context.preset:
            if is_in_capabilities(mapping.event_combination, capabilities):
                logger.debug(
                    'Grabbing "%s" because of "%s"',
                    path,
                    mapping.event_combination,
                )
                needed = True
                break

        if not needed:
            # skipping reading and checking on events from those devices
            # may be beneficial for performance.
            logger.debug("No need to grab %s", path)
            return None

        attempts = 0
        while True:
            try:
                device.grab()
                logger.debug("Grab %s", path)
                break
            except IOError as error:
                attempts += 1

                # it might take a little time until the device is free if
                # it was previously grabbed.
                logger.debug("Failed attempts to grab %s: %d", path, attempts)

                if attempts >= 10:
                    logger.error("Cannot grab %s, it is possibly in use", path)
                    logger.error(str(error))
                    return None

            time.sleep(self.regrab_timeout)

        return device

    def _copy_capabilities(self, input_device: evdev.InputDevice) -> CapabilitiesDict:
        """Copy capabilities for a new device."""
        ecodes = evdev.ecodes

        # copy the capabilities because the uinput is going
        # to act like the device.
        capabilities = input_device.capabilities(absinfo=True)

        # just like what python-evdev does in from_device
        if ecodes.EV_SYN in capabilities:
            del capabilities[ecodes.EV_SYN]
        if ecodes.EV_FF in capabilities:
            del capabilities[ecodes.EV_FF]

        if ecodes.ABS_VOLUME in capabilities.get(ecodes.EV_ABS, []):
            # For some reason an ABS_VOLUME capability likes to appear
            # for some users. It prevents mice from moving around and
            # keyboards from writing symbols
            capabilities[ecodes.EV_ABS].remove(ecodes.ABS_VOLUME)

        return capabilities

    async def _msg_listener(self) -> None:
        """Wait for messages from the main process to do special stuff."""
        loop = asyncio.get_event_loop()
        while True:
            frame_available = asyncio.Event()
            loop.add_reader(self._msg_pipe[0].fileno(), frame_available.set)
            await frame_available.wait()
            frame_available.clear()
            msg = self._msg_pipe[0].recv()
            if msg == CLOSE:
                logger.debug("Received close signal")
                self._stop_event.set()
                # give the event pipeline some time to reset devices
                # before shutting the loop down
                await asyncio.sleep(0.1)

                # stop the event loop and cause the process to reach its end
                # cleanly. Using .terminate prevents coverage from working.
                loop.stop()
                return

    def run(self) -> None:
        """The injection worker that keeps injecting until terminated.

        Stuff is non-blocking by using asyncio in order to do multiple things
        somewhat concurrently.

        Use this function as starting point in a process. It creates
        the loops needed to read and map events and keeps running them.
        """
        # TODO run all injections in a single process via asyncio
        #   - Make sure that closing asyncio fds won't lag the service
        #   - SharedDict becomes obsolete
        #   - quick_cleanup needs to be able to reliably stop the injection
        #   - I think I want an event listener architecture so that macros,
        #     joystick_to_mouse, keycode_mapper and possibly other modules can get
        #     what they filter for whenever they want, without having to wire
        #     things through multiple other objects all the time
        #   - _new_event_arrived moves to the place where events are emitted. injector?
        #   - active macros and unreleased need to be per injection. it probably
        #     should move into the keycode_mapper class, but that only works if there
        #     is only one keycode_mapper per injection, and not per source. Problem was
        #     that I had to excessively pass around to which device to forward to...
        #     I also need to have information somewhere which source is a gamepad, I
        #     probably don't want to evaluate that from scratch each time `notify` is
        #     called.
        #   - benefit: writing macros that listen for events from other devices

        logger.info('Starting injecting the preset for "%s"', self.group.key)

        # create a new event loop, because somehow running an infinite loop
        # that sleeps on iterations (joystick_to_mouse) in one process causes
        # another injection process to screw up reading from the grabbed
        # device.
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)

        # create this within the process after the event loop creation,
        # so that the macros use the correct loop
        self.context = Context(self.preset)
        self._stop_event = asyncio.Event()

        # grab devices as early as possible. If events appear that won't get
        # released anymore before the grab they appear to be held down
        # forever
        sources = self._grab_devices()

        if len(sources) == 0:
            logger.error("Did not grab any device")
            self._msg_pipe[0].send(NO_GRAB)
            return

        numlock_state = is_numlock_on()
        coroutines = []

        for source in sources:
            # copy as much information as possible, because libinput uses the extra
            # information to enable certain features like "Disable touchpad while
            # typing"
            try:
                forward_to = evdev.UInput(
                    name=get_udev_name(source.name, "forwarded"),
                    events=self._copy_capabilities(source),
                    # phys=source.phys,  # this leads to confusion. the appearance of
                    # an uinput with this "phys" property causes the udev rule to
                    # autoload for the original device, overwriting our previous
                    # attempts at starting an injection.
                    vendor=source.info.vendor,
                    product=source.info.product,
                    version=source.info.version,
                    bustype=source.info.bustype,
                    input_props=source.input_props(),
                )
            except TypeError as e:
                if "input_props" in str(e):
                    # UInput constructor doesn't support input_props and
                    # source.input_props doesn't exist with old python-evdev versions.
                    logger.error("Please upgrade your python-evdev version. Exiting")
                    self._msg_pipe[0].send(UPGRADE_EVDEV)
                    sys.exit(12)

                raise e

            # actually doing things
            event_reader = EventReader(
                self.context,
                source,
                forward_to,
                self._stop_event,
            )
            coroutines.append(event_reader.run())
            self._consumer_controls.append(event_reader)

        coroutines.append(self._msg_listener())

        # set the numlock state to what it was before injecting, because
        # grabbing devices screws this up
        set_numlock(numlock_state)

        self._msg_pipe[0].send(RUNNING)

        try:
            loop.run_until_complete(asyncio.gather(*coroutines))
        except RuntimeError as error:
            # the loop might have been stopped via a `CLOSE` message,
            # which causes the error message below. This is expected behavior
            if str(error) != "Event loop stopped before Future completed.":
                raise error
        except OSError as error:
            logger.error("Failed to run injector coroutines: %s", str(error))

        if len(coroutines) > 0:
            # expected when stop_injecting is called,
            # during normal operation as well as tests this point is not
            # reached otherwise.
            logger.debug("Injector coroutines ended")

        for source in sources:
            # ungrab at the end to make the next injection process not fail
            # its grabs
            try:
                source.ungrab()
            except OSError as error:
                # it might have disappeared
                logger.debug("OSError for ungrab on %s: %s", source.path, str(error))