#!/usr/bin/env python3
import functools
import contextlib
import signal
import sys
import time
from argparse import ArgumentParser
from pathlib import Path
from evdev import InputDevice, ecodes

BUTTONS = [
        "KEY_OK",
        "KEY_MENU",
        "KEY_ESC",
        "KEY_UP",
        "KEY_DOWN",
        "KEY_LEFT",
        "KEY_RIGHT",
        "KEY_RED",
        "KEY_GREEN",
        "KEY_YELLOW",
        "KEY_BLUE",
        "KEY_0",
        "KEY_1",
        "KEY_2",
        "KEY_3",
        "KEY_4",
        "KEY_5",
        "KEY_6",
        "KEY_7",
        "KEY_8",
        "KEY_9",
        "KEY_INFO",
        "KEY_PLAY",
        "KEY_PAUSE",
        "KEY_STOP",
        "KEY_RECORD",
        "KEY_FASTFORWARD",
        "KEY_REWIND",
        "KEY_NEXT",
        "KEY_BACK",
        "KEY_POWER2",
        "KEY_CHANNELUP",
        "KEY_CHANNELDOWN",
        "KEY_PREVIOUS",
        "KEY_VOLUMEUP",
        "KEY_VOLUMEDOWN",
        "KEY_MUTE",
        "KEY_SUBTITLE",
        "KEY_EPG",
        "KEY_CHANNEL",
        "KEY_FAVORITES",
        "KEY_MODE",
        "KEY_TIME",
        "KEY_PVR",
        "KEY_SETUP",
        "KEY_TEXT",
        "KEY_PROG1",
        "KEY_PROG2",
        "KEY_PROG3",
        "KEY_PROG4",
        "KEY_AUDIO",
        "KEY_VIDEO",
        "KEY_IMAGES",
        "KEY_FN",
        "KEY_SCREEN",
        ]

RC_SYS_DEVICES = Path('/sys/class/rc/')
DEVPATH = Path('/dev')
debug = functools.partial(print, file=sys.stderr)


def print_keymap(keytable, protocol, keys):
    print("[[protocols]]")
    print(f'name = "{keytable}"')
    print(f'protocol = "{protocol}"')
    print('[protocols.scancodes]')
    for keyname, scancode in keys.items():
        print(f'{scancode:#0x} = "{keyname}"')

def read_from_device(dev):
    def btn_generator():
        for btn in BUTTONS:
            yield btn
        while True:
            yield None

    btn_gen = btn_generator()

    keymap = {}
    last_scancode = None
    last_ts = float('inf')

    button = next(btn_gen)
    first_btn = button
    with contextlib.closing(InputDevice(dev)) as dev:
        debug(f"Please press a button for {button}")

        for ev in dev.read_loop():
            advance_button = False
            if ev.type == ecodes.EV_MSC:
                ts = ev.timestamp()
                if (
                    ev.value == keymap.get(first_btn)
                    and last_scancode == keymap.get(first_btn)
                    and ts - last_ts > .5
                ):

                    # skip button because user pressed KEY_OK
                    # and it's not an unwanted repeat
                    advance_button = True
                    debug(f"skipped learning button {button}")
                elif last_scancode == ev.value:
                    # repeated key
                    pass
                elif ev.value != keymap.get(first_btn):
                    if ev.value < 0:
                        ev.value &= 0xffffffff
                    debug(f"Got scancode {ev.value:#06x} for {button}.")
                    advance_button = True
                    keymap[button] = ev.value
                    last_scancode = ev.value

                last_ts = ts
                last_scancode = ev.value

            if advance_button:
                button = next(btn_gen)
                if button:
                    debug(f"Please press a button for {button} (press KEY_OK to skip)")
                else:
                    break
        return keymap


def list_devices():
    devices = []
    for rc_device in RC_SYS_DEVICES.glob('rc*'):
        device = {}
        device["path"] = rc_device
        device["sys"] = rc_device.name

        with open(next(rc_device.glob('input*/event*/uevent'))) as f:
            # read DEVNAME attribute (and others)
            for line in f:
                key, value = line.rstrip().split('=')
                device[key] = value

        with open(rc_device.joinpath('uevent')) as f:
            for line in f:
                key, value = line.rstrip().split('=')
                device[key] = value

        with open(rc_device.joinpath('protocols')) as f:
            protocols = f.read().rstrip().split()
            active_protocols = [p[1:-1] for p in protocols if (
                p.startswith('[') and p != "[lirc]")]
            inactive_protocols = [p for p in protocols if not p.startswith('[')]
            device["protocols"] = protocols
            device["inactive_protocols"] = inactive_protocols
            device["active_protocols"] = active_protocols
            devices.append(device)
    return devices


if __name__ == '__main__':
    parser = ArgumentParser(description="create keymaps for rc-core devices")
    parser.add_argument('-p', '--protocol', metavar='PROTOCOL',
                        help='set ir-protocol')
    parser.add_argument('-d', '--device', metavar='DEVICE', default=None,
                        help='ir device (e.g. rc0)')
    parser.add_argument('-o', '--output', metavar='KEYMAP', default=None,
                        help='write the keymap to this file instead of printing to stdout')
    args = parser.parse_args()

    devices = list_devices()
    if not devices:
        sys.exit("No rc-core devices found. Exiting.")
    elif len(devices) == 1:
        print(f"Using device {devices[0]['NAME']}", file=sys.stderr)
        dev = devices[0]['path']
        input_dev = devices[0]['DEVNAME']
        keytable = devices[0]['NAME']
        protocol = ",".join(devices[0]['active_protocols'])
    else:
        if args.device:
            for d in devices:
                if (d['sys'] == args.device
                        or d['path'] == RC_SYS_DEVICES.joinpath(args.device)):
                    dev = RC_SYS_DEVICES.joinpath(args.device)
                    input_dev = d['DEVNAME']
                    keytable = d['NAME']
                    protocol = ",".join(d['active_protocols'])
        else:
            for i, d in enumerate(devices, start=1):
                if not args.protocol:
                    print(f"{i}) {d['DEV_NAME']} ({','.join(d.get('active_protocols'))})")
                else:
                    print(f"{i}) {d['DEV_NAME']}")
            try:
                dev_num = int(input("\tUse device numer: "))
                if dev_num < 0 or dev_num > len(devices):
                    raise ValueError
                d = devices[dev_num - 1]
            except (ValueError, IndexError):
                sys.exit("invalid device number")
            input_dev = d['DEVNAME']
            keytable = d['NAME']
            protocol = ",".join(d['active_protocols'])
            dev = d['path']

    # set ir-protocol(s)
    if args.protocol:
        try:
            with open(dev.joinpath('protocols'), 'w') as f:
                f.write(args.protocol)
        except PermissionError as e:
            sys.exit(f"Error: insifficient permissions to change protocol - are you root?")
        except IOError as e:
            sys.exit(f"Error: could not set protocol(s) to {args.protocol}: {e}")
        protocol = args.protocol

    input_dev = DEVPATH.joinpath(input_dev)
    debug("using device: ", input_dev)

    def signal_handler(signum, frame):
        sys.exit()

    for signame in {'SIGINT', 'SIGTERM'}:
        signal.signal(
            getattr(signal, signame),
            signal_handler)
    try:
        keymap = read_from_device(input_dev)
    except PermissionError as e:
        sys.exit(f"Error: can't open {input_dev} - are you root?")
    else:
        if args.output:
            with open(args.output, 'w') as output:
                print_keymap(keytable, protocol, keymap, output)
        else:
            print_keymap(keytable, protocol, keymap, None)