import evdev
import json
import sys
import select
import os

class KeyboardLedMonitor:
    def __init__(self):
        self.last_state = {"caps": "0", "num": "0"}
        self.kbd_devices = []
        
        # ищем все устройства, которые умеют в CapsLock
        devices = [evdev.InputDevice(path) for path in evdev.list_devices()]
        for dev in devices:
            capabilities = dev.capabilities().get(evdev.ecodes.EV_KEY, [])
            if evdev.ecodes.KEY_CAPSLOCK in capabilities:
                self.kbd_devices.append(dev)

        if not self.kbd_devices:
            sys.exit(1)

        # выводим начальное состояние
        self.push_update(self.kbd_devices[0])

    def get_led_state(self, dev):
        # проверяем коды
        leds = dev.leds()
        return {
            "caps": "1" if 1 in leds else "0",
            "num": "1" if 0 in leds else "0"
        }

    def push_update(self, dev):
        # отдаем json в stdout при изменении
        current_state = self.get_led_state(dev)
        if current_state != self.last_state:
            sys.stdout.write(json.dumps(current_state) + "\n")
            sys.stdout.flush()
            self.last_state = current_state

    def run(self):
        # создаем мапу файловых дескрипторов для селектора
        devices_dict = {d.fd: d for d in self.kbd_devices}
        
        try:
            while True:
                # ждем событий от любого из устройств
                r, _, _ = select.select(devices_dict, [], [])
                for fd in r:
                    dev = devices_dict[fd]
                    for event in dev.read():
                        # если прилетело событие изменения светодиода
                        if event.type == evdev.ecodes.EV_LED:
                            self.push_update(dev)
                            
        except (PermissionError, KeyboardInterrupt):
            sys.exit(0)

if __name__ == "__main__":
    KeyboardLedMonitor().run()