import evdev
from evdev import InputDevice, categorize, ecodes
import threading
import time
import selectors
from selectors import DefaultSelector, EVENT_READ

selector = selectors.DefaultSelector()

qrdevice_list = [
    "Honeywell Imaging & Mobility     1900",
    "Manufacturer Barcode Reader",
    "SM SM-2D PRODUCT HID KBW"
]

qrkey_list = {'KEY_0': '0',
              'KEY_1': '1',
              'KEY_2': '2',
              'KEY_3': '3',
              'KEY_4': '4',
              'KEY_5': '5',
              'KEY_6': '6',
              'KEY_7': '7',
              'KEY_8': '8',
              'KEY_9': '9'
              }


class QRReader:
    __qrstr = ""
    __myReader = {}
    __numdigits = 10
    __dev = None

    def __init__(self):
        self.getQRlist()

    def getQRlist(self):
        devices = [evdev.InputDevice(path) for path in evdev.list_devices()]
        for device in devices:
            if device.name in qrdevice_list:
                self.__myReader['NAME'] = device.name
                # print(self.__myReader['NAME'])
                self.__myReader['PATH'] = device.path
                # print(self.__myReader['PATH'])
                self.__myReader['PHYS'] = device.phys
                # print(self.__myReader['PHYS'])

    def IsQR(self):
        return 'NAME' in self.__myReader

    def getQRNumber(self):
        return self.__qrstr

    def openQR(self):
        if self.IsQR():
            self.closeQR()
            self.__dev = InputDevice(self.__myReader['PATH'])
            return True
        return False

    def closeQR(self):
        if self.__dev:
            del self.__dev
            self.__dev = None

    def readQR(self):
        """" Sync Read up to numdigits """
        count = 0
        self.__qrstr = ""
        if self.__dev:
            self.__dev.grab()
            for event in self.__dev.read_loop():
                if event.type == evdev.ecodes.EV_KEY:
                    c_event = categorize(event)
                    if c_event.keycode in qrkey_list:
                        if c_event.keystate == 0:
                            self.__qrstr += qrkey_list[c_event.keycode]
                            count += 1
                            if count == self.__numdigits:
                                break
            self.__dev.ungrab()
            return True
        return False

    def wait_event(self, timeout):
        selector.register(self.__dev, selectors.EVENT_READ)
        while True:
            events = selector.select(timeout);
            if not events:
                return False
            else:
                return True

    def readQRasync(self, timeout):
        count = 0
        r = False
        self.__qrstr = ""
        if self.__dev:
            self.__dev.grab()
            if self.wait_event(timeout):
                for event in self.__dev.read_loop():
                    if event.type == evdev.ecodes.EV_KEY:
                        c_event = categorize(event)
                        if c_event.keycode in qrkey_list:
                            if c_event.keystate == 0:
                                self.__qrstr += qrkey_list[c_event.keycode]
                                count += 1
                                if count == self.__numdigits:
                                    r = True
                                    break
            self.__dev.ungrab()
            return r
        return False

# qr = QRReader()
# if qr.openQR():
#    print(qr.readQRasync(2))
# qr.closeQR()