#!/usr/bin/env python3

import subprocess
import time
import Xlib
import Xlib.display

display = Xlib.display.Display()
root = display.screen().root
NET_ACTIVE_WINDOW = display.intern_atom('_NET_ACTIVE_WINDOW')

def main():
    root.change_attributes(event_mask=Xlib.X.PropertyChangeMask)

    handle_active_window_change()

    while True:
        event = display.next_event()
        if is_active_window_change(event):
            handle_active_window_change()

def is_active_window_change(event):
    return (
        event.type == Xlib.X.PropertyNotify and
        event.atom == NET_ACTIVE_WINDOW
    )

def handle_active_window_change():
    window_id = get_active_window_id()
    if not window_id:
        focus_xfdesktop()

def get_active_window_id():
    prop = root.get_full_property(NET_ACTIVE_WINDOW, Xlib.X.AnyPropertyType)
    if prop and prop.value:
        return prop.value[0]

def try_with_sleep(fn):
    def wrapper(*args, **kwargs):
        count = 0
        while True:
            try:
                return fn(*args, **kwargs)
            except:
                if count > 5:
                    print("Failed finally")
                    raise
                print("Failed, will retry")
                time.sleep(1)
                count += 1
    return wrapper

@try_with_sleep
def focus_xfdesktop():
    print("Focusing xfdesktop")
    subprocess.check_output([
        'xdotool',
        'search',
        '--onlyvisible',
        '--class', 'xfdesktop',
        'windowfocus',
    ])

if __name__ == '__main__':
    main()