#!/usr/bin/env python3
"""Move X input focus into a child of the current test client window."""

import ctypes
import sys


def main() -> None:
    parent = int(sys.argv[1])
    x11 = ctypes.CDLL("libX11.so.6")
    x11.XOpenDisplay.argtypes = [ctypes.c_char_p]
    x11.XOpenDisplay.restype = ctypes.c_void_p
    x11.XCreateSimpleWindow.argtypes = [
        ctypes.c_void_p, ctypes.c_ulong, ctypes.c_int, ctypes.c_int,
        ctypes.c_uint, ctypes.c_uint, ctypes.c_uint,
        ctypes.c_ulong, ctypes.c_ulong,
    ]
    x11.XCreateSimpleWindow.restype = ctypes.c_ulong
    x11.XMapWindow.argtypes = [ctypes.c_void_p, ctypes.c_ulong]
    x11.XSetInputFocus.argtypes = [
        ctypes.c_void_p, ctypes.c_ulong, ctypes.c_int, ctypes.c_ulong,
    ]
    x11.XSync.argtypes = [ctypes.c_void_p, ctypes.c_int]
    x11.XCloseDisplay.argtypes = [ctypes.c_void_p]

    display = x11.XOpenDisplay(None)
    if not display:
        raise RuntimeError("X11 display unavailable")
    try:
        child = x11.XCreateSimpleWindow(display, parent, 0, 0, 1, 1, 0, 0, 0)
        if not child:
            raise RuntimeError("could not create child window")
        x11.XMapWindow(display, child)
        x11.XSetInputFocus(display, child, 2, 0)  # RevertToParent, CurrentTime
        x11.XSync(display, 0)
        print(child, flush=True)
        sys.stdin.readline()
        x11.XSetInputFocus(display, parent, 2, 0)
        x11.XSync(display, 0)
    finally:
        x11.XCloseDisplay(display)


if __name__ == "__main__":
    main()