Cancel input() with CancelIoEx()

cancel_input.py

# Cancel input() with CancelIoEx().
#
# There is known problem: https://github.com/microsoft/terminal/issues/12143

import msvcrt
import sys
import threading

from win32more import UInt32
from win32more.Windows.Win32.Foundation import TRUE
from win32more.Windows.Win32.System.Console import INPUT_RECORD, KEY_EVENT, WriteConsoleInput
from win32more.Windows.Win32.System.IO import CancelIoEx
from win32more.Windows.Win32.UI.Input.KeyboardAndMouse import VK_RETURN

exiting = threading.Event()
console_input = msvcrt.get_osfhandle(sys.stdin.fileno())


def worker():
    while not exiting.wait(3):
        cancel_console_input_blocking()


def cancel_console_input_blocking():
    # Cancel input() in main thread.
    CancelIoEx(console_input, None)

    # WORKAROUND: Reset console internal state by sending key event.
    # You need to press Enter twice for second input() without this.
    rec = INPUT_RECORD()
    rec.EventType = KEY_EVENT
    rec.Event.KeyEvent.bKeyDown = TRUE
    rec.Event.KeyEvent.wRepeatCount = 1
    rec.Event.KeyEvent.wVirtualKeyCode = VK_RETURN
    rec.Event.KeyEvent.uChar.UnicodeChar = "\r"
    rec.Event.KeyEvent.dwControlKeyState = 0
    WriteConsoleInput(console_input, rec, 1, UInt32(0))


def main():
    t = threading.Thread(target=worker)
    t.start()

    while True:
        try:
            result = input("Press Enter to exit (canceled in 3 seconds)")
            print(f"{result=}")
            break
        except EOFError:
            print("Canceled!")
        except KeyboardInterrupt:
            print("Interrupted!")
            break

    exiting.set()

    t.join()


if __name__ == "__main__":
    main()